Question about Whirlpool MH1150XMQ Microwave Oven

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"Starting Capacitor" All I see is the High Voltage cap in the parts list. I am trying to replace the starter cap. to see if that fixes my hood vent fan from only humming. Thanks -bob mc

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I just posted an exhaustive answer to this on another new thread you just started. This makes thread number five on this issue.


Posted on Dec 05, 2007


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Jenn air microwave buzzes then trips breaker

it could be the power relay trying to latch during startup,it could be a leaky high voltage capacitor or high voltage diode leaking or a magnetron tube starting to draw a high amount of current,the cap and diode would only be starting to leak,because if either were shorted the internal ceramic safety fuse would blow

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I have a Sharp R-1480 hood range microwave that is not heating up

this is either the magnetron , high voltage capacitor or high voltage diode that has failed and will need replacing
hope this info is at least worth a fixya , since for sure one of these has failed and testing to find out which one and replacing it will fix the heating up problem, and this is a common fix and most likely the magnetron will need to be replaced , magnetron cost around $100

Dec 12, 2008 | Emerson MW8778 Microwave Oven

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Kenmore microwave 721.80593402 died

If it went dead almost immediately after pressing the Start pad, that's usually a shorted high-voltage capacitor.

If it went dead a few seconds after pressing the Start pad, that's usually a failing high-voltage transformer.

If you or someone you know wants to look into this, we have critical safety, disassembly, and troubleshooting info at our site, and our link is at our listing here on FixYa:

You can probably find exploded views and order parts by entering your model number here:

There should also be a "mini-manual" hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting & testing.

We're happy to help and we appreciate your thoughtful rating of our answer.

Jul 09, 2008 | Kenmore 80809 Microwave Oven

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Power surge

The high-voltage transformer being overloaded by something shorting it out. Either the magnatron or the high-voltage capacitor and diode. Replace the capacitor and diode then if still not working, replace the magnatron. The magnatron is only affordable to do it yourself - buy the part on EBAY - lookup "universal magnatron"
Hope ya fix it!

Feb 10, 2008 | GE JE1860 Microwave Oven

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1000w emerson microwave

The high-voltage transformer is being overloaded by something shorting it out. Either the magnatron or the high-voltage capacitor and diode. Replace the capacitor and diode then if still not working, replace the magnatron. Its only affordable if you do it yourself - buy the part on EBAY - lookup "universal magnatron"
Hope ya fix it!

Feb 10, 2008 | Microwave Ovens

1 Answer

Microwave repair, 6 year old White-Westinghouse WW1000

High voltage parts: Capacitor, Diode, Magnatron are suspect. Need to put a voltmeter on the input (primary) side to the high-voltage transformer (big heavy iron thing in there) Should be getting 120Vac when it goes to cook cycle. Don't touch the other (high voltage) side of this transformer. If the power is there, you are looking at replacing either the magnatron or the high-voltage capacitor and diode. Its affordable if you do it yourself - buy the part on EBAY - lookup "universal magnatron"
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Jan 09, 2008 | Microwave Ovens

1 Answer

Frigidaire Microwave plmv169dcd Start Capacitor

The starting capacitor is used to start the hood vent fan motor. It's also called the hood capacitor.

On page 8 of the document you refer to above, on figure O-1, you will find the hood capacitor. It is shown on the control unit (circuit board). I've attached a snapshot of that area below.

Its leads connect to terminals A1 and A3. The hood fan red wire goes to A1, and the yellow wire goes to A3.

That part is not shown in this document as a separate part, so you will have to get it generically from an appliance parts store or electronics supplier, but you will have to order it by value.

You need to look on it and it will say something similar to this:
"7 uF 230V". In this example, that would be a 7 microfarad, 230 volt capacitor.

It's okay to get a capacitor with a little higher voltage rating, but not lower.

The capacitor, if truly bad, may not look bad. It can be quick-checked with an ohmmeter to see if it will charge and discharge (the meter will first indicate low resistance then go high to infinity). This is not a full-blown test, but for this kind of capacitor it may be enough.

You should check the solder connections, also. It's a large part, and sometimes they don't get enough solder on them. The connection may be cracked and just need to be resoldered.

Since a new thread was started, it makes it harder to follow along the saga...

But this problem could be a bad (or jammed or obstructed) hood fan motor, a flaky relay on the control board, a bad cap, or bad wiring.

Microwave hood fan motor starting capacitors usually look something like this, and may be red, blue, green, orange, etc.


Dec 04, 2007 | Whirlpool GH7145XF Microwave Oven

1 Answer

Starting Capacitor

Found this Frigidaire question posted under Whirlpool but I'll be happy to answer just the same.

The starting capacitor is connected to the line level voltage, as opposed to the high-voltage capacitor evryone warns about.

The starting cap doesn't store enough of a charge to worry about.

The main thing is to be sure the oven is disconnected from the power line. I prefer unplugging it, but some installations make that hard, so you need to turn off the breaker.

Hood fan failure can happen due to many causes:

If a cooktop light bulb blows or is removed or installed while the oven is still connected to the power line, that can damage the circuit board in the area.

The hood fan motor wiring can short.

The starting capacitor can be bad.

There may be dust, hair, debris, etc. in the bearings of the hood fan motor jamming it. The filters are supposed ot help prevent this, but things happen.

Behind the control panel on Whirlpools is a very helpful mini-manual that can help you check and diagnose quite a few problems with these.

On some brands it's located on the control circuit board, in others it's mounted on or in the hood fan assembly.

If you post your brand and model we can probably steere you better on a mini-manual and the capacitor.

Dec 03, 2007 | Whirlpool MH1150XMQ Microwave Oven

2 Answers

Frigidaire PLMV169CD Micowave Hood Vent fan Hums, but won't run

If you have an old analog multimeter, you can put it across the motor start capacitor and the needle should deflect to low ohms position then ramp up to the open or infinite ohms position. You can remove it and test it the same way. Also, doing this test should store a dc voltage on the leads which can then be read even with a digital multimeter. I have even used an audio output from a cheap amplifier to determine if audio is transmitted from one lead to another. The capacitor works by shifting the starting current by 90 degrees and the motor acts as you say it does if the cap is bad. Make sure you orient the cap properly with the positive and negative terminals in the proper holes

Nov 30, 2007 | Whirlpool MH1150XMQ Microwave Oven

2 Answers

GE JVM1870 Runs, but won't heat up

My brother check the magnetron and the high voltage cap they are bad.or you got to take your microwave to a tech replace both component.good luck.

Apr 03, 2007 | GE JVM1870 Microwave Oven

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