S-plus/Barcrest Top dollar help needed.

[David G]

The other thing that is confusing me is,

 based on az slots post that I copied and pasted... and I am sure he is correct because I am not.

pins 3 and 4 should read  minus 12.1 vdc  and i get that on pin 3 but pin 4 reads zero.. and that should be minus 12.1 vdc as well.
 So with that said where am I getting the positive 12 volts to even power the bulbs? Is that where pins 8&9 come in with the positive 34 volts  for the power?

[David G]

Here is a bigger pic. hope it helps, Notice further change to the resistors especially the second burnt one from the left. compared to previous pic above.

[cowboygames]

It's a matched pair. One should be 12v+ and the return line should be 12v-. If you're missing the return line then something in the circuit is shot and the loop isn't complete

[David G]

Since my testing I have never had a POSITIVE 12 volt DC. at power supply
So are you saying,  the post that shows pin3 and 4 as negative 12 volts from az slots is incorrect?


my pin 4 shows negative 12.1v.. which is the return.. my three pin reads zero which you are suggesting should be positive 12.1v ?  if that is what you are saying, then wouldn't that suggest a bad power supply
BECAUSE  the power supply is not putting out 12 volts positive at pin three and the only place to get power would be the power supply?

This all suggests to me that p/s as well as the mpu4 board are no good.



   

[cowboygames]

I would have been more likely to suspect a missing -12v before a mission g +12v, kinda weird. Can't you try and trace the +12 back into the power supply? Might be something burned up on there. Two negative 12v supplies can't be right

[KirkLasVegas]

It's been years since I owned one of these.Going from memory it's a "Strobed" type of deal. You have a X buss and a Y buss..several of them. It pulses a X transistor AND a Y transistor at the same time to light a single lamp.If I remember there are diodes mounted by the sockets.
The failure mode of the resistors bothers me. While they DO tend to run warm this is NOT the failure. I would replace them anyways and stand the new ones up off the board by a 1/8 of an inch.
So WHAT is the failure? I bet it's a burnt molex pin (seen it several times before in slots and pinball machines) or the 34 volt supply can't deliver the current needed to get the job done.You need to get the topbox into the "Test" mode where it flashes ALL lamps.Shorted transistors results in blown lamps or lamps that are on when they should not be.
Either the 34 volt supply has failed or something is sinking it badly (shorted capacitor).With the machine off..measure the resistance from the 34 volt line to ground. It should be close to a open circuit.
Unplug the connectors on the topbox power supply...a few times and reconnect to make sure it's not in that connector.Look at it this way, if the lamps draw 250 Mils each and there are 30 of them..it's 7.5 amps thru a molex pin..they get hot..they lose spring tension, they burn up.
Test mode will flash ALL top box lamps at the same time and might help you find the problem...


Kirk

[David G]

After all this time, MY TOP DOLLAR is up and running! The problem was the top box power supply. I picked up a barcrest mpu5 power supply (sps045w) because the original power supply(sps036l) appear to be very hard to find. and re pinned the molex. Today I Finally got the last piece of the puzzle, (the CHIP par sheet)  Thanks to Alex for that! I also want to thank each and every one of you who added your two cents,  as it was, you were all correct! Cowboy a special thanks to you as you were there the whole time.  Moderator, please mark this problem as solved.

Again Thank you all 

[shortrackskater]

Good to hear! You got the best help. 
Post a picture of your working Top Dollar.