TECH: Punch out Video Sync Issues

shatter1

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I've narrowed down the problem to the center video board in the stack. The game plays but the video doesn't sync to either monitor. I've tried all adjustments and ruled out the monitors by using a known good game board.

I was wondering if anyone had seen this issue before.

any ideas?
 
I bought this machine from shatter1, I would like to bump the request for help :)
 
Thank you! I did actually on his site, he's on vacation from board repair. Ill give him a buzzz here
 
If sync is out on both monitors then there's an issue with the global sync generated on the video PCB (middle board). If you don't have a logic probe then I would start by replacing 6V on the video PCB. If it's still not syncing, replace 6U.
Report back if neither of these do the trick.
 
Thank you so much! I'll let you know what happens!
 
Ajcrm125, would you happen to know what is at those positions? Or link me to tech info that will show me? I won't be able to access the board for a few days, and want a jump on ordering caps, or transistors , or whatever is there ;)
Thank you!
 
I got a video of the sync issue...
I replaced 6V and a transistor at q14
still not good, I have the chip for 6U, Ill replace it tomorrow and report back

here is a video of what I am facing
doesnt get much better with adjusting the pots

http://www.flickr.com/photos/sorhp/10635575874/

thanks for any help getting this fixed~!
 
OK, Got the 6U replaced too, plugged it in and the top monitor is synced!!! But... The bottom monitor is not still :(

ajcrm125, Thank you so much for showing me what you have, can you please help me get this figured out too, I feel like we are pretty close!

Thanks again!

Heres a link to a video showing what I have

http://www.flickr.com/photos/sorhp/10654958954/
 
That actually looks like a horizontal sync issue on the lower monitor. Try tweaking the horizontal sync pot located near the middle of the lower monitor chassis.
 
That actually looks like a horizontal sync issue on the lower monitor. Try tweaking the horizontal sync pot located near the middle of the lower monitor chassis.

I did alot, never got it to stay still
 
I'll switch the cables to the monitors and see what happens, although shatter1 said he put a good one in, and the problem persisted.... Ill still do it and report back
 
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Switched the cables around to check the bottom monitor feed...

adjusted the pots to try to get the image to stand still...
http://www.flickr.com/photos/sorhp/10670253495/

then switched them, back...

adjusted the pots to try to get the image to stand still here too...

http://www.flickr.com/photos/sorhp/10670333534/

@ ajcrm125, what do ya think?



p.s. I purchased a probe, If you could give me a few pointers on where too hook op the hot, and gnd clips on the board, (while plugged in, I guess?) and what chips to search to find the problem area, I can do that :)
 
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After you swapped the cables it didn't look like the lower monitor was setting video at all.. it looked all white to me. But regardless... the lower image should have synced so I suspect there's still an issue with the lower monitor sync.

Since you're getting video on the upper monitor with the cables plugged in normally we at least know the global sync circuity on the Video PCB is working. The lower monitor's sync circuity is on the bak PCB is a single transistor with a handful of resistors.

I would start with replacing R69.. I've seen cases where a monitor goes out and takes that resistor with it. If that doesn't fix it.. then replace the transistor next followed by the other 2 resistors.
 

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I apologize, I should have stated that I did not hook up the good video feed, here is a new video with them completely switched,

http://www.flickr.com/photos/sorhp/10675281225/

I may have a sound issue with the voice "body blow" not coming through, but I can tackle that after I get this one fixed :)

Thank you!!!
Ill look into getting those transistors and resistors replaced, and report back, Thank you again!
 
@ajcrm125

I replaced R69, R68, R67, and Q13

It's Still Doing the same thing, what else should I look at replacing?


Thank you
 
@ajcrm125

I replaced R69, R68, R67, and Q13

It's Still Doing the same thing, what else should I look at replacing?


Thank you

When you swapped the cables did you do it at the monitor or at the boardset?
If you did it at the monitor and the cable is bad the symptom would just follow.
If you do it at the boardset and the symptom follows then we know it's the boardset.
 
I swapped the cables in the cabinet, not cables on the board, I'll swap those, then let ya know
 
ok, I swapped the black long cables, then fired it up, same issue
then swapped the gray short ribbon cables, fired it up, same issue, so it must be something on the board for sure.
 
Sorry what I meant was when you swapped the video cables going to the monitors dis you swap them on the monitors (where they plug into the monitor) or on the board (where they plug into the board). Lets say the video cable for the lower monitor is bad.. if youunplug that cable from the lower monitor and plug it into the upper the problem will follow., and you have no idea if it's the cable or the board. If you go the the board itself and simply swap the video cables and the problem follows.. you've taken the cables out of the loop and you know it's the board.

The reason I'm hesitant to say it's the board bis because if you look the schematic.. the same sync signal gets used for both monitors and it feeds right into those transistors. So if you've replaced the one for the lower which has no sync and are still having issues it seems like it might just be that lower monitor cable.
 
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