WG4600 verticle hold problem

BobsterD

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I have a WG 4600 that I recently recapped with a Bob Roberts kit and it really made a nice improvement for a few weeks. Over the last few days I have had a verticle hold problem, and have reached the limit on adjustment, so I can not stop it. Other than changing VR301 on the daughtercard, is there possibly something else that could be causing this, and/or should I reinstall a changed value of VR301?
 
I have a WG 4600 that I recently recapped with a Bob Roberts kit and it really made a nice improvement for a few weeks. Over the last few days I have had a verticle hold problem, and have reached the limit on adjustment, so I can not stop it. Other than changing VR301 on the daughtercard, is there possibly something else that could be causing this, and/or should I reinstall a changed value of VR301?

The screen is rolling left to right or is distorted top to bottom? You shouldn't need to change the value of VR301. If it is off that much you have a bad component elsewhere that needs to be fixed.
 
When you recapped the monitor, did you reflow the header pins on the X/Y card?
 
Yes, reflowed every connector pin on main boards as well as daughtercards. I am wondering if there's a specific adjustment sequence that i must follow... It's just that it worked great for awhile, then for each of the last few days I've needed to make an adjustment, but now out I've hit the stops.
 
How do you have the sync hooked up to the interface card? Does wiggling either the input wires or the output to the neckboard do anything to help?
 
I guess you could say that the sync is plugged in with the "standard" input plug. (White plug about an inch long, quite a few wires with the sync wires to one end). I've tried the jiggling to no avail... are there any parts in circuit with vr301 that could be falling out of spec, or perhaps affected by heat?

Bobs site mentions issues with the L351 adjustment, but also mentions the possibility of a jumper across C315. Thoughts?
 
Is the edge connector on your Galaxian game board clean? A dirty edge connector foil could be impeding the sync signal causing the sync signal to be too low for the monitor.
 
I guess you could say that the sync is plugged in with the "standard" input plug. (White plug about an inch long, quite a few wires with the sync wires to one end). I've tried the jiggling to no avail... are there any parts in circuit with vr301 that could be falling out of spec, or perhaps affected by heat?

Bobs site mentions issues with the L351 adjustment, but also mentions the possibility of a jumper across C315. Thoughts?

The L351 wouldn't be what your problem is. That is actually why I verified the directionality of the issue when I first posted. I had to adjust L351 on mine, but it was for a horizontal timing type problem that screws it up from top to bottom.
 
Edge connector seems ok... I inspected when I recapped the gameboard (for the heck of it) when I recaqpped the monitor. But I will look at it again....
 
make sure the video ground wire is connected to the ground next to the sync wire input and not on the ground near the RGB input.
 
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