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!
@@Epictronics1 New Subscriber here - couldn't help thinking If the memory chips were almost all bad, is there possibility something is wrong with the voltages on board itself that is ruining them?
@@francistaylor1822 Yes, that is a possibility. The original PSU may have gone bad and zapped those chips. The C64 PSU is known for going bad and creating over voltage. I wish I had it to test
The PLA was the victim of a chemical mixup. Interestingly, it still worked, but the life was shorter. And with some not liking MOS, Mostek was even worse.
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. :)
First 64 I repaired had an all black screen with the line on it. Initial thought was the VIC-ii was dead, but same day I was watching and I remember hearing Adrian saying that this is often times a bad PLA. So rather than spending $100 on a replacement VIC-ii, I spent $15 on a GAL PLA and that part started working. Board had other issues, but that got me a screen I could see.
@@robertsissco2439 yeah, testing a VIC-II is difficult without a working spare board, Hopefully one day we'll get a cheap modern replacement for the VIC-II
@@Epictronics1 The vicii-kawari project looks promising. I have a Sixty Clone build with as many modern part part replacments in it as I could get to compare to original hardware (just for fun, no reason other than that), and I hope on their next pre-order to get one to put into that build.
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!
Hello Greece! I'v been to Corfu ones and I loved it! Especially the squid, fried in olive oil, sea salt and garlic. One of the best dishes I had so far! Thanks : )
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.
I loved seeing the whole process, I really enjoyed this video. In other repair videos I've seen on UA-cam, 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.
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.
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!
Interesting, I didn't know they did great MIL stuff. The thought crossed my mind while I was editing the vid. The "brick of death" is not an unlikely cause of this boards faith. I report back on the remaining μT RAM chips after some use
That could be why the 4067 page-mode DRAMs in my PS/2 Model 25 haven't given out. I do know they used a rather unique process to make their DRAM back then.
Maybe it's good that something as cheap and easy to replace is so sensitive to overvoltage. Because it would render the machine unusable early on and discourage people from continuing to use it long enough for the valuable chips like the VIC to get fried. And then, years later when the machine is dug out of the attic by someone who knows about the PSU issue, they can just put new RAM in it, get a new PSU, and it'll be fine again.
@@stevethepocket yeah, that probably saved a few C64s for us to play with now. Although, in my "dead parts" bin there are mostly CIA chips. Probably killed by the user with static by touching the bare connector at the back of the Commodore
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 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.
If i ever get the.chance to get a c64, the first thing i will do before turning it on is to check for mt ram chips and if so i will replace them and then throw them in the trash bin
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 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.
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 totally agree, he's a fun guy, I have been watching and learning from his videos for years. I had some more stuff to take care of up in Seattle, so I drove back. Thanks : )
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.
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."
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)
@@onnonius Oh, good old Programmers reference guide :) I did some reading in it way back in the day but I didn't read it all. Obviously lol. I still have an original ring binder actually. Didn't know someone made a digital copy, Thanks for letting me know
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.
Interesting. I have checked (and modded) my PSU. Another fault is bad power switches. I completely forgot to check this one. They can drop quite a bit of the 5v
@@Epictronics1 yeah my switch was also bad. Replacing that increased voltage slightly. Only like .2/.3 but still. When your voltage was only 3.5v (with the U2+ cart installed 4.2V without) to begin with every bit helps. lol
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.
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.
Cool. This topic may actually turn out the be the most interesting thing about this board. The label is dated 1989 and the Signetics chip is dated 1988. Why is this chip much older than when Commodore used Signetics PLA's? Did Jedermanns program this chip?
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.
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.
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.
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.
Cool, The PLA was from 1988. I guess Jedermanns Software replaced the chip in 1988? The odd thing is that Commodore had long sins stoped using Signetics PLA's by that time. I wonder if Jedermanns programmed that chip? If they did... I wonder if that code could be obtained and used/modified for another ROM? thanks for the info!
@@Epictronics1 They might have done some custom work on it or, more likely, they just had a ton of spare parts in a bin and slapped their sticker on it for warranty repairs.
@@JasonPullara Well, the sticker is dated 1989 but the chip is dated 1988. So, the chip is made later than when Commodore used these Signetics PLA's...
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.
There is always one first, and when it goes the C64 is unusable. So that means that all the other ships go bad on their own? Or is there a voltage spike killing multiple at the exact same time or some kind of cascading. Just curious to know how this would be possible. If they go bad on their own, then it is just a matter of time before the others go as well.
@@pe1dnn Well, we wont know for sure but my theory is that MT brand was more susceptible to over voltage than other brands. The C64 power supply is known to go over spec when the 7805 goes bad inside due to a questionable design
@@pe1dnn They go bad on their own and usage of the computer has no or little influence. It's just like radio-active decay: After a certain period of time, half of the chips are gone.
If I’m repairing a C64 and I see MT RAM on it, I just remove, socket and replace the chips proactively. In most cases, if I see MOS logic chips, I do the same.
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.
The thought crossed my mind while I was editing the vid. The "brick of death" is not an unlikely cause of this boards faith. Perhaps I'll pull the SID off one board some day and see what actually happens with a C64 when it gets over voltage.... But then again, I would probably get the lynch mob after me : )
@@Epictronics1 Personally I couldn't bring myself to do it but it might be interesting to apply a single memory chip to increasing over voltage and then test to see when it fails, maybe one of each manufacturer.
@@MrMaxeemum I will. The funeral will be held at Buckingham Palace and the the ashes will be spread out in the Atlantic from the aft of Titanic. There will be a full ensemble of young virgins playing the violin. It will be all over the news, you won't miss it
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...
OOERR MISSES say no more say no more, each to their own, I won't say anything if you don't me to. I like Adrian also but I'm quite happy just to watch his videos.😂🤣😂
@@Epictronics1 It almost reminds me when I was playing megarace back in the 90's and there was dog hair in the CD drive. The color palette started changing like crazy. It was like an acid trip. NOTHING has ever been able to recreate that experience. lol
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?
well, there actually exist such a thing, but I have not tried it out and I have not done my readon on it. I have been very lucky when it comes to the RAM in my Commodores
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.
There is a publishing company called Jedermann Verlag that might have had a software department in the 80s since everybody did basic books back then. But i can't say for certain.
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.
That is very likely what happened. The weird thing about this PLA is that the chip is from 1988. By that time Commodore had long sins moved to MOS branded PLA's
@@Epictronics1 The Signetics kept on making PLAs though for use in other things up to at least '93. What you have is a PLS100N, I think the ones on the earlier C64 were marked N82S100N with the S below it. The Repair shop may have replaced it with this chip in 89 based on what they had on hand and/or programmed a new one.
@@coreykirkpatrick4392 Yes, that is likely what happened. But that would also mean that "Jedermanns Software" had access to a very expensive programmer? Something like the Data I/O 2900?
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
Unfortunately I wasn't paying attention. Hopefully someone else will recognise it and answer here. Yeah, I seriously need to find one of those Vectrex! What a cool machine!
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.
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.
That was a pretty good guess : ) I don't know why, but the caps on all my C64's are still good. It's a bit strange sins I have had to replace so many caps in other systems
@@Epictronics1 Going to get some hate for this but I still prefer the sleek (for the time) look and modern light gray color of my C64C. But due to the chance of bad caps and not wanting to spend the money on an aftermarket power supply and lack of a true monitor I will probably never power it up again. Numbers started to add up when I looked at a SD adapter to replace the floppy drive and power brick and recapping and also the video adapters to correct the non standard video signals. Etc etc etc. I miss it but $500 is too much to spend to see that Ready prompt.
@@jeromewink557 Well, if you have soldering skills, you could just replace the 7805 in your brick. There are modern parts that won't fail catastrophically for less than $1 on ebay
@@jeromewink557 It is, and you are quite likely to make cracks in the case while getting inside. I just leave the old 7805 in the epoxy and screw a new 7805 down on the side of the large aluminium block inside. It's a bit dodgy but hey, it works : ) I'm planning a new vid about the brick and will show how I do it
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.
I actually bought it like this. There will be a video where we restore it. My better looking 1084 died a few weeks ago, so I had to pull this one out for this vid. I guess I need to make two 1084 videos now : )
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 wonder if they might actually be good under normal conditions but more sensitive to over voltage than other brands. Many C64's had bricks that killed our Commodores with over voltage back in the day.
@@Epictronics1 According to Bil Herd it was a problem in the semiconductor process. He says Commodore did actually sue Micron because of it, because already back in the day, they had unacceptable failure rates with Micron. The case did result in a settlement where Commodore did acquire Micron's DRAM process, so Commodore could manufacture their own DRAMs. According to Bil, Commodore ran into the same issues as Micron did suffer from, and failed to bring any DRAM chip to the market.
@@danielmantione Cool, I presume it has been discussed on his channel? Do you remember what episode? Links don't work on yt comments but I could search if I know what to search for
@@Epictronics1 Let me try to link to the video, my experience is as long as you link within UA-cam, comments don't get deleted: ua-cam.com/video/2wULKtIE-SI/v-deo.html
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!
Yeah, I was expecting some bad MOS logic for sure. I guess someone had a Data I/O 2900 in California back in 1989 :)
@@Epictronics1 New Subscriber here - couldn't help thinking If the memory chips were almost all bad, is there possibility something is wrong with the voltages on board itself that is ruining them?
@@francistaylor1822 Yes, that is a possibility. The original PSU may have gone bad and zapped those chips. The C64 PSU is known for going bad and creating over voltage. I wish I had it to test
The PLA was the victim of a chemical mixup. Interestingly, it still worked, but the life was shorter.
And with some not liking MOS, Mostek was even worse.
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. :)
Totally agree : )
First 64 I repaired had an all black screen with the line on it. Initial thought was the VIC-ii was dead, but same day I was watching and I remember hearing Adrian saying that this is often times a bad PLA. So rather than spending $100 on a replacement VIC-ii, I spent $15 on a GAL PLA and that part started working. Board had other issues, but that got me a screen I could see.
@@robertsissco2439 yeah, testing a VIC-II is difficult without a working spare board, Hopefully one day we'll get a cheap modern replacement for the VIC-II
@@Epictronics1 The vicii-kawari project looks promising. I have a Sixty Clone build with as many modern part part replacments in it as I could get to compare to original hardware (just for fun, no reason other than that), and I hope on their next pre-order to get one to put into that build.
@@robertsissco2439 Did you notice the small antistatic bag laying next to the Commodore at the security check in this video.... : )
Thanks to you both for showing us a little different perspective from Adrian's basement as well. :)
I'd be doubting my troubleshooting skills after 2 bad chips. Well done.
Thanks : )
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!
Hello Greece! I'v been to Corfu ones and I loved it! Especially the squid, fried in olive oil, sea salt and garlic. One of the best dishes I had so far! Thanks : )
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.
The fault is actually kinda cool, we used to pay money for screensavers like that for Windows.
haha, true!
You really need to get yourself a retro chip tester pro from 8bit museum. You’ll save yourself hours in testing time.
I probably should : )
12:00 C64 has become sentient and tries to communicate and you classify this as fault?!?! YOU JUST KILLED IT!!!!
lol
A friend of Adrian Black's is a friend of mine! Recently subscribed your channel! 😁👍
I do love it when multiple UA-camrs that I follow appear on each others channels! Great repair! :)
Thank you : )
duet repair show could be great!
I loved seeing the whole process, I really enjoyed this video. In other repair videos I've seen on UA-cam, 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.
Thanks : )
I'm not surprised at all that there are multiple bad RAM chips here, especially MT RAM. Nice video!
I don't repair C64s, I repair TRS-80 CoCos. But bad RAM does sometimes comes in multiples. The CoCos use many of the same DRAM chips.
Thank you : )
That was very forward thinking of them, calling it empty memory.
Repaired hundreds of these boards between 1990 and 1996 for the company i worked for back then.
cool. Do you remember what was the most common fault?
A behind the scenes for Adrian's Digital Basement wow
I actually never planned this video, it just sort of happened : )
Nice crossover dude! Love both of yours channels.
Thanks
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.
cool, do you remember if you ever looked at the label to see if it was made locally or imported?
You're Commentary during the memory faults are great, clicking the red button.... oh it's raining...
Those DK PCB's are sweet looking
Thanks : )
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.
yeah, it makes sens to put all MT RAM in sockets for sure
It feels so good to see you two TOGETHER! 🥳
Oh hello there
Just wanna say you guys dont seem nearly as scammy as other companies ive seen sponsored so yeah
@@kami-kun_va 🥰🥰
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!
Interesting, I didn't know they did great MIL stuff. The thought crossed my mind while I was editing the vid. The "brick of death" is not an unlikely cause of this boards faith. I report back on the remaining μT RAM chips after some use
That could be why the 4067 page-mode DRAMs in my PS/2 Model 25 haven't given out. I do know they used a rather unique process to make their DRAM back then.
@@douro20 A broken Model 25 is very high up on my bucket list : ) If it ever dies, please let me know : )
Maybe it's good that something as cheap and easy to replace is so sensitive to overvoltage. Because it would render the machine unusable early on and discourage people from continuing to use it long enough for the valuable chips like the VIC to get fried. And then, years later when the machine is dug out of the attic by someone who knows about the PSU issue, they can just put new RAM in it, get a new PSU, and it'll be fine again.
@@stevethepocket yeah, that probably saved a few C64s for us to play with now. Although, in my "dead parts" bin there are mostly CIA chips. Probably killed by the user with static by touching the bare connector at the back of the Commodore
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 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.
Interesting, were they MT RAM by any chance?
If i ever get the.chance to get a c64, the first thing i will do before turning it on is to check for mt ram chips and if so i will replace them and then throw them in the trash bin
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.
That is totally possible. It would have been a fun project to repair an all red-screen C64 though : )
Coming over from Adrian's basement. Hehehe.... Had to laugh when you said Adrian offered you a broken Commodore 64.
The broken Commodores are the fun Commodores : )
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.
wow, that is a lot of dead chips! The thought crossed my mind. Maybe this board suffered from the "brick of death"?
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 totally agree, he's a fun guy, I have been watching and learning from his videos for years. I had some more stuff to take care of up in Seattle, so I drove back. Thanks : )
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.
Yeah, that might be what happened to my C64 back in the day too
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."
Yeah, I also wonder if they got some help from the "brick of death"
Not just bad reputation... but also the bad quality to back it up.
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)
Thanks! Wow, you really know the C64 well! Is there a good write-up someplace where I could learn some more? : )
@@onnonius Oh, good old Programmers reference guide :) I did some reading in it way back in the day but I didn't read it all. Obviously lol. I still have an original ring binder actually. Didn't know someone made a digital copy, Thanks for letting me know
I love your accent. Those long transcients I vowels sounds so nice.
You are really in his basement next to the water heater LOL!!!!
haha, the heater yes... lol
"yellowed to perfection" very well stated.
: )
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.
I'll let you know, just keep 8-bit dancing and partying : )
Looking forward for the next couple of planned vids.
Vintage IBM servers coming up!
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.
Interesting. I have checked (and modded) my PSU. Another fault is bad power switches. I completely forgot to check this one. They can drop quite a bit of the 5v
@@Epictronics1 yeah my switch was also bad. Replacing that increased voltage slightly. Only like .2/.3 but still. When your voltage was only 3.5v (with the U2+ cart installed 4.2V without) to begin with every bit helps. lol
I have a C64 with MT ram and still going. Only had to replace some logic.
Could be that a lot of MT RAM chips died with over voltage from bad PSU's
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)
Yeah, I probably should at least put them all in sockets
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.
Welcome aboard, Leave your MT RAMs at the door : )
Only Commodore can have faults that are awesome
lol 😅
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.
Yeah, but then again, matching dates on the chips. I wonder if they were killed by a bad PSU
@@Epictronics1 : From what I hear from other comments, this seems the most likely scenario, indeed.
Well done! Great video! Thank you.
Thanks : )
I found a Jedermanns Software & Hardware in Camarillo California but couldn't find details on the business
Cool. This topic may actually turn out the be the most interesting thing about this board. The label is dated 1989 and the Signetics chip is dated 1988. Why is this chip much older than when Commodore used Signetics PLA's? Did Jedermanns program this chip?
Jedermanns is German for anyone's or everyone's. Not that that is any help ...
What a great video. Thanks!
Thank you : )
Great repair! I really enjoyed watching that.
Thank you : )
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.
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.
Sometimes when C64 Power supplies break, they fry some chips with overvoltage
MT RAMs, they make you feel like a....Dentist! I pulled 6 bad ones out of an Atari 130xe board once.
Glad to hear it was MT RAM and not teeth lol
@@Epictronics1 After removing the third MT RAM in a raw, you feel like you are pulling teeth.....😄
@@nickolasgaspar9660 😬
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.
cool, I wonder how that chip found its way to Adrian's basement
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.
Cool, The PLA was from 1988. I guess Jedermanns Software replaced the chip in 1988? The odd thing is that Commodore had long sins stoped using Signetics PLA's by that time. I wonder if Jedermanns programmed that chip? If they did... I wonder if that code could be obtained and used/modified for another ROM? thanks for the info!
@@Epictronics1 They might have done some custom work on it or, more likely, they just had a ton of spare parts in a bin and slapped their sticker on it for warranty repairs.
@@JasonPullara Well, the sticker is dated 1989 but the chip is dated 1988. So, the chip is made later than when Commodore used these Signetics PLA's...
@@Epictronics1 Guess we won't know until you dump it ;)
@@JasonPullara I did some research! Turns out it can be done! ua-cam.com/video/nicaN-IdzNI/v-deo.html
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
It's definitely the highest "bad chip" count so far...
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 UA-camrs.
yeah, a few comment below sugests that this is not an uncommon faith of Commodore 64's
ITS THE MATRIX!
Yep, And I am going for the blue pill lol
Adrian was probably using it as as a storage bin for his bad RAM chips... 😜
Haha, I'll send them all back for his next SMMC ;)
So weird seeing Adrian in someone elses video.
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.
holy cow, that is a lot of dead chips! yeah, I think it's good practice to at least put all μT RAM chips in sockets for an easy repair in the future
There is always one first, and when it goes the C64 is unusable. So that means that all the other ships go bad on their own? Or is there a voltage spike killing multiple at the exact same time or some kind of cascading. Just curious to know how this would be possible. If they go bad on their own, then it is just a matter of time before the others go as well.
@@pe1dnn Well, we wont know for sure but my theory is that MT brand was more susceptible to over voltage than other brands. The C64 power supply is known to go over spec when the 7805 goes bad inside due to a questionable design
@@pe1dnn They go bad on their own and usage of the computer has no or little influence. It's just like radio-active decay: After a certain period of time, half of the chips are gone.
If I’m repairing a C64 and I see MT RAM on it, I just remove, socket and replace the chips proactively. In most cases, if I see MOS logic chips, I do the same.
A mate bought a German Commodore with the ntsc label on it. It's pal tho!
huh, that's interesting. did it have a "made in West Germany" & NTSC label on the case?
Thanks for sharing. 😉👌🏻
Great video. Adrian is a really nice guy!
He sure is, I had a good laugh visiting him : )
Could it have been the airport x-ray damaging so many chips?
Interesting thought, what effect does an x-ray have on fragile vintage chips? : ) These chips seem to have gone bad before the flight though
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
cool, I'd love to fix an Atari XE some day : )
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.
The thought crossed my mind while I was editing the vid. The "brick of death" is not an unlikely cause of this boards faith. Perhaps I'll pull the SID off one board some day and see what actually happens with a C64 when it gets over voltage.... But then again, I would probably get the lynch mob after me : )
@@Epictronics1 Personally I couldn't bring myself to do it but it might be interesting to apply a single memory chip to increasing over voltage and then test to see when it fails, maybe one of each manufacturer.
@@MrMaxeemum I did some thinking. I think I have to make this vid...
@@Epictronics1 I hate destroying things but if it's for informational purposes I think it's worth it. Please give the poor chips decent burials.
@@MrMaxeemum I will. The funeral will be held at Buckingham Palace and the the ashes will be spread out in the Atlantic from the aft of Titanic. There will be a full ensemble of young virgins playing the violin. It will be all over the news, you won't miss it
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...
That is an insane amount of bad chips! yeah, probably zapped by a bad PSU
Pretty jealous, I wanna be in Adrian's basement as well. No pun intended.
He's a fun guy for sure, I had a good laugh
OOERR MISSES say no more say no more, each to their own, I won't say anything if you don't me to. I like Adrian also but I'm quite happy just to watch his videos.😂🤣😂
@@MrMaxeemum lol
@@MrMaxeemum No speculation here. We all know what we're thinking here, a it's probably right. Although not a crime.
@@graealex We'd better end this thread here : )
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).
He even has a Practical Peripherals modem.
cool, I didn't notice
ok this has to officially be the coolest C64 fault I've ever seen. lol
I'm surprised the MOS chip wasn't bad.
yeah, more modern computer don't offer such fun faults : )
@@awilliams1701 Me too!
@@Epictronics1 It almost reminds me when I was playing megarace back in the 90's and there was dog hair in the CD drive. The color palette started changing like crazy. It was like an acid trip. NOTHING has ever been able to recreate that experience. lol
@@awilliams1701 haha, yeah, weird faults are more fun to fix for sure : )
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?
well, there actually exist such a thing, but I have not tried it out and I have not done my readon on it. I have been very lucky when it comes to the RAM in my Commodores
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.
Interesting, thanks
There is a publishing company called Jedermann Verlag that might have had a software department in the 80s since everybody did basic books back then. But i can't say for certain.
@@cpt_nordbart Interesting, I wonder how this chip ended up so far away from Germany
this is very possible with a faulty power supply. The Commodore power bricks regulators were known to fail and kill the ram
yeah, the thought crossed my mind when I was editing this vid. I also think that's what happened with my C64 when I was a kid
10:50 take a screenshot of that, makes some funky wall art.
yeah, that would make a nice piece on the wall in my living room. I may actually do that : )
I had to replace 6 MT memory chips once on a c64 repair... they are pretty crappy!
holy crap! that's a lot of RAM chips!
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.
That is very likely what happened. The weird thing about this PLA is that the chip is from 1988. By that time Commodore had long sins moved to MOS branded PLA's
@@Epictronics1 The Signetics kept on making PLAs though for use in other things up to at least '93. What you have is a PLS100N, I think the ones on the earlier C64 were marked N82S100N with the S below it. The Repair shop may have replaced it with this chip in 89 based on what they had on hand and/or programmed a new one.
@@coreykirkpatrick4392 Yes, that is likely what happened. But that would also mean that "Jedermanns Software" had access to a very expensive programmer? Something like the Data I/O 2900?
Good video thanks.
Thank you : )
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
Thanks : ) The baking soda reacts with the super glue and fills gaps and cracks. This method is extremely durable. I highly recommend it, it's great
What is that game at 0:15?
MineStorm is a very good game which should had had an arcade version.
Unfortunately I wasn't paying attention. Hopefully someone else will recognise it and answer here. Yeah, I seriously need to find one of those Vectrex! What a cool machine!
game is Mega Turrican, also released on Amiga as Turrican 3. The whole series has incredible music
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.
Sounds like him from necroware.
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.
I probably should at least put them all in sockets knowing how failure prone they are
Lol I like your channel logo
Adrian lives near Portland, OR, not Seattle, WA.
yes, a couple of hours drive. I had plenty of time and a rental :)
West German NTSC would be for US Bases in Germany ?
yeah, that could possible be a very rare machine. He'd better not give it away to visiting UA-camr's : )
Guessing before finishing.
1 changed with temperature (capacitors)
2 wrong characters. (RAM)
I am probably wrong. Just wanted to take an early guesss.
That was a pretty good guess : ) I don't know why, but the caps on all my C64's are still good. It's a bit strange sins I have had to replace so many caps in other systems
@@Epictronics1
Going to get some hate for this but I still prefer the sleek (for the time) look and modern light gray color of my C64C.
But due to the chance of bad caps and not wanting to spend the money on an aftermarket power supply and lack of a true monitor I will probably never power it up again.
Numbers started to add up when I looked at a SD adapter to replace the floppy drive and power brick and recapping and also the video adapters to correct the non standard video signals. Etc etc etc.
I miss it but $500 is too much to spend to see that Ready prompt.
@@jeromewink557 Well, if you have soldering skills, you could just replace the 7805 in your brick. There are modern parts that won't fail catastrophically for less than $1 on ebay
@@Epictronics1 isn’t that trapped in an epoxy block?
@@jeromewink557 It is, and you are quite likely to make cracks in the case while getting inside. I just leave the old 7805 in the epoxy and screw a new 7805 down on the side of the large aluminium block inside. It's a bit dodgy but hey, it works : ) I'm planning a new vid about the brick and will show how I do it
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.
They sure are. I didn't mention in the vid, but they behaved differently when cold/hot
With that many bad chips, I wonder if it got hit with a power supply regulator failure?
That is very likely. I'm tempted to try that some day
Did the stand break on your Samsung 213T? I've had two snap.
actually no, I had it on a wall mount in my old lab and I haven't decided if I should use the stand in the new studio or not
Is it possible the West German NTSC machine was intended for the American military market in the southern sector?
Very possible. We wont know until we get hold of someone who worked at Commodore in BRD at the time
MT RAM chips are notorious for failing.
Yeah, this set was no exception : )
Did anyone notice that he said the board number was 240407.look close it is 250407.
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.
yeah, I should really at least put all of them in sockets
Could that VIC-20 have Alps switches? Please tell!
No, unfortunately not. That would have been tits though
What happened to your 1084? Shipping damage?
I actually bought it like this. There will be a video where we restore it. My better looking 1084 died a few weeks ago, so I had to pull this one out for this vid. I guess I need to make two 1084 videos now : )
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.
Could be. But the programmer that could program these Signetics were insanely expensive if I'm not wrong
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 wonder if they might actually be good under normal conditions but more sensitive to over voltage than other brands. Many C64's had bricks that killed our Commodores with over voltage back in the day.
@@Epictronics1 According to Bil Herd it was a problem in the semiconductor process. He says Commodore did actually sue Micron because of it, because already back in the day, they had unacceptable failure rates with Micron. The case did result in a settlement where Commodore did acquire Micron's DRAM process, so Commodore could manufacture their own DRAMs. According to Bil, Commodore ran into the same issues as Micron did suffer from, and failed to bring any DRAM chip to the market.
@@danielmantione Cool, I presume it has been discussed on his channel? Do you remember what episode? Links don't work on yt comments but I could search if I know what to search for
@@Epictronics1 Let me try to link to the video, my experience is as long as you link within UA-cam, comments don't get deleted: ua-cam.com/video/2wULKtIE-SI/v-deo.html
@@danielmantione It worked! I'll try to watch it today. Thanks : )
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.
yeah, I should probably just have replaced them all :)
Space needle
Yeah, great view of Seattle
I didn't know Adrien lived in Seattle.
He doesn't. A few hours drive down to Portland OR from Seattle.
"Everyman's software"?
Or the "common man's" software?