RE: Random Characters

From: Ed Johnson <*ejohnson.ed_at_gmail.com*> Date: Sun, 29 Jan 2012 10:01:37 -0500 Message-ID: <5855989374AD482B9C02961AA59E2D7A@dell6400> · ejohnson.ed_at_gmail.com

I don't see that chip. Can you identify it in this photo?

http://upload.wikimedia.org/wikipedia/commons/8/86/C64motherboard.jpg

-----Original Message-----
From: owner-cbm-hackers@musoftware.de
[mailto:owner-cbm-hackers@musoftware.de] On Behalf Of Gerrit Heitsch
Sent: Sunday, January 29, 2012 8:56 AM
To: cbm-hackers@musoftware.de
Subject: Re: Random Characters

On 01/29/2012 02:29 PM, Ed Johnson wrote:
> I have a C64 that displays random characters on the screen and locks 
> up when powered on. Sometimes it powers on correctly but within 
> seconds displays random characters and locks up. I bought it off eBay 
> and it worked fine for about a week of heavy use but then this problem
started.

The usual suspects in this case are the PLA (906114-01), the 74LS258, the
CIA that supplies the 2 extra address bits for the VIC and maybe the RAM.

Also, if any of the chips I mentioned are in sockets, see if removing them
and putting them back in helps.

  Gerrit

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