Thread: Dead Bench grinder?

Does the motor make any kind of a humming sound when you switch it on, indicative of a bad capacitor? (if so try spinning it up by hand to see if that will start it. If so its the cap)

Hi Jim,

Try what Greg suggested, if it's not the cap, then check for loose connections, terminal blocks, corroded terminations, also, check the switch, if it's fairly new, then I'd be looking for a faulty switch or loose connection. something simple.

If you have a multimeter, check for continuity on the motor windings.

Regards
Ray

seem like ray and greg have this one well covered. does it turn nicely.

Hi Jim,
Yes, Like they have said +.
Switches from Jaycar are reasonably cheap.
I fixed my 1/2 HP motor on my small Leda Wood Lathe with a Capacitor from a 2 x 40W. Flouro, which most likely costs next to nothing.
Of course you will have to check it out to see if it is the right one.
There's a quick fix.

Guys,
Have checked continuity on the switch, all ok.No humming noise so maybe no bad cap(damn).I have got a multimeter.Did try spinning it to start as I have an underpowered honey extractor that needs some encouragement when its got a bit of honey on board.So should I use the ohm function and look for continuity between the active and neutral going to the windings?
Cheers Jim

Hi Jim,

Make sure it's unplugged from the mains first...

Here are a couple of possible circuit options, only difference is the centrifugal switch.





You should see low resistance across the main winding. If the cap has gone short cct, you might have to disconnect the cap before measuring.

Locate the terminal on the cap that goes to neutral, probably a blue wire, and it might go to neutral via a centrifugal switch (as in the top diagram), then measure resistance from the other terminal on the cap to active. That's the start winding.

Hopefully, one of the circuits above will match up with what you've got.

Regards
Ray

As far as I can remember the cap is in series with the start winding - usually through a relay that disconnects the cap after a second or two. The cap alters the phase of the current/voltage so that the start winding is energised before the actual motor windingsthis gives the motor a head start . MIKE . The start relay on my compressor cooked itself , I disconnected it but the motor still starts OK without it

Hi, took it apart,looks brand new inside.termination blocks? on the wires look epoxied. Bypassed the switch still nothing.No way of testing the cap with my multimeter. Looks like I might just give it back for a refund and keep looking.
Thanks for your help guys

Jim

If it is a RY_BI with its own belt sander give it back.

However , should it be a Multi Tool it is one of the best belt sander linishers on the Australian market.

A multi tool can be unbolted from the original grinder and fitted to a newer better unit.

Multi Tools are easy to get parts for and reliable .Had mine near 20 years and no probs.

If I had to sell all my tools the Multi Tool would be the last to go.

Grahame

Originally Posted by jimmyratsbreath

Hi, took it apart,looks brand new inside.termination blocks? on the wires look epoxied. Bypassed the switch still nothing.No way of testing the cap with my multimeter. Looks like I might just give it back for a refund and keep looking.
Thanks for your help guys

Jim

hi jim you can test capactors on most multi meters. first set your meter to the highest omh's scale put the leads against the capacitor terminals and hold there for a while maybe up to 30 sec. remove the leads from the cap and set your meter to DC volts maybe a higher scale then put the meter leads on the capictor. watch to see the reading. it will give you some ideas of the capitors condition.

i wouldn't worry about testing for continuity on the switch id just check if you have 240v going to the motor. be carfule thou.
aaron

Originally Posted by Grahame Collins

If it is a RY_BI with its own belt sander give it back.

However , should it be a Multi Tool it is one of the best belt sander linishers on the Australian market.

A multi tool can be unbolted from the original grinder and fitted to a newer better unit.

Multi Tools are easy to get parts for and reliable .Had mine near 20 years and no probs.

If I had to sell all my tools the Multi Tool would be the last to go.

Grahame

Evening Graham - just curious, does your unit look like this (but 20 yrs older)? Multitool Plus Grinder/Sanding Attachment + 6 " Bench Grinder #PO362PLUS


Cheers, Mark

Originally Posted by jimmyratsbreath

Hi, took it apart,looks brand new inside.termination blocks? on the wires look epoxied. Bypassed the switch still nothing.No way of testing the cap with my multimeter. Looks like I might just give it back for a refund and keep looking.
Thanks for your help guys

Jim

Hi Jim,

All indications are that there is an open cct somewhere, worst case is that it's open cct in the main run winding, there isn't a thermal cut-out somewhere on the motor that has tripped and needs to be reset? perhaps?.. A few pictures would help.

If it's the motor gone open cct, I'd say cut your losses and get the refund.

Regards
Ray