Commodore Fixty Four (Another Black Screen Repair)
HTML-код
- Опубликовано: 26 окт 2024
- If you would like to support the channel via Patreon (keep the channel running) - / gadgetuk164
You can also buy me a coffee or donate via Ko-fi - much appreciated! ko-fi.com/gadg...
Merch is also available - gadgetuk164.my...
Yet another black screen C64 repair! Thanks to both ElectronAsh and Plan C for parts used in this video.
Plan C - / antidote21984
#commodore #c64 #repair
![Intro to Tool Dev in Unity - An Improvised Live Course [part 1/4]](/img/1.gif)
Regards the CIAs - it will boot without them, you wont get a screen without text though (when both are removed) - Basic causes that screen without text issue. As seen on the next video!
Love these c64 repairs. Missed them. Good to see them being covered again 👍💯
Outstanding video as always. Always love seeing these old machines getting fixed up and put back into top order by you. Thanks very much for the shout out! I really appreciate the mention. Glad the PLA helped to get another C64 going! Love that music too.
Thanks for sending that PLA =D The little message on it made me LOL too =D
"Of course, in the dark, it looks even better".... That's what sh... I'll get me coat.
MT RAMs *and* MOS 77xx logic chips in the same machine? That's one unlucky breadboard err I mean breadbin.
Yeah I had a black screen C64 once where I couldn't find the fault (all outputs on the 257s were toggling). I just got an In-Circuit Chip Tester (DIT ABI 24), I used it on the LS257s and they failed with different patterns. I tried it on a working machine and the 257s failed with the same pattern. So I swapped the one that was off and was greeted by the Blue Screen Of Life.
When you get the out of memory error you can often determine the bad chip if you also get random characters on the screen. In your case you could also see reverse space on one part of the screen. The screen code for space is 20 in hex and a reverse space is A0. This indicates that bit 7 is stuck high for some addresses.
Good point!!!
Bel lavoro al C64,ottimo video!
To clean the case, I use oven cleaning foam. I let it act for 1 minute then I immerse it in soapy water. I scrub with a soft sponge. The result is awesome. I dismantle everything beforehand. :)
Always great videos and another C64 lives for another day :) And those GAL based PLAs are a life saver!
Loving the Last Ninja tunes while you work.. Very nostalgic.. Im fixing an 800xl with a ram fault.. Guess the make ...lol
Atari 8 bit computers also often have a combination of NEC and MT RAM chips.
Great idea about the turn-pin chip condom! :-D
LOL, I never thought about it like that!
Nice attention to detail good job and interesting to watch.
Thank you very much!
i wonder if the badge couldn't be completely fixed by putting it in between two soft wood blocks and clamping it down in a vice?
Great repair as always, and the info you pass on is equally important, well done that man. You touched on the issue of loading disk files from the Kung Fu flash etc, there will always be issues like that across machines. On the atari we have a cart called AVG and it like the 1541 ultimate uses a cable to go in to the SIO (IEC 64) to allow hard coded titles to still work as they are still using the bus for that machine. That's why I have an avg and a 1541 ultimate ++, almost 100% compatible..Anyway, looking forward to some more C64 content...Keep safe..
11:33 Nice to see an Atari donor help save a c64 life! 😁👍
Nice! Another C64 repaired with a PLA20V8 :) This machine had everything that breaks: A PLA from 1983, Micron RAM and MOS logic chips. This won't be its final repair.
Thanks for the video, I've loved it.
Thanks!
Thanks!!!! Super appreciated =D
Awesome video. I've always found it safer and easier to cut those garbage chips out and remove the legs with tweezers. Those Mt chips belong in the bin anyway.
Those MT-branded chips are empty; there’s nothing inside - that’s shy they’re always bad. The person who decided using them was a good idea was MT-headed. Totally vacuous. Probably a bean counter. 😂🤣
Wait. A Commodore 64 with a black screen? How unusual :-p
Hehe =D Guess what the next C64 repair is?
@@GadgetUK164 lol
You mentioned being from the industry a couple of times Chris, care to elaborate? The reason I ask is that I was also in the industry but a bit earlier than you (heading towards pipe and slippers time here). Apart from technical Atari computer sales I was also working for a certain company that I know you will know, Maplin Electronics, I was management for them in London after the they dropped home computers from their line up. Interested to hear what line you were in but from your knowledge I'd guess engineer / computer support (but real IT, not a script reader, a genuine hands on guy with the qualifications.). I loved growing up and working with the home computer launch, met most of my programming heroes, even sold a certain Archer Mclean his first disk drive. Far too many long stories to go in to but I love hearing from others that navigated the industry.
=D I started working for an electronics repair (and component sales) shop - Eteson Electronics. That was whilst studying electronics. I then moved to a local computer repair company. From there I took over that business and ran it for a few years, but eventually left and moved to a larger repair business - to get more experience. Running it on my own for that period of time was great and all, but the senior engineers had left and there's only so much you can learn on your own. Incredible to have met Archer Mclean! =D
@@GadgetUK164 Well as we were an Atari centre it was sort of natural, we got loads of celebs and devs in, Fergal Sharkey, Linford Christie etc etc, plus we were just down the road from the BBC so they came to us..
(@37:23) - look, CommodoreCoin - a new cryptocurrency. 😏
To clear up the confusion about PLA20V8 GAL timing: Both the 20ns and 15ns GALs can be used to build a compliant PLA and whatever you choose, it will not cause RAM problems. There have been very few problem reports for both...
... however, here have been some boards with 200ns RAM where KERNAL replacement cartridges didn't work. In these cases switching to 15ns GALs proved to be the solution. This isn't a general incompatibility problem with 200ns RAM, normally you get full compatibility for both speed grades.
I didn't think it was correct to screw down the 12v voltage regulator, had the previous owner done that by mistake?
It's just optional really on the 7812! It doesnt really need screwing down as it doesn't get that hot, but it doesn't hurt to screw it down!
@@GadgetUK164 I was under the impression that the heat generated if dissipated through the board when screwed down can radiate its way towards the VIC II chip and cause failures further down the line. I've seen the 12v voltage regulator to be over 50ºC in operation, so I would be reluctant to do it. However, if anyone has had their 12v reg screwed down for years after 100s or 1000s of hours of usage without a VIC failure then fair enough, but it may be one to look into further though.
You know, looking at the C64 logo thingy you fixed, it’d be cool if the rainbow-colored parts were actually oLEDs, and modify the startup sequence (in the Kernal ROM) to light them one at a time, then all on, then you see the C64 basic screen. If there’s a RAM fault, it could indicate it with the color of LED it stops on, sort of like the colored screen, but would work even if the VIC II chip (or the RF modulator) was bad! Damn. Now I may have to get a C64, a Raspberry Pi nano, and an oLED display, and do some hacking. But with the chip shortage, this project will have to wait. 🥺
That would be cool =D
👏🏼👏🏼👏🏼
Is the dead test program always accurate? I've got 2x C64s - a C64c and a 1983 model and it reports the same problems with both of them but they work 100%: games, Commodore BASIC etc.
What problems does it report with them?
@@GadgetUK164 "BAD" for SIDs and CIAs U1 & U2 but demos, games, BASIC, joysticks etc. all work. (I don't have the harness setup to test further.)
@@captaincorleone7088 That's exactly what I was trying to explain in the video - when the test harness isn't connected, it will report the SID and CIAS as bad, when they aren't. So it sounds like both machines are OK.
@@GadgetUK164 Thanks, I appreciate the answer and the clarification! One other question if you've experienced this, the SID on my 1983 Breadbin has a constant high pitched tone when sound is played. Is that a normal quirk with these ageing ICs or does it need replacing?
Hi love your videos. Do you have a website or way to get in touch for repair work? Not sure if you just make videos or this is a business for you. Thanks Jamie
Hi, thanks! Sorry I don't offer customer repairs at the moment!
Also replace the 7805 with a TSR-1 2450.
I am reluctant to swap the linear regs with DC2DC - Jan Beta did that (and I tried at one point) and you get audible noise on the SID, and video too. It's basically the high switching noise.
Replace them there ceramics.
You could, but there's no real advantage tbh - other than perhaps lesser tolerance on modern parts.