Question about Sharp R-930AK Convection/Microwave Oven

1 Answer

HV Transformer and Maganatron

My Sharp R930AW microwave oven does not heat. Controls work, but no heat. I read 110 volts to the primary side of the hv transformer, but no voltage on the secondary side. I also show continuity between both leads to the magnatron. Is the transformer bad, and if so has the replacement part changed from RTRNA535WREO to RTRNA527WREO? Also, does continuity on the magnatron indicate no problem there?

Posted by on

  • tomnterry1 Mar 16, 2009

    I can turn the microwave on the light works the timer works but no heat and the turn table doesn't work? what do you think Thanks also where can i download a free manual thanks again

×

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Superstar:

    An expert that got 20 achievements.

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

  • Sharp Master
  • 8,862 Answers

I would not recommend an inexperienced measuring secondary voltage on the high voltage transformer! The filament winding produces about 3VAC but the high voltage winding produces well over 2000VAC! And that can be instantly lethal!

I would only recommend measuring the resistance (in ohms) of the windings with power off and capacitor discharged.

We have the full service manual for this model and have uploaded it to our site here to help you.

You will need the free Acrobat Reader to view or print it.

The part number listed by the distributor for the high voltage transformer is RTRN-A527WRE0 (zero on the end, not "oh") which is the same number shown in the service manual.

The two continuity checks on a magnetron are across the filament terminals, which should read about zero ohms, and from each terminal to the case, which should read open or infinity.

Even if a magnetron passes these continuity tests, it can still be bad.

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

Posted on Oct 04, 2008

×

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 is my Sharp Microwave Drawer KB-1614LS not heating?


You should check for 3 volts on sec coil supply for magnetron but do this check with the hv capacitor and hvr disconnected if 3volts is present , most probably your magnetron is deffective, replace it with the same type

May 13, 2014 | Sharp Microwave Ovens

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

2 Answers

It will run but it won't heat. It also makes a funny "humming" sound and smells like burning plastic.


Sorry to read about your problem, I hope this helps you out.
you may one of these issues.
  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. Damaged protective VDR from filament to chassis (not commonly used).
  7. Defective HV relay (not commonly used).
Microwaves must be serviced by technicians due to the inherent dangers involved in repairing these appliances. Internal capacitors can retain a lethal electrical charge even though the unit is completely unplugged. A microwave radiation leakage test must be performed on the unit following any internal component repair.

I tried to help you. Please help me and Rate/Vote on my response. We take the time to answer your question's. take the time to rate us.Thanks and good luck

4 Thumbs - Very Helpful
3 Thumbs - Helpful





Jan 04, 2011 | Maytag MMV5156AAS Microwave Oven

1 Answer

Microwave activate but will not heat food all light and buttons work but will not heat up


Sorry to read about your problem, I hope this helps you out.

You can many different issue's
  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. Damaged protective VDR from filament to chassis (not commonly used).
  7. Defective HV relay (not commonly used).
Microwaves must be serviced by technicians due to the inherent dangers involved in repairing these appliances. Internal capacitors can retain a lethal electrical charge even though the unit is completely unplugged. A microwave radiation leakage test must be performed on the unit following any internal component repair.

I tried to help you. Please help me and Rate/Vote on my response. We take the time to answer your question's. take the time to rate us.Thanks and good luck

4 Thumbs - Very Helpful
3 Thumbs - Helpful

Jan 04, 2011 | GE Spacemaker JVM1640SJ Microwave Oven

1 Answer

GE JVM1440 will not heat.


Sorry to read about your problem, I hope this helps you out.

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. Damaged protective VDR from filament to chassis (not commonly used).
  7. Defective HV relay (not commonly used)
Microwaves must be serviced by technicians due to the inherent dangers involved in repairing these appliances. Internal capacitors can retain a lethal electrical charge even though the unit is completely unplugged. A microwave radiation leakage test must be performed on the unit following any internal component repair.

I tried to help you. Please help me and Rate/Vote on my response. We take the time to answer your question. take the time to rate us.Thanks and good luck

4 Thumbs - Very Helpful
3 Thumbs - Helpful

Jan 01, 2011 | GE JVM1440 Microwave Oven

1 Answer

WMH1162 not heating



Sorry to read about your problem, You have a major failure, I suggest you contact a service company. If you feel like making repairs yourself, i will give you some pointers below.

There are other variations depending on whether the cooling fan, oven light, and so forth are located down stream of the fuse.

Some models may have a separate high voltage fuse. If this is blown, there will be no heating but no other symptoms. However, high voltage fuses are somewhat rare on domestic ovens.
A number of failures can result in the fuse NOT blowing but still no heat:

  • Bad connections - these may be almost anywhere in the microwave generator or the primary circuit of the HV transformer. A common location is at the crimp connections to the magnetron filament as they are high current and can overheat and result in no or intermittent contact.
  • Open thermal protector - usually located on magnetron case. Test for continuity. It should read as a dead short - near zero ohms.
  • Open thermal fuse - some ovens have one of these in the primary circuit. It may be in either connection to the HV transformer or elsewhere. Test for continuity. It should read as a dead short - near zero ohms.
  • Open HV capacitor - see the section: A shorted HV capacitor would likely immediately blow the fuse.
  • Open HV diode - see the section:
  • Open magnetron filament - This failure may also be due to loose, burnt, or deteriorated press (Fast-on) lugs for the filament connections and not an actual magnetron problem.
  • Open winding in HV transformer.
  • Defective HV relay. A few models use a relay in the actual high voltage circuitry (rather than the primary) to regulate cooking power. This may have dirty or burnt contacts, a defective coil, or bad connections
  • Shorted HV diode -
  • Short or other fault in the magnetron - see the section:
  • Short in certain portions of the HV wiring.
I tried to help you. Please help me and Rate/Vote on my response. We take the time to answer your question. take the time to rate us.Thanks and good luck

4 Thumbs - Very Helpful
3 Thumbs - Helpful

Dec 30, 2010 | Whirlpool Microwave Ovens

1 Answer

I have the model FMAC101D1PS and now it's not heating. I press the minutes to heat, it run but it doesn't heat anyting.


Most likely causes are an open thermal protector or thermal fuse but could also be blown fuse in HV area of microwave (somewhat uncommon in domestic microwaves).
Less likely causes are failure of other parts in the HV area.



If the main power fuse is located in the primary of the high voltage transformer rather then at the line input, the clock and touchpad will work but the fuse will blow upon initiating a cook cycle. Or, if the fuse has already blown there will simply be no heating action once the cook cycle is started. There are other variations depending on whether the cooling fan, oven light, and so forth are located down stream of the fuse.

Some models may have a separate high voltage fuse. If this is blown, there will be no heating but no other symptoms. However, high voltage fuses are somewhat rare on domestic ovens.

A number of failures can result in the fuse NOT blowing but still no heat:

  • Bad connections - these may be almost anywhere in the microwave generator or the primary circuit of the HV transformer. A common location is at the crimp connections to the magnetron filament as they are high current and can overheat and result in no or intermittent contact. See the section: See the section: Testing the magnetron (see repair manual link below).
  • Open thermal protector - usually located on magnetron case. Test for continuity. It should read as a dead short - near zero ohms. See the section: Testing thermal protectors and thermal fuses (see repair manual link below).
  • Open thermal fuse - some ovens have one of these in the primary circuit. It may be in either connection to the HV transformer or elsewhere. Test for continuity. It should read as a dead short - near zero ohms.
  • For the various HV parts and how to test them follow this link: Microwave Repair Manual link.

A shorted HV diode, magnetron, or certain parts of the HV wiring would probably result in a loud hum from the HV transformer but will likely not blow the main fuse. (However, the HV fuse - not present on most domestic ovens - might blow.)

Depending on design, a number of other component failures could result in no heat as well including a defective relay or triac, interlock switch(s), and controller.

Oct 21, 2010 | Frigidaire Microwave Ovens

1 Answer

Model 721.64282 microwave/convection oven - microwave not heating and making a loud noise. convection oven works


No heat but otherwise normal operationA shorted HV diode, magnetron, or certain parts of the HV wiring would probably result in a loud hum from the HV transformer but will likely not blow the main fuse. (However, the HV fuse - not present on most domestic ovens - might blow.)
If the main power fuse is located in the primary of the high voltage transformer rather then at the line input, the clock and touchpad will work but the fuse will blow upon initiating a cook cycle. Or, if the fuse has already blown there will simply be no heating action once the cook cycle is started. There are other variations depending on whether the cooling fan, oven light, and so forth are located down stream of the fuse.

Some models may have a separate high voltage fuse. If this is blown, there will be no heating but no other symptoms. However, high voltage fuses are somewhat rare on domestic ovens.

A number of failures can result in the fuse NOT blowing but still no heat:


  • Bad connections - these may be almost anywhere in the microwave generator or the primary circuit of the HV transformer. A common location is at the crimp connections to the magnetron filament as they are high current and can overheat and result in no or intermittent contact. See the section: See the section: Testing the magnetron.
  • Open thermal protector - usually located on magnetron case. Test for continuity. It should read as a dead short - near zero ohms. See the section: Testing thermal protectors and thermal fuses.
  • Open thermal fuse - some ovens have one of these in the primary circuit. It may be in either connection to the HV transformer or elsewhere. Test for continuity. It should read as a dead short - near zero ohms.
  • Open HV capacitor - see the section: Testing the high voltage capacitor. A shorted HV capacitor would likely immediately blow the fuse.
  • Open HV diode - see the section: Testing the high voltage diode.
  • Open magnetron filament - This failure may also be due to loose, burnt, or deteriorated press (Fast-on) lugs for the filament connections and not an actual magnetron problem. See the section: Testing the magnetron.
  • Open winding in HV transformer. See the section: Testing the high voltage transformer.
  • Defective HV relay. A few models use a relay in the actual high voltage circuitry (rather than the primary) to regulate cooking power. This may have dirty or burnt contacts, a defective coil, or bad connections
  • Shorted HV diode - see the section: Testing the high voltage diode.
  • Short or other fault in the magnetron - see the section: Testing the magnetron.
  • Short in certain portions of the HV wiring. See the section: Testing and repairing the wiring and connections.

Depending on design, a number of other component failures could result in no heat as well including a defective relay or triac, interlock switch(s), and controller.


If you are interested in doing it yourself the following link will help : Microwave Repair Manual

(**All the above references to tests are found here)

Oct 21, 2010 | Kenmore 63663 Microwave Oven

1 Answer

Just replaced the magnetron in my Panasonic NN-S543BFR. I still don't get any heat from my oven. Everything works as set but still no heat in oven. Need suggestions on repairs.


When you say "Everything works as set" do you mean the microwave appears to function properly, but then doesn't heat?

If the magnetron is new, then the magnetron must not be receiving the required high voltage (2000V or more) from the HV circuit. Make sure you've got 120V to the PRIMARY (don't attempt to measure secondary voltage of the HV transformer without special equipment) of the HV transformer. After that check the HV capacitor and diodes. If these components test OK, then either your HV transformer is bad or your new magnetron is faulty. My experience is that the problem is usually in control circuitry, preventing 120V to the HV transformer, or opens/shorts in the HV components (diodes and capacitors).

Mar 15, 2010 | Panasonic NN-S543BFW Microwave Oven

2 Answers

Microwave oven problem


If your microwave is doing everything, but heating it could be any one of the following components: Magnetron HV Capacitor HV Diode HV Transformer This network works in conjunction to produce the high voltage required to heat. Taking live voltage measurements is dangerous and not recommended. You can, however, do resistance checks on the components with the unit unplugged to see if you can isolate the problem any further. The HV Diode should be mounted somewhere on or near the HV capacitor and will read an open in one direction and a relative short in the other. If you put a meter on the capacitor you should see a varying resistance as the capacitor charges and discharges. There should should be a wiring diagram inside your control panel with the resistance readings for the primary and secondary windings of the transformer and the filament of the magnetron. In a nut shell, you probably have either a bad magnetron or a bad diode. Those are the two components that fail more frequently. Of course, double check all your interconnecting wires too. Good luck and let me know if this helps.

Jun 22, 2007 | GE JVM1660 Microwave Oven

Not finding what you are looking for?
Sharp R-930AK Convection/Microwave Oven Logo

310 people viewed this question

Ask a Question

Usually answered in minutes!

Top Sharp Microwave Ovens Experts

William Miller
William Miller

Level 3 Expert

8862 Answers

Devabhakthuni...
Devabhakthuni...

Level 2 Expert

224 Answers

Donald DCruz
Donald DCruz

Level 3 Expert

17129 Answers

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

Answer questions

Manuals & User Guides

Loading...