Question about Whirlpool Microwave Ovens

1 Answer

Whirlpool RM278BXP Over the range Microwave

When the door is open, the light is on. Close the door and the light goes off. Enter time and hit start -- a relay clicks and the display counts down, but no light / fan / etc. I think the high voltage cap may be toast -- no countdown to 0 and increase to infinity -- just a zero resistance reading. Would this cause the problem I am seeing?

Posted by on

  • 2 more comments 
  • kingm73 Jul 12, 2008

    The transformer primary winding, filament and high voltage windings test OK -- .2 ohms, zero resistance (infinite to ground) and 50 ohms (my service sheet says 55 to 61 -- so a bit low). Magentron tests fine -- zero resistance across terminals and infinite to ground. Here's the problem -- I am getting infinite resistance at the high voltage cap, as well as across the rectifier (I'm reversing the leads -- infinite both ways, not the infinite and 75K-200K ohms I'm expecting).



    It seems like my high voltage cap and rectifier are toast. Would this explain the behavior? Is there an explanation why this has occurred -- other than the unit is about 21 years old? I want to make sure that if I am going to spend about $100 on parts, that this isn't going to immediately recur.


    Thanks!

  • kingm73 Jul 12, 2008

    Hi Reg501,



    Main fuse has continuity. The interlock monitor and light switches have all checked out OK (proper continuity or lack thereof when door opened and closed) -- primary interlock, secondary interlock, monitor, light and door switch. The thermal protector on the magnetron, the aux fan motor thermostat and the thermal fuse (top of cavity) all have continuity. What would you suggest next?



    Thanks!

  • kingm73 Jul 12, 2008

    Do you think we’re talking about some kind of failure on the control board? There is a component labeled as follows – I am assuming that this is the main relay:

    (part description from top)
    Guardian Electric
    Cont 15A RES 120AC
    1345 S SERIES
    A410-367215-101
    COIL 24V DC
    FSP
    Part No. 81460
    861039
    Japan 5 8 5NA

    This part looks like it has at least 6 outputs. One of these pokes through the PC board – no contact, no solder – assuming it is just for stability and to facilitate proper mounting. However, directly opposite this, there is a contact that looks slightly burned with little to no solder left. I am not sure if this is another “stabilizer”, if it was a factory error (i.e. someone soldered the wrong contact, or if this could actually be the source of my problem? Would you suggest replacing the relay, or just trying to re-solder the connection?

    Thanks!

  • kingm73 Jul 12, 2008

    While waiting for a response, I went ahead re-soldered the relay connection. Fixed! I do recall reading elsewhere that opening and closing the door while the unit is still running can put undue stress on some components and cause arcing... Could this have been the cause?



    Thanks for your help!

×

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Master
  • 413 Answers

The capacitor and diode will not cause the problem you describe. You will not be able to measure the diode with an ohmmeter, the forward breakdown is about 5-6Vdc. The normal failure mode for the capacitor is a short which will blow the fuse.
If any high voltage components go bad, the microwave will operate normally just not heat.
You should focus on the door interlock switches and safety thermostats, especially the cavity thermostat located somewhere on the top of the cavity.

To make a high voltage diode tester, wire up a 9V battery, LED and a 220 ohm resistor. Hooked up one way the LED will light reverse the connection the LED will not light.

If you need further assistance, let me know
Regards,
reg501

Posted on Jul 12, 2008

  • Richard
    Richard Jul 12, 2008

    Based upon your previous post, I was going to suggest control board failure. Good job for troubleshooting the board. Solder connections that do not have a good mechanical connection will fail over time. This problem has nothing to do with open or closing the door while the unit is running. Again congrats for a job well done!

    Regards,
    reg501


×

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

Why won't my interior microwave light turn off and my microwave won't start?


It sounds to me that your door switches aren't working.Your oven is protected by a couple of switches that engage when you open or close the door.They control a couple of safety features and also your interior light.One of them seems defective.

Dec 17, 2014 | KitchenAid Microwave Ovens

1 Answer

INSIDE LIGHT WILL NOT GO OFF


Simple issue here,there is a micro switch that shuts the light off when you close the door ,it may also open a circuit depending on yuor particular switch that lets the microwave think the door is open.Not hard to fix if you are handy,remove the screws to the sheet metal cover ,locate the switch and make sure that the switch is being made when you close the door.Could just be it is loose,could be the pin that hits this switch is missing,broke or out of adjustment.In any event,do this with no power on ,also these devices can still store power so be careful here .If you are not careful you could get seriously hurt so remove plug and or call someone that has some electrical experience this is totally at your own risk.

Apr 19, 2014 | Whirlpool MH3185XP Microwave Oven

1 Answer

I have a amana road range microwave and the door won't close . AMV3204VAB-0


proceed according . God bless you

Open Lever


If the microwave door won't open the open lever might be broken. This part can be replaced separately.

Enter your model number to see parts for your microwave.

Help me find my model number
picunavailable175.jpg

Door Spring


If the microwave door won't open the door spring may have broken. The door spring is located inside the door and keeps downward pressure on the door hook.

Enter your model number to see parts for your microwave.

Help me find my model number
picunavailable175.jpg

Door Latch


If the microwave door won't open the door latch might be broken. The door latch is inside the microwave. The door hook, which is part of the door, engages with the latch to keep the door closed during operation. If the door latch or actuator breaks the door may not open.

Enter your model number to see parts for your microwave.

Help me find my model number
picunavailable175.jpg

Door Hook


If the microwave door won't open the door hook might not be releasing properly. The door hook is installed inside the door and normally releases when the door is opened. The hook is made of plastic and will break over time. When this happens it will need to be replaced, it can't be repaired.

Enter your model number to see parts for your microwave.

Help me find my model number
picunavailable175.jpg

Button Spring


If the microwave door won't open the button spring might be broken internally. The button spring can be replaced.

Enter your model number to see parts for your microwave.

Help me find my model number
picunavailable175.jpg

Button


If the microwave door won't open the button might be broken internally. The button can be replaced.

Enter your model number to see parts for your microwave.

Help me find my model number
picunavailable175.jpg

Handle Actuator


If the microwave door won't open the handle actuator might be broken. This is a plastic part which can become brittle over time. This part is connected between the door button and the door latch assembly.
d31f5fb8-f006-4b06-9ef7-cd77a15f3422.gif

Apr 02, 2013 | Microwave Ovens

1 Answer

Microwave oven will not start after I put in the time. It says open and close door and press start. Still won't start


Probably a bad door switch or mount. The door switch help file is here.

On some models though (you didn't mention yours) the door circuit is very complicated, and may be showing the door error due to a blown fuse or cavity TCO.

Accessing the cavity TCO for testing and possible replacement will require you to remove the oven from the wall.

If so, the installation instructions are very handy, and it's best to have two people since the microwave can be heavy and awkward.

You can download Whirlpool owner's manuals and installation instructions here.

The drawing below shows what to check:

12_20_2011_2_42_28_am.jpg

You can find handy exploded views and order parts by model number
here.

At our Web site, we have a video available showing how to remove a typical over the range control panel assembly in under 5 minutes.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

Dec 04, 2011 | Whirlpool Microwave Ovens

1 Answer

Sometimes when I go to heat something in the microwave it doesn't heat but when I open the door and then close it it sometimes will work?


Sounds like the door switch is going bad this is the switch that "tells" the microwave the door is closed so that way it doesn't run with it open

Apr 26, 2011 | Whirlpool 1.6 Cu. Ft. Over-the-Range...

1 Answer

Microwave not working


HI, this is a faulty control panel. replace asap if possible.

May 29, 2009 | Whirlpool Microwave Ovens

1 Answer

GE microwave won't turn off


Just checked the GE website. Had the same problem with my 5 year old microwave. GE website says to close and open the door quickly three times. First time I did this it didn't work. Second time I closed the door with some significant force and reopened it more quickly. Worked. Unplugged the microwave, plugged it back in, still fine.

Mar 21, 2009 | Microwave Ovens

5 Answers

Microwave shuts off by itself


The microwave has a safety door switches (2-3 micro switches)
The door mechanism should hit these micro switches. If you can open the machine, you can see that these micro switch has a holder that you can adjust and tighten to make sure that the hook of the door should activate them.

Mar 30, 2017 | Whirlpool GH8155XJ Microwave Oven

Not finding what you are looking for?
Microwave Ovens Logo

Related Topics:

261 people viewed this question

Ask a Question

Usually answered in minutes!

Top Whirlpool Microwave Ovens Experts

William Miller
William Miller

Level 3 Expert

9011 Answers

sonic boom...
sonic boom...

Level 3 Expert

1557 Answers

Gerry Harvey
Gerry Harvey

Level 3 Expert

1456 Answers

Are you a Whirlpool Microwave Oven Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...