Author Topic: Dim Microwave Oven Display  (Read 243 times)

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Offline bostonman

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Dim Microwave Oven Display
« on: January 13, 2020, 03:53:45 pm »
I have an LG Microwave Oven, model LMV1813SW /01.

The LED display has been dim for a few years . I've looked at various repair manuals, but don't see much about the display. I'm wondering if an easy way exists to remove the display and repair it without disassembling the entire oven (which I'm not about to do because it's too dangerous).

Has anyone repaired one of these?
 


Online andy3055

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Re: Dim Microwave Oven Display
« Reply #2 on: January 13, 2020, 05:41:20 pm »
Any thing that works on electricity is dangerous if you don't follow the safety procedures in repairing them. Make sure the plug is pulled out before taking the covers off. Be aware that the huge capacitor terminals will have a charge even after mains power is disconnected. You should leave it off for the charge to dissipate first. Even then, I would not touch any of those terminals on the cap.

Do not attempt anything if you are not sure how to go about it in a safe manner. If that is the case, take it to a professional repair person! Any information given by anyone on this site (or any other site for that matter) should be followed at your own risk.
 

Offline bostonman

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Re: Dim Microwave Oven Display
« Reply #3 on: January 13, 2020, 05:47:48 pm »
All the safety I know, but I also know messing with microwave ovens is not safe.

If I could just remove the display, then I may attempt repairing it, otherwise, I'll eventually buy a new one.
 

Offline SeanB

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Re: Dim Microwave Oven Display
« Reply #4 on: January 13, 2020, 07:07:08 pm »
If it is a VFD, then likely the dim displat is more likely to be failing capacitors in the power supply, along with a failing display itself, as they spend all the time on.

As an aside, the controller on a microwave actually uses more power than the rest of the microwave over it's lifetime, simply because it is powered and using around 3-5W all the time, while your typical microwave magnetron operates for 5 minutes a day.
 

Offline macboy

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Re: Dim Microwave Oven Display
« Reply #5 on: January 14, 2020, 03:39:09 pm »
The display is VFD, not LED.  A VFD in a microwave has a hard life, because it is operating 24/7. Any VFD will dim over time for three main reasons:
- the filaments wear out, reducing the rate of emission of electrons, reducing brightness of the entire display, and sometimes resulting in blotchy looking display (usually brighter under each filament wire, and much dimmer between wires).
- the phosphors wear out, reducing brightness of the most-used digits/segments/characters.
- too-low voltage driving the filaments or the grids and anodes, due to (partial) failure of the power supply.

You can't do anything about the phosphors. You can increase the emission of the filaments by driving them at a higher current. This will restore some brightness to the display, but will also increase the rate of aging. It will eventually dim again, sooner rather than later. A power supply problem is best case scenario, because it isn't a failure or problem with the relatively irreplaceable VFD display itself.
 

Offline bostonman

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Re: Dim Microwave Oven Display
« Reply #6 on: January 14, 2020, 03:44:19 pm »
The display began getting dim about three-years after I bought it. I don't know the age of VFD's, but know I've seen microwave ovens that are two-decades old and still have a bright display.

I'd bet on capacitors, but again, they would be fairly new.

In any case, I'd like to disassemble it, but know it's not worth dismantling it as any error in reassembling my cause leakage.
 


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