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NOTE: Always check for latest ROM/ECO upgrade. If socketed IC is suspected bad, be to check socket with ohmmeter.

No LED's on power up. Is Power cord plugged into wall outlet correctly?
Is Power cord plugged in the disk drive correctly?
Check line fuse.
Check power switch.
Check clock on 6502 pin 37.
Check +5 and +12 volt lines.
Error LED flashes on power up. Check all RAM and ROM locations.
Error LED stays on all the time. Check 6502 microprocessor.
Check ROMs.
Drive motor runs continuously
and red LED stays on.
Check +12V.
Check 6502, logic gates, logic array.
Drive motor runs continuously
and red LED stays off.
Check Rom
Check drive motor PCB.
Drive motor runs continuously
with no red or green LED's.
Check VR2 (5V Regulator)
Check Power Transformer.
After the drive warms up the
motor runs continuously.
Check 6522s.
Check motor control PCB.
Loads programs with red LED
Check drive speed.
Check stepper motor.
Loading is intermittent. Check ROMs.
Check drive alignment.
Does not load when hot or LED
flashed 3 times.
Check ROMs.
Searches with LED flashing
Check ROMs.
Searching with no red LED. Check 6522s, logic gates, logic array.
is displayed
Clean drive head w/alcohol.
Check 0 stop adjustment.
Check alignment.
Drive fails to read. Check the 311, 9602, and 592s.
There are two +12 volt sources for stepper output
and read circuit, make sure both are good.

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This page has been created by Sami Rautiainen.
Read the small print. Last updated September 05, 2020.