I got 3 HP-UHU kits from
Paul over at CNCZone, he and Irfan have made a splendid
job of putting the kits together at a very reasonable
price, they arrived nicely packed and labeled, something
I didn't really expect:
What's not included in the
kit is the actual servo processor, the UHU-chip. That
had to be ordered from Uli Huber in Germany together
with the 24Mhz crystal that goes with the chip.
Otherwise it's all there except mounting hardware.
I quickly started
assembling my first drive which went pretty smoothly, a
couple of capactiors was a little bigger than footprint
on the PCB but that's no problem. The two capacitors in
the output filter thoguh, was both too big and had way
to large legs to fit the holes in the PCB so exchanged
those smaller ones of the same type.
The MOSFETS are attached
to the heatsink underneath the PCB but unfortunately
there's no holes thru the PCB to gain access to the
screw that holds them to the heatsink. It's very easy to
assmeble the first time but when you need to take it
appart, like had to do several times when
troubleshooting it was a complete PITA so I made some
brackets out of thick FR4-like material with threaded
inserts. This way I could clamp the MOSFETS to the
heatsink with screws from the back instead of under the
When I started the testing
it turned out that the motor delivered torque in only
one direction. It took a little while to figure out why
but once found it was pretty obvious:
See the trace going from
U7-pin 6 (that's the MOSFET driver) up to R17 (that's
the resistor in series with the MOSFET gate)? Right
where the trace "enters" the ground-plane there's a tiny
short. Once that was removed and the drive put together
I got torque in both directions.
I tested the drive with
voltage up to 160VDC and it seemed to work just fine.
Here's a final shot of the test-setup with a powersupply
voltage of 130VDC which is what will be used on the