Repairing Micropolis 1304 HD

[Elektraglide]

I am having another go at getting a pair of Micropolis 1304 40MB HD running. Both exhibit the infamous spin up, hold for a time and spin back down.

However I think they may have different problems. I happened to touch the aluminium case near the power transistors on one of them, and it was super hot on one side - the 4 power transistors on the other side of the chassis are barely warm.

I am presuming that is "not normal" ??

I'm going to replace the TIP42 and TIP41 and see if it helps.

Any other advice for getting these devices working again? Any schematics online? I've yet to find any.

Adam

 

[czunit]

Stuck head actuator. Have you tried tapping the side with a rubber chicken? Or a rubber mallet?

 

[Elektraglide]

Stuck head actuator. Have you tried tapping the side with a rubber chicken? Or a rubber mallet?

Yep, also opened it up and gently shoved it and it can move. Currently tracing signals on the controller / motor board to see what happens as it transitions from Hall effect speed control to sensor data. It does get to speed to trigger PA and PAen but heads dont move.