Powermax SG9120B Teardown and Rebuild

[gpflepsen]

Some great pointers, I have my 9120B on the bench in pieces right now waiting for a spare hour or two to replace some electronic components. Mechanically I think mine has a slightly bent worm shaft I think I can bend back into shape after I work on the electronics and get that part working again. The motor was only operating in one direction, likely excessive load caused by the bent shaft caused component failure.

What electronic components are you replacing?

I'd be sure you have a bent worm shaft before trying to straighten it, I'm talking about measuring runout down to the thousandths. It's easy to mess it up instead of fixing it. Mine acted like there was serious runout somewhere in the gear train, but after doing what is posted above, it's a good runner now. I was so close to ordering another motor last week on two occasions. I'm glad I didn't now.

[Cham]

So far looks like a diode and a resistor, and possibly a relay. Need to spend some more time tracing the circuits and looking at some unused circuits boards replacement parts.
Motor only turned one direction and would almost stall once per revolution. Not sure how to measure the runout other than installing it and measuring turning force by listening to the motor loading up etc. Once the motor works both directions I'll look closer into the mechanical issues and pay some extra attention to the wedge adjustments.

[Cadsulfide]

Nice work!

[Cham]

Thought I would resurrect this thread rather than start a new one:

9120B play in shaft assembly:

Noticed some extra play in the motor shaft lately. Thought the gear backlash or worm shaft end-to-end play was the issue, seems my previous adjustments are still holding. Play is in the connection between the inner shaft and (bent mast) where the dish attaches. I removed the bolt and re-installed (seemed very tight to remove). Couldn't see any major issues with the connection between the two parts of the shaft or bolt. Re-assembled the shaft components and tightened the bolt (7mm hex I think) as much as I thought required, about 20ft/lbs without stripping or breaking the bolt. There is still a bit of play though.

I am thinking the nut (fits into a hex shaped tube to hold it in place) is not tightening as the steel motor (inner) shaft is threaded and only the hex head is actually tightening. Over time the bolt hole in the mast has likely worn a bit. Maybe installing a washer under the hex head of the bolt would help? Any pointers to remove this play?

Otherwise the motor has been working well for the last few months.

Tnx!
-C.

[Magic Static]

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Been there before When you get it tight enough the play goes away. I used a normal hexhead bolt with a custom made spacer under it. Then I could get enough muscle to it to make it tight.

[Cham]

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Sounds good. Will look for a longer grade 8 bolt and a spacer. Not sure if it is metric or standard, likely have something around that would work from the extra bolt pail..