Question about GE Spacemaker JVM1640SJ Microwave Oven

1 Answer

Ge Spacemaker microwave jvm240 wv Micro hood combo.

Blows 20A line fuse upon starting a cook cycle. Checked HV Cap, All interlocks, MGT TCO, Cabinet TCO. Checked for continuity across magnatron filament. HV diode OK. My best guess is a bad HV transformer. Has a slight transformer burn smell when the cook cycle is started. Fuse blows approximately 1 second later.
When microwave is powered up with a new 20A line fuse, everything else works fine, ie: fans, lights, keypad, clock etc. Fuse only blows when starting a cook cycle. Using a mug of water in microwave as test. We have had the microwave since 1996 without a hitch. Is it worth replacing the transformer? I have found them online for $152 + S+H. I am a tech so I will be providing the labor. Thank you for your help.

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  • 2 more comments 
  • Tom Giardino Jan 06, 2008

    Followup to my troubleshooting as of yesterday. The cap reads infinity
    across each contact to the cap case. Yesterday, before I headed off to
    work, I disconnected everything from the HV transformer secondary side
    ie. HV cap, magnatron, etc.. Insulated all connectors thorughly to be
    sure of no arcing. Installed new line fuse, restored power to
    microwave. Everything worked fine until I started a cook cycle. Entered
    1 min and hit start. Microwave ran for 1-2 seconds then fuse blew.
    Smelled of typical burnt transformer smell after that. This seemed like
    a pretty positive sign that the HV transformer is bad. Let me know what
    you think. Than you for your help.

  • Tom Giardino Jan 10, 2008

    UPDATE. REPAIRED. Installed a new HV transformer and the microwave is back in service. My son was elated. He has never known life without a microwave. What a hardship!! Thank you for the help and input. This site is a goldmine for information.

  • Skh0516 Feb 04, 2008

    I have a similar problem with my GE Spacemaker Profile microwave, but I'm not a technician. Symptoms are similar, internal fuse blows a couple seconds into the cook cycle and there's a burnt smell. How hard is it to replace the transformer for a non-technician. I understand there can be some voltage in the microwave even when it's unplugged.

  • danderai1990 Feb 20, 2008

    My GE Spacemaker just did the same thing. It comes on, then a second later it starts to hum, it does not heat up and it smells like electrical burning when the door is opened.



    I have not taken any steps to resolve the issue except for looking here.

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Sounds to me like the magnatron has shorted out. i don't know of a way to test them unless you have some high dollar equipment. a continuity test prob wont tell you anything. what reading did you get on the cap when you tested it?

Posted on Jan 06, 2008

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1 Answer

Control pad is dead


Dead, meaning no display, no light when you open the door and no beeps when you press a pad on the keypad?

Is the outlet working?

A microwave can be dead for many reasons.

It may be the fuse, which is usually located behind the grille, on the floor of the oven behind the control panel, between the door switches, or on the filter board near where the cord comes into the unit.

If the fuse is good, it may be an open thermostat or thermal cutout (TCO) / thermal fuse on or near the magnetron or on top of the cavity / body of the oven.

This model has a bottom TCO, a 20A fuse, a cavity TCO, and a magnetron (MGT) TCO.

If it goes dead for a while during or after cooking then comes back on, the magnetron is probably overheating and causing the magnetron thermostat to open.

Then when it cools, it closes the circuit and allows power through again.

This would indicate a bad magnetron or a bad cooling fan.

When checking TCOs or thermostats, if it has a hood fan thermostat, that should read open, as opposed to the others, which should read closed.

So don't let that fool you.

To check some thermostats, you'll need to pull 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 GE owner's manuals and installation instructions here.

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

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

If it goes dead or blows the breaker (or GFI) when you plug it in or open or close the door, then there's a problem with a door switch or door switch mount.

If it's intermittent or random, it may be a bad connection, usually on the control board or a loose fuse holder, or even an intermittent fuse.

There should be a "mini-manual" (tech sheet) hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting, testing, and locating components.

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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.

You can find helpful exploded view diagrams and order parts by entering your full model number from the tag on the oven here.

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

Aug 21, 2010 | GE Adora DVM1850 Microwave Oven

Tip

Troubleshooting Guide


  • Problem: Totally dead oven.
    Possible causes:
    1. No power to outlet (blown fuse or tripped breaker or GFCI).
    2. Blown main fuse - likely due to other problems.
    3. Open thermal protector or thermal fuse.
    4. Defective controller or its power supply.
    5. Clock needs to be set before other functions will operate (some models).

  • Problem: Totally dead oven after repair.
    Possible causes:
    1. Cabinet screws replaced in incorrect location (safety interlock not engaged).
    2. Any number of screwups. :)

  • Problem: No response to any buttons on touchpad.
    Possible causes:
    1. Door is not closed (some models).
    2. You waited to long (open and close door to wake it up).
    3. Controller is confused (pull plug for a minute or two to reset).
    4. Defective interlock switches.
    5. Faulty controller or its power supply.
    6. Touchpad or controller board contaminated by overenthusiastic cleaning.
    7. Defective/damaged touchpad.

  • Problem: Oven runs when door is still open.
    Possible causes:
    1. Damaged interlock assembly.
    2. Cooling fans (only) running due to bad sensor or still warm.

  • Problem: Oven starts on its own as soon as door is closed.
    Possible causes:
    1. Defective triac or relay.
    2. Controller is confused (pull plug for a minute or two to reset).
    3. Defective controller or its power supply.
    4. Touchpad or controller board contaminated by overenthusiastic cleaning.
    5. Defective/damaged touchpad.

  • Problem: Oven works but display is blank.
    Possible causes:
    1. Defective controller or its power supply.
    2. Broken display panel.
    3. Oven needs to be reset (pull plug for a minute or two to reset).

  • Problem: Whacked out controller or incorrect operation.
    Possible causes:
    1. Previous or multipart cook cycle not complete.
    2. Controller is confused (pull plug for a minute or two to reset).
    3. Defective controller or its power supply.
    4. Touchpad or controller board contaminated by overenthusiastic cleaning.
    5. Defective/damaged touchpad.
    6. Defective sensor (particulalry covection/mirowave combos).

  • Problem: Erratic behavior.
    Possible causes:
    1. Previous or multipart cook cycle not complete.
    2. Bad connections in controller or microwave generator.
    3. Faulty relay - primary (or HV side, much less commonly used).
    4. Defective controller or its power supply.
    5. Bad contacts/connections on mechanical timers. Intermittent fuse.
    6. Power surge at start of cook cycle confusing controller.
    7. Microwave (RF) leakage into electronics bay.

  • Problem: Some keys on the touchpad do not function or perform the wrong action.
    Possible causes:
    1. Touchpad or controller board contaminated by overenthusiastic cleaning.
    2. Defective/damaged touchpad.
    3. Controller is confused (pull plug for a minute or two to reset).
    4. Faulty controller.

  • Problem: Microwave oven does not respond to START button.
    Possible causes:
    1. Defective START button.
    2. Faulty interlock switches.
    3. Door is not securely closed.
    4. Faulty controller.
    5. You waited too long - open and close door to wake it up!

  • Problem: No heat but otherwise normal operation.
    Possible causes:
    1. Blown fuse in HV transformer primary circuit or HV fuse (if used).
    2. Bad connections (particularly to magnetron filament).
    3. Open thermal protector or thermal fuse.
    4. Open HV capacitor, HV diode, HV transformer, or magnetron filament.
    5. Shorted HV diode, HV capacitor (will blow a fuse), or magnetron.
    6. Defective HV relay (not commonly used).

  • Problem: Timer and light work but no heat, cooling fan, or turntable rotation.
    Possible causes:
    1. Defective (lower) door interlock switch or door not closing fully.
    2. Faulty relay or triac.

  • Problem: Fuse blows when closing or opening door:
    Possible causes:
    1. Defective door interlock switch(s).
    2. Interlock switch knocked out of position.
    3. Misaligned door.

  • Problem: Loud hum and/or burning smell when attempting to cook.
    Possible causes:
    1. Shorted HV diode, magnetron.
    2. Burnt carbonized food in or above oven chamber.
    3. Shorted winding in HV transformer.
    4. Frayed insulation on HV wiring.

  • Problem: Arcing in or above oven chamber.
    Possible causes:
    1. Burnt carbonized food deposits.
    2. Exposed sharp metal edges.

  • Problem: Fuse blows when initiating cook cycle.
    Possible causes:
    1. Defective interlock switches or misaligned door.
    2. Shorted HV capacitor.
    3. Shorted HV diode.
    4. Shorted magnetron (probably won't blow main fuse but HV fuse if used).
    5. Defective triac.
    6. Old age or power surges.
    7. Defective HV transformer.
    8. Short in wiring due to vibration or poor manufacturing.

  • Problem: Fuse blows when microwave shuts off (during or at end of cook cycle).
    Possible causes:
    1. Defective triac (doesn't turn off properly).
    2. Defective relay.
    3. Shorting wires.

  • Problem: Oven heats on high setting regardless of power setting.
    Possible causes:
    1. Faulty primary relay or triac or HV relay (not commonly used).
    2. Faulty controller.

  • Problem: Oven immediately starts to cook when door is closed.
    Possible causes:
    1. Shorted relay or triac.
    2. Faulty controller.

  • Problem: Oven heats but power seems low or erratic.
    Possible causes:
    1. Low line voltage.
    2. Magnetron with low emission.
    3. Faulty controller or set for wrong mode.
    4. Stirrer (or turntable) not working.
    5. Intermittent connections to magnetron filament or elsewhere.
    6. Faulty primary relay or triac or HV relay (not commonly used).

  • Problem: Oven heats but shuts off randomly.
    Possible causes:
    1. Overheating due to blocked air vents or inoperative cooling fan.
    2. Overheating due to bad magnetron.
    3. Bad connections in controller or microwave generator.
    4. Faulty interlock switch or marginal door alignment.
    5. Faulty controller.
    6. Overheating due to extremely high line voltage.
    7. Stuck stirrer fan resulting hot spots detected by sensors.

  • Problem: Oven makes (possibly erratic) buzzing noise when heating.
    Possible causes:
    1. Fan blades hitting support or shroud.
    2. Vibrating sheet metal.
    3. Vibrating transformer laminations.
    4. Turntable or stirrer hitting some debris.

  • Problem: Oven light does not work.
    Possible causes:
    1. Burnt out bulb :-).
    2. Bad connections.

  • Problem: Fans or turntables that do not work.
    Possible causes:
    1. Gummed up lubrication or bad motor bearing(s).
    2. Loose or broken belt.
    3. Bad motor.
    4. Bad thermostat.
    5. Bad connections.

on Mar 30, 2008 | Kenmore 80412 Microwave Oven

1 Answer

GE spacemaker xl 1800 died while cooking,has power to outlet, no display or lights, won't work at all.


Hi and welcome to FixYa. I am Kelly

When a micrwave quite during use it does have a tendancy to make the user wonder just what happened. There are several components that can cause this symptom.

1. The High Voltage Capacitor
http://www.appliancepartspros.com/partsearch/model.aspx?model_id=5227571&diagram_id=22974428#d22974428
(item 49)

2. The diode in the diode cable has failed
(Item 50 in the link above)

3. An open thermostat (Item 110) of above link (there are 2 of them)

4. A failed Magnatron (Item 73) This is pretty rare that a magnatron fails... It is usually something else.

Since you do not have any lights or appearance of power the fuse is probably blown.

http://www.appliancepartspros.com/partsearch/model.aspx?model_id=5227571&diagram_id=22974429#d22974429
(Item 47)

It can also be the duct thermostat item 27 but again this is a rare failure.

Usually what happens is either the HV Cap or the Diode in the Diode wire fails.

IF you even attempt repair... make sure to short across the HV Cap terminals at least 3 times. The first time if the cap is good it will really make a bang and spark.

To test the diode wire... "unhook / disconnect one end of it and use a meter to read it using resistance. One direction it should read. Reverse the leads and it will appear open.

There are a few other things like interlocks, HV transformer and control panel board that can cause this but again the instances of failure are pretty slim.
Replace the 20A fuse in the fuse holder. IF it blows again either the diode or the Cap is most likely the problem

An informational note... IF someone opened the door slowly without pressing pause / stop it can via the door interlock switch blow the fuse.

Hopefully this give you a clue as to what has happened and what to look for as far as repair and expected expenses.

Thanks for choosing FixYa.

Kelly

Jun 27, 2010 | GE Spacemaker JVM1640SJ Microwave Oven

1 Answer

GE Spacemaker Microwave JVM1441 BH04 tripping circuit breaker


your power transformer for the magnetron could have a shorted primary power winding,the door safety interlock switch could be mis-adjusted,this normally blows the internal unit fuse,a shorted high voltage capacitor,or diode,a bare wire inside the unit,more than the microwave on that circuit or a weak circuit breaker in the house power panel

Jun 19, 2010 | GE JVM1441 Microwave Oven

2 Answers

Kenmore Ultra Wave Microwave has no power


after removing the cover of microwave chk for continuty of cavity thermostat usually calld TCO(thermal cut off). it is located on top of the cavity and circular in shape.usually neutral wire goes through this 2 control board and this TCO is for protection of cavity from overheating.if this tco is open.then replace it.usually this happens when u cook for 2 long.

Aug 15, 2009 | Goldstar MV-1515 Microwave Oven

1 Answer

My GE jvm230 blows fuse when the start key is pressed. Refused and all is well until start key is pressed again and the fuse blows. I think my HV cap. is shorted. The HV capaciator isreading less than 1...


It might be the cap but it is probably a bad diode. The diode if shorted to the cabinet will of course blow the fugging fuse every time. The diode should have continuity in one direction only. If the 2 leads between the mag are shorted to chassis the fuse will also blow. You have 3 suspects the diode the cap and the mag. I would replace the cheapest thing first and that would be the diode and i am correct a shitload of times. Peace brother.

If you need further help, reach me via phone at https://www.6ya.com/expert/dan_73bbd84fe1d95b61

Jun 09, 2009 | GE Spacemaker JVM1640SJ Microwave Oven

1 Answer

GE JVM1870 Spacemaker Microwave Fan Malfunctioning when Cooking


There are two different fans in this model, as with almost all over the range microwaves.

One is the hood vent exhaust fan, which you can turn on and off at will, and which should always be on when cooking on the stove top.

This fan does not automatically come on when you cook with the microwave.

The fan which should always be on (automatically) when you are microwaving is the internal magnetron cooling fan.

If the cooling fan fails, the magnetron can overheat and the thermal cutout (TCO) / thermostat will open, killing the power to the oven. Ideally, this protects the magnetron from being destroyed.

If the thermal device is a thermostat, it will reset when it cools down, and the oven will work.

If the thermal device is a true thermal fuse, it is a one-time device and if it blows, it will have to be replaced.

If your cooling fan is bad, it needs to be replaced before using the microwave.

You can usually find helpful exploded view diagrams and order parts by entering your full 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 you with free advice and we'd appreciate your thoughtful rating of our answer.

Sep 16, 2008 | GE JVM1870 Microwave Oven

1 Answer

No lit LED, No panel control. Vent fan, running


We regularly repair these control panels for customers nationwide with our guaranteed $39.95 service.

Full details of our service are at http://www.microwavedisplay.com.

Feel free to contact me directly for more information & help.

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

William E. Miller
prototech@usa.net
http://www.microwavedisplay.com

Aug 14, 2008 | GE JVM1850 1000 Watts Microwave Oven

1 Answer

Fuse


The Interlock Monitor Switch is an added
safety check on the Primary and
Secondary Interlock Switches. If the
Primary and Secondary Interlock Switches
allow the oven to operate with the door
open, the Monitor Switch will blow the
fuse.

You can get more information about adjuting the interlock switch from this link

http://136.166.4.200/contents/Microwave/LMVM1935xx/LMVM1935xx_Service_Manual.pdf

sections 7-11 thru 7-12 discuss the door interlock adjustment that will cause the 20A fuse to blow if it isn't set up right. I hope this helps you...

Aug 03, 2008 | LG LMVM1935 Convection/Microwave Oven

1 Answer

Micro stopped working


Try looking at the microswitches behind the door.

Apr 05, 2008 | GE Spacemaker JVM1640SJ Microwave Oven

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