Galaga Monitor AC connector plug.

barrysfarm

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I attained a project galaga cabinet yesterday and i started the troubleshooting today. i bought it as non-working.

The monitor is a Hantarex MTC 9000. I don't know if it works or not. The first problem is that I can't find where to plug the 2 pin power molex connector connects to the power supply in the bottom of the cabinet. There doesn't seem to be a female connector. Anyone know where I could find it?

The power supply appears to turn on, though it looks like someone hacked a switcher in. It's not pretty.
 
Look for the isolation transformer in the bottom of the cabinet - there should be a cable coming off of that with a plug on it. The monitor connects to the output of the isolation transformer.

It could be that a previous owner robbed the transformer/harness out of the game, or that the monitor was installed but never connected because the connectors didn't mate... you may have to change one of the connectors.

-Ian
 
You can try powering up the machine and checking the output with a meter. Or you can post pics and we can point you in the right direction.
 
How do i tell which one is which?

If it's original transformers....Midway labeled them. Look at the paper label that wraps them....one will be 120V (maybe 110 or 115) in and 120 out...the other one will be 120 in and 7/12 or 14 volts out.

Edward
 
Alright. I located the ISO, and followed the wires coming off of the output tabs. There were a few wires cut in the harness, so I soldered some wires and a molex directly to the output tabs.

Crossed my fingers and turned it on. The monitor turned on, but all I got was a vertical line down the center (on the vertically oriented monitor). After about 10 seconds, the line faded. I turned the machine off, then back on a few minutes later and didn't get the line, but the monitor chassis did start to smoke. I couldn't tell where. I unplugged it immediately. It won't turn on any more.

I disconnected the monitor and checked the voltage coming off the output of the ISO transformer. It was about 127v, so high. I'm not surprised, the transformer is extremely rusted. I'm guessing the high voltage probably took out a part on the chassis.

I rebuilt the power circuit with a new wire, new base, and a few other minor components. I hooked up the line filter and the iso transformer to the circuit and it was still reading 127v. So either the transformer or line filter is too high. I've got new ones on the way.

What part of the MTC 9000 chassis was smoking?
 
127v, unloaded, is about right. Under the load of the monitor, it will read a bit lower. I think your isolation transformer is fine.

As for the monitor smoking, it started out with a vertical deflection fault, but now it probably has something more fried. Look for smoked components, burn marks, etc. Or, plug it in again and look for the part that is smoking.

-Ian
 
Hopefully when you found cut wires and wired in you connector, you actually connected them to the OUTPUT of the isolation transformer, and not to the wires coming from either the interlock or power switch to the INPUT of the isolation transformer. If you connected the monitor to the input wiring, it's no wonder it smoked.


Also, if you get it to power up with the line again, turn it off right away....
 
I actually desoldered the broken wires connected to the iso transformer, and soldered the new ones directly to it, so no worries about connecting them to the input.

I won't be able to get back to it until this weekend, but I'll keep adding to this thread when I do.
 
I got a chance to hook up the monitor to a new harness today, as well as a new switching power supply (well..the monitor isn't hooked up to the switcher, but the game pcb is). I'm still using the old iso transformer.

When powered on, I don't see or smell any smoke, but I do hear a faint clicking noise from within the tube. I don't get an image, though I don't know for sure if the game PCB works or not. Perhaps the flyback was what was smoking and needs to be replaced?
 
While waiting on the adjustment board & east/west board to arrive, i worked on the power supply a bit. I've pretty much replaced all the parts.

I've got a switching power supply, new AC filter, and a new ISO transformer (all from bob roberts). When switched on, with game board and monitor attached the ISO output reads 137v now. That seems pretty high, right? The monitor doesn't fully come on, just the clicking i was getting before (i'm not surprised about this, since i haven't done the cap kit yet or replaced the flyback).

The old one gave out 127v without the load of the monitor. Why would the new one give out 137v? Just because it's new and not rusted over? Will this be ok for the monitor?
 
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