Tuesday, 6 November 2018

Phoenix pcb repair

This board appeared to be completely dead at first but it turned out to be running blind. I narrowed this down to the 7407 near the edge of the board, the resistor network it is connected to was getting very hot.

After removing and replacing the 7407 with a good one I got a monochrome image.

I traced this back to the prom at ic41, the green pin was pulsing away but the blue and red pin were both stuck low. The bad 07 obviously took out the prom too.

 With a new prom burned and fitted...

The board is now fully working, repair complete.

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