Cool it loves again! I'm surprised the MOS TTL logic stuff wasn't bad!! And yes, I guess someone was programming and selling replacement PLA chips at some point. Interesting the MOS part was failing even back then!

Thanks to you both for showing us a little different perspective from Adrian's basement as well. :)

If you're a retro fan and don't have both of Adrian's channels on lock... Seriously, do yourself a favor and sub to both of them. Man is a flippin' legend. I was really excited to see you had visited him and that he sent you home with something fun. :)

I'd be doubting my troubleshooting skills after 2 bad chips. Well done.

You really need to get yourself a retro chip tester pro from 8bit museum. You’ll save yourself hours in testing time.

12:00 C64 has become sentient and tries to communicate and you classify this as fault?!?! YOU JUST KILLED IT!!!!

Three ram chips, the CPU and the SID and a CIA on the last one I fixed. Cost me more to fix it that it did to buy - which was a shame - but I did learn a lot - mostly about how not to desolder ICs from commodore PCBs - lifted three pads getting it working.

When you proceeded changing those RAM chips one by one you will notice on the screen that the crazy characters were dissappearing gradually and at the 4th RAM chip change the screen was solid and only the error message came up. Also I am pleased with how helpful the dead test cartridge was in this really weird situation of a fault and also a first as far as I concern of all the C64 video repairs I have seen. Keep up the great work and content, greetings from Greece!

The fault is actually kinda cool, we used to pay money for screensavers like that for Windows.

Repaired hundreds of these boards between 1990 and 1996 for the company i worked for back then.

I do love it when multiple KZfaqrs that I follow appear on each others channels! Great repair! :)

A friend of Adrian Black's is a friend of mine! Recently subscribed your channel! 😁👍

That was very forward thinking of them, calling it empty memory.

I loved seeing the whole process, I really enjoyed this video. In other repair videos I've seen on KZfaq, they will replace everything that might be causing the issue and throw the old stuff away never really finding the actual source of the problem. So, it's really cool seeing you use another board to confirm which chips were bad and which one were probably still good.

I'm not surprised at all that there are multiple bad RAM chips here, especially MT RAM. Nice video!

Nice crossover dude! Love both of yours channels.

A behind the scenes for Adrian's Digital Basement wow

8 bit dance party on. 5 bad ram chips is quite a lot, would be interesting to see how reliable the rest of that C64 is in a few months time.

The West German model that was NTSC may have been sold to a visiting American soldier at a base store? That Retro TINK reminds me of the actual "Tink" (Disney Tinkerbell). Always up to mischief.

I bought an NTSC c64 on my Canadian base in Germany in early 1983. If it has gray F keys it may be one of those.

Great repair! I really enjoyed watching that.

You're Commentary during the memory faults are great, clicking the red button.... oh it's raining... Those DK PCB's are sweet looking

Driving from Seattle, WA down to Portland, OR is a solid 3 hour drive, but for a visit to see Adrian, totally worth it! Did you end up flying home through PDX airport or did you have to drive all the way back to Seattle (SEA) airport? As a side note I've been friends with Adrian for many years. Great guy and of course super nice! Luckily for me he's only a short drive away for visits and to just hang out to do retro computer goodness. I actually found your channel because of him. Great channel by the way 🙂

I love your accent. Those long transcients I vowels sounds so nice.

Coming over from Adrian's basement. Hehehe.... Had to laugh when you said Adrian offered you a broken Commodore 64.

As Adrian has pointed out on his channel, MT RAM has a VERY bad reputation, so I'm not surprised you had to replace so many of them. From a keyword search: "Micron Technology RAM chips ("MT" letters printed on the chip) are known to fail more often than the other types used in C64s."

When I fixed my C64, I knew exactly which RAM chip was bad. I replaced it and it worked, but after that I replaced all of them because they were all MT ram. I figured it's preventative maintenance. In the end my only issues were bad bit value 128 (I don't recall the U number) and a bad cartridge slot.

Speaking from bitter experience, I had a potted power brick go bad on my 64, and when I got the 64 back after repair, it had 8 sockets and a full set of new RAM chips (and a new aftermarket brick), so I recognized the problem the minute that 64 was powered up at Adrian’s.

If it weren't for the pristine under side of the board, I would have thought this machine had been used for spares and somebody "stored" the bad chips in it.

It feels so good to see you two TOGETHER! 🥳

I recently fixed my TRS-80 Model I - it had SIX bad RAM chips, found thanks to the diagnostic ROM Adrian and others developed. Thankfully the chips were already socketed so a lot easier to swap. No idea how so many went bad all together.

Adrian's C64 must've been exposed to a bad (overvolting) PSU. DRAM in C64s does fail quite often because of that and Micron Technologies DRAM seems to be particularly sensitive to that at least in my experience.. Micron did make reliable DRAM chips though but it got a bad rep, especially because of the C64's bad PSUs. Their military grade DRAM ICs like the 1259-series is actually very reliable (I mean it's military grade so they actually did make very high quality parts as well). I have loads of these and not a single one failed, even after severe maltreatment ;-) These 4264s: Not so much.. How cool that you got to visit the legendary mr. Black in person!

Well done! Great video! Thank you.

"yellowed to perfection" very well stated.

This wired pattern caused by ram chip is probably caused by faulty refresh circuit inside dynamic ram chip, and after some time it starts to messup its content.

I had once 6 bad RAM chips in a Plus/4 which in the DRAM area is quite similar to the C64. It is typically the result of an over voltage on the 5V line.

What a great video. Thanks!

i seem to recall something discovered from watching Adrian, was that the MT ram can go faulty in a way that the data outputs are asserted even when the chip select is OFF, making it appear that other ram when selected is the faulty one. although in this case multiple ram chips were faulty as you tested them one at a time in the good board.

In my vintage computers, I automatically replace MT RAM chips if I see them. It saves me some heartache when diagnosing any issues down the line. (MT chips are an "MT" promise of functionality)

Well well, what do we have here? Another fine retro-computing channel found thanks to Adrian. Well done, exorcising those demon MT RAMs. Cast them out to the hell that spawned them! I will be interested to check out the other projects you have under way.

Looking forward for the next couple of planned vids.

MT RAMs, they make you feel like a....Dentist! I pulled 6 bad ones out of an Atari 130xe board once.

I wonder if this was a natural occurrence, as if there was some crazy power surge and it fried all those memory chips or if someone was playing around and destroyed all those chips on that system.

Great video. Adrian is a really nice guy!

You are really in his basement next to the water heater LOL!!!!

I can't say I'm surprised by the number of bad MT RAM chips. They seem to be a steady source of problems for a number of retro computing KZfaqrs.

Great work!. As you can see in the C64 memorymap, a part of the memory is screen memory ($0400) That is the first thing you should think of seeing this kind of error. Every byte in RAM is contructed using all memory chips. bit 0-7 There are 8 memorychips with 65536 bits. So 8x64bit is 64K. U11 and U24 defective create an ascii character (zero) 0 on the screen. inverted @ = $80 = D7 = U12. So by looking carefully at the screen you can also see what chips you must replace. ! = $21 (D5)(D0), " = $22 (D5)(D1), 0 = $30 (D4)(D5), @ = $80 (inverted) (D7) Black square = $E0 (D7D6D5), U21(D0), U23(D4), U11(D5), U24(D6), U12(D7)

In the video when you checked the voltages that 5v line is only for the vic and possibly the sid. I've seen C64 repairs where the normal 5v circuit had something causing it to dip down but the vic 2 5v line was fine. I actually had an issue with mine, but it turns out if the wire gague in the power supply isn't thick enough, that will cause a voltage drop. I had tons of issues that simply got solved by replacing the power cable. My homemade power supply was fine just the cable.

Thanks for sharing. 😉👌🏻

I have a C64 with MT ram and still going. Only had to replace some logic.

Really enjoyed the video, found another great channel. Could i ask a question though. What was the baking soda for, when you fixed the case, I've never come across that before, sorry for the noob question

I found a Jedermanns Software & Hardware in Camarillo California but couldn't find details on the business

Good video thanks.

Only Commodore can have faults that are awesome

If you have Micron RAM on your board, it is very likely multiple chips are bad. I had this many times, not just C64. I think an Atari 800XL with MT RAM has my personal record: 6 out of 8 chips had to be replaced before it worked again. I guess that the best advice for Micron RAM is that it is best to replace all RAM chips if it is encountered. If they aren't bad now, they will be soon.

Jedermanns = Everyone's in German. So, Everyone's Software. I can't find any real references to it, so it was likely a local repair shop that's long since gone out of business.

this commodore wanted to to a little bit of trolling this have to be the commodore whit the most broken chips i've ever seen

The PLS100N was made by Philips in the Netherlands as a replacement for the Commodore 906114-0. As far as the white sticker is concerned, end-"s" without apostrophe is typical of a German genitive, so "Jedermanns Software" suggests that the chip was purchased via Jedermann Publishing House in Heidelberg, Germany, which had been specializing since the 1980s in books and software for professionals and still exists today. The hand-written note might be a date that gives you a "terminus post quem" for the purchase of the chip as well.

Great video! I just have one small question: How come that no one has created yet a small solution which replaces and bypasses all the old RAM chips with a single PCB and a modern memory solution?

ITS THE MATRIX!

Gosh, I found five bad DRAM chips, all at once, between two C=plus/4 computers (I think four in one and one in the other).

A mate bought a German Commodore with the ntsc label on it. It's pal tho!

That brand of RAM is known to be a mayor headache! Many chips dying all at once…..I had that same issue in atari xe’s

So weird seeing Adrian in someone elses video.

Could it have been the airport x-ray damaging so many chips?

this is very possible with a faulty power supply. The Commodore power bricks regulators were known to fail and kill the ram

I would suspect this machine was used with a failed death brick power supply. Those poor MT rams may have a bad reputation but having excessive voltage shoved up their clackers can't have helped. As an engineer I very quickly learned that finding one fault is often not the end.

He even has a Practical Peripherals modem.

Pretty jealous, I wanna be in Adrian's basement as well. No pun intended.

What is that game at 0:15? MineStorm is a very good game which should had had an arcade version.

Currently working on a c64 with 5 bad ram chips 2 bad 74LS257 chips, 1 74ls258 chip, a bad PLA, bad SID, bad Kernal and a bad CLI. It's back working again, but wow! My suspicion is this got some serious static zaps or a seriously bad power supply...

Adrian was probably using it as as a storage bin for his bad RAM chips... 😜

Could that VIC-20 have Alps switches? Please tell!

10:50 take a screenshot of that, makes some funky wall art.

Hy the one Chip says Jedermann software. That's German and literally means Everybody Software. But, and that's the interesting thing. I think it was used in 80es Germany as German translation for the Term Open Software. Hope I remember that right.

Pretty sure that was a replaced PLA, and Jedermann's was most likely the shop that repaired it. Even I had a '84 C64, that I had to take in to have a PLA replaced in 89 (Still have the invoice for the repair, and hey I was only like 14 at the time, so that sort of repair was outside my wheal house). PLA's failed even without age.

Lol I like your channel logo

ok this has to officially be the coolest C64 fault I've ever seen. lol

You could run the high color mode blindly an during ingame press F11 and select other resolution. Seems the default resolution (refresh rate ) didn't work with your monitor.

Is it possible the West German NTSC machine was intended for the American military market in the southern sector?

Did the stand break on your Samsung 213T? I've had two snap.

Sounds like him from necroware.

What happened to your 1084? Shipping damage?

I had to replace 6 MT memory chips once on a c64 repair... they are pretty crappy!

Adrian lives near Portland, OR, not Seattle, WA.

MT RAM chips are notorious for failing.

Did anyone notice that he said the board number was 240407.look close it is 250407.

With that many bad chips, I wonder if it got hit with a power supply regulator failure?

RAM is weird. I had a system that when you booted it, it would display about 36k of RAM free. Rebooting always showed about 2-3k RAM less than last time, but if I let it sit off for 10 minutes, I had the odd 36K again. Turned out I had 4 RAM chips that never reported the same memory available causing it, and when those were replaced, I would have that lovely 38911 free, but the other RAM chips still failed diagnostics, so I ended up replacing all 8 of them to get it to pass.

Never had this many bad ram chips. MT chips will die if you breathe on them wrong though. You may want to go ahead and replace the logic chips ahead of time. I ordered an Arduino DIY kit ram tester from Ebay for 20 bucks and it works great for checking ram on 8 bit machines.

Guessing before finishing. 1 changed with temperature (capacitors) 2 wrong characters. (RAM) I am probably wrong. Just wanted to take an early guesss.

West German NTSC would be for US Bases in Germany ?

MT RAM Chip are known to fail. Sooner or later all of them will be defect. Better replace all of them instead one after one.

lol, I can identify with this one. I ran into one board that has 7 out of the 8 MT ram bad. Best practice with those us just replace them all.

The error in line 40 is a missing THEN.

Jedermann is the German word for "Anyone". It could be simply meant as a joke of who rplaced the PLA.

I think it would be interesting if someone created an online database of MT RAM date codes that have high failure rates. I have 2 C64's that both have original MT RAM with no issues but I've fixed at least 4 that did.

I didn't know Adrien lived in Seattle.

Space needle

Probably a bad brick. The C64 stock psus were very Crappy. Here we has a manufacturer that used to build a far more robust version ..... if you care about getting something better for your C64. It is not because it is lineal and oldschool ... but the lack of crowbar or any protection circuit .... well ... to sold the C64 at 125 by late 84 .... you cannot ask more. Same with the datasette unit. Here we got some units made in Brasil .... they feel a bit cheaper at first glance ... but they barely got any issues while 1531 / C2N was a pain to own and operate.