MICROWAVE OVEN SUPER TROUBLESHOOTER

You Can Fix Any Microwave Oven with This Free, Common Sense Troubleshooting Guide for Diagnosing and Repairing Microwave Oven Problems

© 1989-2011 J. Carlton Gallawa All Rights Reserved Worldwide

(NOTE: This is a work in progress. If you don't find what you're looking for, please try again at a later time)
(Updated 3/2011)
GO BACK MICROTECH HOME PAGE CONTACT US IMPORTANT SAFETY WARNINGS ABOUT THE AUTHOR FREE CASE HISTORY DATABASE OF MICROWAVE OVEN PROBLEMS & SOLUTIONS DOWNLOAD FREE SAMPLES FROM THE CD: The Complete Microwave Oven Service Handbook: Operation, Maintenance, Troubleshooting and Repair

Important Safety Information for Repairing Microwave Ovens

Repairing a microwave oven is a very dangerous task. To avoid personal injury or death, please read, understand and follow these very IMPORTANT SAFETY PRECAUTIONS as well as our TERMS OF USE and DISCLAIMER at the bottom of this page BEFORE proceeding with any tests or troubleshooting 

The following troubleshooting flow chart provides a comprehensive selection of symptoms, problems, failures and fixes that can occur in both commercial and residential models of microwave ovens.

When troubleshooting an oven, identify the symptom as accurately as possible and refer to the following chart for tips and guidelines. Please note that symptoms, causes and remedies are listed in logical order and probability of occurrence, starting with general categories of the most common complaints.

When diagnosing the microwave oven, it is best to follow the sequence of checks without skipping any steps, progressively narrowing down the likely causes until only the real culprit remains.

Many of the possible causes will require that a specific test be performed, a link will take you to that procedure.

    If you are unsure or uncomfortable about a procedure, test or any other aspect of this Site, please STOP and call a qualified professional technician.

MICROWAVE OVEN TROUBLESHOOTING GUIDE

Heating or Cooking Problems

 Oven runs, but does not heat at all Oven produces unusually loud hum and/or electrical burning smell Shorted high-voltage (HV) diode - TEST  
Shorted HV transformer - TEST
Shorted magnetron - TEST
Magnetron dome (or antenna) damaged from arcing (if this is the case, check for a stalled stirrer/antenna) INSPECT/FIX
Magnetron insulator breakdown INSPECT/FIX
Short in the HV wiring - Visually inspect
Shorted HV capacitor (this will usually cause the fuse to blow within seconds after cook cycle is started) - TEST
There are no unusual sounds or odors
(except perhaps the lack of the normal hum of the magnetron)		 Open HV diode - TEST
Open magnetron filament - TEST
Intermittent or oxidized connection to one or both magnetron filament terminals - INSPECT/FIX
Open HV transformer (usually the primary winding) - TEST
Defective interlock switch - TEST
Burned slip-on connector to interlock switch. INSPECT and repair as necessary.
Defective triac - TEST
Open fuse in HV circuit (more common in commercial models)
Open HV capacitor (uncommon) TEST
Faulty HV relay (used mostly in older models) - TEST
Weak (low) heat

Low line voltage

How to safely measure the outlet (line) voltage
Weak magnetron

In any of the following cases, the magnetron is failing and should be replaced:
Failure in one or more HV sections in commercial models with multiple magnetrons  
Intermittent heat Loose or burned magnetron filament connection(s) Intermittent or oxidized/burned connection to one or both magnetron filament terminals - INSPECT/FIX
Door interlock switches out of adjustment  
Faulty connection to one or more of the door interlock switches INSPECT for a a burned slip-on connector due to a poor crimp joint, or weakened connection. Repair or replace as necessary.
Uneven heat (hot spots) Non-rotating antenna/stirrer motor Check for mechanical bind, loose terminal connection or open motor windings (test procedure coming soon)
Starts cooking by itself / Only cooks at full power Shorted triac Defective triac - TEST
 
Electric Power Problems Completely dead (as though unplugged) One or more open fuses  
Goes dead intermittently    
Goes dead in mid-cycle (overheats) Faulty blower (cooling) motor Check for mechanical bind, loose terminal connection or open motor windings (test procedure coming soon)
Clogged air intake filter Inspect - Clean as necessary
Blocked exhaust vent Inspect - Correct as necessary
 
Timer, Control Panel or Feature Problem Timing problem Rotary (mechanical) timer stops intermittently Check for mechanical bind, loose terminal connection or open motor windings (test procedure coming soon)  
Oven goes into cook cycle, but rotary timer does not turn  
Rotary timer turns either too fast or too slow  
Control or programming problem Some pads on the touch panel either do not respond, require excessive pressure to respond or produce the wrong result (i.e., press 5 and get 9) Defective touch panel (keypad). NOTE: If none of the pads respond, the problem could be elsewhere. More info to come.
Display Problem Missing digits, erratic, flickering or chinese-like characters Defective control board (main printed circuit board)
  Error (Fault) Code  
  Feature problem (i.e., temperature probe, sensor cook, autocook, etc) Defective control board (main printed circuit board) or sensor unit
         
 
 

USE OF THIS SITE : Through your use of this Site, you certify that you have read, understood and agreed to the following TERMS OF USE, including the following disclaimer as well as these safety precautions.

TERMS OF USE: Through your use of this Site, you hereby acknowledge and agree that troubleshooting and repairing a microwave oven can be dangerous and can involve risk of serious injury and/or death and/or property damage. Further, you consciously and voluntarily assume all such risks, dangers and hazards inherent in these procedures and assume the same risks for any invitees including minor children or legal wards.

DISCLAIMER: The author and/or owner and/or administrator of this Site assumes no liability for any incidental, consequential or other liability from the use of this information. All risks and damages, incidental or otherwise, arising from the use or misuse of the information contained herein are entirely the responsibility of the user. Although careful precaution has been taken in the preparation of this material, we assume no responsibility for omissions or errors.

Copyright © Information: Unless otherwise noted, all materials at this cite (including without limitation all text, html markup, graphics, and graphic elements) are copyrighted © 1989-2011 by J. Carlton Gallawa. The material available through this site may be freely used for attributed noncommercial educational purposes only. We ask that due credit and notification be given the author. All materials appearing on this Web site may not be reproduced, stored in any retrieval system, or used in any way for commercial purposes without the express prior written permission of the copyright holder. Send correspondence to: Microtech, P.O. Box 940, Gonzalez, Florida 32560

© 1989-2011 J. Carlton Gallawa . All Rights Reserved Worldwide

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Microwave Oven Parts Suppliers & Manufacturer Contacts 

You can contact these microwave oven parts suppliers and equipment manufacturers directly for replacement parts, product literature, dealer locations, technical assistance, etc. Please e-mail additions or corrections to: j.gallawa@cox.net 

 

Replacement Parts For Microwave Ovens and Major Appliances
Search by part number or model number for best results.
If you don't know your model number - try searching by appliance type, brand or part type.


 
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