fzabkar wrote:
Measure the resistance of diode D2 near the power connector. If it is shorted, remove it with flush cutters. If there is no other problem, your drive will work without it. Just be absolutely sure your PSU is OK, as you will no longer have overvoltage protection on the affected supply rail.
If you need to replace the PCB, there is an S93C76 EEPROM chip at U5 that will (may?) need to be transferred from patient to donor. I believe you should also match the Infineon MCU, p/n UAB-M3057-HT, version V3.3PF-ROM. It appears to contain a mask ROM.
Thanks. It was shorted but removing it did not fix the problem. It looks like there is still a short somewhere. I get a kind of pulsing on the power supply now, that may have been there before unnoticed.