It's great to see your troubleshooting steps in realtime as you are reasoning through it. A more challenging problem like this made for an even better video! Kudos!
Thank you for sharing your technique of using the vacuum desoldering tool followed up with hot air. These last few days I have also been working on a 250407 board and have needed to remove and check several chips during the faultfinding process. I do not yet have a mechanical vacuum gun, instead I am still using a manual solder sucker. I had always been frustrated that I could never get all of the solder out of the holes. Heating the solder joins with hot air (~240 DegC) and applying gentle extraction force after initially using the solder sucker has allowed me to remove multiple chips with no damage to the PCB and chips.
Your soldering station gives 20 flashes starting at 13:53, I think it wants to be a dead test cart rather than a soldering station like the duck that wanted to be a rooster in the movie babe. lol. Good video so far!
Adrian Black had a C64 that would sometimes pass RAM tests on deadhead cart but fail on diag cart and vice versa. Also, the reported bad RAM may not be accurate if more than one chip is bad, so absolutely recommends replacing all MT RAM because even if a chip is working now, it will likely fail in the future.
I've been wanting to replace my fan. Not because it is faulty (yet) but because it is so damn noisy. Is there a quieter version someone can recommend? I believe its voltage requirement makes it a bit non-standard.
Always love the process of going through all the possibilities. Also, yeah, as another person who repairs these, you never know what you'll get. It might seem easy. Black screen when you get it, check the PLA with the scope and yes, replace it. It boots now yay! Start testing it for a longer duration and you start getting lockups or failures several hours into testing. Got two problem children right now that take a few hours to show their stripes. :) Keep making the great content!
I really enjoy seeing your reasoning for the fault, and then the eventual solution. I have yet to get a C64, but I'll be ahead of the game when I do :-)
There are DRAM testers on eBay. I recently bought one with two ZIF sockets, it supports 4116, 4132, 4164 and 41256. Tested it only on 41256s and it works good.
Jan welcome to the Rabbit Hole Club. We all have gone down that hole one or more times and can certainly go down it again. No worries about being premature with your video release and having to take it down. It shall return and its a video you can place in the que, I got a chance to watch it and I even check the website only to find it was not available. I have to go through all my C64's to look for the board revisions I might not have in my collection so I can seek them out which is on my ever growing list of things to do but right now my focus is on wrapping up my Amiga Projects.
For testing logic ICs and in-circuit ram chip testing, you should look into Evie Solomon's Backbit Chiptester. It can also test VIC/SIDS/PLAs and the ROM chips.
Last week I repaired my first broken C64. I had persistent U1 CIA failure (indicated bad and timers didn't match). Swapping CIAs around and replacing them with new ones didn't help. I once saw bad U28 4066 indicated in the test screen but that disappeared and didn't reoccur. As I didn't find any explanation to my problem I in desperation also replaced the 4066 with a new one and the CIA problems disappeared. I didn't find an explanation why as I didn't manage to find any troubleshooting texts that linked the 4066 and CIA together in any way but ok, happy with the working machine now. But, it seems like the 4066s can cause unexpected indicated errors in other components.
Jan, your video was great, if the likes of Intel or Apple can't stop leaks, it's not a tragedy it also happens in the retrocomputing community. Nice stuff those super maximites :)
Just turned on my Plus/4 a few hours ago and it still works fine despite using MT RAM chips and every single time I encounter these, they're always senile. Except in my Plus/4!
Disregarding the fact that the ram chips were MT, how many would have been bad because of the broken capacitor? lol Nice video, I enjoyed it thouroughly.
I need to replace the cartridge port on mine. De-oxit was fixing it, but not anymore. At one point I noticed green sludge on my U2+ so obviously the contacts corroded. The replacement port should be arriving soon, but it's going to have to wait until I get through Mass Effect Lengendary edition. That gets released tomorrow and I get to see my name sake in 4K!!! I swear I did not name myself after a Mass Effect character. lol I may have changed my name legally in 2015, but using Ashley dates back to 2001. Anyway hopefully after replacing the cartridge slot my C64 will be good to go for a while. I've already replaced the MT ram chips it came with although only 1 of them was actually bad. It's the one responsible for bit value 128. I think that's like U12 maybe? Other than that it's been a good system.
I usually set it up at around 350-370C which works well for most vintage things. Be aware that the temperature controls on these cheapo hot air stations might be way off though, so your mileage may vary and you may have to find your own good temperature by trial & error. :)
Thank you for the next awesome retro repair tutorial! I have also question about resocketing Atari 800XE motheboard. Do you recommend precision or regular sockets?
Great video. This is not uncommon. If you check the schematics, color ram is connected to system bus(rom chips), VIC-II and U16. Since roms and vic2 is working that had to be the 4066 IC.
so, jetzt steht die frage im raum um was für ein neues produkt es sich handelt das bald offiziell vorgestellt werden darf. hast du vielleicht einen link auf andere youtube videos ohne selbst direkt verraten zu müssen um was es geht?
Ja, diesen Rotz hatte mein Opa schon im Keller stehen. Damals wurden Timex Sinclair Computer gekauft. Damit sind die dann rüber gegangen zu Commodore und haben einen C 64 abgegriffen. Dann kam das legendäre Modell C 16 das erstmals einen Reset Button hatte. 1200 Öken für nen C 64 war zu happig. Dann lieber einen günstigen Computer bei Aldi holen und den dann aufrüsten mit 64k ram. Voila!
I am just asking about your opinion recreating C64 or Vic-20. What you think about this: How much is changeable to create new c64/vic-20 with modern components/connectors and keep c64/vic-20 as much compatible as possible. I think, that there is nowadays ways to do C64/vic-20 smarter...
Oh, that’s already been done several times now. Most prominently, there’s the 64 Ultimate and the 64 Reloaded projects. Way earlier, there was the FPGA implementation in the C64 DTV, which is also a very accurate modern implementation of the C64. And of course there’s emulation, like in The C64 and The VIC-20.
Hi Jan, I found a new project on github called Pistorm. This looks very interesting for many Amiga 500, 2000 owner . A CPU replacement/emulation , Turbo - card for about 60 EU including the Raspberry PI. The PCBs Gerber files are available for download or you can order boards from PCB Way. The problem is the CPLD chip. It seems the chip is not available this time. Hope someone could send you a Board for a Video .
They are factory mods to protect the CIAs. I’ve seen them quite often on the older boards. The newer boards already have them on the PCB I think. Cf here: www.eevblog.com/forum/vintage-computing/c64-diode-bodge/
That does not always guarantee clearing the fault - it depends in what way the chip is faulty. If it's holding a line when it shouldnt, piggybacking wont clear it and may damage a good chip. As Jan rightfully suspected those MT chips, it was best just to get rid of them. Personally I wouldve replaced the lot in one go :)
The only question yet to be answered here is at what point do you just scream and throw the computer out of a window for not working despite doing every fix you have ever heard of?
It's great to see your troubleshooting steps in realtime as you are reasoning through it. A more challenging problem like this made for an even better video! Kudos!
DON'T BE UPSET JAN YOU'RE A Awesome DUDE
Seconded!
Indeed Jan don’t be upset you are making great content we love you dude !
C64 repairs always calm me down... so pleasant! 😁
A C64 repair is always welcome 💙
Still here either way, always love the process of fixin' any old computer especially since it's always an adventure, Danke Jan!
Thank you for sharing your technique of using the vacuum desoldering tool followed up with hot air. These last few days I have also been working on a 250407 board and have needed to remove and check several chips during the faultfinding process. I do not yet have a mechanical vacuum gun, instead I am still using a manual solder sucker.
I had always been frustrated that I could never get all of the solder out of the holes. Heating the solder joins with hot air (~240 DegC) and applying gentle extraction force after initially using the solder sucker has allowed me to remove multiple chips with no damage to the PCB and chips.
Your soldering station gives 20 flashes starting at 13:53, I think it wants to be a dead test cart rather than a soldering station like the duck that wanted to be a rooster in the movie babe.
lol. Good video so far!
The fact that it was more than a simple PLA or Micron RAM chip made the video way more interresting to watch.
I have never owned a C64, and probably never will, but I find these repair videos fascinating. Keep them coming.
Adrian Black had a C64 that would sometimes pass RAM tests on deadhead cart but fail on diag cart and vice versa. Also, the reported bad RAM may not be accurate if more than one chip is bad, so absolutely recommends replacing all MT RAM because even if a chip is working now, it will likely fail in the future.
Keep up the good work, Jan. You never disappoint.
No problem Jan, keep up the amazing content :)
Replace the broken fan of your desoldering station. My ZD-915 had the same fault.
I've been wanting to replace my fan. Not because it is faulty (yet) but because it is so damn noisy. Is there a quieter version someone can recommend? I believe its voltage requirement makes it a bit non-standard.
Jan Beta, I can never get tired or any Commodore Repairs!....or Atari...! You always do a fine job.. :) Tony K, Melbourne, Florida (Age: 50)...
I love c64 repair videos😃good you found all issues. Nice video!
Throughly enjoyed watching this repair. Good job :-) 👍
Always love the process of going through all the possibilities. Also, yeah, as another person who repairs these, you never know what you'll get. It might seem easy. Black screen when you get it, check the PLA with the scope and yes, replace it. It boots now yay! Start testing it for a longer duration and you start getting lockups or failures several hours into testing. Got two problem children right now that take a few hours to show their stripes. :) Keep making the great content!
The c64 repair episodes are my favorites - thanks!
Love it - more troubleshooting please!!
Thanks! More troubleshooting videos coming soon. :)
I really enjoy seeing your reasoning for the fault, and then the eventual solution. I have yet to get a C64, but I'll be ahead of the game when I do :-)
Nice one Jan, another one saved!
There are DRAM testers on eBay. I recently bought one with two ZIF sockets, it supports 4116, 4132, 4164 and 41256. Tested it only on 41256s and it works good.
Das ist wunderbar, Glückwunsch Jan Beta
There is an Arduino based DRAM tester. Doesn't cost a lot, definitely worth to make.
Jan welcome to the Rabbit Hole Club. We all have gone down that hole one or more times and can certainly go down it again. No worries about being premature with your video release and having to take it down. It shall return and its a video you can place in the que, I got a chance to watch it and I even check the website only to find it was not available. I have to go through all my C64's to look for the board revisions I might not have in my collection so I can seek them out which is on my ever growing list of things to do but right now my focus is on wrapping up my Amiga Projects.
8 flashes = replace all MOS Technology ICs made in 1983...
For testing logic ICs and in-circuit ram chip testing, you should look into Evie Solomon's Backbit Chiptester. It can also test VIC/SIDS/PLAs and the ROM chips.
Agreed!
I can't justify the purchase myself yet 🥺
Good job again Jan! Thanks for the vid.👍
Thank you for the links Jan. Didn't know the one with the oscilloscope pictures. Amazing !!!!!
Last week I repaired my first broken C64. I had persistent U1 CIA failure (indicated bad and timers didn't match). Swapping CIAs around and replacing them with new ones didn't help. I once saw bad U28 4066 indicated in the test screen but that disappeared and didn't reoccur. As I didn't find any explanation to my problem I in desperation also replaced the 4066 with a new one and the CIA problems disappeared. I didn't find an explanation why as I didn't manage to find any troubleshooting texts that linked the 4066 and CIA together in any way but ok, happy with the working machine now. But, it seems like the 4066s can cause unexpected indicated errors in other components.
Luckily! Everything will be fine in the end!
Greetings, Doc64!
I always enjoy your repair videos, great work Jan!
Hooray! another retro resurrection!
I saw it anyway! Don't be upset, worse things happen at sea.
Saw what?
Hopefully a TheAmiga clone by the people who make the TheC64 clone...
Bravo, Jan Beta!! Good work!
Jan, your video was great, if the likes of Intel or Apple can't stop leaks, it's not a tragedy it also happens in the retrocomputing community. Nice stuff those super maximites :)
The only blind alley to my mind was checking the vic2, other than that your troubleshooting was very good.
Great work Jan, love all your vids!
Just turned on my Plus/4 a few hours ago and it still works fine despite using MT RAM chips and every single time I encounter these, they're always senile. Except in my Plus/4!
It sucks about the video, but don't get upset. Your content is always great, and we love it!
You should look at getting an IC tester. Tests something like 13K different IC's also you can get a ram tester that tests 4164 and 4116 ram chips.
Great upload. Love the Monkey Island Shirt
Is that a three headed monkey?
Disregarding the fact that the ram chips were MT, how many would have been bad because of the broken capacitor? lol Nice video, I enjoyed it thouroughly.
Great Job again !!⭐⭐⭐⭐⭐👍
This is also my motherboard in East Tennessee, US. I am learning from you and expect to fully restore my C64... unless you're interested. NTSC.
Oh I missed the previous video, because I left it for the next day, and it was gone ! Big big mistake ! And yes I am angry ! Hahahahaha !
I guess Micron didn't always make good RAM. Nice work.
Nice stack of shoe boxes!
I need to replace the cartridge port on mine. De-oxit was fixing it, but not anymore. At one point I noticed green sludge on my U2+ so obviously the contacts corroded. The replacement port should be arriving soon, but it's going to have to wait until I get through Mass Effect Lengendary edition. That gets released tomorrow and I get to see my name sake in 4K!!! I swear I did not name myself after a Mass Effect character. lol I may have changed my name legally in 2015, but using Ashley dates back to 2001. Anyway hopefully after replacing the cartridge slot my C64 will be good to go for a while. I've already replaced the MT ram chips it came with although only 1 of them was actually bad. It's the one responsible for bit value 128. I think that's like U12 maybe? Other than that it's been a good system.
Good stuff! Well done!
Don't worry, Jan. We ALL suck at Nebulus.
Great video! At what temperature do you have your rework air gun set at to help remove chips/sockets?
I usually set it up at around 350-370C which works well for most vintage things. Be aware that the temperature controls on these cheapo hot air stations might be way off though, so your mileage may vary and you may have to find your own good temperature by trial & error. :)
Thank you for the next awesome retro repair tutorial! I have also question about resocketing Atari 800XE motheboard. Do you recommend precision or regular sockets?
Jam in all new TDK SMD ceramics.
I have an aircraft length drill the diameter of the barrel on those handpieces to remove hard clogs.
Great video. This is not uncommon. If you check the schematics, color ram is connected to system bus(rom chips), VIC-II and U16. Since roms and vic2 is working that had to be the 4066 IC.
nice video. thanks
Great video! Where do you source your replacement chips? Also what type of brush do you use to clean the board?
what are them dodgy looking red diodes on the left of the board soldered to the ground plate? Are they factory?
I was wondering that too!
Großartig gemacht! An affiliate link to the shirt would be appreciated (because I beat her too! :)
I liked the video before watching it, so whatever happens (reading the comments), I love them Jan!
It's okay Jan! I'll just watch the video again when you release it again. No worries, friend.
What are those couple of added diodes on the left side of the board?
Based on the shirt, can we be expecting a Jan-leaked fan-made new Monkey Island game video soon? Asking for a friend! Great video as usual.
Did you replace all the capacitors?
Angry? Not at all! But I am rather excited by said device! :-)
so, jetzt steht die frage im raum um was für ein neues produkt es sich handelt das bald offiziell vorgestellt werden darf.
hast du vielleicht einen link auf andere youtube videos ohne selbst direkt verraten zu müssen um was es geht?
Ja, diesen Rotz hatte mein Opa schon im Keller stehen. Damals wurden Timex Sinclair Computer gekauft.
Damit sind die dann rüber gegangen zu Commodore und haben einen C 64 abgegriffen.
Dann kam das legendäre Modell C 16 das erstmals einen Reset Button hatte. 1200 Öken für nen C 64 war zu happig.
Dann lieber einen günstigen Computer bei Aldi holen und den dann aufrüsten mit 64k ram.
Voila!
Ich liebe c64 videos, Dankeschön :)
I am just asking about your opinion recreating C64 or Vic-20.
What you think about this: How much is changeable to create new c64/vic-20 with modern components/connectors and
keep c64/vic-20 as much compatible as possible.
I think, that there is nowadays ways to do C64/vic-20 smarter...
Oh, that’s already been done several times now. Most prominently, there’s the 64 Ultimate and the 64 Reloaded projects. Way earlier, there was the FPGA implementation in the C64 DTV, which is also a very accurate modern implementation of the C64. And of course there’s emulation, like in The C64 and The VIC-20.
@@JanBeta Thanks for tip. I will check out these: 64 Ultimate and the 64 Reloaded -projects.
Hi Jan, I found a new project on github called Pistorm. This looks very interesting for many Amiga 500, 2000 owner . A CPU replacement/emulation , Turbo - card for about 60 EU including the Raspberry PI. The PCBs Gerber files are available for download or you can order boards from PCB Way. The problem is the CPLD chip. It seems the chip is not available this time. Hope someone could send you a Board for a Video .
Hm, my C64 is suffering from some nasty chroma bleed... I wonder if that could be the culprit?
You did it!
Oh, btw, what's with the elephant in the room? You didn't mention anything about those diodes going to GND on the left!
They are factory mods to protect the CIAs. I’ve seen them quite often on the older boards. The newer boards already have them on the PCB I think. Cf here: www.eevblog.com/forum/vintage-computing/c64-diode-bodge/
No sweat Jan :-D
It's all a question of socketing all ICs and then swapping them ...
Jan, why not piggyback the ram as it comes up broken in order to test quicker?
That does not always guarantee clearing the fault - it depends in what way the chip is faulty. If it's holding a line when it shouldnt, piggybacking wont clear it and may damage a good chip. As Jan rightfully suspected those MT chips, it was best just to get rid of them. Personally I wouldve replaced the lot in one go :)
I always stop when a video by Noel Llopis, Jan Beta, or Adrian Black is on YT! Electronics porn! 😝
Ben fatto jan
Oh well, it's another system that boots right into basic... put in a port expander and you're 90% there
You fight like a dairy Farmer!
I am rubber you are glue
The only question yet to be answered here is at what point do you just scream and throw the computer out of a window for not working despite doing every fix you have ever heard of?
what are these diodes to the left of the ram?😶
They're supposed to be there. From memory those particular ones shunt stray voltages from the serial bus i believe.
@@ownpj Bodged by factory :) My C64 is sadly long gone...
i said u21 and pla before i pressed play...........
DAT SHIRT
Be aware, this video has flashing imagery.
So funny: 16:43