STAR WARS AVG help

ls1chris

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okotoks, alberta, Canada
recently resurrected a dead avg board , although it still has something messed up with it .
the bottom 1-1/2 inch is wiggly and messed up. please see photo's .
it is something common in the out put as when its in the grid screen and i change between the colors it shows the same systems. it also has weird systems in the red raster screen but i will have to take photos for that.
the 4-10 at 1N was burned up as the original problem.
1- not main CPU related, the problem does not show with two other working AVG boards.
2- not interconnect related , the problem persists between with any of the 3 interconnects i have.
3- no burn on any of the finger board connectors , they have been cleaned with a fiberglass pen , and the physical cond of this board is like new, i suspect it had very little use prior to failing and went to the shelf early on.
4- all V's and sense and present and proper.
unsure where to look and what to test now.
would love some input and suggestions what to test and where to look.
chris.
 

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more pics, also the amp just received a full once over with a delux build kit from Ian.
the raster screen starts out stable for about 3-5 seconds but a trapezoid shape then goes to those bouncy lines in the photo then always drops off to the left corner as seen in pic 2. the brightness is turned way down , the camera on my phone is showing it super bright like that.
 

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Last edited:
the raster screen starts out stable for about 3-5 seconds but a trapezoid shape then goes to those bouncy lines in the photo then always drops off to the left corner as seen

sure sounds like something heating up and failing
I use the back of my finger to detect heat

the hope is you can find the problem that way but short of an oscilloscope...

good luck
 
the 2nd sets of pics are from this am from a cold start in a cold canadian garage :( i do have an o-scope ) hopefully someone will chime in to give a clue where to start looking. i think the raster screen might have something to do with it.

sure sounds like something heating up and failing
I use the back of my finger to detect heat

the hope is you can find the problem that way but short of an oscilloscope...

good luck
 
im thinking it the bip pots, sprayed them down really good and cycled them a few times and now it 10X worse with no adjust ability. threw an old one from spare / old parts bin and somewhat better but the 10k pot i used is crap also. anyone know where to get those 10k square pots the atari boards use?
 
I'm pondering this one... it does look like Y bipolar or Y linearity, but only in the lower quadrant.

But that raster screen may be the key. Hmm.
 
Doug thats what im leaning to also, i did use a 10k pot , ( misread the schematics) and the raster screen did become stable. i may pull a pot off of one of next avg repair project just for testing until new ones come in. not sure what to check as in regards to the wonky raster screen. it is the Y BIP at R88.
 
swapping the pot was no change , a little better stability/adjust ability on the BIP screen. probing pin 4 of 6D on this AVG put spot killer on, on good board the logic probe does not set the spot killer off on pin 4 of the DAC @ 6D. i think i am getting closer!!
 
socketing and swapping the DAC no change :( metered out all the resistors, desoldered and checked all the caps everything checks out good. time to re-think and dig in deeper with o-scope.
 
chinook day today! t-shirt weather, lenardo dicaprio is having an anurism somewhere over it today! the culprit was 7D, picture is stable and sharp, lettering is still abit off but i am happy for now and will try 9B/C tomorrow
thanks Doug!
Chris.

So it's winter and you're in Alberta and have the game in the garage?
Heated garage, I hope.
 
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