LG Microwave Oven

The magnetron is malfunctioning. Throw it away and get a new microwave oven.

I just went through this about a month ago. Even if you had the knowledge to be able to fix it, parts are not available. Sorry.

I've seen that on a previous thread and forgot about it. That's a great use for a broken microwave!

In the USA mailboxes have to be approved by some bureaucrat in the postal service.

Could be the Magnetron (or its drive circuit) that provides the microwave energy. Do you hear a hum (the Magnetron) when the microwave is operating (cooking)?

I cannot remember if there is a separate fuse protecting the Magnetron, but a main fuse operation would take out the controls and prevent the whole thing working, so I would say with the limited information given that the Magnetron drive circuit has failed. A faulty door interlock switch would prevent the microwave from starting its cooking cycle, so I don't think it is that.

Can you provide more information please.

hi thanks for the information, what is happening is that when i switch on the oven from the switch, it comes on normally, then when i put anything to warm up or cook, i get no effect on the things i put inside the oven. so all is working ok except it has no effect on the things inside it. it's not doing what it is intended to do.

Most of the time it is only a small part. Unplug the oven!!!!!! At the capasitor you find a "high-voltage diode" usually a pencil thick, about an inch long, part with one wire connected with a flat "spade-"termininal to the capasitor and its other side has a round terminal screwed to the casing [earth].

It might be that the oven sound is a bit louder when this coconoligater-thinge has given the ghost. It is very inexpensive....should be less than 2 dollars.

If it still does not heat food it might be anything like the cap.;transformer or seldom the magnetron. Most ovens has a wiring circuit on the inside of the cover. Hope it is the diode for the other parts is expensive.

Jurie

Before you rush out and by another. Check if it has an internal fuse and a varistor.

I have seen a lot of equipment junked because of a voltage spike. The varistor is meant to clamp down (short out) during a voltage spike and blow the fuse.

WARNING: Even after unplugging the unit, the large capacitor can hold a vary serious charge for some time. It will want to bite you! Discharge it first.

If the above checks out, confirm that the door switches are good. Other than that, it is more than likely the magnetron

Contact manufacturer if it is still under warranty.

If this is a ~$100 model and is PAST warranty, I suggest you just buy a new one.

Even IF replacement parts are available (fuses, magnetron, HV diode, capacitor, transformer, etc) it will likely cost more to have someone accurately diagnose and repair it. DIY repair will be difficult and very dangerous unless you have experience working on high voltage power supplies.

It's broken.

Hi, I had the same problem some 20 years ago.

Had bought a combination of a microwave oven & 2 other oven types

all services by a programmable electronics section and all in one case.

My cost was 400 US $ at the time including a minus 25% intro rebate!

The microwave part of the oven died and I decided to repair it myself,

for whatever reason I cannot remember. Studied what a magnetron is

and how it operates. Did measurement with power applied (NOTE: this

is risky business - 3000 volts DC, lots of current! TAKE CARE!). At last

I had the circuit diagram of the high tension power supply. Conclusion

was that a wire was broken!? Close examination of the particular wire

proved it had a soldered-in inline fuse - added a new inline fuse holder

and a fuse with a little larger rating. Has worked ever since.

If you choose to attempt the repair yourself, thoroughly read through this site

http://www.repairfaq.org/sam/micfaq.htm

and please be very careful. Good Luck!

Great info at the link. Thank you. Do you have anything like this for home HVAC unit?

I have a problem with my blower not starting at times. Sometime I have to manualy give it a push. The motor and capacitor were changed 18 months ago. The motor humms but does not move. Do you think the capacitor needs changing or both motor and capacitor need to be changed? Sorry for asking you this in this thread.

Sounds like the centrifugal switch for the start winding is sticking open. If you have the mechanical ability and the motor can be disassembled you may be able to free up the switch by cleaning and lubing. The other potential problem with the switch is a weak spring but that is less likely unless the motor has significantly overheated. You may also need to lube the motor bearings.

Thank you for the info. I will remove the motor. I replaced it myself so it should not be a problem. I will do it this week end and will post the result on Monday.

Is the a Permanent split capacitor motor

Being an Lg product I would not suggest to waste anytime on it, even if you repair it you will usually find something else fails again shortly after . LG = Lucky if it Goes

I have a very old microwave, and have repaired it several times. One door microswitch, and at least twice the relay that switches the power to the transformer that creates the high voltage. The contacts slowly burn up. This may not apply to your model, and I caution you if you are not familiar with high voltage power circuits and do not have the instruments, then stay out of the box. I still have large boxes of bits and pieces. (My wife says I am hording). A new microwave from Walmart can be as little as $60, less than the cost of the replacement relay these days.

There is no such thing as hording parts.

You never know when you just might need that thingamajig! Not to mention nuts, bolts, screws etc.

Amongst my freinds I am conciderd to be the nearest hard ware, electrical, plumbing and electronics store

If it is an inverter type, throw it out, buy a new one. If it is the older hefty transformer type, try changing the HV diode, they seem to be the most common failure point. If you can find a decent supplier these can be had for a couple of bucks each. Buy them from the appliance repair guy and he'll probably charge you something like $50, not worth it.

Cheers

Martin

baxterm; good answer, i've found the diode or capacitor bad, diode $6.00 .cap $10.00 or there abouts. perry

Cost price in South Africa is R12.5. Less than 2 dollar for the diode.

Use an insulated wire to discharge the capasitor before working on oven innards further it is no more dangerous than working on any mains power! I have been shocked a couple of times by the capacitor......although it is 2800 volt the amps is low and did not do any harm so far!

Why does so many people [many times without knowledge about the thing they are talking about] frighten people away from repairwork........if you do not learn and experiment...you stay stupid!

Look for a fuse to the magnetron power supply. I have replaced fuses in this location on multiple ovens. All will behave normally but magnetron will not activate (no hum sound). Second check that door switches are making contact as stated in an earlier post. All this can be checked with a simple multimeter following standard safety procedures. Stay away from the high voltage areas if not familiar with working with HV.

Hello,

Check the cooling system efficiency. Dust and any kind of obstruction can reduce the airflow, increase the internal temperature and make the thermal sensor to switch off the magnetron (direct experience with a Whirlpool microwave oven!).

Regards

Just an interesting side note.

The company now known as LG, used to be called GoldStar up until 1995. GoldStar was synonymous with very cheap consumer electrical products. Along with the name change, LG launched a massive, and pretty successful, advertising campaign, in which their products were portrayed as very high end. While the name has been changed, the products themselves remain the same.

LG supposedly stands for "Lucky Goldstar" (not so according to the corporate site). Don't know if you can infer anything into that like wishful thinking.

We've been through this with a previous thread about 2 or so years ago, where there were some very helpful instruction manuals mentioned.

Depending on where you are you may be able to obtain the diode and fuse, if seems likely this is the fault, at a small cost from a local dealer. (The big outfits won't supply you in the UK 'cos of elf 'n safety).

If it's other than the diode then you have the problem with tracing through the interlocks.

That is typical of big business and H&S working out they can make bigger profits on new sales if they do not sell spare parts to repair existing equipment. It increases there carbon footprint of course but why worry about that, only Joe Blow at the bottom of the pile has to apply the green rules. Bring back the good old days when you could apply yourself to problems without a massive self perpetrating bureaucracy sticking there nose into your life. H Voltage diodes, these parts can be obtained through electronic supply houses also.

I tried the electronic supply houses and got nowhere as the specs of what was available were not matched by what was needed. I noted that the electronics stores in NZ & Australia tended to have a more comprehensive range than those of UK.

Anyway, the diode I eventually got did the trick on the Sanyo, having returned the extortionately expensive (& incorrect) diode I got in Spain, and the LG was done (in Spain) under warranty .

Glad to here you fixed the problem. Most of the diodes have about the same voltage rating but for different wattage magnetron the current rating varies, nothing wrong with using a diode for a higher rating magnetron in your [if it is] a lower rating unit. I used to pick up various microwaves from the recyclers so accumulated piles of spare parts [ until H&S decided it was not safe for people to rummage through the stuff] including diodes. Have got two pallets full of old microwaves slowly wasting away under cover people would just as soon buy a cheap one from the supermarket nowadays so there is no profit in fixing them any more.

Before trying anything more sophisticated...

Just unplug the thing. Wait a while. Then plug it back in.

It could also be low current. My microwave behaves like that sometimes...But if it is continuous then i guess u should go with what they are saying...

Rule #1, electricity can kill you!

Rule #2, capacitors hold an electrical charge, even when the power cord is unplugged. They might not kill you, but could make you wish it had.

Now here comes the Master Card Commercial...

Price for a new microwave... $50-100

Price for a trip to the emergency room... $1000 + lots of Bam Bam Bucks

Cost for insurance premiums going up because the house caught on fire... ???

(hey, they gotta pay Bam Bam Bucks too.)

Price of Wife showing cell phone picture of you in the ER to all of your friends and then putting the video on YouTube... Priceless

Projects like this are dangerous.

If you are not skilled with a volt meter,

don't have the knowledge of how to safely discharge a capacitor,

don't know the difference between a fuse and a diode,

then you should not even take the cover off of one.

I don't say this lightly, I work in a Power Plant on the control systems and am very knowledgable of electronics and electricity, and simply put, I would replace my microwave before I would try to fix it. Why? because keeping in mind, what ever part I would find went bad, was caused by some other part before it that was the cause of it going bad. So now you blow a good new part and find out that you need two parts instead of just another blown first part.

Find a skilled technician to help you or guide you to be on the safe side, or better yet, just buy a new one.

"Experience", the ability to make the same mistake twice, and realize it...

You said. "I don't say this lightly, I work in a Power Plant on the control systems and am very knowledgable of electronics and electricity, and simply put, I would replace my microwave before I would try to fix it. Why? because keeping in mind, what ever part I would find went bad, was caused by some other part before it that was the cause of it going bad. So now you blow a good new part and find out that you need two parts instead of just another blown first part." This is not necessarily true. due to the quality and manufacturing variations many parts fail because they do not have the guts so to speak and many fail on this point. This is not to say you should not check the overall operation of the system parts and I take it as a given if you are not knowledgeable with electronics to leave things alone.

So when your car needs sparkplugs......buy a new one for the steering might break next............or do not touch anything under the hood for the ignition system delivers 30 000volt.

One must be realy stupid or know nothing about electricity if one can not "cautiously" work on a microwave oven.

One day, when we meet, I will show you the scar on my elbow. This was caused by me pulling back after an electric shock and hitting a sharp edge very fast. Its the hidden dangers, the ones not in the handbook.

Then again, I'm the guy trying to change brake pads with the hand brake on

Been there and sort of done that.

Locked off and tagged a 500 ton chiller. Worked on it for four days. When I reinstalled the main fuses at the unit, I woke up 1/2 hr later. Someone in the plant had cut the lock, thinking that it was feed their machine, as it had stopped working.

Had to replace my boots and still have the marks on my feet.

Needless to say that they were not trained to read the tag, and no one would fess-up as to who did it.

A survival mode on their part, as I had a good use for the destroyed boots!