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NOTE: Always check for latest ROM/ECO upgrade, refer to schematic notes and ROM chart. If socketed IC is suspected bad, be sure to check socket with ohmmeter.
No LED's on power up.
  • Is Power cord plugged into wall outlet correctly?
  • Is Power cord plugged into the disk drive correctly?
  • Check line fuse.
  • Check power switch.
  • Check clock on 6502 pin 37.
  • Check + 5 and + 12 volt lines.
Flash code.
  • See power-up diagnostic on page 5.
Device not present message appears.
  • Check for device number change.
  • Check UA2 (7414) and the ATN line on the IEEE.
  • Check UB1, UB2, UD2 (MC3446).
AC ripple in 5 or 12 volt lines.
  • Check power supply filter caps.
No reset pulse.
  • Check 555 and related components on digital board.
Motor won't run and head does not move.
  • Check UM3 (6522).
  • Check UJ2 (741s00).
  • Check + 12 voltage sources.
One or both drive motors runs continuosly.
  • Check + 12V.
  • Check UH3, 6522 and logic gates.
  • Check ROMs.
Loads programs with red error LED flashing.
  • Check drive speed.
  • Check stepper motor.
  • Check drive alignment.
  • Check controller ROM UK3.
Loading is intermittent.
  • Check ROMs.
  • Check drive speed.
  • Check drive alignment.
Does not load when hot.
  • Check ROMs.
Locks-up when loading.
  • Check IEEE components.
  • Check ROMs.
Message of 'FILE NOT FOUND' is displayed.
  • Clean drive head w/alcohol.
  • Check read circuits.
  • Check alignment.
Drive fails to read.
  • Check the 311, 9602, 592's, etc. on analog board.
  • Check stepper and drive motors.

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This page has been created by Sami Rautiainen.
Read the small print. Last updated August 27, 1998.