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HP 9845B - S/N 1838A01653
General Notes
Donated 4/2018.
Non-functional when received - no monitor, no power supply.
Initial Inspection
Includes Eventide WMAZ-4 in undocumented WMAZ-4(3) configuration, corresponding to 3 HP 128K memory boards. Includes supplemental ROM from Structured Software Systems with PUP+, MMS and CMD programs.
The Option 100 power supply was removed from 9845T S/N 1838A06653 and (re-?)installed in this machine. Initial power up resulted in single beep, fan noise and power LED lighting on processor but no video output.
Voltage readings from the power supply test points were as follows:
- C17: 165.9V, C18: 165.7V
- +17: 17.97V, +13: 13.04V, -17: -18.06V
- +18: 19.02V, +12: 2.18V, +7: 6.98V, +5: 5.14V, -12: -12.14V, -18: -19.06V
Other than the +12 value, everything is within spec (+/-17V and 18V call for a +/-1V variation, but I'm not worried about a few hundredths of a volt). This is pretty amazing performance from a 40ish year-old power supply.
Now on to the +12V problem …
Repair
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