What did I do to my Ms. Pac-Man Machine?

Waterborn

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I was working on my Ms. Pac cab last night and decided to test a back-up monitor that I had just recapped. I was already having some issues with a vertical band running through the game screen and was led to the the article over at BR regarding the original fuse holder and edge connector. So I went ahead and ordered those. The same issues (loud hum and vertical banding) were occurring regardless of what monitor I used. So I turn off the cab and disconnect the spare monitor, then discharge it to the chasis of the monitor still inside the cab. Reconnect the original monitor and nothing. I check fuses and see several in the ps blown. So i pick up new fuses today and install them. Still nothing. Checked power out of the ps (original btw) and getting around 112 on the back side of the fuses.

Any idea of what the hell I did to my machine? I wish I just left it alone and now discharged the external monitor. Where do I start to try and figure this out?

Thanks,

Dane
 
You broke it :)

Which fuses are blown, any in the 4 position block? If so, those are for the game pcb so possible you plugged the edge connector in backwards?
Test for 120v at the plug that goes into the monitor chassis. You will at least get neck glow even with no power to the pcb.
You say you have 120v on both sides of the fuses on the 2 position block fuses? If so that rules out power switch and interlocks. On power issues always start at the power cord and work your way in. If you downloaded that manual I suggested you will see a nice wiring diagram to help you track it down.
 
Got the manual. To be honest the wiring diagrams still confuse the shit out of me.

Definitely did not plug the edge connector in backwards. I am a new, but not THAT new :)

I plugged in a dead blob board and get some distorted lines on the monitor, so it is firing up. power out of the two main fuses on the 2 position block read about 112V. All power out of the four fuses on the other position block are within 1/2 V of spec. These were the ones that were blown.

I think I may have jacked up something on my board. Not sure how to go about checking that.
 
All power out of the four fuses on the other position block are within 1/2 V of spec. These were the ones that were blown.


Thats AC power and its normal for it to be a little off spec. Did you ohm out the fuses to be sure they were blown? Put your probe on the fuse holder itself when checking voltage, not the fuse. Its common for these fuse holders to loose tension, make sure they have a good connection. Do yourself a favor and replace the fuse block.
 
Check your voltage on the main pcb and see what your getting. Check across cap C3(I think)...its the smaller one right behind the two big ones. You should have +5 there +/- .2vdc
If its low check inboard side of the two large diodes and the two 1n4001's on the top right. If your power is around 2.8-3v on cap C3 then you probably have a bad transistor on the big heatsink. Replace with a TIP31, I use 31C.
If you have a good 5v across that cap then the board should run.
 
OK, I finally got around to checking some of the voltages and I am beyond confused. First, let's confirm that I am actually doing this correctly. When checking V's on a cap, I put the red probe on the + end and the black on the - end, correct?

So to make sure I don't fry my "good" ms. Pac board, I hooked up a Glob board that I know has issues but would sent a garbled signal to the monitor.

As you suggested, I took voltages on C3 first. Got absolutely .04 - .06 Volts.

http://i464.photobucket.com/albums/rr5/AOW_Waterborn/Coin-op Games/PB240002_01.jpg

Then for a lark, I check V's across the two big Caps above C3 (C8 7 C9 I think) and got the same results. I started to check other points and caught a spark which fried all four fuses coming out of the low voltage side of the transformer.

Not sure what to do at this point. I fear that I am taking these measurements incorrectly and that to continue will just cause more issues.

Another question: What does the red micro switch on the top right of pac-man boards do? If I accidentally hit this would that screw anything up?

http://i464.photobucket.com/albums/rr5/AOW_Waterborn/Coin-op Games/PB240001_01.jpg

Any additional help or ideas would be great. So frustrated right now.
 
The red button is just a reset, wont hurt anything to push it.
Want to send your board to me for testing/repair? PM me if so.
 
The red button is just a reset, wont hurt anything to push it.
Want to send your board to me for testing/repair? PM me if so.

Thanks for the info on the Red Button. Was curious what that did.

As for your offer, I will keep it in mind. I am a stubborn "do it myself" type of guy and want to figure this out on my own if possible. My guess is that there is some kind of issue with the power supply/transformer on this cab. I want to eliminate any possible issues there before giving up or fixing this board. No use sending the board out for repairs only to have it get fried as soon as it goes back into my cab.
 
The only thing in the bottom of the cab that usually goes bad is the fuseholders. The transformer could go bad but that would be a VERY rare case. As long as your fused right your not going to cause damage to the pcb.
Since your not getting +5 on the board you need to check and make sure you have AC voltage coming into the pcb. If all 4 legs have power then no need to check anything in the bottom of the cab. Do yourself a favor and replace the fuse block now whether they look good or not. If you have ac coming in, check all 4 diodes and make sure they are good. Put an ohm meter on both of the ceramic resistors and make sure they are good.
 
New fuse block from BR should be here tomorrow. Do you have a schematic for which leads on the board are the 5+ & 12+? Also, exactly what fuses should go into the 12V & 7V fuses spots? The closest I can find around here are 32V fuses. I will wait for the fuse block to arrive and then start testing everything.

Thanks again.
 
Well, installed a new fuse block and edge connector and still nothing on the screen. In an attempt to figure out what is up, I just checked the voltages going into and out of the fuse block and they seem off. To check these voltages, I am placing the red probe of my multimeter on the connections in/out of the fuse block and then the black probe on a common ground. Is this correct? I get 12 V for the first one, 7.9 V for the second, 9,2 V for the third and 1.2 V for the fourth (they should read 12V, 12V, 7v & 7v respectively). Am I doing something wrong in measuring these or is my transformer fried?
 
Your measuring it wrong. Look at the transformer and there are six lugs on top, two pairs of three. The middle of each three are the neutral for the hots on either side of it. Make sure your meter is set on AC. If it were me I would just check on the inboard side of the 4 diodes of the main board for DC voltages. If you got it theres no need to check all the stuff before it.
 
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