Fireball Classic
Bally, 1985Working on a machine for someone. All the displays are "doing the wave". Trying to link a video. the digits change brightness right to left in a sweeping manner.
My first thought is AC ripple, but I am not sure if this would cause the displays to alternate brightness all digits at once or if it would cause the sweeping pattern.
Any and all advice is greatly appreciated!
Solenoid driver board C26 filter cap failure or is out of circuit from connector issue seems likely (isolated ground return wire back to rectifier board). The wave is the display interrupt and the zero cross going in and out of phase.
I got to do a little investigating, the voltage at tp4 reads about 160v, at tp2 it's down to about 125 v. On tp4 switching to ac voltage I see over 300 volts. So I am guessing that the filter cap is definitely shot. Would that also drop the DC voltage down on tp4? Just wondering if I also need to rebuild the power section or if I just need to replace the filter cap?
Replace the cap, then re-check the output to see that it's what you have it adjusted for. If so, you’re done. If not, then troubleshoot and repair the rest of the circuit. No need to repair something that isn’t broken.
Quoted from Mthomasslo:Replace the cap, then re-check the output to see that it's what you have it adjusted for. If so, you’re done. If not, then troubleshoot and repair the rest of the circuit. No need to repair something that isn’t broken.
I have to order part(s), that is why I was asking. I want to avoid paying shipping twice as well as waiting for a second order...
Disconnect the coin door and see if the wave goes away. If it does you have a switch shorted to ground on the door via its diode. If it doesn't it's likely the cap.
Quoted from slochar:Disconnect the coin door and see if the wave goes away. If it does you have a switch shorted to ground on the door via its diode. If it doesn't it's likely the cap.
I could see that possibly dragging down the dc, but it wouldn't cause the 300v ac on TP4 would it?
Quoted from mrarcade:I could see that possibly dragging down the dc, but it wouldn't cause the 300v ac on TP4 would it?
Yes it will cause that. It's probably more in the 200 - 250 vac range, but your meter is probably improperly displaying 300 due to its inability to accurately convert the 120 HZ pulsating DC into a valid RMS AC reading.
Quoted from mrarcade:I have to order part(s), that is why I was asking. I want to avoid paying shipping twice as well as waiting for a second order...
Definitely a legit concern, maybe ordering one of the kits from Big Daddy or another Pinside advertiser would be a good idea, you'd get the cap that's needed for sure, and have the rest of the parts, "just in case"
Per post #2 by barakandl , your C26 filter cap is out of circuit. This is the reason you're only measuring 160V at TP4 because it's not filtering the DC ripple.
If you measure zero volts across the cap, it either has bad solder joints or there's a bad connection on the white ground wire to the cap either at the solenoid driver board on J3 pin 3 or less likely the source at the rectifier board at J3 pin 7.
Suspect C26 itself only after you confirm it has in range DC voltage across it.
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St Marys, OH