Rayman

Following the bearing check my next step was to check voltage in and I initially suspected that based on my findings, this was possibly part of the problem. However I fooled around with different supply voltage and it made little or no difference. I will try your suggestion of the capacitors next. I don't have a 'scope but know someone who may be able to help me with this aspect.

Hi Tom Thanks for all your help and input on this, it really has helped. I found this particular motor available here http://spwindustrial.com/moons-stepping-motor-type-16hy0405-08-10-each/?setCurrencyId=1but with an MOQ of 10 it isn't worthwhile given the original motor is about 12 years in the running. I have removed the armature and the bearings seem good but I have oiled them anyhow. The datasheets and your notes have been especially helpful as I hadn't been able to obtain one for the motor at all. I have also found a German reef store selling the motor's individually for around 50 Euro + postage but this is too expensive given a replacement stepper of similar characteristics will be around $15 or $20. In the event I source a good replacement NEMA 16 type motor I will update the thread. Thanks for all your input, help and advice. Duanne

I found this post really useful as I am havimg similar issues. Unfortunately, mine doesn't seem to be a bearing problem. The armature just becomes difficult to turn after running for a few hours and I think my motor is trashed. I am led to believe this is a Moons stepper motor type 16HY0405-08. They only seem to be sold in MOQ's of 10 for around 20 bucks each. I looked on their website but couldn't find a datasheet for it. If anyome can point me in the right direction or has a circuit diagram I would be grateful.