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vic-20 issues

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pighair47

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Sep 16, 2012
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i recently got a vic-20, i was told had rf issues, i made a video cable for it but now it all it shows is a light blue border, with a gray inside the border and nothing else, every soo often a partially filled yellow box like a cursor will flash on the screen, pushing the keys on the keyboard seems to add more yellow boxes to the screen sometimes. any idea where to start trouble shooting ?
 
using that guide it looks like it could be ud7 901460-03. how would i go about testing that chip?
 
azog said:
It almost sounds like you're getting some video, so how adventurous are you? I currently have two VIC-20s, and each of them needed the pot tweaked to properly display on an LCD monitor connected to the video port (composite video, not RF video). You can find some pix here: http://sleepingelephant.com/denial/wiki/index.php?title=Video_signal_adjustments
Click to expand...


i saw those pots when i was poking around inside looking for any obvious failures and considered adjusting them, but didn't have any clue what they were so i didn't touch um , i will try adjusting um now that i know what they do.
 
UE11 901486-01 ROM BASIC
Startup screen with borders but no characters. Disk commands do not
work, but game carts still work.
Click to expand...

To test it you need to replace the chip or build an adapter and read your in a eprom programmer to see if it's correct.
(And yes, it probably is your problem.)

Later,
dabone
 
i ordered the 901486-01 and 901460-03 seeing as they looked to be the culprits, i never thought of reading the chip out. -_-
 
i replaced both of those chips and still nothing any other ideas ? i have tried it with two different carts too.
 
OK, so you see the correct colours but a mostly blank screen, right? If not completely blank, can you post a picture?

My next suspect would probably be RAM.

rob
 
To me it looks like a bad vic chip.


UB7 6560-101 VIC VIDEO/AUDIO
White or blank screen, garbled or no video, screen full of (or few
random) "garbage" characters. "Blind" disk commands may still work.
Partial failure: Dark or smeary image, loss of color, garbled or no
sound, game paddles or light pen doesn't work.
Click to expand...

Later,
dabone
 
Another, otherwise dead VIC-20. If the 6560 is socketed, it is somewhat easy to swap between a known good chip (if you would have one available) and see if it makes any difference. Some resellers of vintage chips may have loose 6560 chips, it could be worth checking if you can't get hold of another machine (at least to borrow) locally.
 
okay i picked up a second non working vic-20. the new broken vic i got sends out no video with its 6560, i put the 6560 in from my vic and get the same result soo is that chip the likely culprit ?
 
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