I picked up this Baldor grinder 620 for free on CL because the previous owner said the grinder had overheated and stopped working. After opening it up I noticed the start capacitor had come apart. If the capacitor has overheated does that affect the wiring or can I just replace the capacitor and not expect any further problems?
Baldor grinder question
- Thread starter WWShop
- Start date
That should be a run capacitor, and it controls a parallel winding in the motor that stays permanently energized when the grinder is on. The way it blew up, it looks like it would have dropped that winding out of the circuit and preventing the motor from spinning from a startup. If the windings don't look burnt as well, that grinder should be fine with a new capacitor installed.
mattblast
Well-known member
Cheapest place to get these is at Home Depot with free shipping to store. Last one cost me $4
http://m.homedepot.com/p/Unbranded-...-SearchPLPHorizontal1_rr-_-NA-_-204415820-_-N
This was what I used on another model. It you can find one there that will match Baldor specs for about the same price
http://m.homedepot.com/p/Unbranded-...-SearchPLPHorizontal1_rr-_-NA-_-204415820-_-N
This was what I used on another model. It you can find one there that will match Baldor specs for about the same price
Free is a great score, replace the cap and give it a try.
So here is a pic of the capacitor. A google search with the printed numbers isn't turning up much. I'm hoping someone smarter than me can help me out. It looks to be 330 vac but the numbers/letter before that I can't make out because they are so worn. I took several pics and this is the best one to read all the printing whether it has been worn or not.
Attachments
If I Google those numbers it shows me a bunch of start capacitors. Exmaxima said it was a run capacitor, so I'm not really sure where to look for a capacitor. I'm not experienced in this at all.
Here you go:
https://www.grainger.com/product/DAYTON-Oval-Motor-Run-Capacitor-2MDV2?functionCode=P2IDP2PCP
You can always go higher voltage.
You just need to make sure it fits. Sometimes that means needing to get one from the OEM.
However I'd do more diagnosis before ordering anything.
I appreciate your help Dave, and I will definitely do some more investigation on the grinder tomorrow before I start ordering a capacitor. I clicked on your link and it said it was an invalid link. So going to 370v is ok? I was thinking that would maybe do damage to the motor. Do I still need to keep the mfd number the same? Your thoughts?
Last edited:
I don't know what happened to the Grainger link. Rule of thump is to stick with the MFD + or - 10%.
However you can go > or = 330VAC. Higher voltage means a bigger can which might not fit the base.
Good luck.
Dingleburry
Well-known member
should be a start cap to get motor direction. without cap installed plug in grinder. flick the switch on briefly. you should hear a hum. thats good. flick it on again and quickly spin the motor either direction doing by hand is okay just need to start moving it in either direction. single phase motors can run either direction without harm. it should start to spin. run caps as far as ive ever known are only for power factor correction for industrial facilities or to give it more torque. if it is indeed a run cap itll have a centifugal switch inside for start windings and run winding after is at full speed. that you may check. check the contacts on them/connections etc. also you can check your resistance to ground on both windings. 50m ohms or more and your good. itll run at lower. but really you want OL. overload/open circuit etc. and you cap you want same mdf and like others said same or + voltage.
rately work on single phase motors. this is just off the top of my head. hope this helps. check bearings also.
rately work on single phase motors. this is just off the top of my head. hope this helps. check bearings also.
Last edited:
Many older Baldor grinders were Capacitor Run, which used a small value cap for the secondary winding. Some Baldors employ Cap Start, but most of those used a current sensing relay in lieu of a centrifugal switch. The OP's grinder has a small value cap (3uF) and does not appear to have a relay, so it is most likely a Cap Run model. Here's how they work:
"The capacitor run motor is very useful in this type of application, because the motor can be designed to have low vibration under full-load. The capacitor serves to shift the phase on one of the windings so that the voltage across the winding is at 90° from the other winding, thus making the capacitor run motor a truly two-phase machine at its rated load. Since the capacitor remains in the circuit at all times, no centrifugal switch is required. When running at no-load, the motor is always noisier than at full-load, because only under full load it runs as a true two-phase machine. If the proper value of capacitance is chosen, the currents through each of the two equal stator windings (under full-load) can be made such that the power factor is close to 100%. However, the starting torque is rather low and the capacitor run motor is not recommended for severe starting conditions."
bczygan
Well-known member
Call the mfg. with the model and SN, and get the specs for the replacement part.
Bill
Bill
Dingleburry
Well-known member
ohh awesome thanks! ya learn something new every day!thanks for the info. i work on 3 phase 98% of the time 
fatfillup
Well-known member
Well worth throwing a capacitor at it.
Why spend $'s on parts when he doesn't even know what the root cause of the problem is?
It's so easy to test the old cap, motor windings and bearings. That's where I'd start.