Pincoder Diagnostics Inc. Version 2020.06.23.0506

ROM NAME
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02-blanking (Williams sys7)



PURPOSE
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Keeps Blanking signal alive.



PROCEDURE
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Connect a Logic probe to the MPU board as follows:

  | Black wire: TP10 (GND)
  |   Red wire: TP9  (+5V)
  |  Probe Tip: TP4  (BLANKING)

EXPECTED RESULTS
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Both LEDs on the MPU board will appear to be lit. In fact they are alternating back and forth
at 120Hz. TP 4 should stay HIGH (without pulsing). If so you can move on to the next test.

If TP4 is LOW (or is HIGH but occasionally pulses LOW) then the board is failing this test.

Check for pulsing signals on (in this order):

    * PIA1 Pin4 - If not pulsing then replace PIA1 (oscilloscope users: pulses at 120hz or
    every 8.36ms)

    * System 6: IC7 Pin6 - If not pulsing then replace IC7

    * System 4: IC7 Pin10, Pin9, Pin8 - If not pulsing then replace IC7

    * IC23 Pin12 - If not pulsing then replace Q5


    NOTE: Oscilloscope users: The signal on PIA1 Pin 4 will refresh at different rates for the
    remaining test ROMs based on how they were written and may fluctuate on those ROMs. For
    this ROM, it should perform consistently at the rate stated above.


If the above three are all good and still no blanking signal on 1J1-37 then replace IC23.

Pincoder Diagnostics Inc. Version 2020.06.23.0506
