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Williams Space Station MPU Repair and Test

Note the fractured trace in the opening "flyover". A prior "tech" must have been prying on the chip to remove it. The fractured trace connected the IC to one of the switch matrix inputs.

Although the original problem description on this board was "no voices", after I replaced 2X 10uf caps in the sound section, voices were normal. Also replaced 22uf cap in reset section and all 3 100uf filter caps for 5/12/-12VDC.

Q77 acted shorted. Even though it tested good via diode test, I replaced Q77 and the pre-driver as I was weary from moving this board back and forth to the bench. Replacing Q77 and the 2N4401 predriver corrected the special solenoid circuit.

I am retired from my day job as a chief engineer at the Boeing Company. "Miller Time" can occur at any time of the evening... :-)