C64 problems

29xthefun

New member
Joined
Sep 5, 2012
Posts
66
Country
Glasgow
Region
Scotland
Hi all,
Looking for advice/info on two c64 machines I have. First one is a breadbin model 1983 REVB 250407. Switching it on gives nothing on screen but their is something going out as the screen does go black. Kind of very light distortion on the screen. Opened up the system and one of the small capacitors is split the C200 one. Also chip 906114-04 (U17) is very very hot. I have a new capacitor on order but wondering if this chip is also away?

Second is the 64C and has a flickering screen. The details on screen are all correct but as if the machine is going off and on again. I can type and the characters come up ok.

Thanks for any info/help.
 
1st one. Replace the PLA. Ask @eslapion here.

2nd one. Check the on/off switch.
 
get a dead test cart, easy to figure out what's wrong with one (if it doesn't work either CPU, PLA or VIC is bad, it only needs 3 chips to work)
If it works it may give you some hints with startup screen flashes or on-screen info.

Diagnose by picture....
http://derbian.webs.com/c64diag/
 
Little update on my C64s The PLA replacement has not solved the problem but I do now get less distortion on the screen and if I leave it on I get a screen of garbled stuff so thinking it could be a ram problem.
The newer one is still a puzzle as I put in a new switch and it still flickers off and on, now it seems to stay off after a few flickers.
Any ideas on the newer one would be great.
 
check news 13th march 2017 here
For other issues check post #6 above for the answer.....
 
Last edited:
Hi all, quick update on my two C64 machines. Got a new switch for the newer one and seems it is still flickering.
Now I am using one of those scart to HDMI things and decided to try the C64 on a normal TV that takes scart and it works great. No flickers at all so seems the box is to blame for the flickers.
The old machine I have got some output that shows the RAM chips are to blame. So will get new ones and try them.
 
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