4900 Crooked Picture

Torin

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I'm starting a new thread because this is a new problem with the cracked 4900 I've been working on.

Does anyone know what I can do to get this curl out? I have checked the yoke and it is the right version for this chassis. The chassis has been capped and B+ is reading 128.5. I have adjusted every pot on the chassis and this is the best I can get. It has a hard time syncing at all. Could a yoke adjustment get rid of this? I appreciate any ideas.

Here's the pic:
 

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Sure, here's a couple of larger pics.
 

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I don't think it's the monitor. The problem looks like it's in the board.

Look at the right edge of the screen- The raster scans all the way to the side with a straight edge.

I'd say something is wrong with the CPU board clocking out the picture data. Try the monitor with a different game to verify this.

Kerry
 
The board works fine with two other monitors. I still think something is wrong with the sync circuit on the chassis. I just don't know exactly where to look. The board was shipped to me working and was cracked during shipping. I have jumpered it to get the picture back but now have this curl.
 
Thanks, I will look closely at the H Hold Pot. From the manual, for Horizontal hold control adjustment, it says the following:

With the monitor being driven from the game signal, short TP601 and TP31. Adjust VR351 until the picture stops sliding horizontally. Remove the short.


This might be a dumb question, but how do I short TP601 and TP31?
 
Yes!

Well, I can finally put this one to bed. After spending a ton of time looking at the chassis through a magnifying glass, I found solder had bridged two connections on the IC301 which was causing the crooked screen. I might have done that by mistake when re-flowing the joints. I also found one more cold solder joint. Problem is fixed. 5 jumpers later...
 

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i knew those jumpers would serve you well:D
now you need a real project smash another one for more practice or i can mail you a poorly packed one:D

glad you found your problem cold solder and cracked traces suck.

Peace
Buffett
 
i knew those jumpers would serve you well:D
now you need a real project smash another one for more practice or i can mail you a poorly packed one:D

glad you found your problem cold solder and cracked traces suck.

Peace
Buffett


Yeah, this one sucked but it feels damn good to conquer it. Thanks Buffett for your help as always but I don't need another cracked one for practice. :) I don't want to see the back of a 4900 for a while!

Torin
 
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