Can we repair Adrian Black's Commodore 64 board? So many issues! I was expecting an easy repair :)
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- Опубликовано: 31 дек 2022
- Adrian Black gave me a working C64 board. But it broke! In so many ways! Let's try to repair it : ) Part 1...
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Repairing Adrian's Commodore 64 video here: • Adrian Black gave me a...
Adrian's Digital basement: / @adriansdigitalbasement
Adrian's Digital basement II / @adriansdigitalbasement2
Join me on Twitter: / epictronics1
Music recorded from a real Commodore 64 SID
Tools I regularly use
DeoxIT D5 Contact Cleaner
Hanstar 861DW Hot Air Rework Station
Pro'sKit SS-331 Desoldering Station
UNI-T UT61E Auto Ranging Multimeter
UNI-T UT890D Manual Ranging Multimeter
PINECIL Soldering Iron
TS-100 Soldering Iron
AMTECH NC-559-ASM Flux
PinePower Charger/PSU
TL866 II Plus Programmer
Tektronix 2246A 100 MHz four-channel analog scope
MaAnt Grinding Pen 
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The lead free solder cutoff date is 2006. That's when RoHS was passed.
Ok, I was expecting much earlier, thanks
@@Epictronics1 Same... I was surprised too when I first heard that date. Of course there's nothing stopping a company from having used lead free before that date, but after that date everyone was using it.
@@Epictronics1 My memory was that unleaded solder didn't start to become a 'thing' until the early 2000s, or at the earliest the late 1990s, say around 1998 or 1999. Commodore was out of business by the end of 1995.
@@lwilton Ok, thanks :)
If I've learned anything from Adrian's videos: suspect the PLA chip. It seems to be, along with MT ram, and Mostek logic one of the most common failure points.
The PLA is definitely involved. It's on the suspect list now for sure. MOS logic are horrible lol. But I still don't have any Mostek chips in my "dead parts bin"
@Mr Guru That's my bad too...I meant MOS logic chips
Cool! You've got an 8-bit dance party and a disco-C64! :D
As for the fault: After a quick search, it's very likely the PLA chip. It's often the PLA chip when running into those unexplainable problems, which are often inconsistent (at least, with a dead test cartridge).
I'm looking forward to part 2!
Thanks, yeah, the PLA is at the very top of the suspect list now
It's either U16 (4-bit data bus bridge to color RAM), U27 (logic to color RAM chip select), or the PLA (write enable to color RAM).
Totally agree
My retrobright setup is a 10 gallon aquarium that I lined with UV reflective window film. This way you can use the full submersion method and get 100% even coverage without worrying about swirls from plastic wrap. Efficient, reliable, on demand retrobrighting while mitigating the majority of issues that occur in most retrobrighting attempts. I've even used a heating pad under the aquarium on occasion, to maintain a peroxide mix temperature near 120°F.
I have a peroxide bath too. Thanks for the tip about the UV reflective window film, I'll see if I can find some
Can't wait for part 2. I've only been repairing these for 2 years now, but I would also guess the pla (along with more ram chips ...maybe) anyways nice trouble shooting so far:) happy new year
Thanks : ) Yes, the PLA is on the suspect list now. among quite a few other chips lol. Happy new year!
Happy New Year, great video looking forward to part 2.
Thanks : ) Happy new year
Looking forward to part 2. 😃
As soon as I have some more solder and sockets!
I thought I saw a lot more cold solder joints watching your video than you pointed out! :) happy new year!
Could be, I'll check! Happy new year :)
The best way to kick off the new year.
Thanks : )
Re: leaded solder, no retro-computer will ever have lead-free solder. RoHS made products with leaded solder illegal effective mid-2006, and that is what prompted many manufacturers switching, even if products weren't meant to be sold in the EU.
And you can always mix leaded with lead-free for desoldering, just make sure you clean the pads afterwards, and then use only one sort of solder (leaded is always fine for hobbyists, and definitely necessary for retro computers).
Ok, I was expecting much earlier, thanks
@@Epictronics1 Companies had little incentive to switch before that.
And the switch was quite problematic. A customer of ours, which happened to be a manufacturer for large-scale soldering lines did complain quite a bit about how difficult it was to get it right.
The video game console that got hurt by that the most was the Xbox 360 because it used leaded solider and then got told at the last minute to change to lead free.
@@tspawn35 Did they have to make changes to the design in any way?
@@tspawn35 Well, it's not only about the solder, but you also need to source RoHS-compliant components. At that point it might be more about certification, even if parts potentially don't contain lead either way. It also meant another blow for hobbyist components, because many obsolete parts just kept getting sold, until RoHS would have either meant changing the part, or at least certifying it for RoHS-compliance.
Plus, lead isn't the only substance regulated by RoHS.
Nice! :D
A problem with diagnosing graphics problems with a "modern" screen is that when the video signal is poor (weak, out of sync, dirty, etc.), the screen just turns blue as if there was no signal, even though there actually IS a signal, and you can't see what's going on. Older CRT TVs would display the signal, be it good or just garbage. I think your board outputs a constant dirty video signal but your Samsung Syncmaster played a bit against you here by letting you think the board was rebooting ;)
Just a hunch though.
Interesting, I guess I'll try it out with a CRT before I move on. Thanks
Interesting video. Good luck with the repair.
Thank you. I just finished the repair a few weeks ago: ruclips.net/video/ZUgN9hu5q0I/видео.htmlsi=oLwxOh2JOAOzixV9
Nice retrobrighting setup there 👍👍
Thanks :)
Thanks for sharing!! I still think it's the PLA, we will see :)
I'd say that's a pretty good guess!
Hang in there! You're doing great.
Thanks : )
Concerning UV lights, I'd suggest going for 265nm LEDs. While 275 and 290 are still UV, their visible light portion is probably so large, that the "uv power" is too diminished to be useful for retrobriting.
The spec doesn't tell much about this light, unfortunately. But it does work really well : )
@@Epictronics1 : A good indicator of which wavelength is the dominant one is, the colour you can see.
290nm lights are rather purple. While 260nm glow almost greenish, with the reflection on white paper being purple.
@@bikkiikun Ok, this light has two switches. One of them turns half of the LEDs on and they are glowing red. The other switch turns on blue and purple LEDs. I think it's made for different stages of plant growth
I said you could have a RAM issue, but the big problem wasn't related. I suspected it was one of the logic chips in the VIC-2 area. If it was a RAM problem then you'd get a screen. Maybe it's black, maybe it's garbled, but with no screen at all that to me suggested VIC related areas. The VIC itself is the easiest to swap and fortunately that turned out to be the issue. I don't think it's a RAM problem now. I think it's a logic issue either with the PLA or one of the logic chips supporting the color ram. I did suspect the color ram itself, but that wasn't the case as you saw.
Totally agree, the two main suspects right now are PLA and one of the logic chips involved in handling color RAM
Where do you get your sockets from?
I'm having a hard time finding a steady supply, especially for the machined ones. They always seem to be on back order.
I placed an order from a random eBay seller this time because I just wanted to get some quickly. I have moved away from machined sockets though. I use to swear by them but I have actually had much better luck with dual wipe sockets for re-used chips. I made a video about this topic a while back: ruclips.net/video/LwCeHc6wVyA/видео.html
@Mr Guru Good to know there is a problem the other way around too. I'll avoid using dual wipe sockets for components with machined pins
@Mr Guru Now that I think about it... I have a project here on YT that I think I called "the hong kong commodore* It has a PCB with machined pin headers stuck down in single or dual wipe sockets. I'll see if I can pull it out and do some test
Some of those other joints on the ram chip look cold... Perhaps reflow them?
I didn't notice. I'll check, thanks
@@Epictronics1 it looked like at 13:00 there is a need for more solder work.
@@TheThomasites You're right, that CIA doesn't have enough solder on some of the pins. I'll reflow it first thing in part 2
I’ve got one piece that was baaadly yellowed, and it’s a tower case front, so it’s a major cosmetic issue. It didn’t respond as well to retrobriting as stuff usually does, so I figured - what the heck, let’s go for broke. I let it soak for nearly a week. It’s a wash of over-bleached and not quite done yet. I’m going to keep going until it just doesn’t respond any more, then see what I can do about the albino plastic.
Everyone’s afraid to push it - and I get it. But in this case, I’ve got nothing to lose, so I’m going to see what happens when you do. :-) IMO, it can’t be any worse than an orange front panel.
Yeah, in worse case you can always respray it in a similar color.
The flickering is most likely color-RAM being selected when it shouldn't, random stuff is written into it, and so it displays random colors. Or perhaps something is being selected instead of it. When nothing is being written, color-RAM isn't changed and text stays the same color.
This could be several things:
Obviously, color RAM itself (which you ruled out)
Select-logic chips including PLA: These are most likely culprits.
A short or break in an address trace or SELECT signal for the chip: actually this is quite likely as well
A bad chip that is effecting the address lines: possible but unlikely given the symptoms
CPU: unlikely since it seems to work otherwise, however maybe one of address output drivers is not good enough?
Short or cross-talk around the VIC-chip: On one hand it really doesn't look that way, on the other you did have a dead VIC so.. hmm... maybe worth a look if only to make sure the second VIC doesn't die the same way first did...
RAM chips may be bad but that is not what creates color-flickering issues
Probably the best way to go about this is to use a o-scope to compare SELECT line signals of a working and a non-working machine and trace it back to CPU one chip at a time.
Also look at signal levels of address lines starting with the higher ones. Try to spot any weirdness. Then try cutting traces to see what causes it.
It could be a problem with cold solder joint or broken trace. See if you can spot something like that near color-RAM select, since everything else seems more or less fine.
Although this is quite a bit of a bother, but you will probably need to socket the PLA and try to swap it. If you don't have a replacement PLA it may be possible to cobble together a replacement for only the misbehaving signal(s) using logic chips, (EP)ROMs or PAL/GALs.
@Mr Guru Everyone has their own belief of how best to approach repairs, but to me "no smart person would do" is taking it way too far. If it's easier to you to desolder a 14-pin dip package - go for it, but I personally don't have a fast desoldering tool and would not do it that way. I'm not saying cutting a trace cannot create issues, but if you do it carefully enough and solder-blob the cut afterwards it's usually harmless enough. It would take quite a bit of convincing me to accept that it "just causes issues", "a thing of the past" and "very bad". C64 is actually pretty complex, not as complex as modern PCs, but still can take quite a long time to figure out. It's not always continuity, sometimes one chip effects others even though it shouldn't. I don't have that good of a memory, but Adrian probably ran in that issue many times. Although it is rare with address and select lines, it is still possible. Not all chips can be tested reliably out-of-system, even if your tester has software to test PLA, it sure cannot do much about SID, and testing video output of VIC while not impossible is probably not what those testers can do either.
Thanks, the main suspect right now is the PLA. I have a GAL-based replacement if we need it. I will also do some more tests as you and many others suggested
@Mr Guru ok I see where you are going with that reasoning, but I do not have good repair equipment *at home* , and do not do commercial/professional repairs there, but still repaired a few things. I certainly wasn't a tech 40 years ago but I think I know enough to do at least some of repairs. Should I not be doing them? Maybe but I still do. Not everyone in lower-income countries can afford all the professional-ish equipment or space to put it. So although I see your point, I'm still not convinced.
Anyone related to Adrian, I will subscribe to... Its funny how my youtube rabit hole went from Clint (LGR) > To David (The 8 bit guy) > Robin (8 bit show and tell) > Adrian (Adrian's Digital Basement) > You
Thanks mostly to mentions but also to the youtube algorythm.
That's some great channels you got listed there : ) I'm watching them too
The problem you experience is either the colour RAM, the 4066 or the PLA. Considering you have a PLA from 1983, which die if you just look at them (in this case perhaps literally), the PLA should be the first chip to suspect.
The color RAM was tested and it's ok. The PLA is on the suspect list now for sure. I have only had one 4066 go bad ever. I'll keep it in mind, thanks
@@Epictronics1/videos To me it seems that the color-RAM is being selected and written to when it shouldn't.
The PLA is definitely on the list of suspects, but traces involving that and CPU-PLA address lines also are.
Before desoldering chips you might want to scope the SELECT/ENABLE line and compare it to the working machine one, even to just show us what it looks like.
If this turns out to be the only issue with the PLA and you don't have any spares, it may be possible to desolder that one line from PLA and replace that logic with a bunch of 7400, a programmable ROM or PAL/GAL. Although it is more likely that the PLA is bad in more than one way.
@Mr Guru Thanks for the heads-up. I reported the comment to YT but I don't know if it helps much. And thanks for the recommended steps to check!
@@jwhite5008 Thanks, The main suspect right now is the PLA. I have a bunch of GAL-based PLA replacements we could use if needed
People even apply fresh solder to more easily desolder components on radios from the 1930's and 1940's (Such as on the excellent YT channel Mr. Carlson's Lab). So I don't think the trick is only useful when desoldering modern lead-free solder.
Ok, yeah, I think he really knows what he is doing
Leaded solder oxidizes slowly over time. Some fresh solder helps a whole lot with heat transfer past the oxidation layer, so the old solder will then melt. It also introduces fresh rosin, which is also important for solder flow.
@@lwilton Ok, Then I'll keep adding fresh solder on older boards too, thanks
They are soldered with lead based solder the RoHS laws came in in 2006.
Thanks
That looks like a VGA monitor, what are you using to connect the C64 to it?
I don't use this display for Commodores anymore, but if I remember correctly I used it with the cheapest adapter on ebay. I think it's called AV2HDMI.
@@Epictronics1 Oh, OK, I thought it was a VGA monitor, it is HDMI then...
When did manufacturers stop using leaded solder? in short, they haven't.
I prefer leaded solder, as it flows better than lead free, and was surprised that when I tried to order some, they wouldn't sell leaded solder to me because I wasn't an industry.
Yeah, I tried lead-free solder ones and it was crap.
I used to do repairs on these 1986
Your thumb looks like you were in a diaper in 1986
Do you think the x-ray at the airport damaged it?
You know, It has crossed my mind. Maybe the x-ray is too much for these old MOS chips to handle?
It could have possibly damaged SRAM or erased EPROMs with very long exposure, but the VIC?
@Mr Guru That's kind of my point. That being said, earlier chips did not have as much protection as newer ones do. But VIC does not seem to be the one that would be effected as much. And by the way, didn't that whole module have an RF cover on in transit?
@@jwhite5008 I don't know. This whole project was a surprise to me. When I left Adrian's place to board worked fine. And now we seem to have at least two dead chips!
@@Epictronics1 Now that I think about it, maybe it's a good idea to check for cracks, bad soldering or other problems around power regulators and such, and the PSU itself - maybe bad power supply really damaged it? Or maybe slightly lower/higher voltage was the difference between seemingly working and having all the issues?
I wonder if your board got hit with a high dose of X-Rays? I took a bit of medical equipment to the USA once in my checked luggage and it reported a fault when I plugged it in (I never fixed it)
I don't really know enough about x-rays to even guess if they could kill vintage MOS chips
PLA is stuffed -- programmable logic array
Very likely, let's find out
Wow, what a fantastic diagnosic caper.
I also think you should reflow anything that was previously "repaired". That soldering job looks horrible. It might help. I thought the CIA especially looked bad, but I don't think that's the culprit.
yeah, I think that's a good idea too. I'll reflow those chips when I get some more solder
If there's Mt ram I'm looking there first!
Not this one!
@Mr Guru Ok, thanks, I'll probably put them all in sockets in part two
@Mr Guru That's interesting. I didn't know that they might be driven out of spec. Yes, I have a couple of C128s. I think they still work but I'll have a look inside
If a product is made without lead, it is probably marked as ‘RoHS-compliant’ Reduction of Hazerdous Substances european regulations forbid the use of Cr-VI, Pb, pcb’s and a couple of other substances. Expect products to comply starting at 2002 or later. Certainly not the early eighties.
Thanks
I wonder if a chip got radiation damage during the flight...
Well, something zapped at least two chips
@@Epictronics1 That definitely seems suspicious. Flying, especially at northern latitudes, gives an appreciable dose of neutrons and whatnot.
@@brianclimbs1509 Interesting, I didn't know that
Top Tip:
Once the retrobrighting is done, give the case a light coat of satin clear Lacquer to protect it from yellowing permanently.
Sorry, but I'm a bit disappointed in this video. Why did you not use an oscilloscope? I bet you did not even have a valid clock signal out of that VIC-II (not to mention RAS/CAS signals), of if you did, the video output was not a valid NTSC/PAL signal, as the monitor had a difficulty picking it up. This basically gave away a timing/VIC-II fault. I'd have suspected the contents of the tin can first. You could have spared a few sockets, and a bunch of solder.
Regardless, can't wait for the next episode, as I love your content. :) But please, next time, don't be afraid to use that pretty scope.
Thanks for the honest feedback. My thought was that any chip on the board could have had a short. The VICII just happened to be in a socket and got first in line. You're right about me being lazy with the scope. I only have a big and heavy vintage scope and it has to be put away after every time I use it. I tend to guess more than I should instead of pulling that big old scope out
@@Epictronics1 All I have is a hantek 6022BE but it's perfectly capable for these low frequency boards. Cost: about $35 on average, prices are going haywire at the moment.
What I want to say it's an ideal low budget scope. And I doubt you don't have a pc with windows or linux nearby.
@@paulmichaelfreedman8334 I have the plan to move some stuff around in the lab to make room for a permanent scope on the bench. If that plan doesn't work out I'll buy a smaller scope
The clocks stop at 00-0035AM
That is correct, the system seised to respond several times during my tests
@@Epictronics1 I should say "The clocks stop at 00-0035AM several times." I don't now if you used the same recording multiple times.
@@toreediassen144 Interesting, I didn't notice. I did not reuse any footage, they are all individual test
The grow light is 12 x 26 (= 312) LED chips. A 2000 Watt unit would assume way over 6 watts per chip.... No... most certainly not. At best they are 3W, more likely 1W chips.
Maybe they used the apparent power (which could be 2kW, if we consider 3W chips and a power factor of 0.5, which would be normal for a capacitive dropper).
The sad thing is, in parts of America and Europe some energy companies already started charging based on apparent power consumption (that usually happens when you get a "smart meter"). So while you're certainly not using 2kW, you'll be charged for it.
How weird, they really shouldn't do that. I guess we'll never know how powerful this light is, but at least it's speeding up the process many times. From this first test, I would say it does 1 day's of work in one hour! (at room temperature)
Can he fix it?
There's only one way to find out ;)
Notification Squad! :D
Weird problems like these mean 99% bad power.
It may look like it but unfortunately this problem is probably not caused by bad power supply.
His PSU seemed to be stable enough for this machine.
C64 were not the most repair-free equipment to begin with, and aging didn't do them any good.
But a bad power supply could have easily damaged the chips in the past.
If you look closely, color flickers only when code is running. This looks like the chip is enabled when it shouldn't or something else is enabled instead. Probably the PLA is bad.
Well, I checked the voltages and we are all good. My PSU is modded and safe. The PSU Adrian used when he tested the board in his basement was also a reliable modern replacement. I don't think we killed it with a bad PSU
A Dutch eBay seller (a business) had a good C64, but according the description, it was used to test other commodore psu's. It ended as you can guess. I think they doesn't know the "old psu problem". I think too many "electrocuted" parts.
@@user-marco-S Oh wow. I don't know if I should laugh or cry. I was once given an ATX PSU that had +13V on +5VSB line - silently killing your motherboards before you even pressed the power button.
@@user-marco-S haha, that was a bad idea, I wonder why they didn't just use a multimeter :)