V2000 - BALLY POKER - POWER SUPPLY BLOWING C6 - CAP

[GOS]

i have a bally v2000 poker - games keeps dropping out - when I checked the power supply I noticed the C6 (4.7mfd 25v Tant cap) was blown.  Replaced it - powered up and it blows with a bang.  The only circuit I can trace it to is the R711A diode.  Do not know how to test that diode or could there be another cause?

I AM TRYING TO FIX THIS PART MYSELF - I know who fixes them - I know I can buy one - I know where to buy the components.  Now - back to the question.
thank you.

[Amechanic]

Give Larry Weber at K-Lar, 702-363-9998. He might be able to answer your questions. They work on those old poker machine boards..

Gary

[Sunrise Side]

Bump


I have a board with same issue.


Thanks!

[Sunrise Side]

Barry, were you able to find out what was causing this?

[rokgpsman]

i have a bally v2000 poker - games keeps dropping out - when I checked the power supply I noticed the C6 (4.7mfd 25v Tant cap) was blown.  Replaced it - powered up and it blows with a bang.  The only circuit I can trace it to is the R711A diode.  Do not know how to test that diode or could there be another cause?

I AM TRYING TO FIX THIS PART MYSELF - I know who fixes them - I know I can buy one - I know where to buy the components.  Now - back to the question.
thank you.

When a new tantalum cap blows after being freshly installed it usually is either because it was installed backwards (these type of capacitors are polarized, must connect the positive end to the right place on the board) or because the working voltage of the cap is lower than the voltage being applied to it by the circuit. Since this is a 25v rated capacitor if there is a defect in the power supply that causes the voltage to be higher than 25v where the cap is connected the cap will self-destruct. If you have a voltmeter I'd say to measure the voltage where the cap is connected to see how much is there. Double-check that you know where the positive end of the cap gets connected. Someone may have installed it wrong in the past and when you replaced it you went by the old caps orientation, so the new one got installed wrong also.

I don't have the drawing of your power supply, if you can send it to me or post it here I'll be glad to take a look at it and possibly have suggestions. A diode can usually be tested with a multimeter using the resistance function. Best to remove or disconnect one lead of the diode from the circuit or board to isolate the diode from things that could affect the meter measurement. The resistance of a diode is much higher in one direction compared to the opposite direction. You can connect your meter leads to the diode and get a reading, then reverse the leads and get the second reading. Diodes are low cost, you can also just replace the suspect one to see if that fixes things.