# Start capacitor problem



## bimfi (Nov 23, 2011)

I have a 1985 Hobart food mixer, model A200 (20 qt) that I recently rebuilt. The motor is a 1/2 hp inductive motor. The stator is bolted to the inside of the mixer housing and has a removable rotor that is held in place inside of the stator by two shaft bearings. It also uses a start capacitor and an "old fashioned" mechanical clutch plate assembly. This plate engages the cap connections at rest, and after it spins up, disengages the cap. It took me a long time to figure out how to connect all of the wires to get it to run.
Here is my problem. When I initially finished rebuilding it, I flipped the toggle switch on and the motor started up like a champ. Obviously, the start capacitor did it's job correctly. A couple of days later, I tried to start it and it gave a very loud humming/buzzing noise. The motor did not start at first. I shut off the power and tried again. This time it took off as it was supposed to do. A couple of more days later, I started it up and it ran with no problem, but later on that day I tried it again and it gave the same loud buzzing noise. 
Now, the only way I can get it to run is to power it off, shift into 2nd gear, rotate the shaft that will in turn spin the rotor rapidly. Then with the rotor spinning, I can turn on the power and it starts running. Could it be that the capacitor is either shot, or close to it. The problem is that it was a brand new cap when I installed it. I could replace the cap with a new one, but if it also craps out, then what else could be creating this problem? I have no way of measuring the cap or even seeing the inside of the motor housing when it is running because the whole motor is enclosed in the casing while running. Such a dilemma. Any suggestion would be greatly appreciated.


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## Doc Holliday (Mar 12, 2011)

If it is not the cap then I'd suspect the windings are worn.


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## carmusic (Oct 11, 2011)

check for bad contact in your mechanical clutch


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## micromind (Mar 9, 2008)

Capacitors usually work or they don't. I doubt it is the capacitor, it sounds more like a problem with the centrifugal switch. It is not engaging the start winding when the motor is at rest. This is the typical failure mode of such a switch. 

They can be a real bear to fix, sometimes it's easier to forego the switch and install a potential relay. This will work only if you can get the wires out of the motor to the remotely mounted relay. 

Rob


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## bimfi (Nov 23, 2011)

I believe you are correct about the centrifugal switch. I remember the first time I started it up without the plastic disk that makes contact and it sounded exactly like that. I guess I need to look at that first and see if it is broken or damaged. Thanks, everyone for the help!


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## bimfi (Nov 23, 2011)

micromind said:


> sometimes it's easier to forego the switch and install a potential relay. This will work only if you can get the wires out of the motor to the remotely mounted relay.


I replaced the cap with a new one just to rule that out as being the problem, and it started up with no problems. The issue is that the centrifugal switch disk ends up locking itself back from the contacts when it shuts off. I really believe that the disk is the problem. It has two slots that the clutch locks into. If I could find a disk that has no slots, I think it will work better, but maybe not. I'm really thinking about replacing the mechanical switch with a potential relay. I am not really electrically proficient, so would a potential relay replace the switch or both the switch and the capacitor? Where would I go to find more information about modifying this?

Thanks,

Paul


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## micromind (Mar 9, 2008)

When a potential relay is used, the capacitor stays in the circuit. 

The relay replaces the centrifugal switch. But it needs 3 wires, not just two. It needs to see both ends of the start winding, plus break the circuit; just like the centrifugal switch.

I've had pretty good luck using submersible pump potential relays. A motor shop would likely have them, or can get them. Just match HP and voltage.


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## bimfi (Nov 23, 2011)

I decided to take your advice and modify it with a relay. Because the original mechanical clutch is pressed onto the rotor shaft, I've decided to keep it attached, but removing any moving parts that could potentially interfere. I would like to attach a wire diagram showing what I propose to modify for review by either you or someone else. All suggestions will be greatly helpful.

Thanks again!

Paul


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## swschrad (Dec 6, 2011)

I would have bought a new centrifugal switch and kept it factory. Hobart is still around. if this is a home mixer, the parts have probably gone with KitchenAid.


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## bimfi (Nov 23, 2011)

No, it is not a "home" mixer, though I am using it at home. It is still a small industrial appliance manufactured by Hobart. You are right, that I should keep it factory. It's just that Hobart inflates their component parts so much that it is not truly feasible for someone like myself to dish out that kind of money. Plus, I don't believe that old switching technology is as dependable as the modern types. Just my ignorant view point. I will look into it though. Thanks.


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## micromind (Mar 9, 2008)

The diagram will work. It's not too hard to connect the wiring, but you'll need to find a spot to mount the relay. 

Rob


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## bimfi (Nov 23, 2011)

I'm not very knowledgeable in electricity and electronics, so bear with me. I could not find a "potential" relay that would either fit or meet the requirements, but I did find a relay from Grainger. It's an 8 pin DPDT 15a relay. It's made by Dayton (model 5YR16N) and is rated for 120vac. According to Hobart, the relay should have 2 poles and be rated under 150vac. I don't know if I purchased the right type or not. I did a continuity test with my multimeter on pins 1 and 5, then pushed in the test button which seemed to disengage the contact. If that is all it is supposed to do, then I may have the right one. I'm just concerned about when the contact is supposed to open after starting. Should I be concerned about PU voltage or DO voltage? Here are pics of the relay, if that helps.


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## micromind (Mar 9, 2008)

This is a general-purpose relay, not a potential relay. I doubt if it'd work, maybe though. I think it'll disengage the start winding too quickly.

A potential relay has a different coil, and is more precise as to when it'll transfer its contacts.


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## bimfi (Nov 23, 2011)

Thanks for the information. I will have to do some more research and locate one. Thanks, again!


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## bimfi (Nov 23, 2011)

Just wanted to let you know that I've decided to put the modification on hold. First, I was having a hard time finding the right potential relay. Second, I fixed the culprit of the original problem. It was that the disk that makes contact with the switch, wasn't. This was due to it being locked back away from the contact by two slots in the disk. I filled in the slots and it works fine, now. I tested it numerous times to make sure. I do thank all of you that took the time to assist me.

Paul


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## micromind (Mar 9, 2008)

Glad you got it to work!

It's always nice to hear that someone succeeded with a project.


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## Nube (Mar 6, 2017)

*Hobart a200 start switch*

sorry for bother but your thread is a similar with my problem 

I just bought a Hobart mixer but when the first time I tried to used it after five minutes started to getting hot and shut down, I checked every posible reason, so we changed the capacitor, the relay witch and also a replacement for start switch, the problem is that the replacement for the old started switch only has three wire without number, and the replacement has for four cables with number, we guessI changed but it not working, what should we do wrong.


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## circuitman (Aug 9, 2013)

check the old ones with an ohm meter.see which ones are closed. have a feeling this switch may have a normally open & a normally closed contact set. possibly one set of wires to each set of contacts , thus 4 wires.a pic of the two switches would help.:biggrin2::biggrin2::biggrin2:


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## Nube (Mar 6, 2017)

Here's some photos of the old one


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## Nube (Mar 6, 2017)

Old ones


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## Nube (Mar 6, 2017)

The new replacement


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## Nube (Mar 6, 2017)

We changed the capacitor, the relay switch, but we are having problems with start switch, because is so different and we put the wire in 1,2,4, doesn't start, then we put the wire 1,2,3 mixer tried to start but just with a noice, we turn it off immediately


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## Nube (Mar 6, 2017)

Another one


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## Nube (Mar 6, 2017)

Please help!!!!!


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## Nube (Mar 6, 2017)

Because the replacement is so different numbers are 1,2,3,4, and the old one has numbers from 1 to 6. So we changed the wires 1 to 1, 2 to 2 and 3 wire in 3 then on 4 
Doesn't work. 
The funny part is that we put it back the old one and started to work, but is getting hot


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## circuitman (Aug 9, 2013)

it should have a diagram with it! compare the two.


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## Fishbulb28 (Jul 8, 2016)

The old relay likely has a common terminal for both the coil and contact. It's easy enough to jumper the new relay for the same configuration, but we need a wiring diagram first. What's the model of the mixer?

Also, exactly what is overheating? It's rare for overheating to be caused by any of the wiring itself. Usually it's mechanical - a bound up transmission or a stuck brake.


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## Nube (Mar 6, 2017)

Thank yo so much for your reply 
Is a Hobart a200 T
After the first 5 minutes of used started to getting hot and after 12 to 15 minutes shut down, so we started to look for posible problems, and changed the capacitor, the relay, but with this start switch, we had the problemsThe old one has 1,2,4,5,6, but it was used only 3 exits 1,2,5.
The new one use 4 exits with 1,2,3,4. So we put 1 to 1, 2 for 2,and 5 with 3.
Doesn't work, we changed 5 to 4, turn on but doesn't work either, I think we are so closed to fix the problem, that honestly am afraid to call somebody and charge a lot of money probably for something easy.
Thanks in advanced 
Any advice are welcome


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## Fishbulb28 (Jul 8, 2016)

I looked in the service manual and it appears a single double pole relay has been replaced with two single pole relays. The pictures also show the mixer has been extensively modified, likely to get it going when exact replacement parts were not available. So other than repairing everything back to its original state, the best bet is going to be identifying that relay. Are there any other numbers or identifiers on it? The number visible in the photo does not match up to anything I can find.


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## Cactus Gazer (4 mo ago)

micromind said:


> When a potential relay is used, the capacitor stays in the circuit.
> 
> The relay replaces the centrifugal switch. But it needs 3 wires, not just two. It needs to see both ends of the start winding, plus break the circuit; just like the centrifugal switch.
> 
> I've had pretty good luck using submersible pump potential relays. A motor shop would likely have them, or can get them. Just match HP and voltage.






 I saw this on YouTube and explains how to replace the centrifugal switch with an electronic one , hope it helps


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