Hi All!
'tis my first post. I've been lurking for a while. Stumbled in to a problem & hoping I can get some insight from the many experts here?
I picked up a Vic-20 with an Arfon Micro expansion, serial #536734. It appeared to be in fair condition, minus a few keys. The PSU appears to be working, but the Vic itself isn't outputting video correctly. Just a blue screen with a black band across the top. Can't see any activity when I mash the keyboard either.
I'm wondering if anyone has experienced this or something similar, and whether or not I should cut my loses & just try find a working Vic? I'm very much hoping it's possible to fix.
You have video, this is a start. The VIC-I / 6560-101 is socketed? lift it gently and reseat. Perhaps this will help, if not then you need to replace it. Ideally you need a working VIC20 to test your ICs.
Are you happy with your Arfon? I thought these are supposed to be rare.
Ajax appears to be from Australia where the video standard is PAL and the VIC-20 video chip is probably a 6561.
Unfortunately most PAL machines have their video chip soldered directly to the board.
Also, judging by the symptoms, I would more likely consider a faulty kernal ROM or CPU; if there was a problem with the video chip, I strongly suspect there wouldn't even be a light colored screen with black bar.
eslapion wrote:
Unfortunately most PAL machines have their video chip soldered directly to the board.
Both my original PAL VIC-20s have socketed VICs. I'm guessing the Japanese-built PAL models have similar construction to the NTSC ones. The images I've seen of them* look to have all the major chips socketed.
mrr19121970 wrote:Are you happy with your Arfon? I thought these are supposed to be rare.
It seems well built but I can't really say I have an opinion as the Vic itself isn't working
I opened it up this morning & I can confirm it is socketed. I reseated all the IC's but there was no change.
I went over the board looking for anything out of the ordinary. FB11 looks a bit off, but current is still going through it. Not sure what this particular component is? Ferrite?
How difficult is it to source a replacement CPU, ROM or any other IC's?
I have a healthy supply of new old stock pal vic-I 6561-101 chips. See supermarket section.
You can replace the 6502 and 6522 with rockwell. Eslapion can make you a kernel and basic rom. Also there is a guy in Italy who makes very smart ROM replacements too.
Last edited by mrr19121970 on Tue May 10, 2016 1:51 am, edited 2 times in total.
ajax wrote:
I went over the board looking for anything out of the ordinary. FB11 looks a bit off, but current is still going through it. Not sure what this particular component is? Ferrite?
Yes, it's a ferrite bead. Looks like yours is chipped but I wouldn't think that will affect its functioning.
Do you have a tape or drive drive? If so try blindly loading, that will tell you if the CPU and I/O chips are working.
Wow! I only just saw this. I have the exact same combination, and I'm in Brisbane. I got mine for under $60 locally a few years ago now.
Mine has the same revision pcb, but keyboard has the pet-style keys.
Check and see if any of the rom chips are extra hot, also check ram chips, they should be only slightly over ambient temps.
The hottest chip should probably be the 6561, but roms and 6502 and 6522's ahould be roughly the same temps. You could try
and see what happens if You remove the 6522's one at a time.
Also I just noticed some gunk around the 7406 ic, clean that up if You can.
I modded mine for s-video, it was fairly easy and the picture quality is quite good on a LCD monitor.
