HP-97 troubleshooting

[teenix]

If sounds like print head element(s) as you don't mention the motor keeps trying to turn.

By turning on the power then off shortly after, you should be able to feel the print head and see if it gets warm or hot.

If it is heating up then...

one or more of the print head driver ICs' may have failed.
the PIK chip could have partially failed and is turning on the heads in error.
there is a short one of the boards

All the printer circuit board pins #8 - #14 should be close the 0 volts. If they are higher than (guessing) 3 volts then the PIK chip may be at fault.

If the print head flex cable is removed, then you can take your time testing these pins. Test with the printer board connected and not connected. It may point to which board is at fault.

Pins #3 and #4 are the ground pins for the printer board.

cheers

Tony