Re: 6561-101

From: Clockmeister <>
Date: Wed, 26 Oct 2016 09:00:28 +0800
Message-ID: <>
On 26/10/2016 4:38 AM, Hegedűs István wrote:
> Hi,
> It has black screen of course. I know that the Kernal ROM or VIC used 
> to be the guilty ones. I have burnt a 27c128 with Kernal but still 
> have to build an adapter so I cannot 100% rule out Kernal issue. The 
> guy who sold it said that the 6502 is also sick (he has tried the CPU 
> in an 1541), though with oscilloscope I have seen e.g. proper phi2 
> signal coming out. I have bought some Rockwell 6502s to replace it. 
> Anyway even if it turns out that VIC is good it is better to have a 
> spare IC.
> I should hook up my logic analyzer to it but so far I had no time (or 
> I was just too lazy).

Whilst mask ROM (and RAM for that matter) failures are common on vintage 
equipment, the last two VIC-20's with a black screen that I repaired had 
a bad 6561-101.
In my case both were easy to diagnose by simply plugging in a cartridge 
or blind loading a game. On both occasions the game you could hear the 
game playing even though there was a black screen.

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Received on 2016-10-26 02:00:02

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