Midway's NBA JAM pcb Video sync problem

Long Hair

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Ok, so I have an nba jam that worked with a transcoder feeding my Hitachi 51S700 rptv.
Now I have a working cab to put it in, but the video acts like there's a sync or maybe video ground problem. I can half-ass see the video but it's real wavy and distorted. Does anyone know where I should begin at trying to fix this? I was going to hook the board back up to the transcoder but, I used the jamma harness in my cab. Also the cab has a Mortal Kombat I pcb in it right now and all is good.
Thanks: Long Hair
 
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update

Well I Found that there was no continuity from sync on jamma pin to the first chip (T74LS04B1) a Hex inverter, so I added a wire and now the boot screen rom check or CMOS screen sync's up but the game still won't sync up?
 
So the test screen sync but the games does not?
Did you replace the 74ls04 or did you find an extra gate and rerouted the signal?
Maybe you should look at the chip that sends the singal to the 74ls04?
 
So the test screen sync but the games does not?
Did you replace the 74ls04 or did you find an extra gate and rerouted the signal?
Maybe you should look at the chip that sends the singal to the 74ls04?

Here are some pics to show all of you want I'm seeing. All I did was add a jumper wire pic#1.
 

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And the chip that sends the signal, I believe it to be the one circled in red. One ? could this be a symptom of low voltage on the 5volt. My fluke Multi-meter was reading 4.8volts.
 

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What kind of monitor is in the cab? I had sync issues trying to get an NBA JAM to work on a Hitatchi arcade monitor in a Japanese candy cab. Found a thread somewhere where someone said some Williams boards just won't sync with Japanese monitors. Same board worked fine on a WG I had, so I just ran it with that one.
 
What kind of monitor is in the cab? I had sync issues trying to get an NBA JAM to work on a Hitatchi arcade monitor in a Japanese candy cab. Found a thread somewhere where someone said some Williams boards just won't sync with Japanese monitors. Same board worked fine on a WG I had, so I just ran it with that one.

The tube is a Phillips and the chassis is a wei-ya 425H.
 
I tought I would do an update. I used the k4900 in my Hyper sports cab and the screen synced right up. So all so good, I tested these a long time ago. I just thought I would update this thread.
 
Good stuff! thanks for the update and being able to put a close to this issue :)
 
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