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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...

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...

Hi Dave, Suddenly my 8032 stopped to display the image on screen. It does the usual chirp, but I get only a black screen. Defined that the CRT is working, I decided to use your pettester (edit) and - surprise! - it's displaying the usual test pattern on the screen. (sorry for the scan lines...

hello friends! I have an Olivetti M10 that worked fine when I got it. A couple of years ago I tested it and I discovered it no longer booted. I found that the internal battery was leaking, so I removed it and cleaned the PCB. It seems to me no damage occurred on the board. If I move the...

hi my friends, I have a CBM 8296 that I got about 10 years ago or more, all original. She worked like a charm until now (probably it was the only C= computer that never had a problem). After a couple of years without to use her, now she's showing a strange behavior. It boots (and does the usual...

Hi all, maybe many of you already know this youtube channel; it appeared randomly on my YouTube, due to my interest for retrocomputing. Since I found it quite interesting and yet different, I wish to share it with you: https://www.youtube.com/c/ChernobylFamily cheers from Brazil, Giovi

Hi all, I have an old PETdisk (not the newer PETdisk max). Years ago I saved the 3.0beta firmware in a folder with the idea to upload it as soon as I would use the PETdisk again. Now I got back the PETdisk from its shelf and I decided to update it before to use. This ended in a big mess...

Hi all, I have an 8250 that was more or less working until now (it worked better on D1 than D0). I formatted some disks with the HEADER command and wrote some small programs just to test it. Suddenly it refused to format any other disk; I tried with some new disks, no way: I always get the "bad...

Hi all, I was trying to use an old 8250 I partially fixed some years ago (the d0 doesn't work, just the d1) and I got this funny and strange behavior: I suspect the problem is about the 8032-sk I'm using (because I tried with another 8032 without problem). I tried to replace the 6520s and the...

Hi all, I have a chiclet 2001 with a fully working romset - except for the char ROM. I order to prevent the old chips as far as possible I planned to replace them with EPROM, as I did for the RAM set. No need for a new idea: on the D'Asaro's web page you can find his clever and sleek solution...

Hi all, hoping everybody is alive and kicking, I'm here with a question: is there any modern replacement/adapter for 6520 and 6526? There more or less a workaround for almost any C= chip: the RRIOT 6530 can be replaced with a 6532 [that's still in production by Rockwell, afaik] + eprom +...

hello guys, the CRT assy of my SX-64 bit the dust some months ago and stopped to work suddenly. I replaced it with an LCD display, but I wish to fix the CRT; unfortunately I know almost nothing about CRT... Since the tube doesn't light (the filaments of the neck don't glow), I checked the...

Forget Lucifer, Commodore socket is evil :D I had a lot of issues related with the Commodore sockets, especially (but not only) the PET sockets. Contact cleaner, alcohol etc. don't solve: sometimes the problem is mechanical: loosen clips that make bad or no contact at all. So, when I'm having...

hello guys, my PET 2001 started today with an odd video problem. At first boot things seem to be stable for some seconds, than it starts to show the problem in the video below. At first the problem seemed a vertical sync problem, with the image waving up and down a little, so I tried to change...

Hi, I have a chiclet PET with all the original 6550 ram chips working, but I built the Donni's RAM adapter (http://www.8bit-homecomputermuseum.at/repair/bluepet/small/pet_ram_replacement.zip) to preserve the unavailable original RAM chips. The computer works fine with its own RAMs..... but...

Hi all! Just for fun, I made an internal RAM expander for a VIC-20, using 4x 6264 memory chips + EPROM adapter for the BASIC ROM. The idea is to plug it on the BASIC ROM socket because I have all the address lines and enough space on the left to put the board. I got the idea from an old post of...

Hi guys, I need to buy a crystal for a VIC-20 PAL. It requires a 4.433618 MHz crystal, but I can only find 4.433619 MHz crystals. Will it work? The difference is so little (just 1 Hz) than maybe it can be ajusted with the trimmers (and possibly there's some tolerance on the same crystal...?)...

hello, I have a strange problem with an Amiga 500 rev 3 I picked up from the litter about 15 or 20 years ago. It simply didn't boot (no video signal); I checked EMI406 (it is a line filter in the later revisions of the A500, but a simple 1 ohm 1/4w resistor in rev 3) and it was cracked. I put...

I finally fixed the sx-64 faulty computer board, just to discover the internal monitor is faulty, too. It worked when I got it. I left it unplugged since I was using an external monitor during the fix but now I discovered the fuse was burnt. I replaced it with another one; it didn't burn again...

Hi all, I'm trying to repair a spare 64-SX I have. The main board is a little damaged at the RAM section, so I had to fix it. All the big ICs are OK; I only have some doubts about the VIC II, since it's a 6567: I have just one spare 6567 and I can't test it (I only have 6569 based machines)...