I respected you before I saw this video but after seeing that you've taught your daughter to solder and you play MInecraft with her, I think you're freaking awesome.
It is easy to see that Noel is a fantastic father. Additionally, I think that Noel got the better of the deal in the "You solder the IC sockets and I will play Minecraft with you". Noel I am so impressed with your teaching your daughter how to solder. You are something else! A high-quality human being. God bless you sir. Fred
It is so very authentic and traditional to let children solder some of the part of the Amstrad boards. Fathers and Mothers in Hong Kong all put their children to work, although mine craft was considered inhuman.
@Rob Taylor, Hats off to you with the board! I can't believe you copied the actual traces, sooooooo much patience. I contemplated doing the same thing for a CoCo 2 and CoCo 3 board but I ended up hand routing just the power and a few other lines and then used an auto router.... You've inspired me and I might go back and copy the traces.
I’d love to see a post mortem on that transistor. Why you thought it was equivalent, how it wasn’t, and hopefully a new modern equivalent. Great video!
The ZTX312 is a high speed switching transistor, with on/off/storage delays barely over 10ns. By contrast, the BC547 datasheet doesn't even hint at its switching speeds (none that I could find anyway), so it's very likely very slow, and not suitable for MHz operation.
The circuit looks strange. There is no base resistor. Bipolar transistors must have a current limit for the base current. I bet a base resistor around 1k to 10k would have totally fixed the problem. The BC547 has a gain bandwidth of 300, which means it can do 1 MHz at a gain of 300 or 300 MHz at unity gain, or anything in between. It is plenty fast enough.
An equivalent would be 2N2369 to the ZTX312 as mentioned in datasheet for the original transistor. The 2N2369 is still available. The other equivalent being the BSV25 by the same original manufacturer is not.
Looking at the circuit diagram rather than which transistor is most similar to a ZTX312L, a 2N7000 MOSFET would fit perfectly and I would expect it to result in a proper clock signal.
in the 80's I had a summer job while at Uni fixing avionics boards for GEC, and one way we found shorts on PCB's was to connect a current limited supply to the traces in question, and use an accurate voltmeter to measure the voltage at various points. As you get closer to the short the voltage gets lower, as you get further away it goes up. If you use a low enough voltage you can often avoid activating semiconductor junctions and thus cut out that source of errors - I traced one fault using a quarter of a volt and a (very expensive!) accurate voltmeter. I suspect that nowadays a relatively cheap multimeter with decent probes would probably be stable enough to work. The very low voltage power supply might be more of a problem!
I've seen people use milli ohm meters to do similar, basically check the resistance at each location and then check/rework the area with the lowest reading.
Love that you got your daughter doing some hands on learning. Kids need more early introduction to skilled trades. Even if they never pursue it as a career, they will always have the knowledge.
A good way to remove unwanted traces is to use an X-Acto knife. The X-Acto knife works really well and looks really clean when you’re done. This looks like a fun project but finding the shorts on your own would’ve just driven you nuts, glad you found the shorts and were able to take care of them.
That's sweet that your daughter helps you like that. My daughter helps me build guitar pedals that we sell but she's a teenager now so offering to play Minecraft wont cut it, they want cash. lol
I cut traces normally with a sharp blade knife or scalpel, cutting at a slight inward angle from both sides, essentially cutting out a shallow V underneath the trace.
I came to comment just that, usually I do it a bit over-wide and remove the copper in the center, to be REAL sure it's cut and won't bite me in the future. Ask me why ... :P
Two cuts and then the island of copper in between is thermally isolated from the rest of the track, so a soldering iron can easily soften the glue enough that the piece of copper just slides off. Much easier and cleaner than trying to scrape enough away mechanically!
Problem with current fpga’s is that they are 3V3, so as well as the fpga, logic converter chips are also required. The low end Tang Nano and Lattice MachX02 can easily replicate the digital functions contained in the gate array chip for those 8-bit computers. So if I designed a replacement solution , it would be a small board containing a few chips to plug-in where the gate array chip goes.
Instead of scraping the track away with a screwdriver, you should have used a scalpel to slice through the unwanted track. Much quicker, more precise, and neater. A trick I learned from my years in the Air Force.
I am actually surprised that only 3 board errors were present from photo-copy/tracing the original board. At the same time, I'm also surprised that this was never tested, not even once, before shipping it. In my humble opinion that I greatly respect, the best replica of an Amstrad CPC (64K, 128K, with tape or with floppy) would be a modern redesign of the board, with as many quality of life features as possible, while still being "layout compatible" with original cases. I would not mind if it included a R-Pi-0 GPIO header to sandwich a Pi-0 on the board for WiFi, ROM-loading/dumping, etc., maybe even HDMI video and sound. This would be something like the ultimate sleeper Amstrad CPC fully upgraded and not emulated/FPGAtiated. Running SymbOS Z80 (in addition to original and modern software) on such a machine would be a treat.
Nice video, hope to see more with repair part of old CPC like Kay board ribbon or floppy disk. For the extension question, I agree with a pizero solution connected directly on the Z80 or the expansion connector. Think about the pistorm for the amiga, what about a similar solution for the amstrad with a pi connected that offer storage, wifi, hdmi, emulated hardware like playcity or what you want. This will be awesome.
i think you maybe looking for something like the USIFAc II ... pic micro connected to expansion port, runnin FDC emu, USB, TTL serial port, esp32 wifi addon..and a whole bunch of other features.. and IMO pi-zero is too powerful for retro!
Excellent work. Rob is doing a great service, creating these beautiful boards. Getting a replacement board from Rob is my next step if I can't locate the broken trace or solder bridge on my C64.
As a woman in electronics tech I just want to tell you how much I love that you involve your daughter in your projects and teach her the trade. Thank you for your wonderful content and your great parenting. :)
The Harlequin, (a Spectrum 128K clone), uses off the shelf logic chips to replace the ULA. Larger modern RAM chips, a surface mount chip for the video and a PCB that fits into a rubber key case or a 48K+ case. It also has Svideo out. It was fun to build, but yes, all those IC sockets were the boring part of it.The only original IC I had to use was the AY chip.
Yeah, that's definitely an option, although I suspect there's more logic than in the Spectrum ULA. You can actually see it in the prototype Gate Array boards that are floating around.
@@NoelsRetroLab It has 55 IC's. A Z80A, an AY-8912, a 32K EPROM, and 2 64K Memory chips and an AD742JR video chip, the other 49 are just the logic. LOL.
I've put whole ZX to some scrap Altera CPLD. Also implemented some scandoubler to convert output to VGA. Even made independant clock for z80- turbo mode up to 8MHz CPU clock and no wait states for computer. Total 5 chips: CPU, RAM, ROM, VRAM, CPLD. So, replacement of antique gate array must be easy task. Two GAL chips replace C64 chip...
Another great video from yourself and board from Rob. Definitely going to get one of these once it goes on sale. The 40007 version of the gate array always comes heatsinked from the factory in all the CPCs I've ever seen, so would likely be worth adding one to your board rather than risk another one dying prematurely.
This took me back to 1984 when the CPC464 was my first computer. I was still using it and my second machine the CPC6128 on release, right up to 1995. It was here I bought my third computer a Packard Bell with Windows 95. I had a great collection of the cassette tape games, along with the not so Floppy, floppy discettes. The monitor to tv converter and digital clock, Primary and secondary disc drives, the Romantic Robot from STS and disc. I even had the Eprom boards for blowing my own chips. Though the best mod I ever did on my CPC6128 was to fit the 464 chip, piggy backing the 6128 chip with one pin bent outward from each chip. Then with a toggle switch wired to those pins that when thrown it connected to the pin hole on the PCB. This in turn when the switch was thrown one way or the other before start up, would then boot the Amstrad into either CPC464 or CPC 6128 mode. That gave me two Amstrads for the price of one. I can't remember now about the mod, but I am sure if you don't know it, someone out there will know how it was done. It is a neat little mod to do if you are interested in both Amstrad models. Going back to the cassette tapes, I had all the Amstrad Action magazines and cover tapes. After purchasing the Romantic Robot from STS, I ran the game Chips Challenge, pressed the Button on the RR and up popped the code. During the game each level had a 4 character code to by pass levels you all ready played and continued from the higher level if the correct code was inputted. After having about 12 or so levels completed, I looked for the codes in the lines of the game programme code lines. These where broken up into four blocks and each block equalled a letter of the code as 1st, 2nd, 3rd and 4th if spread sheeted into columns. I found them all and a few bonus levels too and wrote to Amstrag Action with the results and had them printed in the next available issue. For the life of me I can't remember the issue number, but I am sure there is a copy of the magazine out there somewhere. Sorry for the long comment (excuse my grammer etc), but I thought you and the other readers would be interested in reading my experience with my Amstrad CPC machines etc.
That's awesome to see Rob making more of these boards available. I'm currently building up one of his C64 boards. The great thing about the C64 boards is that new cases are available too.
There is a technique for locating a short like the ones you had. Set your power supply to something like 1 volt, and set the current limit to maybe 100 mA. This will prevent damaging any traces on the board. Now apply 1V to wherever it would normally come from, either a voltage regulator if there was one, or a power connector. The voltage will drop down to a low value because of the current limit. Maybe 0.1V or less at the source. Now using the mV scale on your DMM, measure the voltage between VCC and Gnd at various points on the board. The voltage difference at points between the short and the power feed will be very small, but not 0 due to the trace resistance. It may only be a few mV at some points. As you get closer to the short, the voltage will drop. If you measure between VCC and Gnd on the "other side" of the short from the power feed, there will be no voltage, so that would also tell you that a short is between where you are measuring and the power feed.
Maybe I'm weird... I like to solder IC sockets!. When you get a VCC - ground short it's time to get out the €4,000,000,000 precision resistance meter... No, I don't have one either. The picture-in-picture of the 'scope probe on the schematic is excellent... liked that a lot.
I LOVE these retro-forensics videos! And YES, using the original hardware is always the prefered way. Just like vintage cars, we don't put anything "modern" that will look out of place, unless we have to. That's the whole point, to keep it as close to the original as possible.
Just a couple of mistakes and an omission on a big board he hasn't yet tested? That's actually very impressive. Rob did a terrific job with that and kudos to you for building and testing it. Now Rob can get a perfect working replica board out there thanks to you.
So... who is going to do one of these with an XC95288 in parallel with the dip40 gate array socket? You could have a jumper to enable one or the other. A JTAG socket too, obviously.
I have a question: Since there is #Septandy, #DOScember, and now #JANstrad, how many more of these are there? And will there eventually be a full retrocomputing calendar? Some modest proposals (often forced and sadly not all microcomputers): FMtowrary MarchSX Apprel (I + II) Maycintosh JACKune (for Tramiel micros) JuClive (Sinclair) Amigusta (yes, also a pun on Me Gusta) Orictober (or maybe ORISCtober, for retro RISC machines, e.g. Acorn Electron, Archie...) NOVAmber (for the the Data General minicomputer; basically AkBKukU's month).
I forgot to say this in my last post..... I've never used and Amstrad CPC but your video is so good that you've inspired me to one day build one. Thanks for this video!
@@NoelsRetroLab I will definitely build one. I owned a CPC464 back in late 80s. Do you know when the these board will be available? ...and any good source for the gate array? Thanks.
Hahhaha employing child labour is against so many treaties, Noel 🤣 But on the other hand, there’s not enough meritocracy going around and she does it a lot better than you 😉 So I won’t report your child labour sweatshop to the authorities. Heck, I may even send over some work 😜
You mentioned that the gate array is the only IC on the board that is not being manufactured today. That makes me wonder: What is being used for sound? I think it is marked as AY-3-8912 on the board - is that currently in production?
Thanks! Good question about the total cost. I didn't calculate it because I don't know how much the Amstrad PCB will be (probably similar to the C64 or the VIC-20 one) and the rest of the components (other than the Gate Array) are quite low. Maybe 10-15€ for all of them? So it's not bad at all.
@@NoelsRetroLab It's better than not bad it's great! I didn't have a CPC when I was a kid although I have always been curious about one. Maybe I'll get a second revision board when available. Thanks so much
Great vid - may I suggest the use of a scalpel to cut tracks rather than a screwdriver? It's more precise and reduces the risk of accidental track damage.
15:40 at least with the C64, we have good replacements with GALs, but the CPC is a whole other story! So much of its logic was in what was almost a CPLD. (As a C64 kid, I'm obviously biased, but the CPCs were nice machines only held back by their clock speed. And I really appreciate the plus series.)
I still have my original 6128, and it worked the last time I tried (except the rubber drive band of course). But that's 20+ years ago, so the knowledge I gain by watching efforts like this may come in handy one day!
sooo cool... im gonna have to grab one of these boards, can you post a reminder when they are released please Noel... cool to hear about a 6128 board being worked on, i may even just wait for that, and drop my 464 bits into it...(with a 40007 mod or replacement CPLD/FPGA)
Awesome video, I love this kind of project! That's an interesting approach to reproduce the PCB, the final render is really clean. Just a question, when you said "from new parts" did you also include refurbished? The TMS4164 DRAM chips are not made anymore if I am not mistaken
I wondered that. I think it's more accurate to say "more widely available old stock" since things like RAM, CRTC and PPI chips are common to a lot of old machines.
@@Zeal8bit you'd probably replace all of the DRAMs with 1 SRAM (like the Harlequin does) plus some interfacing circuit to map ras/cas to a linear address
I’m surprised to see a transistor wired in common emitter mode, which doesn’t have a current limiting base resistor. Then again I have no idea about the characteristics of pin 39.
It looks like in the GA schematics they mention that the clock pin (39) has a passive pull up. So that's the current-limiting base resistor that is built-in already.
If I want to remove a piece of PCB track, I cut each end of the piece I want to remove with a sharp scalpel and then heat the copper track with a soldering iron and it lifts away quite nicely 🙂
This channel is a real inspiration for most of us. Your content, edition and explanations are on the best of RUclips. Thanks, Noel, for these videos!!! Keep up the good work!!!
Excellent video as ever! Great to see these boards exist, and if there are new 40007 coming, even better. I see this as a great repair item for a CPC that has had serious board damage, use the case and keyboard etc from that to save it from the rubbish bin!
Really great job building and debugging this first revision board Noel! You have some seriously sharp troubleshooting skills sir!!! Thank you for sharing your voyage down "Amstrad Lane" with us Noel. Fred
Could be a gain issue on the transistor - those old Ferranti e-Line transistors had a typical hFE of about 80 and you had to drive them pretty hard - by the standards of the time, they were pretty fast (ft ~= 400MHz), but were low gain. For comparison, even the really old BC109C had a hFE of 400-800. Since it looks like the primary intent was to square up the clock coming out of the gate array, the resistors would probably have been selected to drive it quite hard - you might find that if using a higher gain part then a higher value resistor would work better.
Just dropping a line to say a fair amount of this went over my head, but I couldn't stop watching. (The hardcore, old-tech-loving, nerd in me...) In fact. I'm halfway through my life and considering an engineering degree. The interesting things that happen when you figure out you are on the ASD spectrum super late in life, you stop giving ***ks about everyone else and what they think and go after what makes you happy. Watching these videos is among those things. :)
Glad to hear that. And I don't think that has anything to do with the ASD spectrum and all about just getting older since the same thing happens to me 😃
Wow, great job! But the AY chip is also getting rarer. And I suspect the available replacements that work in the Spectrum for example aren't going to work here, because the Amstrad uses it for keyboard encoding (?) besides from only sound generation and that is not working with those replacements, is it?
Hi Noel, this is kind of a love letter comment to your channel. I am in awe. I am not really familiar with these devices and generally anything from their era but I've always been fascinated. I think you're by far (even though this could be personal opinion) the most interesting channel about this stuff. I absolutely love your personality, your editing, and your skillset. I hope to be able to learn something from how you run your channel. You're one of my inspirations, I don't think it means much right now, but maybe someday it will :) Absolutely loved this video. I was even a little sad when it ended.
Great video!!! Having done the same thing for CoCo 2 and the CoCo 3 replica boards, I can totally relate to the snags you experienced. I'm currently in the process of searching for a handful of equivalent modern replacements for some diodes and transistors.
16:14 - Wow, that was a long time ago now. lol I did that Verilog translation after some other clever peeps like Gerald did the hard part (the decapping, and die analysis) to make an internal schematic. I don't know if anyone actually tested the old Verilog yet, but I tried to make it as close as possible to the schematic.
I couldn't figure out why PCB software would allow a short between a power pin and ground at first on the CPC recreation. But it was a mammoth effort by Rob to do a "full" recreation like that, tracing out every track. So this issue is actually quite small in the scheme of things. hehe tbh, I personally think it makes a video more interesting when there are faults or issues to fix. I realize this was a beta board, and I think people enjoy seeing the whole building and testing process.
A small CPLD should be enough to fit the ULA logic. The main issue with most retro projects is the 3V3 to 5V translation thing. You can still buy some of the older Altera or Xilinx CPLDs that run on 5V (or run on 3V3, but have 5V-tolerant IO pins). People have of course made repro "chips" for things like arcade PCBs, using small voltage translators / buffers, it just takes longer to do the layout for that.
I should say, btw - my Verilog translation of the ULA was only a starting point. Others have discovered errors in the schematic and other issues since then, and a lot has been fixed. It's interesting looking back at the cpcwiki posts again, and the newer posts. I haven't visited that forum in quite a while.
Always good to know people out there are making sure the legacy of some of these old machines are being kept alive. My guess is a CPLD would be more than enough to handle that Gate Array chip. Of course some of those single board computers might be an alternative using an adapter to pop into the socket. Nice troubleshooting also!
Thanks! The GA is beefy enough that apparently it's a tight fit in a CPLD, but that's the solution I'll be testing soon. Really looking forward to that.
This is wonderful. Also, this lovely replica board is based, i believe, off a RevA board i stripped from my original CPC, gave to a friend who in turn gave it to Rob. I'm pretty sure this is the case.
When you first mentioned the short problem my first thought was, "Nah, no way in hell it's the fault of the kid's soldering job. Can't be." And of course it wasn't.
I know I'm late to the party, but the CPC 6128 was really the box I should have gotten back then (but haven't zero funds ...). I borrowed one for some days to work on extending the Small C compiler under CP/M. It was successful, but hilariously compiling the compiler took about an hour IIRC. It might be fun to swap the membrane out of some modern mechanical switches, fixing one of the worst problems with the machines of that vintage. Done right it could be a total sleeper.
BOUT 10 years ago, at the dawn of the Mechanical Keyboard era, I was at Uni. I got my first £7000 grant / cheque and, while I've always been a frugal and intelligent gamer, never splurging on top end overpriced hardware but using my nogging to build in the perfect "sweet spot" over the years, I thought .... hell with it. I'm buying a nice keyboard. Read the reviews etc - settled on a Logitech G710. It was very expensive, £144 ... but it felt amazing, ridiculous build quality, and felt like and reminded me of my old Amstrad CPC machine. Still lives to this day and, while OOP for a long time, I managed to snag 2 brand new sealed german versions a few years back for £45 each from eBay. Swapped out the keycaps and I have two here, probably enough to last a lifetime, keeping the CPC464 vibe going on my desk.
Why don't you use the prefixes "nano" in capacitors capacitance? 74LS well why would I use HD from Hitachi, if I can use the Russian S series or from Tesla MH74S or classic TTL, or if you want to save power consumption and maybe money, the 74HCT series with small modifications is enough. ZN7400E hm I only have a socialist replacement MH7400 :) Instead of Z80CPU I will use East German clone U880D and instead of M5L8255AP I will use Tesla MHB8255A. What you say (is not very important about electrolytic capacitors), I would venture to say that it is very important and that no dry junk, but for sure honest tantalum capacitors and it is not worth saving. But it seemed to me that the temperature of the soldering iron in your daughter's hands did not even reach 100 ° C, and not even lead tin could smelling rosin :) Aren't you ashamed to use those cheap low quality DIP sockets? And even ridiculous is to use a Chinese multimeter, I'm not saying it's not good, I use UT70A, it just doesn't fit the assembly of the legendary computer :) An RLC bridge is used to accurately measure low resistances, say below 0.1 Ohm ... PCB via Eagle drew your daughter or? Instead of replacing the BC547, I will use a Tesla KC507 in a metal package :) The Chinese desoldering station ZD-915 somehow doesn't fit in your workshop, but I have it too :) You still need to learn a lot :) I started with this around of 1983 year. ruclips.net/video/VxIJMGFXT9w/видео.html pmd85.borik.net/wiki/Download/Dokument%C3%A1cia&setlang=en ruclips.net/video/0_azgCr45YA/видео.html ruclips.net/video/3hTjRmQ4gDU/видео.html ruclips.net/video/20ZjXs_63M8/видео.html
Apart from the gate array, there are several parts that are not manufactured anymore. The CPU, the audio chip, the RAM... There may be more stock of them, but it's old stock.
Will it work? Are you cutting corners or using substandard parts (rhetorical question)? No, of course not. It is absolutely going to work. I would say your biggest problem is the old software needed to run it. I don't have much experience with computers as old as the Amstrad but I do know how finicky a Commodore 128 in 64 mode is running cassettes. Don't get me started on old floppies...what would happen if you used a faster, yet compatible CPU? Would it scream, work as intended, or completely fail? Addendum- I want to build a miniature 486DX2.
I try to build a new one, but i do not have a FERRANTI ZN7400E NAND gate for the clock circuit. I saw on your video that you make it work with a TI SN74LS00N NAND gate. I really try to understand how you did it, but i failed. Can you give me some help ?
In my opinion the Amstrad guys back then were a bit more geeky or nerdy than the C64 ones... C64 was way more common (at least in Germany) and always trying to convince them that the CPCs were at least equal was a mere undertaking :) I loved my CPC
This is so encouraging to see. I dusted off my CPC664 this evening, cleaned it up and inspected it... I won't be risking plugging in the monitor until it's had a thorough recapping so I can't power it up... I need to sort out an alternative PSU and some kind of video lead in the meantime. I spent so many hours in front of it as a teenager and really loved the machine, I was involved in the fanzine scene running a small CPC fanzine for a period of time - we were featured once in Amstrad Action. I also have a dead CPC464 I picked up about 20 years ago which I know doesn't work but it's in great cosmetic condition and has the proper retro GT65 green screen monitor. Some of your diagnostics on this new board will surely help me to diagnose it and I'm really pleased it seems most components or alternatives can still be purchased (apart from the ULA obviously). I'll be certain to watch more of your vids and have subscribed -- thankyou for producing this content!
I went the first path with recreating an Apple //e board to learn more about circuits back in highschool years ago. My favorite machine of that era is the Apple IIGS, thankfully my Woz Edition I got in the late 90s loaded with the best expansions and accelerator of the time still works great. I fear when it breaks with the GS not exactly being very popular compared Macintoshes and //e's of the period. I have had to repair a //e titanium that had the GS upgrade kit installed but thankfully it was a simple fix.
like watching the rebuild of the apple 2... u know what would sounds cool and intruiging.. building a 80s bulky laptop with modern pc hardware inside... perhaps with a mini itx desktop pc inside..
A NET short is VERY rare and in most EDA software it is basically impossible to export a design with it having shorted lines or broken design rules...but since it is a visual copy it is VERY error prone
the only time I ever met a celebrity was when I delivered pizza as a student, and delivered one to Simon Forrester, tech writer for Amstrad Action magazine and someone who had an entirely unsuspected influence on my young mind
Hi Noel / Community. As a beginner in the field of Electronics struggling with understanding the complexity's of the subject I would like to know of a good place to start. I understand some of the most basic equations, well sorta :D and i'm looking for a good book or video series that teaches the fundamentals of electronics. Id like to get to a level where i understand IC operation and data buses and addressing etc but right now my knowledge on some of these subjects is fragmented and i suspect incomplete. Would love to hear from anyone with some useful advice. Have a nice day and stay healthy and safe.
6128 sounds interesting - have to look in my "safe" (hidden below the amongst other not that most used things!) if I still got mine from about 1982 ...
Good video. However, have I missed something here? Was the vcc to gnd short a one off, just the board you received (a pcb manufacturing error) or was this an error in the layout? If it was a layout error it seems odd the Bob had not picked up the board short while prototyping the design. You are right, the board would look good in a picture frame on a wall.
Good question. Unfortunately I didn't follow that up because I was already late releasing the video 😃 But yes, I would guess too much base current, which is why the transistor was there in the first place since that clock signal might not even be able to drive the CPU itself. I just pulled that transistor out of an equivalent table, but clearly some parameters were not correct (I did double check that the layout was correct).
Hi! There is a good way to save some time and alcohol while cleaning PCB after soldering done. Just use regular paper towel soaked with alcohol. Sure, towel will be destroyed, but paper will accumulate all the residues. Just use some brush to clean all the paper scraps.
Scraping tracks with a screwdriver made me sad. Invest in a cheap rotary engraver such as a Dremel and you can get much less obvious track cuts. Awesome video btw.
Why not just use an xacto knife to cut the traces you need? Other than not owning one, but you have lots of nice equipment so i figure a razor blade is probably nothing lol. The patch fixes for that cap and such seem right for an early home pc mobo, many old computers did get released with manual revisions to prevent delays.
I respected you before I saw this video but after seeing that you've taught your daughter to solder and you play MInecraft with her, I think you're freaking awesome.
It is easy to see that Noel is a fantastic father. Additionally, I think that Noel got the better of the deal in the "You solder the IC sockets and I will play Minecraft with you". Noel I am so impressed with your teaching your daughter how to solder. You are something else! A high-quality human being. God bless you sir. Fred
It is so very authentic and traditional to let children solder some of the part of the Amstrad boards. Fathers and Mothers in Hong Kong all put their children to work, although mine craft was considered inhuman.
Sounds like an Iron Maiden parody: "Bring your daughter, bring your daughter to the solder!" 🤘
Also I taught my daughter to solder. But she teaches Minecraft to ME.
So glad you got it going. And sorry you had to be the guinea pig tester! Thanks for your effort and patience and keep up the great work.
No worries. That was the fun part! Thank you for the wonderful board you created!
Hi Rob.. I love your work on the commodore as well.. great work indeed..👍🏻👍🏻👍🏻👍🏻👍🏻
Can't think of a better beta tester.
@Rob Taylor, Hats off to you with the board! I can't believe you copied the actual traces, sooooooo much patience. I contemplated doing the same thing for a CoCo 2 and CoCo 3 board but I ended up hand routing just the power and a few other lines and then used an auto router.... You've inspired me and I might go back and copy the traces.
thanks for your efforts too Rob!.. i will be getting one for sure!
AN easy way to find PCB shorts is to run a couple of amps through it and use either a thermal camera, or film of alcohol to look for hotspots.
I’d love to see a post mortem on that transistor. Why you thought it was equivalent, how it wasn’t, and hopefully a new modern equivalent. Great video!
Yeah agreed. I never get bored of Noel going down the rabbit hole :)
The ZTX312 is a high speed switching transistor, with on/off/storage delays barely over 10ns.
By contrast, the BC547 datasheet doesn't even hint at its switching speeds (none that I could find anyway), so it's very likely very slow, and not suitable for MHz operation.
The circuit looks strange. There is no base resistor. Bipolar transistors must have a current limit for the base current. I bet a base resistor around 1k to 10k would have totally fixed the problem. The BC547 has a gain bandwidth of 300, which means it can do 1 MHz at a gain of 300 or 300 MHz at unity gain, or anything in between. It is plenty fast enough.
An equivalent would be 2N2369 to the ZTX312 as mentioned in datasheet for the original transistor. The 2N2369 is still available. The other equivalent being the BSV25 by the same original manufacturer is not.
Looking at the circuit diagram rather than which transistor is most similar to a ZTX312L, a 2N7000 MOSFET would fit perfectly and I would expect it to result in a proper clock signal.
in the 80's I had a summer job while at Uni fixing avionics boards for GEC, and one way we found shorts on PCB's was to connect a current limited supply to the traces in question, and use an accurate voltmeter to measure the voltage at various points. As you get closer to the short the voltage gets lower, as you get further away it goes up. If you use a low enough voltage you can often avoid activating semiconductor junctions and thus cut out that source of errors - I traced one fault using a quarter of a volt and a (very expensive!) accurate voltmeter. I suspect that nowadays a relatively cheap multimeter with decent probes would probably be stable enough to work. The very low voltage power supply might be more of a problem!
I've seen people use milli ohm meters to do similar, basically check the resistance at each location and then check/rework the area with the lowest reading.
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Wonderful =D Nice fault diagnosis there on the VCC to ground, and with the CPU clock! Rob did a great job on that PCB re-creation!
Thanks! Yes, he did a fantastic job.
Love that you got your daughter doing some hands on learning. Kids need more early introduction to skilled trades. Even if they never pursue it as a career, they will always have the knowledge.
A good way to remove unwanted traces is to use an X-Acto knife. The X-Acto knife works really well and looks really clean when you’re done. This looks like a fun project but finding the shorts on your own would’ve just driven you nuts, glad you found the shorts and were able to take care of them.
Very cool Noel, and you have perfectly outsourced the soldering part to your compagnon :-D Great works!!!!
That's sweet that your daughter helps you like that. My daughter helps me build guitar pedals that we sell but she's a teenager now so offering to play Minecraft wont cut it, they want cash. lol
I cut traces normally with a sharp blade knife or scalpel, cutting at a slight inward angle from both sides, essentially cutting out a shallow V underneath the trace.
I came to comment just that, usually I do it a bit over-wide and remove the copper in the center, to be REAL sure it's cut and won't bite me in the future. Ask me why ... :P
Two cuts and then the island of copper in between is thermally isolated from the rest of the track, so a soldering iron can easily soften the glue enough that the piece of copper just slides off. Much easier and cleaner than trying to scrape enough away mechanically!
@@charlesdorval394 Know the feeling! I had dendrites growing past a non-insulated cut once, have lacquered them since as well! :D
Problem with current fpga’s is that they are 3V3, so as well as the fpga, logic converter chips are also required. The low end Tang Nano and Lattice MachX02 can easily replicate the digital functions contained in the gate array chip for those 8-bit computers. So if I designed a replacement solution , it would be a small board containing a few chips to plug-in where the gate array chip goes.
Instead of scraping the track away with a screwdriver, you should have used a scalpel to slice through the unwanted track. Much quicker, more precise, and neater. A trick I learned from my years in the Air Force.
I'll try that next time. Thanks for the tip!
I am actually surprised that only 3 board errors were present from photo-copy/tracing the original board. At the same time, I'm also surprised that this was never tested, not even once, before shipping it. In my humble opinion that I greatly respect, the best replica of an Amstrad CPC (64K, 128K, with tape or with floppy) would be a modern redesign of the board, with as many quality of life features as possible, while still being "layout compatible" with original cases. I would not mind if it included a R-Pi-0 GPIO header to sandwich a Pi-0 on the board for WiFi, ROM-loading/dumping, etc., maybe even HDMI video and sound. This would be something like the ultimate sleeper Amstrad CPC fully upgraded and not emulated/FPGAtiated. Running SymbOS Z80 (in addition to original and modern software) on such a machine would be a treat.
Apparently, this _was_ the testing: Noel was simply selected as a tester for the project.
Like Jared said, I *was* the beta tester for the board. I probably didn't make that clear enough in the video, so don't blame Rob! 😃
Nice video, hope to see more with repair part of old CPC like Kay board ribbon or floppy disk.
For the extension question, I agree with a pizero solution connected directly on the Z80 or the expansion connector.
Think about the pistorm for the amiga, what about a similar solution for the amstrad with a pi connected that offer storage, wifi, hdmi, emulated hardware like playcity or what you want.
This will be awesome.
Some people want super sized retro, others wanted authentic.
Theres room for both. Modern CAD allow easy version control and design.
i think you maybe looking for something like the USIFAc II ... pic micro connected to expansion port, runnin FDC emu, USB, TTL serial port, esp32 wifi addon..and a whole bunch of other features.. and IMO pi-zero is too powerful for retro!
Excellent work. Rob is doing a great service, creating these beautiful boards. Getting a replacement board from Rob is my next step if I can't locate the broken trace or solder bridge on my C64.
i m a great fan of Amstrad CPC... my brain exploded watching this video! I want make a new Amstrad CPC in 2022! Marvelous!
As a woman in electronics tech I just want to tell you how much I love that you involve your daughter in your projects and teach her the trade.
Thank you for your wonderful content and your great parenting. :)
sехism again
Very nice teamwork between Noel and Rob! Great video, as always.
The Harlequin, (a Spectrum 128K clone), uses off the shelf logic chips to replace the ULA. Larger modern RAM chips, a surface mount chip for the video and a PCB that fits into a rubber key case or a 48K+ case. It also has Svideo out. It was fun to build, but yes, all those IC sockets were the boring part of it.The only original IC I had to use was the AY chip.
Yeah, that's definitely an option, although I suspect there's more logic than in the Spectrum ULA. You can actually see it in the prototype Gate Array boards that are floating around.
@@NoelsRetroLab It has 55 IC's. A Z80A, an AY-8912, a 32K EPROM, and 2 64K Memory chips and an AD742JR video chip, the other 49 are just the logic. LOL.
I've put whole ZX to some scrap Altera CPLD. Also implemented some scandoubler to convert output to VGA. Even made independant clock for z80- turbo mode up to 8MHz CPU clock and no wait states for computer. Total 5 chips: CPU, RAM, ROM, VRAM, CPLD. So, replacement of antique gate array must be easy task. Two GAL chips replace C64 chip...
@@kaunomedis7926 Cool.
Another great video from yourself and board from Rob. Definitely going to get one of these once it goes on sale. The 40007 version of the gate array always comes heatsinked from the factory in all the CPCs I've ever seen, so would likely be worth adding one to your board rather than risk another one dying prematurely.
This took me back to 1984 when the CPC464 was my first computer. I was still using it and my second machine the CPC6128 on release, right up to 1995. It was here I bought my third computer a Packard Bell with Windows 95. I had a great collection of the cassette tape games, along with the not so Floppy, floppy discettes. The monitor to tv converter and digital clock, Primary and secondary disc drives, the Romantic Robot from STS and disc. I even had the Eprom boards for blowing my own chips. Though the best mod I ever did on my CPC6128 was to fit the 464 chip, piggy backing the 6128 chip with one pin bent outward from each chip. Then with a toggle switch wired to those pins that when thrown it connected to the pin hole on the PCB. This in turn when the switch was thrown one way or the other before start up, would then boot the Amstrad into either CPC464 or CPC 6128 mode. That gave me two Amstrads for the price of one. I can't remember now about the mod, but I am sure if you don't know it, someone out there will know how it was done. It is a neat little mod to do if you are interested in both Amstrad models. Going back to the cassette tapes, I had all the Amstrad Action magazines and cover tapes. After purchasing the Romantic Robot from STS, I ran the game Chips Challenge, pressed the Button on the RR and up popped the code. During the game each level had a 4 character code to by pass levels you all ready played and continued from the higher level if the correct code was inputted. After having about 12 or so levels completed, I looked for the codes in the lines of the game programme code lines. These where broken up into four blocks and each block equalled a letter of the code as 1st, 2nd, 3rd and 4th if spread sheeted into columns. I found them all and a few bonus levels too and wrote to Amstrag Action with the results and had them printed in the next available issue. For the life of me I can't remember the issue number, but I am sure there is a copy of the magazine out there somewhere. Sorry for the long comment (excuse my grammer etc), but I thought you and the other readers would be interested in reading my experience with my Amstrad CPC machines etc.
That's awesome to see Rob making more of these boards available. I'm currently building up one of his C64 boards. The great thing about the C64 boards is that new cases are available too.
There is a technique for locating a short like the ones you had. Set your power supply to something like 1 volt, and set the current limit to maybe 100 mA. This will prevent damaging any traces on the board. Now apply 1V to wherever it would normally come from, either a voltage regulator if there was one, or a power connector. The voltage will drop down to a low value because of the current limit. Maybe 0.1V or less at the source. Now using the mV scale on your DMM, measure the voltage between VCC and Gnd at various points on the board. The voltage difference at points between the short and the power feed will be very small, but not 0 due to the trace resistance. It may only be a few mV at some points. As you get closer to the short, the voltage will drop. If you measure between VCC and Gnd on the "other side" of the short from the power feed, there will be no voltage, so that would also tell you that a short is between where you are measuring and the power feed.
Maybe I'm weird... I like to solder IC sockets!.
When you get a VCC - ground short it's time to get out the €4,000,000,000 precision resistance meter... No, I don't have one either.
The picture-in-picture of the 'scope probe on the schematic is excellent... liked that a lot.
I LOVE these retro-forensics videos! And YES, using the original hardware is always the prefered way.
Just like vintage cars, we don't put anything "modern" that will look out of place, unless we have to.
That's the whole point, to keep it as close to the original as possible.
Just a couple of mistakes and an omission on a big board he hasn't yet tested? That's actually very impressive. Rob did a terrific job with that and kudos to you for building and testing it. Now Rob can get a perfect working replica board out there thanks to you.
I have a hard time deciding if I want to build a cpc or a msx. As always wonderful video!
So... who is going to do one of these with an XC95288 in parallel with the dip40 gate array socket? You could have a jumper to enable one or the other. A JTAG socket too, obviously.
I have a question: Since there is #Septandy, #DOScember, and now #JANstrad, how many more of these are there?
And will there eventually be a full retrocomputing calendar?
Some modest proposals (often forced and sadly not all microcomputers):
FMtowrary
MarchSX
Apprel (I + II)
Maycintosh
JACKune (for Tramiel micros)
JuClive (Sinclair)
Amigusta (yes, also a pun on Me Gusta)
Orictober (or maybe ORISCtober, for retro RISC machines, e.g. Acorn Electron, Archie...)
NOVAmber (for the the Data General minicomputer; basically AkBKukU's month).
I forgot to say this in my last post.....
I've never used and Amstrad CPC but your video is so good that you've inspired me to one day build one. Thanks for this video!
I'm so glad!
@@NoelsRetroLab I will definitely build one. I owned a CPC464 back in late 80s. Do you know when the these board will be available? ...and any good source for the gate array? Thanks.
Hahhaha employing child labour is against so many treaties, Noel 🤣 But on the other hand, there’s not enough meritocracy going around and she does it a lot better than you 😉 So I won’t report your child labour sweatshop to the authorities. Heck, I may even send over some work 😜
You mentioned that the gate array is the only IC on the board that is not being manufactured today. That makes me wonder: What is being used for sound? I think it is marked as AY-3-8912 on the board - is that currently in production?
ah Noel my very first computer ever. tell me, is there any progress on the replacement gate array chip?
Oh yes! There are replacements already. I need to make a video about that.
Hi Noel - Happy Janstrad! You have to motivate help with Minecraft too, huh? Do you have an estimate of the final total cost of the build?
Thanks! Good question about the total cost. I didn't calculate it because I don't know how much the Amstrad PCB will be (probably similar to the C64 or the VIC-20 one) and the rest of the components (other than the Gate Array) are quite low. Maybe 10-15€ for all of them? So it's not bad at all.
@@NoelsRetroLab It's better than not bad it's great! I didn't have a CPC when I was a kid although I have always been curious about one. Maybe I'll get a second revision board when available. Thanks so much
Great vid - may I suggest the use of a scalpel to cut tracks rather than a screwdriver? It's more precise and reduces the risk of accidental track damage.
A CPLD replacement should do the trick!
15:40 at least with the C64, we have good replacements with GALs, but the CPC is a whole other story! So much of its logic was in what was almost a CPLD.
(As a C64 kid, I'm obviously biased, but the CPCs were nice machines only held back by their clock speed. And I really appreciate the plus series.)
This was based on a board that I sent to Rob. I like to think of that board as Jango Fett and now there's all the clones.
Nice video. But what's about the CPC6128? The would be a gem! 😀
I still have my original 6128, and it worked the last time I tried (except the rubber drive band of course). But that's 20+ years ago, so the knowledge I gain by watching efforts like this may come in handy one day!
Coming soon! 😃
sooo cool... im gonna have to grab one of these boards, can you post a reminder when they are released please Noel...
cool to hear about a 6128 board being worked on, i may even just wait for that, and drop my 464 bits into it...(with a 40007 mod or replacement CPLD/FPGA)
Awesome video, I love this kind of project!
That's an interesting approach to reproduce the PCB, the final render is really clean.
Just a question, when you said "from new parts" did you also include refurbished? The TMS4164 DRAM chips are not made anymore if I am not mistaken
I wondered that. I think it's more accurate to say "more widely available old stock" since things like RAM, CRTC and PPI chips are common to a lot of old machines.
@@HiddenAsbestos I'm assuming there's other designs that substitute the DRAMs for currently produced SRAM?
@@HiddenAsbestos Right, same goes for the AY-3-8912 sound chip.
@Lawrence Manning The smallest parallel DIP (S)RAM I could find is 8KB big
@@Zeal8bit you'd probably replace all of the DRAMs with 1 SRAM (like the Harlequin does) plus some interfacing circuit to map ras/cas to a linear address
I’m surprised to see a transistor wired in common emitter mode, which doesn’t have a current limiting base resistor. Then again I have no idea about the characteristics of pin 39.
It looks like in the GA schematics they mention that the clock pin (39) has a passive pull up. So that's the current-limiting base resistor that is built-in already.
If I want to remove a piece of PCB track, I cut each end of the piece I want to remove with a sharp scalpel and then heat the copper track with a soldering iron and it lifts away quite nicely 🙂
I may have to try that next time. That sounds much cleaner than my method 😃
This channel is a real inspiration for most of us. Your content, edition and explanations are on the best of RUclips. Thanks, Noel, for these videos!!! Keep up the good work!!!
Excellent video as ever! Great to see these boards exist, and if there are new 40007 coming, even better. I see this as a great repair item for a CPC that has had serious board damage, use the case and keyboard etc from that to save it from the rubbish bin!
Hopefully the CPC6128 board surfaces at some point soon too.
It's on it way right now! 😃
4:20 I haven't heard that chiptune since back in the days when I was playing the cracked version of Worms 2
That one is an AY version of that cracked tune. You can see the link in the description for that track (and a bunch other awesome ones).
Really great job building and debugging this first revision board Noel! You have some seriously sharp troubleshooting skills sir!!! Thank you for sharing your voyage down "Amstrad Lane" with us Noel. Fred
Thanks. Glad you enjoyed it! 😃
So when will this board be available for sale?
That's why you really want to do the schematics first, so you have a netlist and can run DRC over that…
Yes, that would make it much better. I agree.
Could be a gain issue on the transistor - those old Ferranti e-Line transistors had a typical hFE of about 80 and you had to drive them pretty hard - by the standards of the time, they were pretty fast (ft ~= 400MHz), but were low gain. For comparison, even the really old BC109C had a hFE of 400-800. Since it looks like the primary intent was to square up the clock coming out of the gate array, the resistors would probably have been selected to drive it quite hard - you might find that if using a higher gain part then a higher value resistor would work better.
Just dropping a line to say a fair amount of this went over my head, but I couldn't stop watching. (The hardcore, old-tech-loving, nerd in me...) In fact. I'm halfway through my life and considering an engineering degree. The interesting things that happen when you figure out you are on the ASD spectrum super late in life, you stop giving ***ks about everyone else and what they think and go after what makes you happy. Watching these videos is among those things. :)
Glad to hear that. And I don't think that has anything to do with the ASD spectrum and all about just getting older since the same thing happens to me 😃
Wow, great job! But the AY chip is also getting rarer. And I suspect the available replacements that work in the Spectrum for example aren't going to work here, because the Amstrad uses it for keyboard encoding (?) besides from only sound generation and that is not working with those replacements, is it?
Hi Noel, this is kind of a love letter comment to your channel.
I am in awe. I am not really familiar with these devices and generally anything from their era but I've always been fascinated. I think you're by far (even though this could be personal opinion) the most interesting channel about this stuff. I absolutely love your personality, your editing, and your skillset.
I hope to be able to learn something from how you run your channel. You're one of my inspirations, I don't think it means much right now, but maybe someday it will :)
Absolutely loved this video. I was even a little sad when it ended.
Thank you! I'm really glad to hear that! 👍
"And just like that, the board continues to assemble itself without my help." 🤣
Great video!!!
Having done the same thing for CoCo 2 and the CoCo 3 replica boards, I can totally relate to the snags you experienced. I'm currently in the process of searching for a handful of equivalent modern replacements for some diodes and transistors.
16:14 - Wow, that was a long time ago now. lol
I did that Verilog translation after some other clever peeps like Gerald did the hard part (the decapping, and die analysis) to make an internal schematic.
I don't know if anyone actually tested the old Verilog yet, but I tried to make it as close as possible to the schematic.
I couldn't figure out why PCB software would allow a short between a power pin and ground at first on the CPC recreation.
But it was a mammoth effort by Rob to do a "full" recreation like that, tracing out every track.
So this issue is actually quite small in the scheme of things. hehe
tbh, I personally think it makes a video more interesting when there are faults or issues to fix. I realize this was a beta board, and I think people enjoy seeing the whole building and testing process.
A small CPLD should be enough to fit the ULA logic. The main issue with most retro projects is the 3V3 to 5V translation thing.
You can still buy some of the older Altera or Xilinx CPLDs that run on 5V (or run on 3V3, but have 5V-tolerant IO pins).
People have of course made repro "chips" for things like arcade PCBs, using small voltage translators / buffers, it just takes longer to do the layout for that.
I should say, btw - my Verilog translation of the ULA was only a starting point.
Others have discovered errors in the schematic and other issues since then, and a lot has been fixed.
It's interesting looking back at the cpcwiki posts again, and the newer posts. I haven't visited that forum in quite a while.
Teaching my daughter how to solder continues to be a highlight of our growing up, and she still talks about it. Well done!
Always good to know people out there are making sure the legacy of some of these old machines are being kept alive. My guess is a CPLD would be more than enough to handle that Gate Array chip. Of course some of those single board computers might be an alternative using an adapter to pop into the socket. Nice troubleshooting also!
Thanks! The GA is beefy enough that apparently it's a tight fit in a CPLD, but that's the solution I'll be testing soon. Really looking forward to that.
@@NoelsRetroLab There are probably some out there that can handle it. With the right optimizations I bet you can fit it.
This is wonderful. Also, this lovely replica board is based, i believe, off a RevA board i stripped from my original CPC, gave to a friend who in turn gave it to Rob. I'm pretty sure this is the case.
When you first mentioned the short problem my first thought was, "Nah, no way in hell it's the fault of the kid's soldering job. Can't be." And of course it wasn't.
Is the HD6845SP video signal generator also still produced? As far as I can tell there is only new old stock available.
@04:58 - what's more boring? Soldering row after row, or playing Minecraft!? Where's that soldering iron...
I know I'm late to the party, but the CPC 6128 was really the box I should have gotten back then (but haven't zero funds ...). I borrowed one for some days to work on extending the Small C compiler under CP/M. It was successful, but hilariously compiling the compiler took about an hour IIRC.
It might be fun to swap the membrane out of some modern mechanical switches, fixing one of the worst problems with the machines of that vintage. Done right it could be a total sleeper.
BOUT 10 years ago, at the dawn of the Mechanical Keyboard era, I was at Uni. I got my first £7000 grant / cheque and, while I've always been a frugal and intelligent gamer, never splurging on top end overpriced hardware but using my nogging to build in the perfect "sweet spot" over the years, I thought .... hell with it. I'm buying a nice keyboard.
Read the reviews etc - settled on a Logitech G710. It was very expensive, £144 ... but it felt amazing, ridiculous build quality, and felt like and reminded me of my old Amstrad CPC machine. Still lives to this day and, while OOP for a long time, I managed to snag 2 brand new sealed german versions a few years back for £45 each from eBay. Swapped out the keycaps and I have two here, probably enough to last a lifetime, keeping the CPC464 vibe going on my desk.
Why don't you use the prefixes "nano" in capacitors capacitance?
74LS well why would I use HD from Hitachi, if I can use the Russian S series or from Tesla MH74S or classic TTL, or if you want to save power consumption and maybe money, the 74HCT series with small modifications is enough.
ZN7400E hm I only have a socialist replacement MH7400 :)
Instead of Z80CPU I will use East German clone U880D and instead of M5L8255AP I will use Tesla MHB8255A.
What you say (is not very important about electrolytic capacitors), I would venture to say that it is very important and that no dry junk, but for sure honest tantalum capacitors and it is not worth saving.
But it seemed to me that the temperature of the soldering iron in your daughter's hands did not even reach 100 ° C, and not even lead tin could smelling rosin :)
Aren't you ashamed to use those cheap low quality DIP sockets?
And even ridiculous is to use a Chinese multimeter, I'm not saying it's not good, I use UT70A, it just doesn't fit the assembly of the legendary computer :)
An RLC bridge is used to accurately measure low resistances, say below 0.1 Ohm ...
PCB via Eagle drew your daughter or?
Instead of replacing the BC547, I will use a Tesla KC507 in a metal package :)
The Chinese desoldering station ZD-915 somehow doesn't fit in your workshop, but I have it too :)
You still need to learn a lot :)
I started with this around of 1983 year.
ruclips.net/video/VxIJMGFXT9w/видео.html
pmd85.borik.net/wiki/Download/Dokument%C3%A1cia&setlang=en
ruclips.net/video/0_azgCr45YA/видео.html
ruclips.net/video/3hTjRmQ4gDU/видео.html
ruclips.net/video/20ZjXs_63M8/видео.html
Apart from the gate array, there are several parts that are not manufactured anymore. The CPU, the audio chip, the RAM... There may be more stock of them, but it's old stock.
Really nice adventure building this computer, thanks!!
Will it work? Are you cutting corners or using substandard parts (rhetorical question)? No, of course not. It is absolutely going to work. I would say your biggest problem is the old software needed to run it. I don't have much experience with computers as old as the Amstrad but I do know how finicky a Commodore 128 in 64 mode is running cassettes. Don't get me started on old floppies...what would happen if you used a faster, yet compatible CPU? Would it scream, work as intended, or completely fail?
Addendum- I want to build a miniature 486DX2.
5:13 so cute, so sweet.
I try to build a new one, but i do not have a FERRANTI ZN7400E NAND gate for the clock circuit. I saw on your video that you make it work with a TI SN74LS00N NAND gate. I really try to understand how you did it, but i failed. Can you give me some help ?
One question! WHY? I used to be product support for the Australian warranty agents. They were RUBBISH!
What did you choose for the ZTX312 btw ? I think I recommended a BC547 to Rob...
In my opinion the Amstrad guys back then were a bit more geeky or nerdy than the C64 ones... C64 was way more common (at least in Germany) and always trying to convince them that the CPCs were at least equal was a mere undertaking :) I loved my CPC
Loved my CPC 464, unfortunately a Man installing radiators killed it, by causing a leak, which doused it in water.
Trace shorting VCC with GND is a real easter egg planted by pcb designer to filter out noobs leaving prohobbist only.
Question... would a slimline adapter board to change the wiring to 40010 layout work ?
This is so encouraging to see. I dusted off my CPC664 this evening, cleaned it up and inspected it... I won't be risking plugging in the monitor until it's had a thorough recapping so I can't power it up... I need to sort out an alternative PSU and some kind of video lead in the meantime. I spent so many hours in front of it as a teenager and really loved the machine, I was involved in the fanzine scene running a small CPC fanzine for a period of time - we were featured once in Amstrad Action. I also have a dead CPC464 I picked up about 20 years ago which I know doesn't work but it's in great cosmetic condition and has the proper retro GT65 green screen monitor. Some of your diagnostics on this new board will surely help me to diagnose it and I'm really pleased it seems most components or alternatives can still be purchased (apart from the ULA obviously). I'll be certain to watch more of your vids and have subscribed -- thankyou for producing this content!
Ok a Amstrad cpc 464 white screen black border what's your diagnosis? Bad dram?
Did you struggle to source an AY-3-8912 chip? I believe that manufacturing of these have now ceased and there's a shortage.
I went the first path with recreating an Apple //e board to learn more about circuits back in highschool years ago. My favorite machine of that era is the Apple IIGS, thankfully my Woz Edition I got in the late 90s loaded with the best expansions and accelerator of the time still works great. I fear when it breaks with the GS not exactly being very popular compared Macintoshes and //e's of the period. I have had to repair a //e titanium that had the GS upgrade kit installed but thankfully it was a simple fix.
like watching the rebuild of the apple 2... u know what would sounds cool and intruiging.. building a 80s bulky laptop with modern pc hardware inside... perhaps with a mini itx desktop pc inside..
BTW, you can cleanly break traces open using a Dremel with a tiny ball-head drill bit (part of the set that comes with it).
Right. Someone else mentioned that. I don't think my set came with the tiny one, but I'll have to check. Thanks!
A brand new Amstad CPC built using child labor, oh my! 😀 I wish my kids were as capable as your daughter at soldering!
A NET short is VERY rare and in most EDA software it is basically impossible to export a design with it having shorted lines or broken design rules...but since it is a visual copy it is VERY error prone
Many hundreds of hours playing Paperboy, Arkanoid, Thundercats, Batman and so many other games on all of the Amstrads we had.
the only time I ever met a celebrity was when I delivered pizza as a student, and delivered one to Simon Forrester, tech writer for Amstrad Action magazine and someone who had an entirely unsuspected influence on my young mind
Build a new computer "from scratch". That indeed. I'd have asked for a refund and go the other way rather than have to butcher a brand new board.
Get me all excited about building something for myself then crap on my day because I can't get all the parts .lol vic20,c64 all the same problem.
Hi Noel / Community. As a beginner in the field of Electronics struggling with understanding the complexity's of the subject I would like to know of a good place to start. I understand some of the most basic equations, well sorta :D and i'm looking for a good book or video series that teaches the fundamentals of electronics. Id like to get to a level where i understand IC operation and data buses and addressing etc but right now my knowledge on some of these subjects is fragmented and i suspect incomplete. Would love to hear from anyone with some useful advice. Have a nice day and stay healthy and safe.
Ahh yes, the number of times I've bribed my children with "If you do this I'll play Minecraft with you later"
6128 sounds interesting - have to look in my "safe" (hidden below the amongst other not that most used things!) if I still got mine from about 1982 ...
Good video. However, have I missed something here?
Was the vcc to gnd short a one off, just the board you received (a pcb manufacturing error) or was this an error in the layout?
If it was a layout error it seems odd the Bob had not picked up the board short while prototyping the design.
You are right, the board would look good in a picture frame on a wall.
This is where using a real pcb layout program comes in handy. DRC (Design rule checking) has saved many of designs
Great video. Do you know why the transistor was not working. Too much base current pulling the signal down?
Good question. Unfortunately I didn't follow that up because I was already late releasing the video 😃 But yes, I would guess too much base current, which is why the transistor was there in the first place since that clock signal might not even be able to drive the CPU itself. I just pulled that transistor out of an equivalent table, but clearly some parameters were not correct (I did double check that the layout was correct).
Hi! There is a good way to save some time and alcohol while cleaning PCB after soldering done. Just use regular paper towel soaked with alcohol. Sure, towel will be destroyed, but paper will accumulate all the residues. Just use some brush to clean all the paper scraps.
5:15 Noel, if this is your daugther, srsly think about fumes extractor while she's soldering.
Scraping tracks with a screwdriver made me sad.
Invest in a cheap rotary engraver such as a Dremel and you can get much less obvious track cuts.
Awesome video btw.
Why not just use an xacto knife to cut the traces you need? Other than not owning one, but you have lots of nice equipment so i figure a razor blade is probably nothing lol.
The patch fixes for that cap and such seem right for an early home pc mobo, many old computers did get released with manual revisions to prevent delays.
17:49 not every hero wears a cape. That's why opensource projects are growing rapidluy - thanks to volunteers ^_^