Ms Pacman WG 19" K4906 fuse blowing

Sid723

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Hey all. I think this one may have been beaten to death in several different ways, but I can't seem to find the solution out there.

I have a Ms Pac with a Wells-Gardner 19" K4906 monitor that keeps blowing the 2 amp fuse in the cabinet. I cleaned it up since it was sitting outside for a few months with the previous owner, and it was able to start at first.

I did find the C701 (1000uf, 25v) reading around 200uf and replaced it with a good one. The HOT checks out on the diode test function on my multimeter. If anyone has any other ideas where to go next, I would really appreciate the help.

Thanks in advance.
 
check the 4 diodes in the rectifier circuit.
and do a full cap kit on it.

unplug your degauss wire and your marquee lite. and see if it works.

Peace
Buffett
 
More MsPac Monitor Trouble

I have the monitor working now. I had it on my test bench and gave it power through an isolation transformer and a 3A fast blow fuse. I think the 3A fast blow is where I went wrong. Today I used a 2A slow-blow and it starts up fine.

I may have a new problem though: I currently don't have the game hooked up to the board. With the monitor on and the screen turned up, the green glow on the screen is brighter on one side of the monitor than the other. Could this be a cap failing? I checked a few of the Electrolytics and I guess I could go through and check the others too. Does anyone know off-hand which electrolytic could be causing this?

After this is I will try powering up the board and putting a signal to the monitor.
 
on a 4900, k7000, sanyo, go7, 4600 and several others. if you replace one cap its useless just replace them all.

so yes a cap kit will fix you rite up.

Peace
Buffett
 
Update:
I got the cap kit installed and I hooked it up to a picture signal from my street figthter game. The picture looks good, just needed to adjust a few things.

Next step:
Time to work on the board. I doubt that the old lady will let me take the whole game downstairs, and I don't want to work on it in the garage. So, I will take the power supply along with the boards out of the game and into the basement to where the monitor is.

Anybody know of an easier way to power the board without taking it out of the game?

Thanks.
 
Ok, monitor is adjusted and works fine with a signal from another game (Street fighter II).

I then tried to hook up the logic board and I keep blowing fuses for that. I then took my meter and checked resistance from the +5 to gnd on the board and find that it reads around 250 ohms. This may be right. It is the same even when I add or disconnect the two daughter boards. What do you guys think?

Also, I checked the regulator, all diodes and everything seems to be ok (not shorted). I was wondering if my next step is to isolate the +5 line and hook it up to see if the regulator is really giving me 5 volts to work with.

Any of you ever troubleshoot a shorted Ms Pac mother board?
 
If I remember correctly....Ms. pac used like 7vac going to the board, and it had it's own regulator onboard to supply the rest of the board the 5vdc. Maybe I didn't understand what you where saying.....where you trying to hook up the board with the jamma from the Street fighter?
 
I just used the Street Fighter video signal to test and adjust the picture on the monitor I just repaired with the cap kit. I did not use the Jamma harness to hook up the Ms Pac board.

The problem I am having now is with the MsPac logic board. I blow fuses in the MsPac cabinet when all I hook up is the Mspac logic board. I have not put the monitor back into the cabinet yet. I also disconnected the front door, speaker and everything else in the cabinet. So, with the logic board connected only, the fuses blow.

I believe they are the ones that go to the two diodes on the board that are used to rectify the 7VAC and supply the regulator.

I still have to make a trip to get some more fuses. Question was: when I do get the fuses, should I isolate the output of the regulator to see if it is indeed supplying +5.0 volts or maybe a higher voltage. If it is higher, that may be causing the fuses to blow.

What do you think?
 
OK, silly me again. It turns out, I had one of the daughter boards plugged in backwards. I corrected that and now the fuses don't blow.

I hooked the board all up and plugged the video into the now repaired monitor. Now I get something on the screen, but it is all jibberish.

After removing some of the older rom chips at 6E, 6F, 6J and 6K, I found some of the chips had missing legs, while others had very brittle legs that just fell off.

I will need to replace these roms next. The book says they are type '2532'. Does anyone know if a standard 2732 rom will work?

If so, I will then have burn the program for these chips and re-install. I also don't like the look of their sockets, so I may have to replace them also.

By the way, I don't remember if I mentioned that this game was sitting outside for about 6 - 8 months. I think that may be what rusted the rom chips. Good thing the transformers are still in good shape.

Till next time.....
 
Question all;

I know this started out as a question about my Ms Pac Monitor. Now that that part is resolved, do you think I should move this conversation to another topic section, since it is no longer about the monitor, but about the logic board.

Just wondering.
 
You probably get more detailed help on your board repair if you did. leave this thread here for future monitor repair searches, and start a new thread in general repair...
 
Thanks Modessitt, and all the rest of you for your help with the monitor issue.

I have moved the rest of the refurbish work to the "General Repair and help" section of this forum.

Good day.
 
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