I wish I had another board to swap as a simple test :0
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Actually... both fuses blowing makes me feel better, since I don't see how one could blow and not the other.Measure with the connector on or off? I pushed the connector on a bit more firmly this time and I think both fuses are blowing now, or at least the second one just did- I could have slipped with the meter prongs and shorted across 19/20.. With the connector on now, and no 1A fuses in I am getting seemingly arbitrary voltages in th eneightborhood of 2-3V across 19/21 20/21... that seems impossible..
I'm pretty sure I am touching the stripes carefully with the meter tips..
Heh, unfortunately with the crazy wiring hackjob, you wouldn't be able to swap another board. :/I wish I had another board to swap as a simple test :0
Just thinking about this... you can skip the pull R52 test. Even if the other side was shorted to GND, with 16V across a 50 ohm resistor, you wouldn't blow a 1A fuse.2) There's only two paths for the voltage to go once it gets to the board. It can either go through R52 into 1R, or to 11A (audio amp). To blow the fuse, one of these paths is drawing too much current. Try desoldering and lifting one side of R52 out of the circuit. Then replace both fuses, reconnect the harness and power up. If the fuse doesn't blow, then it seems there's a problem with 1R. If the fuse still blows, then the problem is likely the audio amp.
While I agree that it's an ugly hack... that's on the 7VAC lines, and the problems are on the 12VAC lines.That's a pretty ugly hack. Funny how a machine that looks so clean inside can have that hackery on the game PCB. Take a really close look at that hack and make sure nothing is shorting to ground. It's likely that moving things around may have jostled the wiring. That's probably what all of that glue is there for. It was a bad job to begin with. I'd pull that PCB and repair the edge connector and go from there.
A little more imagery, info about that weird custom hard-wiring to the edge connector..
There is a blue/red striped wire coming out of the 5th pin from the left (closest to cabinet wall) on the edge connector- it comes out and is connected through a metal ring clip (grounding type?) that is not screwed to anything- also the orange wire you see coming out from that connection goes back through a connector into another wire that is soldered back to that same edge pin location on the board... Judging by the look of the blue wire connectors in this mess matching the ones used on the power cord extension I'd guess this was all done by the same person (before me).
I do not know what the heck is going on with this modification... It's funny because when you slide the edge connector onto the board it actually cannot seat all the way down onto the edge with all of the hard connections, but it seems those hard connected wires are all being spliced back into the appropriate wires coming out of the connector.. just bonkers!?!
This may all be a red herring relating to the fuse blowing since the machine has always worked fine this way before the flyback death..
1) Confirm that the voltage out of the transformer is good. The fuses can be out for this test... measure the AC voltage between the two fuse holders (on the transformer side). You should see approximately 24VAC.
Oh, and one other possibility is that C29 is shorted. With the game off, measure the resistance across C29.
DogP
resistance is zero in this case
Oh, and if the resistance across C29 reads low, it could actually be C49 or 11A causing it as well (they're all in parallel).
DogP
That means it's shorted.
I can't find C49 or 11A on the board...?
Okay, that's good.I get ~24.5VAC between the two empty fuse holders (on the transformer side)
Yep, that sounds normal.Wait- no! My mistake- when I set the multimeter to very high Ohms C29 just keep creeping up indefinitely.. So I think it is fine...
It's possible, though usually when an edge connector is burned up like that, the original pins on the harness side are pretty trashed as well. They might be good enough for a quick test though.And for the record- regarding the burned up edge connector hack- the wires that are hot-glued/soldered to the board just splice into the corresponding wires coming out of the edge connector- so it would seem I *could* just plug the edge connector into a "good" board and it would work- no?
One thing... you said that the other fuse blew once you pushed the connector on tighter... did you have both fuses in place at that time and both of them blow? I'm just curious whether you've tried replacing both fuses, putting everything back together like normal with the harness on tight, and turning it on.
It doesn't seem like you have any shorts on the board, and like you said... everything was working before, and blowing a flyback shouldn't affect the game PCB.