Motor failures for diamondmax 9

Hi a question for all experts. Got a batch of diamondmax 9 drives to play with last week and 5 out of 20 have this same problem. All voltages are ok and output to motor has good voltages. All phases of motor have good readings. 1 drive had spindle stuck but was freed by opening drive and turning platters at hub. The other 4 were free to spin ( I checked through the access hole on the side). Was wondering if this is a common problem with these drives or am I missing something?

Points to add I don't care about data. This is a hobby and just trying to learn more. :wink:

Hi,

maybe the motor's windings are brogen/burnt. check their resistances against a working one!

pepe

yes pepe is right pls check it resistances..

Thanks guys guess I wasn't clear enough.... All phases of motor have good resistance readings (1.9 ohms). 12v at all 3 phases when measured to ground. 0v potential between mot A mot B & mot C so all 3 phases are getting same voltage. Fuse good and 3.3 & 5v good. No servo & no motor spin. Spindle not stuck. Has to be motor as good PCB will not spin also. (checked tonight). So must be motor.......

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Does the disk sing a tune? I have many of these myself

No that's the weird thing, I have had drives that do sing, they usually have bad controllers or are missing voltage to the motor so you are hearing the heads but no spin. These are completely dead but have power at all the right places. BTW I opened one up and found it had been dropped. It is possible for the servo magnet to become displaced on Diamondmax9 even with the cover on. If jarred hard enough the magnet can jump off the locating pegs and they don't use mounting screws!

Shortscurcuits you could disable connections from PCB to the preamp, and leave only motor connected. If drive spin up then most probably preamp is dead , if won't spin again, then for sure the motor is bad. But test it with known good pcb.

Thanks Guys I'll try and get back to you I want to check some more as I must be missing something, probably obvious! :roll: