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alanganes
06-29-2011, 08:37 PM
OK, maybe not a rescue, per se, but it is fun to actually make a significant repair for near nothing once in a while.

The motor in question is out of a large make-up air heater for an indoor shooting range ventilation system. It is a 5HP, 220V 1Phase capacitor start motor. It stopped working suddenly last week. I took a look and found that one of the starting caps had failed (stuff leaked out of the relief, flunked sniff test), and it exhibited classic dead-cap symptoms (motor hums, won't start, then trips motor protector). So I order a new pair of caps. They arrive next day, but one is broken in shipment. I call vendor (Grainger) who apologizes profusely and has a replacement to me the next morning. Great service. Rain and other commitments keep me away for a few days, but when I go back and install the caps, no good. Same symptoms. I put my ohmmeter across where the start winding should show and see nothing. Bad. Over $600 to replace this stinker. So proceed to disconnect and pull the motor which is a big pain in the neck. Get it out and take it home to the shop for dissection, as there is little to lose at this point.

So I unbolt the end bell and pop it off. This bunch of small parts fall out onto the bench:

http://img.photobucket.com/albums/v479/alanganes/HSM_Board/IMG_3025.jpg

Ahh, the centrifugal switch has self-destructed! Makes sense. On closer inspection, there is nothing actually broken except for this silly little-bitty sheetmetal speed-nut:

http://img.photobucket.com/albums/v479/alanganes/HSM_Board/IMG_3026.jpg

It turns out that this was pushed onto the long rivet that all of the switch parts and the spring move on, and held the whole mess together. So I replace the rivet and speed-nut with a 6-32 screw and fasten on the bottom with a ny-lock nut with some locktite on there for good measure:

http://img.photobucket.com/albums/v479/alanganes/HSM_Board/IMG_3028.jpg

Install it all back in the housing:

http://img.photobucket.com/albums/v479/alanganes/HSM_Board/IMG_3030.jpg

apply power and BINGO! it starts up and runs great. As the motor is pushing 20 years old i figured it deserved a new set of bearings so I replaced them. The windings looked fine and passed a megger check, so it all went back together and will get re-installed in the unit tomorrow.

Nice to win one on occasion. Saved us a ton of money, under 50 bucks in caps and bearings, instead of over 600.

I guess the moral of the story if there is one, is if you have nothing to lose, always take it apart just a bit further if only to see what is in there. You might just find an easy fix hiding inside.

38_Cal
06-29-2011, 10:06 PM
Nice save, and a good write-up, too!

David

sasquatch
06-29-2011, 10:10 PM
Yup,, great quickie repair,, and reasonable cost wise also,, we all need a find like that now and then.

Duffy
06-29-2011, 11:08 PM
That is a GREAT repair and report. However, (or as Jack Benny would say, "Well!") you are really being prodigal with your stuff! First a machine screw AND a nylock nut, AND THEN Locktite! NOW REALLY, another new spring nut would have carried another 20 years and then you would be DEAD!:D

alanganes
06-30-2011, 07:56 PM
That is a GREAT repair and report. However, (or as Jack Benny would say, "Well!") you are really being prodigal with your stuff! First a machine screw AND a nylock nut, AND THEN Locktite! NOW REALLY, another new spring nut would have carried another 20 years and then you would be DEAD!:D


You are absolutely right, I went a bit overboard on the fastener, but the truth is, I did not have another spring nut! Otherwise, I may just have taken that route.

Also, thanks for the compliments guys. I always enjoy it when members here post stuff they have done, repairs, projects, tools, doo-dads, techniques, or whatever. I find it sort of an inspiration to see the interesting stuff that the fertile minds and talent around here can cook up in their spare time.

Black_Moons
06-30-2011, 08:23 PM
Spring nuts are meh, A+ on the repair.

Only one better was the table saw I got for free because it wasent working.. Loose wire inside the motor.

boslab
06-30-2011, 11:03 PM
i must admit in my years of skip/dumpster diving i have retrieved loads of usefull bits and bobs, even when its broken its educational to see how it broke
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