Pretty interesting, subscribed. My first computer was zx spectrum and I spent a lot time playing elite dangerous - David Braben legendary game and now still playing new version
Back then i was never into the ZX Spectrum, i started with the Commodore ViC20 and did love all the Commodores i had which where many. Great video Tony hope sometime you do some with a Commodore ViC 20. Keep up the good work my friend.
Great video, Tony! I never worked on a ZX Spectrum too but after seeing this video I’m hyped to try it. I only have to find some machine in need of care. It can be also one of the Brazilian clones from Microdigital, the TKs.
Ah yes. The good old Speccy. My first computer was a second hand 48k +. Marginally better keyboard than the rubber key version. But not by much. I've still got it by the way :-) Re-capped of course. Also got a ZX-HD and DivMMC. You really ran into quite a few issues on this one. Nicely fixed Tony.
I was too young to be playing with these when they came out, I started with the Spectrum +3, but this video was good, there is a 48k in the house, I'm tempted to see if it works...
Sinclair used dodgy RAM - quote from Salkin (UK) website: "The TMS4532 is a 32k x1 bit Dynamic ram. It is actually a 64K static ram that failed testing, in either the upper or the lower portions and was marked appropriately (-4 if the Higher portion was good, or -3 if the lower portion was good.) As such, it comes in two variants that cannot be mixed, the TMS4532-3 and TMS4532-4 variants, which relate to the state required of AR during the CAS phase."
I was aware that the ICs were actually 64KB, but not that it had failed! I wonder whether a failed bit means the whole IC is bad. If you think with today's eyes, a less powerful CPU is often a more powerful silicon die which did not pass the performance required - so it's downgraded to a slower model. AFAIK there's nothing wrong with that but I wonder whether the same applies to those RAM chips! Thanks for the comment, very interesting!
@@tony359 It was Sinclair trying to reduce production costs. The RAM chips worked fine as 32K x 1 DRAM but I guess they have started failing now as they are so old. I remember buying one of these with my savings in December 1982, 5 months before I finished school. It competed with study time for my exams (and usually won). I always used to get copied games on cassette from my school friends and as a result always had to retry loading as they would often fail. I spent more time loading games than playing them on some days. Great video BTW!
Good job. Back in the 80s I wrote a spice node network analyzer for the zx spectrum. Almost all in assembly. Still works great. It supports circuits up to 256 nodes. Let me know if you are interested....
@tony359 oh no sorry. You can set up a electronic circuit and characterize it's 4-pole properties over a range of frequencies. Such software was later known as spice programs such as Lt-Spice for example (you can Google it). Only this highly complex one runs on a ZX spectrum.
@@tony359 It could. The Interface 1 (needed if you were using Sinclair's own Microdrive storage devices) added an RS232 port that could network up to 64 Spectrums. Seriously, the Speccy could do amazing things even out of the box, but the quantity and scope of the additional hardware you could connect to it was astonishing. At one time I had the Interface 1, a floppy disk interface, a MIDI controller, joystick/mouse ports, video capture, external audio (with the usual AY chip) and probably a few more.
Some of that "return to black" treatment would of been great for that plastic. Usually for automotive plastics, but I've seen people use it on consoles they fix.
Is there anything that actually works? I looked into that for my car's bumpers and most are black paint you apply - I don't like the idea as I don't know how much it's going to last and what happens then? Silicone spray only works temporarily AFAIK. Thanks for watching!
@@tony359 I'm not 100% sure. I need to pick some of it up myself and try. The product I had seen used was actually "back to black" and it seemed to do good for a playstation 2 shell. Gave it that glossy sheen along with restoring the black color. I need to get some and try for myself. I wonder if tire shine would have a similar affect. I have some of that. 🤷♂
Wow. My ULA had the exact same fault. The letter doubling IIGGOO etc. with the diagnostic ROM. Still haven't been able to fix the RAM fault on mine. After replacing the RAM the test indicated bad did nothing. Maybe I need to replace some other RAM's too.
That game is supposed to be an achievement for in-game music plus platforming (as speaker is cpu hungry, like in IBM PC). I never liked it hehe. There are newer games like Target Renegade, Robocop or older ones like Jetpack that are much better for me.
Thank you! Well if you see that from a 1982 perspective, my Apple IIe from 1983 could NOT make those sounds :) Even though to be fair the Apple II series was a bit behind when it came to sound and graphics. @jbinary82 Thanks, I'll give them a go on my next ZX!
as for the video input device, i use a gv-usb2 to input some of my older consoles into my pc for various reasons, composite, l/r audio, and svideo inputs, svideo overrides composite. works with ntsc and pal formats fine from what i could tell, but some software suites have issues with the , versus . numeric separators when using the gv-usb2 with them. as far as i know OBS isn't one of them. not sure if this interests you, or is viable with the rest of your setup, but you never know.
Well, in 2020 during pandemic they asked me to show an ID to prove I was older than 25 - I was buying spray paint and I was wearing a mask and a hat. I just removed my hat. :D
I had that case, but the one with the spacebar. It was a huge improvement over the dead flesh keyboard. Then I bought a BBC Micro which was a huge improvement over the Spectrum. 😉 Discuss.
ahah! I've never used either of them so I'll sit here and let more knowledgeable people run the discussion! But yes I hear the BBC micro was a very nice machine! Thanks for watching!
My guess is that the reason it's reporting "ER stuck high" without the speaker resistance is that it's usind the speaker as pull-down. Clearly other things pulls it down eventually but without the speaker it stays high far too long and this is what the test notices (IE not pulled up, lack of pull down). It might even have cleaned up the audio test waveform, we see that the falling edge takes a very long time to hit zero, this may well be due to this lack of "speaker working as pull-down resistor".
@@tony359 these days I don't even power them up before changing caps. Lower ram is very picky about power levels and can be damaged by spikes on power up.
That reminds me about the time when I attached a very high quality surplus typewriter keyboard to a ZX 81 with dozens of diodes. ZX Spectrum was for billionaires. We students could afford ZX 81 back then only. But even the ZX81 solved differential equations numerically in Sinclair Basic.
Besides ESR the problem with shot capacitors is that they grow a resistor in parallel, not just in series, that reads as simultaneously possibly an increase in measured capacity and increased VLoss value, they're basically dumping all the current put into them into heat in relatively short order, including the current used by your meter for capacity measurement. Doubled apparent capacitance is probably an indication that it dumps at least half if not more of the current going into it into heat immediately, and then it loses an additional 6% charge per second when not being actively held up. The ESR per se isn't something these old computers are particularly sensitive to, but the loss or parallel resistance, that's really really bad. Also makes me wonder if just replacing capacitors with fresh ones and preferably high temperature grade low loss type would actually reduce the regulator heatsink temperature by a lot. Because all the unproductive current being sunk by capacitor loss needs to be sourced by the voltage regulator, increasing its heat output. I also wonder what one could do to allow the ULA to remain socketable while giving it a heatsink, exactly how much clearence is there. As a rule of thumb, a copper heatsink needs half the volume envelope of the aluminium heatsink for the same thermal performance, so that's one way to save space, you can get relatively low profile ones; furthermore copper has a high lateral conductivity. Maybe all it takes is a 0.8mm thin sheet of copper and let it overhang over less critical components? Making the area 2-3 times the size can be vaguely equivalent to the difference between a sheet and a finned heatsink for area.
Good point about the regulator being cooler with new caps. I have another ZX, Maybe I can do the caps and then the regulator to see if it changes anything! I really didn't think too much about ULA cooling solutions but you make a good point too! Thank you!
Sinclair products were made down to a price, so they wouldn’t have used the higher quality capacitors anyway, so likely they all needed replacement anyway, it’s not just ESR and capacitance, but also leakage.
Thank you - I looked at that other Spectrum here: ruclips.net/video/eS9BRJent9M/видео.html I'm not familiar with that link, can you help me finding out more? Thank you for watching!
Just have done with it and socket them all. Then go back and recheck the 'faulty' mem chips. The diagnostic may have misreported as all data/address lines are connected to each other. Other chips 'may' be OK.
Anything is possible of course but I'd expect similar issues on socketed ICs where the socket might get dodgy. On a soldered IC I'd say chances that adding a socket might improve the situation are slim! :) Thanks for watching!
@@tony359 Only in terms of testing. If they are soldered you can't easily swap around - as you found during your testing. Some versions of the Speccy had the upper memory bank socketed anyway as they were an upgrade form 16K version - adding an extra 32K. Very rare for a socket to go 'bad' - might need a clean with deoxit or similar if tarnished over time. Also avoids constantly applying soldering heat to 40 year old chips. Good to see them still being kept going after all these years. I might have to dig mine out of storage and fire it up - hopefully still works ....... :)
@@tony359 Sinclair also made a pocket TV set (ruclips.net/video/qCJPF6Ei3Vw/видео.html) :D Unfortunately, it lacks an RF input - but I think you'd be able to add one.
More than one fault almost always indicates a meddling pillock who had no idea what he was doing. If he did know, he would have fixed it, if he didn't fix it, he probably didn't know that his inexpert meddling would just make things worse. Think of the detective and some idiot has contaminated the crime scene.
Maybe - but I believe all those parts are kind of known for failing. But who knows. The board didn't seem to have been worked on before. It was good fun though! Thanks for watching!
@@tony359 In my experience, the first fault stops the device working, so no one uses it again, thus the other four parts can't break because it isn't switched on. I still believe unrelated faults are almosty always caused by a meddler :)
* A technician repairing machines of that era must have a television with a multi-standard RF input. It is something essential. * Please stop bothering everyone with "subscribe" and "hit the bell". If you create good videos, people will. It is impossible to subscribe to all the channels you watch. I wouldn't even have time to watch the videos. * If the computer is executing code, all lines in the data bus are correct. You don't need to check it. * All electrolytic capacitors must be replaced. If they haven't failed yet, they will fail in no time. It's something every technician knows. The computer is running. Congratulation. But you need to understood and learn from your mistakes.
Tony, your smile when you heard the Manic Miner tune for the first time is priceless 😊
It was so cute! :)
That title screen "music" on Manic Miner could easily lead anyone to believe the sound was still faulty ;-) Thanks for the entertainment.
ahh good point! I didn't think of that! Good suspense! :) Thanks for watching!
That is awesome, especially for 1982..
indeed! I thought it was like a toy but it's not!
cheers tony, nice video for the friday warm down
ahah, weekend video! :)
I love the passion You put in those repairs :)
Thank you, very kind of you!
Pretty interesting, subscribed. My first computer was zx spectrum and I spent a lot time playing elite dangerous - David Braben legendary game and now still playing new version
Amazing thanks! I shall give "elite dangerous" on the other ZX I have waiting to be repaired! :)
Back then i was never into the ZX Spectrum, i started with the Commodore ViC20 and did love all the Commodores i had which where many. Great video Tony hope sometime you do some with a Commodore ViC 20. Keep up the good work my friend.
I'd love to have a Vic20 on my bench, never seen one!
Thanks for watching!
Great video, Tony! I never worked on a ZX Spectrum too but after seeing this video I’m hyped to try it. I only have to find some machine in need of care. It can be also one of the Brazilian clones from Microdigital, the TKs.
They should be relatively easy to find, good luck and thank you!
Ah yes. The good old Speccy. My first computer was a second hand 48k +. Marginally better keyboard than the rubber key version. But not by much. I've still got it by the way :-) Re-capped of course. Also got a ZX-HD and DivMMC. You really ran into quite a few issues on this one. Nicely fixed Tony.
Thank you for watching! I guess it would have been boring otherwise :)
I was too young to be playing with these when they came out, I started with the Spectrum +3, but this video was good, there is a 48k in the house, I'm tempted to see if it works...
Good luck with the ZX! Thanks for your kind words!
38 minutes of Tony-goodness? I'm in😊
Can't be so good but thanks! ;)
Hi Tony anaother great video!much appreciated Thanks
Thank you!
Sinclair used dodgy RAM - quote from Salkin (UK) website: "The TMS4532 is a 32k x1 bit Dynamic ram.
It is actually a 64K static ram that failed testing, in either the upper or the lower portions and was marked appropriately (-4 if the Higher portion was good, or -3 if the lower portion was good.)
As such, it comes in two variants that cannot be mixed, the TMS4532-3 and TMS4532-4 variants, which relate to the state required of AR during the CAS phase."
I was aware that the ICs were actually 64KB, but not that it had failed! I wonder whether a failed bit means the whole IC is bad. If you think with today's eyes, a less powerful CPU is often a more powerful silicon die which did not pass the performance required - so it's downgraded to a slower model. AFAIK there's nothing wrong with that but I wonder whether the same applies to those RAM chips! Thanks for the comment, very interesting!
@@tony359 It was Sinclair trying to reduce production costs. The RAM chips worked fine as 32K x 1 DRAM but I guess they have started failing now as they are so old. I remember buying one of these with my savings in December 1982, 5 months before I finished school. It competed with study time for my exams (and usually won). I always used to get copied games on cassette from my school friends and as a result always had to retry loading as they would often fail. I spent more time loading games than playing them on some days.
Great video BTW!
Great job, Tony ! Always enjoy watching your videos . Cheers !
Thank you for watching!
Good job. Back in the 80s I wrote a spice node network analyzer for the zx spectrum. Almost all in assembly. Still works great. It supports circuits up to 256 nodes. Let me know if you are interested....
Amazing, does that mean the ZX could be networked?
@tony359 oh no sorry. You can set up a electronic circuit and characterize it's 4-pole properties over a range of frequencies. Such software was later known as spice programs such as Lt-Spice for example (you can Google it). Only this highly complex one runs on a ZX spectrum.
ah very interesting - I didn't know what a "spice" program was, pretty cool!
@@tony359 It could. The Interface 1 (needed if you were using Sinclair's own Microdrive storage devices) added an RS232 port that could network up to 64 Spectrums. Seriously, the Speccy could do amazing things even out of the box, but the quantity and scope of the additional hardware you could connect to it was astonishing. At one time I had the Interface 1, a floppy disk interface, a MIDI controller, joystick/mouse ports, video capture, external audio (with the usual AY chip) and probably a few more.
Another very interesting video!👍👍
Thank you!
Well done! Very cool custom case
Wondering if the case was suitable for something else as well? Why so much unused space inside?
Thanks for watching!
Some of that "return to black" treatment would of been great for that plastic. Usually for automotive plastics, but I've seen people use it on consoles they fix.
Is there anything that actually works? I looked into that for my car's bumpers and most are black paint you apply - I don't like the idea as I don't know how much it's going to last and what happens then? Silicone spray only works temporarily AFAIK.
Thanks for watching!
@@tony359 I'm not 100% sure. I need to pick some of it up myself and try. The product I had seen used was actually "back to black" and it seemed to do good for a playstation 2 shell. Gave it that glossy sheen along with restoring the black color.
I need to get some and try for myself. I wonder if tire shine would have a similar affect. I have some of that. 🤷♂
I had a quick look around some time ago and I couldn't find anything with a long lasting effect - and I don't want to paint the plastic! :)
Pretty impressive. Thank you for this entertaining video!
Thank you for watching!
Great video!
Thank you!
Wow. My ULA had the exact same fault. The letter doubling IIGGOO etc. with the diagnostic ROM. Still haven't been able to fix the RAM fault on mine. After replacing the RAM the test indicated bad did nothing. Maybe I need to replace some other RAM's too.
Thank you for all the work!
Thank you for bringing them in! I enjoyed working on this one! I hope the other one is a bit happier :)
I never had one of those nor seen one live. Nevertheless, great repair and video! That audio debugging program had better sound than that game 😅
That game is supposed to be an achievement for in-game music plus platforming (as speaker is cpu hungry, like in IBM PC). I never liked it hehe.
There are newer games like Target Renegade, Robocop or older ones like Jetpack that are much better for me.
Thank you! Well if you see that from a 1982 perspective, my Apple IIe from 1983 could NOT make those sounds :) Even though to be fair the Apple II series was a bit behind when it came to sound and graphics.
@jbinary82 Thanks, I'll give them a go on my next ZX!
as for the video input device, i use a gv-usb2 to input some of my older consoles into my pc for various reasons, composite, l/r audio, and svideo inputs, svideo overrides composite. works with ntsc and pal formats fine from what i could tell, but some software suites have issues with the , versus . numeric separators when using the gv-usb2 with them. as far as i know OBS isn't one of them.
not sure if this interests you, or is viable with the rest of your setup, but you never know.
Thank you, appreciated! I'm testing THREE more devices, will come up with a video soon! :)
Thanks for watching!
great video, Tony. it has the same age as me, amazing it works fully now :)
Cool! I have to grab something older to match my age unfortunately! LOL!
Thanks for watching!
@@tony359 you don't look a day older than 25 :)
Well, in 2020 during pandemic they asked me to show an ID to prove I was older than 25 - I was buying spray paint and I was wearing a mask and a hat.
I just removed my hat. :D
I had that case, but the one with the spacebar. It was a huge improvement over the dead flesh keyboard. Then I bought a BBC Micro which was a huge improvement over the Spectrum. 😉 Discuss.
ahah! I've never used either of them so I'll sit here and let more knowledgeable people run the discussion! But yes I hear the BBC micro was a very nice machine! Thanks for watching!
Ohh,zx, my firsts computer. I assembled the 48k version myself. There were a lot of glitches, but I wrote my first program on it.
it must have been a big thing the 48KB upgrade back in the days! Thanks for watching!
My guess is that the reason it's reporting "ER stuck high" without the speaker resistance is that it's usind the speaker as pull-down. Clearly other things pulls it down eventually but without the speaker it stays high far too long and this is what the test notices (IE not pulled up, lack of pull down). It might even have cleaned up the audio test waveform, we see that the falling edge takes a very long time to hit zero, this may well be due to this lack of "speaker working as pull-down resistor".
ahhhhh yes that makes very sense! The circuit is so simple that using the speaker as a resistor seems logical! Thanks for that!
on ZX Spectrum you ALWAYS replace ALL capacitors, no questions asked, EVER!
Yes, I now know that! :)
I'm fixing another one right now and new capacitor went in indeed! :)
Thanks for watching!
@@tony359 these days I don't even power them up before changing caps. Lower ram is very picky about power levels and can be damaged by spikes on power up.
It was my first computer, and also the only computer I've developed homebrew games for😂
eheh I can imagine, it was fun to use! I loved the way they designed the input!
Yes!, you should try a +2A. Amstrad did a nice improvement over the poor speccy. It's also the most reliable.
That reminds me about the time when I attached a very high quality surplus typewriter keyboard
to a ZX 81 with dozens of diodes. ZX Spectrum was for billionaires. We students could
afford ZX 81 back then only. But even the ZX81 solved differential equations numerically
in Sinclair Basic.
I guess back then it was a super WOW thing! NASA technology at home! :)
24:32 Freeze spray and heat gun are your friend in a case like this. 🙂
Yes, that might have triggered some more fault. I use that method very often! Thanks for watching!
Besides ESR the problem with shot capacitors is that they grow a resistor in parallel, not just in series, that reads as simultaneously possibly an increase in measured capacity and increased VLoss value, they're basically dumping all the current put into them into heat in relatively short order, including the current used by your meter for capacity measurement. Doubled apparent capacitance is probably an indication that it dumps at least half if not more of the current going into it into heat immediately, and then it loses an additional 6% charge per second when not being actively held up. The ESR per se isn't something these old computers are particularly sensitive to, but the loss or parallel resistance, that's really really bad.
Also makes me wonder if just replacing capacitors with fresh ones and preferably high temperature grade low loss type would actually reduce the regulator heatsink temperature by a lot. Because all the unproductive current being sunk by capacitor loss needs to be sourced by the voltage regulator, increasing its heat output.
I also wonder what one could do to allow the ULA to remain socketable while giving it a heatsink, exactly how much clearence is there. As a rule of thumb, a copper heatsink needs half the volume envelope of the aluminium heatsink for the same thermal performance, so that's one way to save space, you can get relatively low profile ones; furthermore copper has a high lateral conductivity. Maybe all it takes is a 0.8mm thin sheet of copper and let it overhang over less critical components? Making the area 2-3 times the size can be vaguely equivalent to the difference between a sheet and a finned heatsink for area.
Good point about the regulator being cooler with new caps. I have another ZX, Maybe I can do the caps and then the regulator to see if it changes anything! I really didn't think too much about ULA cooling solutions but you make a good point too! Thank you!
Bravo! 🎉😊
The projector was simpler - this was more fun :)
Sinclair products were made down to a price, so they wouldn’t have used the higher quality capacitors anyway, so likely they all needed replacement anyway, it’s not just ESR and capacitance, but also leakage.
Indeed. Caps rarely last 40 years, those were cheap in the first place and also they lived in an oven :)
Thanks for watching!
good stuff .. when you showed your other spectrum, it looked to me that the upper ram link was not fitted.. this can cause problems
Thank you - I looked at that other Spectrum here: ruclips.net/video/eS9BRJent9M/видео.html
I'm not familiar with that link, can you help me finding out more?
Thank you for watching!
@@tony359 my reply isn't showing 😢
It's not me :)
I checked in the "held for review" section and yours is not there. Sorry!
Just have done with it and socket them all. Then go back and recheck the 'faulty' mem chips. The diagnostic may have misreported as all data/address lines are connected to each other. Other chips 'may' be OK.
Anything is possible of course but I'd expect similar issues on socketed ICs where the socket might get dodgy. On a soldered IC I'd say chances that adding a socket might improve the situation are slim! :) Thanks for watching!
@@tony359 Only in terms of testing. If they are soldered you can't easily swap around - as you found during your testing. Some versions of the Speccy had the upper memory bank socketed anyway as they were an upgrade form 16K version - adding an extra 32K. Very rare for a socket to go 'bad' - might need a clean with deoxit or similar if tarnished over time. Also avoids constantly applying soldering heat to 40 year old chips. Good to see them still being kept going after all these years. I might have to dig mine out of storage and fire it up - hopefully still works ....... :)
👍👍
👍
I had one that had a similar fault but its many years ago and i didnt get it to work.
It's amazing the free tools available today to troubleshoot these machines! Thanks for watching!
You deal with vintage computers but you dont have a TV ? OMFG
Too big - not enough space! It's either me or the TV in the workshop! :D Thanks for watching!
@@tony359 Sinclair also made a pocket TV set (ruclips.net/video/qCJPF6Ei3Vw/видео.html) :D
Unfortunately, it lacks an RF input - but I think you'd be able to add one.
More than one fault almost always indicates a meddling pillock who had no idea what he was doing. If he did know, he would have fixed it, if he didn't fix it, he probably didn't know that his inexpert meddling would just make things worse. Think of the detective and some idiot has contaminated the crime scene.
Maybe - but I believe all those parts are kind of known for failing. But who knows. The board didn't seem to have been worked on before. It was good fun though! Thanks for watching!
@@tony359 In my experience, the first fault stops the device working, so no one uses it again, thus the other four parts can't break because it isn't switched on. I still believe unrelated faults are almosty always caused by a meddler :)
* A technician repairing machines of that era must have a television with a multi-standard RF input. It is something essential.
* Please stop bothering everyone with "subscribe" and "hit the bell". If you create good videos, people will. It is impossible to subscribe to all the channels you watch. I wouldn't even have time to watch the videos.
* If the computer is executing code, all lines in the data bus are correct. You don't need to check it.
* All electrolytic capacitors must be replaced. If they haven't failed yet, they will fail in no time. It's something every technician knows.
The computer is running. Congratulation. But you need to understood and learn from your mistakes.
To learn I need to make mistakes which I am sharing with you! Feel free to skip the parts that bother you!
Thanks for your comment!