You are not alone!
I have a starlight instruments HSM30, which is identical to the Optec counterpart. I made a custom cable to use it with my UPBv2 (I am pretty good at making cables, just as you are).
I exchanged a few emails with Evans at Pegasus regarding pin-outs and the safety of using a 12 V controller to control a 5 V motor, and he assured me that it would be safe. I then connected the UPBv2 to the HSM30 and, to my horror, the motor started making noise like a coffee grinder! I quickly switched off the motor and felt the motor housing. It was very warm after only a brief time. I took the housing off and felt the motor and it was surprisingly hot. I decided right then that I would not be using these two pieces of equipment together.
When I hooked the HSM30 back up to the Optec controller it worked perfectly again, just as it had for years.
that is probably correct, that and what pulse width is set to. STEPPERs can be run at higher voltage without damage (they just run warmer) for higher torque I have 12V steppers I run at 24V on my 2 axis table I use for milling on my small Micromark drill press. Gives me the torque I need to run the table, the steppers do run warm, but has worked reliably for 8 years..
Given that the HSM and MICROTOUCH motors are small low voltage ones that attach to the the 10x speed reducer resulting in a lot of "gearing down" to produce enough torque to turn the focus knob, they have to run fast to have a reasonable fast focus speed, which requires very short pulses, which the HSM controller is set up for.. So knowing the pulse width or ability to adjust it on the Pegasus is important. I've had customers run our big steppers with the micro touch controller, and we've found the micro touch controller has to be set to "normal" speed (not "high speed") so it outputs pulse long enough for our stepper's coils to energize. I don't see anyway in the Pegasus instructions to set the pulse width shorter, so it is probably hammering the HSM motor with a long 12V pulse!
The steppers they use are NIPPON PULSE ones, I used to know the part number (in OPtec TCF they're part no 3152 in their schematic) but haven't found my notes:-(
Edited by rigelsys, 28 October 2019 - 11:24 PM.