Pro 350 RX50 Drive Speed Issues

[Tesla44289]

Hi!

I recently acquired a crippled micro-11, a Professional 350. It powers up fine but stops at

000400
000007
(EMT trap or required file not found)

which leads me to believe the hard drive has either been wiped or is dead.

Now to my actual issue:
When I try to boot from a floppy I get the RX50 error 330, drive speed not in limits. I‘ve already disassembled and relubricated the drive‘s spindle assembly, but to no avail.

Does anyone have an idea where to troubleshoot next?

Many thanks
Milan

 

[NeXT]

I can't remember but did the RX50 have a strobe wheel on it for adjsuting the speed?

Edited: answered my own question with google and that appears to be a no, but there is a potentiometer on the spindle motor control board for adjusting the speed, however no indication where you measure RPM from.

https://forum.vcfed.org/index.php?threads/formatting-non-rx50-diskettes-in-an-rx50-drive.1241278/

 

[Tesla44289]

I can't remember but did the RX50 have a strobe wheel on it for adjsuting the speed?

It unfortunately doesn’t seem to have one.

I’ve also tested the track zero IR LED and photodiode, those seem to be fine.

 

[shirsch]

Use a scope to time the index pulse while you twiddle the speed pot?

 

[Tesla44289]

Use a scope to time the index pulse while you twiddle the speed pot?

That seems like a good idea, I’m currently not where the machine is but I‘ll try it out later.