K7000 sync, then ground issues

jessiewonka

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I'm having issues getting this k7000 chassis to sync. After giving up on my last one, I picked this one up from what appears to be a reputable eBay seller who rebuilt it. I have RGB and GND connected, and the last pin, -h, to sync. No amount of pot fiddling will stabilize it. Tried several things, including running a fresh wire directly from sync to the pin, and two different games. Stumped!

2016-12-28-k7000.jpg
 
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that's what i think as well.

no video ground will do what your seeing.

is this a new JAMMA harness?

Peace
Buffett
 
Is the solder under the input headers good?

I gave the chassis a quick visual inspection, but not with my magnified light. In fact the box was damaged enough to poke a hole in it, but the chassis had foam around it and seemed unaffected. That said, it's obviously old and honestly I'm surprised they survive shipment even under the best of circumstances.
 
make sure the 2 ground sides of the JAMMA harness on both sides are ALL connected.

many PCB's do not have a pass threw on them and the grounds can float.

whenever i install a new harness i will attach them together just to prevent a floating ground issue.

many times the video ground is left out and is floating resulting in image problems like yours.

run a video ground to your PS where the others are and see if your issue is goes away.

Peace
Buffett
 
Hopefully the chassis wasn't damaged. definitely give a good looking over.

Was the package insured for the value of the chassis?
 
1) Chassis -- looked the chassis over again, all looks fine. Header pins look excellent and fresh.

2) JAMMA grounds -- pin 1 & 2 wires all going to ps ground, pin 27 wires going directly to ps ground, pin 28 wires going to control panel for ground.

3) Chassis ground header pins -- tried running ps ground directly to chassis ground pins, even tried both ground pins, still no sync.

4) Chassis -h & -v header pins -- tried one, tried both, still no sync.

5) All sync attempts with a) 4-in-1 multi, b) ArcadeSD, c) JROK -- no sync for all.

6) Sync attempt with Strikers 1945 -- HAS SYNC. What? How?

That said, even with sync on Strikers, there's occasional flickers in the image, and one side is curled and jagged. I think this very slight electrical ticks I hear are what's causing the flickering -- I also heard that with the last chassis which I gave up on.

Frustrated and confused.
 
The noises are slight but I think it's an indicator something's definitely off, despite the one game syncing. As I rewired this whole cab, I'm starting to wonder if I don't have something wrong at the PS. Could it be I have the wires crossed coming in/out of the transformer?

I don't know how to test which of the transformers set of wires are in vs out, and quick searches aren't showing anything yet. If I put the multimeter on them, one pair is showing 3mv ac and the other pair 9mv ac. But I'm just wandering around in the dark. I would think if I'd had them reversed all this time something worse would've happened.

Both sets of wires coming out of the transformer are black and red, and all four come from a vague area at the bottom.

Update: looking back at reference photos, it seems I'm using the same transformer wire pairing that was used when I received the game, assuming it was correct. And knowing that at the time, I had no sync issues, or really monitor issues at all. So maybe this isn't the culprit.
 
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If the monitor chassis doesn't have power plugged into it, the ps area is fine, and switching ps gives solid readings. But once the monitor chassis receives power, the crt makes slight sizzling noises and electric pops as the guns are firing. This seems to be getting worse. At most I've run it for a minute, and twice have seen smoke down around the isolation transformer, then immediately turn it off. The initial little gun pops almost sounded normal, and made me wonder if I'd just never heard it before from other cabs. It doesn't sound like the flyback, it sounds like something's going wrong in the tube.

At this point I've removed every possible complication unrelated to monitor -- no wiring going anywhere but AC > line filter > power switch > distrib block (where two lines tap off to go to switching ps) > iso trans > monitor chassis.

What kind of issue at the monitor would push trouble back down to the iso trans? Grounding?
 
Update: To further isolate the issues, I pulled the monitor entirely out of the cab, and the chassis off the monitor frame. While I'm still not getting sync, it's closer than it was, but more importantly, it's NOT making those worrisome noises, and NOT making anything in the PS area smoke (to be clear, smoke was never coming from the switching PS, but possibly just from AC wiring, or the iso trans, thereabout).

This is good news! But still, no sync, and what's going on when the chassis is attached to the frame, and the frame is inserted into the cab? The only thing the frame touches once in the cab is a metal bracket on the left side -- the only thing touching this metal bracket is an earth ground line I've got running through the cab, down to each PS part, and into the earth ground input on the switching PS. All of this was carefully done according to Bob's article. Could it be that earth ground causing issues?

Furthermore, I noticed that in this external setup, when the video pins (RGB gnd sync) are NOT attached to the chassis, I happened to take a reading off the monitor frame and get 109v AC. Uh what? Isn't that the job of the iso trans? Once even just the RGB and sync are attached, that voltage off the frame goes to almost zero.

1) no video pins connected, getting 109v AC off of monitor frame

2) all video pins connected (RGB, gnd, sync), getting .05v AC off of monitor frame

3) some video pins connected (RGB, sync, NO GND), getting 1.8v AC off of monitor frame


2017-01-01-k7000-outside.jpg


2017-01-01-k7000-outside-sync.jpg
 
Update:

1) Someone pointed out to me that you can't measure any possible voltage coming into the monitor frame by clipping on to it and the switching PS ground, so that 109v ac I was getting was incorrect. Assume I'd have to clip onto the monitor frame and some point on the chassis, tho not sure what. So assuming this art is a non-issue, tho I haven't touched the frame to verify! But again, as this is the iso trans's job, I can't see how the frame would be taking on this voltage.

2) There was a question of whether switching PS earth ground going up to monitor frame was causing some issues. When i ran a wire straight from switching PS earth ground to monitor frame, it blew chassis fuse. But isn't that earth ground setup common? Bob Roberts, "One piece of green 18 gauge wire connected from screw #2 to screw #1 will earth ground your switcher. A piece from screw #3 over to screw #4 will include the isolation transformer in this earth ground circuit. Now a wire from screw #5 to your monitor frame or any other metal in your cab will include that piece in the earth ground circuit." http://arcadecontrols.com/BBBB/acwiring.html So maybe earth ground should connect to monitor frame, or in any case shouldn't hurt if it does, but that may mean I've got something else going on.

3) At this point Strikers 1945 and JROK sync -- this works with just video sync to -h (pin 14). But a 4-in-1 and ArcadeSD still will not sync -- it's only the ArcadeSD that i care about. I've tried every combo I can think of, -h + -v, just -h, just -v, +h + +v, etc.
 
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