TrevEB
Member
I have a new powerboard and all of the voltages from the original main transformer have been tested and verified within acceptable ranges.
Heatsink with 2 power transistors.
Transistor tn6057 which makes the +5vdc's work was burned out.
Replaced with an NTE247
Now, everything powers up, but fuse #3 blows out.
Yes, we have heard this one before.
However, if I remove the heatsink from the sheetmetal panel that it and the power board and sound board are mounted to, then everything is fine.
I found +30vdc coming from from the heatsink fins.
I have tried isolating the power board, heatsink and main transformer from each other and the grounding wire that runs throughout the cabinet.
No difference.
I have remounted the power transistors using the original (heat transfer plastic, or rubber?) thinking maybe these transistors needed isolation from each other?
No difference.
It cannot be normal for 30 volts to be running through the fins.
Further, I found +16vdc at the four corners of the powerboard, (the screw holes)
So when the power board and the heatsink come into contact with each other via the sheetmetal panel. ZAP!
Where is all this excess electricity coming from????
All tests are done without anything else attached to the powerboard.
I also disconnected the monitor, coin door and lighting.
Heatsink with 2 power transistors.
Transistor tn6057 which makes the +5vdc's work was burned out.
Replaced with an NTE247
Now, everything powers up, but fuse #3 blows out.
Yes, we have heard this one before.
However, if I remove the heatsink from the sheetmetal panel that it and the power board and sound board are mounted to, then everything is fine.
I found +30vdc coming from from the heatsink fins.
I have tried isolating the power board, heatsink and main transformer from each other and the grounding wire that runs throughout the cabinet.
No difference.
I have remounted the power transistors using the original (heat transfer plastic, or rubber?) thinking maybe these transistors needed isolation from each other?
No difference.
It cannot be normal for 30 volts to be running through the fins.
Further, I found +16vdc at the four corners of the powerboard, (the screw holes)
So when the power board and the heatsink come into contact with each other via the sheetmetal panel. ZAP!
Where is all this excess electricity coming from????
All tests are done without anything else attached to the powerboard.
I also disconnected the monitor, coin door and lighting.