GO7 issues

hindered

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I just did a complete cap kit, including fuses, hot and flyback on a GO7-CBO that has never worked since its' been in my possession. The small fuse was blown but the big one was still good prior to the cap kit. I completed the cap kit, buttoned everything up, and fired it up. Picture was beautiful, looked good except I couldn't lock in Vertical sync.

Powered everything down, looked at Fromm's flowchart that says to check a couple transistors and the IC. I came back to power up my test rig to check out the monitor a bit more and when I plugged it in, I heard a fuse pop, no HV whine. No B+. Check the small fuse, it's blown again. Fromm's flowchart says this means the HOT is shorted, but it meters good. I didn't have the chassis bolted back in and I had lifted the monitor off my test bench and back onto it, so it's possible that the chassis had slid loose and was touching the metal frame. Any other ideas? Should I just replace the small fuse and try again?

Assuming replacing the fuse takes care of the problem, what should I do about the horizontal drift? Just replace the two transistors and the IC?

EDIT: http://forums.arcade-museum.com/showthread.php?t=71984&highlight=go7+drift&page=2 This thread indicates that to the G07 I need to hook the sync up differently? It's from a Missile Command which appears to use positive sync. However, on my test rig I'm running positive sync from the JAMMA board to pin 3 of the 3 pin connector. If I'm reading this thread right, I need to run that sync to pin 3 and jump it to pin 2? Is that right?
 
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Yes, you need to jump it to pin 2 also for the G07. I guess that means you got it working again?
 
Yes, you need to jump it to pin 2 also for the G07. I guess that means you got it working again?

No sir, haven't touched it yet. Think I can just replace the small fuse and make sure the chassis is not touching the frame? I can't think of any reason why it would work and then just die besides that.
 
You might get lucky, but I had that happen once and it was a lot more complicated than just fixing the fuse. the problem is that you don't always know exactly where it grounded (unless you have a burn mark on the frame) so you have to search all over to figure out what fried.

Check to see if the filter cap is discharged before you touch that fuse...
 
You might get lucky, but I had that happen once and it was a lot more complicated than just fixing the fuse. the problem is that you don't always know exactly where it grounded (unless you have a burn mark on the frame) so you have to search all over to figure out what fried.

Lucky, I guess... It could still use a little more adjusting but I'm def not complaining. Replaced the small fuse, buttoned it back up, and here we are.

Check to see if the filter cap is discharged before you touch that fuse...

Hah yeah I found that out when doing the cap kit. Nice tingle on my hand, then nice flash when I discharged it. That sucker can hold a decent charge.
 

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More sync issues with this monitor. On my Jamma test bench, using negative sync, sync is fine. I put it back into my Missile Command cabinet (with a non working PCB if this makes a difference) and the picture wouldn't sync. MC uses positive sync. So, I figure it could be one of the following:

1: something's wrong with the +sync circuit
2: my big blue is causing the issue (it's original: http://arcadecontrols.com/BBBB/mynotes.html)
3: the game board is booting to garbage so who knows if it's outputting the proper sync

More info on the game board/cabinet here: http://forums.arcade-museum.com/showthread.php?t=150193
 
More sync issues with this monitor. On my Jamma test bench, using negative sync, sync is fine. I put it back into my Missile Command cabinet (with a non working PCB if this makes a difference) and the picture wouldn't sync. MC uses positive sync. So, I figure it could be one of the following:

1: something's wrong with the +sync circuit
2: my big blue is causing the issue (it's original: http://arcadecontrols.com/BBBB/mynotes.html)
3: the game board is booting to garbage so who knows if it's outputting the proper sync

More info on the game board/cabinet here: http://forums.arcade-museum.com/showthread.php?t=150193
Not sure if these resistors are related to positive sync, but here's a post from Ken Layton regarding 2 resistors with wrong values installed at the factory.

On some G07's the factory has mistakenly inserted the wrong value resistors at locations R314 and R317. They both are supposed to be 390 ohms, but the factory stuffed in 4.7 k resistors instead. Both these resistors are in the sync circuit. Check for this factory error first before you change any transistors.
 
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