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Monitor Will Not Sync

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ataridude74 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ataridude74 Quote  Post ReplyReply Direct Link To This Post Topic: Monitor Will Not Sync
    Posted: 16 Jul 2017 at 8:00pm
Help!!!!  ConfusedConfusedConfusedConfusedConfusedConfusedConfusedConfusedConfusedConfused

No matter what I try I cannot get sync in my Pacman cab, it rolls, blue saturation etc (see screenshot).  In fact, there is no difference whether the sync cable is in or out, pot adjustments do very little at all.

What I have already tried and ruled out:

Monitor - original G07.  been serviced and tested.  Also, perfect sync and picture when receiving input across from another PCB in another cab

Isolation transformer - monitor worked fine when used with the PCB in another cab,  using this same transformer

PCB - original Midway.  Also tried with a bootleg Ms Pac.  Both PCBs work on test bench/JAMMA cab but not in this cab

Power supply - using a switcher.  But have also fed power from a switcher in another cab and a linear supply in another cab.  Same result, no sync.

Interference from light - disconnected, no change
Interference from speaker - disconnected, no change
Interference from control panel, coin door - disconnected, no change

AC filter - disconnected, no change

Fuse - used a different fuse holder in case of corrosion, no change

Wiring from edge connector to monitor - completely rewired, no change

Sync wires - every permutation tried, tied, H sync only, V sync only, no change

Voltage - set to 5.00v at the edge connector, tried 5.10v, no change

I would ordinarily look at this and conclude there must be bad joints on the chassis PCB, but I have checked those also, plus it works with a different PCB.

It is a Galaxian cab with a G07 and Midway Pacman board, basically an original set up.  A previous owner had hacked the loom, but I have continuity tested each and every wire plus rewired the monitor wires.

I have spent hours on this and it is driving me mad!!!



(the current image is actually worse than that, but the pots were set fine for the other game)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bods Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jul 2017 at 10:21am
So to sum up

The monitor works fine connected to another cab so not faulty monitor

PCB works on and others work find on Jamma cab/test setup but not in this cab so PCB's ok

But when monitor and PCB's in the cab you get this issue

So it's got to be the wiring still then?  is the wiring info youve worked from deffo correct, there is a lot of wrong info on the Web, not saying it is wrong but worth double checking

I have Pac-Man manual I think and assume the Galaxian is same wiring? or is it same


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bods Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jul 2017 at 10:27am
I know it doesn't help with this but I had something drive me crazy once and it was only a PC and USB ports

I couldn't explain it so I know how frustrating it can be. I had PC case with USB ports on front of it, I connected them to the motherboard USB extra connections, it wouldn't work, tried the other set of pins, didn't work, I tried connecting a plate with USB on both ports and they worked so port connections good

So you would assume the cables to front or the USB sockets faulty, so I took working ports with cables from another case and fitted in this and they wouldn't work, really did my head in and one thing I took defeat on
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ataridude74 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jul 2017 at 2:04pm
Yes, monitor and PCB both fine and other potential interference sources also eliminated, it can only be wiring and to be honest someone had made a total dog's breakfast of the old loom. Only option is to start again and get rid of that loom, it's not the monitor wires as I've done those already but could be something buried in the many splices causing major interference in the chain. Or maybe even the edge connector, badly done as well. FFS - some people!!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tb2000 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jul 2017 at 7:55pm
It could just be that the PCB is incompatible with a g07, or this chassis in particular. I've seen before where a PCB has given a different or problematic output on one monitor where it's fine on another. For example I think Womble on the Aussie forums had a PCB he repaired (think it was a Crazy Kong) where it wouldn't display the right colours on his testbench monitor (a Commodore 1084 I think) but was fine in his cab.

The other option is to rip out the loom and PSU, and send that, the pcb and chassis to someone to see if they can see the fault?

Edit: can't remember if this has been asked before, but even though being original, it should have a proper video ground, have you tried putting a wire from ground to video ground?

Edited by tb2000 - 17 Jul 2017 at 8:00pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ataridude74 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jul 2017 at 8:41pm
I tried the wire from ground to video ground, no change.  I tried so many things I forgot to list them all.

I did also wonder about incompatibility between PCB and monitor.  This was my previous conclusion with the Ms Pac bootleg, but now there's an original Midway Pacman PCB in there with the original G07 monitor, as it would have come from the factory.

Also, I have linked the PCB from the Pacman across to a Kortek monitor in one cab (Crazy Kong) and a Sanwa in another cab (Galaxian), same result.  Different monitors same lack of sync.  Surely an original Pacman board can't be incompatible with three different monitors?!?

The common theme is the wiring coming from the Pacman cab, it won't work with any monitors.

Reversing the theory feeding across the signal from Crazy Kong directly into the G07 and bypassing the Pacman wiring it works fine.

It MUST be the loom, or the edge connector.  I'm wondering if the blue and sync are shorted together this would cause poor sync and blue saturation.

Defeat is not an option, if I put another monitor in there the result is the same.  Likewise another PCB, so short of getting rid of the entire cab after having done a full restoration I have to persist.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote david_orton_2000 Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jul 2017 at 11:43am
I would replace the edge connector and maybe the loom also.
You could test each wire on the loom, to ensure low/0 resistance and no shorts if you wanted to keep it.

Good luck! :-)

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Post Options Post Options   Thanks (0) Thanks(0)   Quote ataridude74 Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jul 2017 at 8:28pm
Does anybody know of a place in the UK that sells Pacman 22-pin edge connectors?  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bones Quote  Post ReplyReply Direct Link To This Post Posted: 20 Jul 2017 at 2:00pm
Just a silly one, try swapping the video blue wire with the synch, I've had this before on pacman and galaxian bootlegs
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