Top Tip: Once the retrobrighting is done, give the case a light coat of satin clear Lacquer to protect it from yellowing permanently.

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 lead free solder cutoff date is 2006. That's when RoHS was passed.

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!

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).

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.

Looking forward to part 2. 😃

Happy New Year, great video looking forward to part 2.

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

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).

I thought I saw a lot more cold solder joints watching your video than you pointed out! :) happy new year!

The best way to kick off the new year.

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 video. Good luck with the repair.

Nice retrobrighting setup there 👍👍

Thanks for sharing!! I still think it's the PLA, we will see :)

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.

Hang in there! You're doing great.

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.

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.

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.

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.

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.

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.

They are soldered with lead based solder the RoHS laws came in in 2006.

I used to do repairs on these 1986

Some of those other joints on the ram chip look cold... Perhaps reflow them?

PLA is stuffed -- programmable logic array

Wow, what a fantastic diagnosic caper.

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.

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.

Do you think the x-ray at the airport damaged it?

If there's Mt ram I'm looking there first!

Notification Squad! :D

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.

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 wonder if a chip got radiation damage during the flight...

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.

The clocks stop at 00-0035AM

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.

Can he fix it?

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.

Weird problems like these mean 99% bad power.