Punch out!! No video output to UPPER monitor yet monitor is fine!!

sugar_ray

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Punch out!! No video output to UPPER monitor yet monitor is fine!!

Weird one guys. your basic Punch out machine. It blew a fuse at the power supply. Replaced fuse and regained power. Now there is NO video signal getting to the upper monitor. The monitor itself is fine.Swapping the video output cables confirms this. Checked PCB connections all seems fine. Tried with filter on and off same results.

Where should I start troubleshooting this bad boy?
 
Weird one guys. your basic Punch out machine. It blew a fuse at the power supply. Replaced fuse and regained power. Now there is NO video signal getting to the upper monitor. The monitor itself is fine.Swapping the video output cables confirms this. Checked PCB connections all seems fine. Tried with filter on and off same results.

Where should I start troubleshooting this bad boy?

Could be that a failed IC on the BAK board is what caused your PS fuse to blow in the first place. And that BAK baord is what drives the upper monitor.
 
is this testable for the home tech?? Or do you need a bench test set up rig for the guys that work on PCB's?? What is the process for testing the IC's and pinpointing which one COULD be bad?

thanks in advance
 
Yeah it's not something you could do @ home with a multimeter etc. You'd need a logic probe for starters and would need to look at the schematic to trace through and debug the video circuitry.
 
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