Odd fault, dissapearing text!

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Mulbin
Vic 20 Newbie
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Odd fault, dissapearing text!

Post by Mulbin »

Can anyone tell me what's going on here? I bought this Vic a while ago and it has random characters disappearing/flickering on the screen. Seems to get worse as is warms up. It's a UK PAL machine with only one adjuster next to the graphics chip which doesnt seem to have any effect on this issue.

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mrr19121970
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Re: Odd fault, dissapearing text!

Post by mrr19121970 »

Looks like 6560 or more likely the char rom. The R has the same defect in both places.
Mulbin
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Re: Odd fault, dissapearing text!

Post by Mulbin »

Yes, the defects are consistent with each character. Is there any way to fix it? Or is this Vic just trash now? All the chips except for the graphics chip are soldered.
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mrr19121970
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Re: Odd fault, dissapearing text!

Post by mrr19121970 »

You can fix it for sure. Desolder the chip, pop in a socket and then a new CHAR ROM.

The problem is that you can't burn the CHARROM, you need an old replacement or an expensive NOS

http://www.ebay.de/itm/182592247956
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MCes
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Re: Odd fault, dissapearing text!

Post by MCes »

"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." (Albert Einstein)
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srowe
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Re: Odd fault, dissapearing text!

Post by srowe »

Do you have any cartridge games that all graphics? Running something that doesn't need the character ROM would help determine if it's that or the VIC (or RAM)
Mulbin
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Website: http://www.goforlaunch.co.uk
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Re: Odd fault, dissapearing text!

Post by Mulbin »

Just tested with 2 carts, definitely looks like it's connected to the character rom. Below are shots of Omega Race (graphics) and Adventureland (text), difference is clear. The text fades and shimmers and seems to get worse gradually.

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srowe
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Re: Odd fault, dissapearing text!

Post by srowe »

I think that pretty clearly indicates it is the character ROM. If you say it gets worse as the system heats up you could try spraying some freezer spray but I'd be looking to replace it if were mine. Is it socketed?
norm8332
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Re: Odd fault, dissapearing text!

Post by norm8332 »

mrr19121970 wrote:You can fix it for sure. Desolder the chip, pop in a socket and then a new CHAR ROM.

The problem is that you can't burn the CHARROM, you need an old replacement or an expensive NOS

http://www.ebay.de/itm/182592247956
See this thread about an adapter for a 2732.
http://sleepingelephant.com/ipw-web/bul ... php?t=7058
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