wei-ya tri-sync chassis unresponsive to horizontal width and pincushion adjustments

Jaelus

Over Top Auto Mechanic
15 Year Member
Joined
Apr 1, 2005
Posts
867
I picked up a used replacement Wei-Ya chassis M3129D01-7 (tri-sync) for my AWSD since the old chassis had some major sync problems, poor quality on 15k, and bad flagging on 31k. The new chassis has a solid quality picture on both 15k and 31k and syncs instantly, however, adjustments made to the horizontal width and pincushion only affect the center third of the screen in a horizontal bar.

If I adjust the pincushion pot from one extreme to the other very quickly, it will work for the whole screen for a split second (while I'm adjusting it), but then revert back to just the center third. The horizontal width only affects the center third (and only to a small degree) no matter what I do. The top and bottom thirds of the screen are always set to full open horizontal width and pincushion.

I inspected the adjustment board for defects and found none, but I reflowed the solder points anyway just to be sure (no difference). I also swapped out the adjustment board cable with the one from my old chassis (no difference). While my old chassis sucked, it didn't have this problem, so I have some spare parts if need be. There's no obvious damage on the chassis and it didn't have this issue on the monitor it was pulled from.

Any clue as to what might might cause this issue that would narrow my search would be greatly appreciated.
 

Hewitson

Metal Slug Mechanic
Joined
Mar 6, 2008
Posts
2,198
Its usually worth replacing the cheap pots they put on these adjustment boards. Check they are working correctly with a multimeter.
 

Jaelus

Over Top Auto Mechanic
15 Year Member
Joined
Apr 1, 2005
Posts
867
I would really be surprised if it was the pots. They were working just fine with the old chassis. I'll check them to be double sure though.
 

pzlate

n00b
Joined
Sep 9, 2017
Posts
3
I know this is an 8 year old necro but I had this same problem with the wei-ya universal chassis and I fixed this.

The solution to this is a very simple fix, replace the dip20 IC that's inline with the adjustment pots, HA11235 is a suitable replacement. Wei-ya uses a DBL2009.

So my issue was very similar, h hold was super sensitive, h pos did nothing. When h-hold did lock it was super offset. I noticed brightness would adjust when I adjusted h hold. All the passives on the board looked fine, the only outlier was the IC, swapped it from one of the chinese clones I had and it fixed it. Once again, sorry for the 8 year old necro.. this was the first result in google and I'd like it if this post had the solution.
 
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Heinz

Parteizeit
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Feb 13, 2005
Posts
22,333
Thanks for the answer, too many of these threads end with no solution.
 
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