Possible causes of dim Microwave Oven display

Thread Starter

Gdrumm

Joined Aug 29, 2008
684
I've seen some Microwave ovens that will not display a backlight anymore. They still work, but the display is so dim, you have to be inches away to read it.

In my mind, (from one personal experience) it seems to be related to bad weather, lightning in our area. Does that make sense?

The display LEDs checked out okay, until I fried them just now with a 9v battery.

Does anyone have any experience to know likely causes?
(Of the display issue, I know the cause of my frying the LEDs.
It's called OMS or DA)
Thanks,
Gary
 

Meixner

Joined Sep 26, 2011
117
Maybe you are discribing VF (vacuum flourescent) displays, they are frequently used in microwave ovens and they get dim with age.
 

sheldons

Joined Oct 26, 2011
613
depends on the microwave-if its an lcd display type that requires a backlight before you see anything displayed-hi brightness leds are used here and they may be special types used depending on model and manufacturer-if its a vf display sometimes its a low supply/missing supply on the filament or a faulty display itself
 

THE_RB

Joined Feb 11, 2008
5,438
Maybe you are discribing VF (vacuum flourescent) displays, they are frequently used in microwave ovens and they get dim with age.
Yes it is a VFD, and no they don't really get that dim with age, they can be at excellent brightness even after 30 years constant use.

However they have a very common fault that makes them get very dim, this is because the caps in the 50v inverter circuit get old and reduce the 50v supply.

Generally they are very easy to return to full brightness. Just get to the PCB and replace any electro caps near the VFD. The inverter caps are usually 63v rated and are near to an inductor of some type (to form a boost inverter).
 
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