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After lightning strike & power outage digital display & oven not working. is there a fuse or reset button? or is the circuit board fried?

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Start by investigating, open at the point where power cord goes in there is a fuse if it is o.k there is another smaller trans former powering the display board that normally uses thermo fuse, find out whether the thermo fuse is blown i hope this solves your problem

Posted on Aug 02, 2010

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Samsung Microwave Oven SMH7159 No Power


The power outage may have been accompanied with a power surge. That can happen with lightning strikes, or if a large inductor (electric motor or equivalent) happened to be on the same power line at the time of the outage. There's a good chance a surge took out the control panel.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/david_29ad5d1dd86564b0

Aug 06, 2016 | Samsung Microwave Ovens

2 Answers

GE JVM1850CH06 MICROWAVE


the panel display is fried. you'll need to remove and replace it...this the sort of thing you enjoy doing?

May 23, 2008 | GE XL1800 1100 Watts Microwave Oven

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What can go wrong The most common problems occur in the microwave generating portion of the system, though the controller can be blown by a lightning strike or other power surge. Bad interlock switches probably account for the majority of microwave oven problems. Also, since the touchpad is exposed, there is a chance that it can get wet or damaged. If wet, a week or so of non-use may cure keys that don't work. If damaged, it will probably need to be replaced - this is straightforward if the part can be obtained, usually direct from the manufacturer. Unfortunately, it is an expensive part ($20-50 typical). The interlock switches, being electromechanical can fail to complete the primary circuit on an oven which appears to operate normally with no blown fuses but no heat as well. Faulty interlocks or a misaligned door may result in the fuse blowing as described above due to the incorrect sequencing of the door interlock switches. Failed interlocks are considered to be the most common problems with microwave ovens, perhaps as high as 75% of all failures
No adjustments should ever be required for a microwave oven and there are no screws to turn so don't look for any!

General system problems The following problems are likely power or controller related and not in the microwave generator unless due to a blown fuse or bad/intermittent connections:
  • Totally dead oven.
  • No response to any buttons on touchpad
  • Oven runs when door is still open.
  • Oven starts on its own as soon as door is closed.
  • Oven works but display is blank.
  • Whacked out controller or incorrect operation.
  • Erratic behavior.
  • Some keys on the touchpad do not function or perform the wrong action.
  • Microwave oven does not respond to START button.
First, unplug the microwave oven for a couple of minutes. Sometimes, the microcontroller will get into a whacko mode for some unknown reason - perhaps a power surge - and simply needs to be reset. The problem may never reoccur.
Note: when working on controller related problems, unplug the connection to the microwave generator (HV transformer primary) from the power relay or triac - it is often a separate connector. This will prevent any possible accidental generation of microwave energy as well as eliminating the high voltage (but not the AC line) shock hazard during servicing.
If this does not help, there is likely a problem with the controller circuitry or its power and you will have to get inside the oven.


Uninvited guests Some cockroaches (or other lower life forms) may have taken up residence on the controller circuit board. It is warm, cozy, safe, and from their point of view makes an ideal habitat. If you got the microwave oven from a flea market, garage sale, the curb, a relative, or friend, or if your kitchen isn't the cleanest in the world, such visitors are quite possible. Creatures with six or more legs (well, some two legged varieties as well) are not known for their skills in the areas of housekeeping and personal hygiene. Clean the circuit board and connectors thoroughly with water and then isopropyl alcohol. Dry completely. Inspect the circuit traces for corrosion or other damage. If there are any actual breaks, these will have be be jumpered with fine wire and then soldered. Hopefully, no electronic components were affected though there is always a slight possibility of other problems.
Totally dead oven First, check power to the outlet using a lamp or radio you know works. The fuse or circuit breaker at your service panel may have blown/tripped due to an overload or fault in the microwave oven or some other appliance. You may just have too many appliances plugged into this circuit - microwave ovens are high current appliances and should be on a dedicated circuit if possible. If you attempt to run a heating appliance like a toaster or fryer at the same time, you *will* blow the fuse or trip the circuit breaker. A refrigerator should never be plugged into the same circuit for this reason as well - you really don't want it to be without power because of your popcorn! If you find the fuse blown or circuit breaker tripped, unplug everything from the circuit to which the microwave is connected (keep in mind that other outlets may be fed from the same circuit). Replace the fuse or reset the circuit breaker. If the same thing happens again, you have a problem with the outlet or other wiring on the same branch circuit. If plugging in the microwave causes the fuse to blow or circuit breaker to trip immediately, there is a short circuit in the power cord or elsewhere.
The microwave oven may be powered from a GFCI outlet or downstream of one and the GFCI may have tripped. (Removing a broken oven lamp has been known to happen.) The GFCI outlet may not be in an obvious location but first check the countertop outlets. The tripped GFCI could be in the garage or almost anywhere else! Pushing the RESET button may be all that's needed.
Next, try to set the clock. With some ovens the screen will be totally blank following a power outage - there may be nothing wrong with it. Furthermore, some ovens will not allow you perform any cooking related actions until the clock is set to a valid time.
Assuming these are not your problems, a fuse has probably blown although a dead controller is a possibility.
If the main fuse is upstream of the controller, then any short circuit in the microwave generator will also disable the controller and display. If this is the case, then putting in a new fuse will enable the touchpad/display to function but may blow again as soon as a cook cycle is initiated if there is an actual fault in the microwave circuits.
Therefore, try a new fuse. If this blows immediately, there may be a short very near the line cord, in the controller, or a defective triac (if your oven uses a triac). Or, even a shorted oven lamp - remove and inspect the light bulb and socket.
If it does not blow, initiate a cook cycle (with a cup of water inside). If the oven now works, the fuse may simply have been tired of living. This is common.
If the fuse still blows immediately, confirm that the controller is operational by unplugging the microwave generator, power relay, and/or triac from the controller. If a new fuse does not now blow when a cook cycle is initiated - and it appears to operate normally - then one of the components in the microwave generator is defective (shorted).
Some models have a thermal fuse as well and this may have failed for no reason or a cooling fan may not be working and the oven overheated (in which case it probably would have died while you were cooking something for an important guest - assuming you would use a microwave oven for such a thing!).
Other possible causes: bad controller power supply or bad controller chip.


Totally dead oven after repair On some microwave ovens, there is at least one cabinet screw that is slightly longer than all the others. This engages a safety interlock which prevents the oven from receiving power if the correct screw is missing or in the wrong hole. Check the length of all the screws and locate the interlock switch behind one of the screw holes. I don't know how common this practice is but have heard of it on some Sharp models.

Dead controller The most common way that the controller circuitry can be harmed is by a power surge such as from a lightning strike. Hopefully, only components on the primary side of the power transformer will be affected.
  • Check the primary of the power transformer - if it is open, there may be a fuse/thermal fuse underits outer insulation. If not, the transformer will need to be replaced. There is a good chance that the surge didn't propagate beyond the transformer and thus the rest of the controlled should be unaffected.
  • In some cases, circuit board traces may have been vaporized (but repair may still be possible by simply jumpering across the crater). Some of these thin traces may be there specifically to act as fuses - and there may even be spares to use for just this situation!
  • Assuming that the main fuse and power transformer primary checks out, then check the power supply for the controller next.
  • As always, also check for bad solder connections.
If the controller power supply is working and there is still no sign of life (dead display and no response to buttons) the microcontroller chip or some other part may be bad. It could be a simple part like a capacitor or diode, but they would all need to be tested. At this point, a schematic of the controller board will be needed - often impossible to get - and replacement controller or even just the main chip may be nearly as expensive as a complete new oven.

on Mar 30, 2008 | Kenmore 80412 Microwave Oven

2 Answers

Where are the fuses in my microwave oven,?


Inside behind the display panel on a small circuit board.

Jan 01, 2013 | Magic Chef MCO160UB Microwave Oven

1 Answer

My amana model number amv1150vas is not working after a power outage


Unplug for 60 seconds to see if it will reset, if no! the fuse in the microwave has opened/ or if the model is the new type, it is the keypad control board or smart board.

Apr 05, 2012 | Amana Microwave Ovens

1 Answer

Have a magic chef mco160uw microwave. Had a recent


No! there is no reset, the power surge has more than likely damaged the keypad controller, and on the back is a circuit board that has the microprocessor with additional components that controls the vital areas of the microwave oven. If that is gone, it is cheaper to replace than to repair.

Feb 06, 2011 | Microwave Ovens

1 Answer

Will not heat baby food for 13 seconds


Depending on the amount of Joules your household/microwave received your low voltage control electronics may have been fried by the lightning strike. For your own safety I recommend a new microwave.

Jun 10, 2010 | Maytag MMV5186A Microwave Oven

1 Answer

Can not reset after power outage


If display is on and you cant reset, the board has been damaged during the power outage. The current shoots up over the safe limit and does the damage. need to replace board and put a surge plug on line

Sep 15, 2009 | Kenmore Microwave Ovens

1 Answer

We had a lightning strike near our home and our Ewave OTR microwave quit, nothing works but the light inside and the vent fan comes on automatically. We've been told that there is a fuse that can be...


If the light and fan work then it cannot be the fuse. When the fuse "blows", it stops the electricity totally from flowing into the microwave and nothing will work or respond. The fuse is behind the control panel and this requires several hidden screws to be removed. Also, you must be very careful of the 2000 volt charge that is stored in the wiring further into the compartment behind the control panel. Therefore, do not attempt to open the micro control panel without proper service knowledge.
Because you say the light and fan operate, the fuse (as I stated ) is not your answer; most likely the problem is in the control panel circuit board. The circuit board is like any sensitive electronic component that goes crazy when there is a voltage surge that strikes it such as lighting throughout the house wiring. The board needs to be replaced unless you can have an electronic wizz-kid test is out and repair it , or just by a new board. By the way, the board is not cheap and may be difficult to locate since I understand the the manufacture stopped producing it.

Aug 13, 2009 | Microwave Ovens

1 Answer

We had a bad power surge during a storm last week which fried my Panasonic NN-T990saf. My question is it worth trying to get it repaired or should I just buy a new micro wave?


Although lightning damage is normally fatal to anything with electronics inside, you might remove the back panel and look for fuse holders. If you find one (minimum) or two (likely), replace them (if you have a cheap multimeter you can check for continuity) and see  if it will turn on. You may have to do a little telephone work to locate the high current fuse which is probably 30 amps.  
If you live in an area of frequent lightning strikes, investing in a 'whole house' surge arrester makes sense. These are installed in the main breaker box and any brand I've seen comes with a $10-25,000 insurance policy to replace any dead appliances that fail despite the surge protector. They cost $150-250 US plus installation which you can save if you are afraid to DIY.     

Feb 23, 2009 | Panasonic NN-T990SA Microwave Oven

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