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Thank you Hugo; I will open it and put the scope. It will take a while, but I should be able to record the scope signal too. BTW: I didn't know it was possible; I "knew" that when the caps are faulty, they must to be replaced. But, considering the current behavior, it makes sense. This is...

Absolutely amazing! I'm wondering if the original developers didn't even imagine that after ~45 years some smart guys would bypass the hardware limits of these machines and give them some graphic capabilities by software...

Finally I got a clip about the problem. Sorry for the dark image, it's not easy to record it; I'm using the monitor attached to a VCR, just to make things not too boring LOL Hope it can give you some clue about the problem. It seems that the problem happen only when the monitor is "cold"...

Hugo, thanks again. I didn't make a video with the issue yet, I hope I will find sometime this week. The monitor isn't cooperating with that, it's working for hours without any issue, now. I'm sure it will become to show the problem soon or later; I'm just waiting for that moment...

Well done! Proof of patience... something that only married people have LOL

Take a look at this pictures and see if some of them is similar to your problem (look at the C64 series first). https://portcommodore.com/rcarlsen/cbm/misc/pict-o-guide/

Hugo, many thanks for your detailed explanation. I tried the whole afternoon to get the problem recorded: it happened only once, obviously when I wasn't recording. As soon as I will get a video with the issue, I will post it here. Sometimes it happens many times, every few minutes, sometimes...

Hugo, sorry for the lack of information. I thought my explanation was clear, but it seems it was for me only. I'm trying to capture the problem on a video (sometimes it take a while before it does that, I'm recording the screen right now) and I will post it here a.s.a.p.; however, it's nothing...

Since you have 3 VIC-20, I would swap the VIC chips and see if it something changes. That way you could get some info about the three VIC chips; - if it doesn't change anything in the VIC-20 with the color issue (screenshot above) you will know the VIC isn't the culprit; - if you get a black...

there's a similar project on PCBway: https://www.pcbway.com/project/shareproject/DIY_AMIGA_500_2MB_RAM_EXPANSION__RETRO_VERSION_.html Yours seems to have the RTC too, since there's a battery.

A little OT about the 6510 scarcity: on github there's a project for an adapter that replaces 6510 and the 264 series CPUs with a 6502. It's a little bit tricky because of the small smd components, but it works like a charm on my C=64.

Hello, my friends, my 1702 has a strange behavior: every few minutes / seconds the image starts waving alone, like when you press the degauss button in some more recent CRT monitors. What could it be? I'm not sure if it always did it or not, I got it recently, after many years sitting in my...

I got a very damaged board, so it was really useful; and it was funny to build :-) That's not something I really need; I haven't a RAM issue, actually and I still have some spare 4164, just in case. What I was trying to do is to "convert" someway my Sixty Clone in a "modern" setup that doesn't...

Sorry for that, my fault. Yes, I've found it too but it's for the latest rev., the C=64 I wish to replace the RAM is an older rev. with 8 ram ICs. All the chips are on socket (it's a Sixty Clone, actually). Thank for the great explanation; I'm not sure I've the knowledge to understand 100% of...

Yep. I'm trying to find a way to replace the original old RAM with some more affordable and modern, but I didn't find any tutorial/guide on-line, only commercial products... I looked at my toolbox and I found many 62256 ICs so I asked here because there are cleaver guys that usually come with a...

Hello my friends, I'm wondering if it's possible to replace the 8 x 4164 RAM ICs (8k x 8 ram) with 2 x 62256 (32k x 8 sram). I found no DIY solutions for C=64 ram replacement, and since I have a lot of these ICs, I loved to make a PCB that fit onto the 8 RAM sockets, using two modern ram ICs in...

How to make a cleaning kit for 5.25" floppy drive at home (for free) Since my old websites are now done, as request by another member I'm making the guide available here. Old 5.25" floppy disks tend to leave dust and debris on drive heads. Sometimes a single bad floppy can make a difference...

I strongly suspected it, but the IC works, so I'm happy, as you told, it could be a fake. It isn't, great! :) I have few WDC spares too (of course, they could be a Chinese copy too, of course). But I didn't test a 6821 as 6520 replacement and so, out of curiosity, I did a try. And it worked...

Hi Dave! nice to read you again! :-) Yep, you're totally right. When I started to fix that PET I had no idea about what to do, and how; it was about the year 2000 or 2001, I guess, and I didn't find any info or help on the web at that time (maybe my fault, I don't know). When about 12 years...

Yep, and I already had it on my PC, but I had totally forgotten about that!!! What a shame, if I read the manual I didn't need to ask help... But the truth is that I have so many stuffs on my PC that I can't remember all (but I should have remember about the pettester manual, since I'm sure I...