• ** REMEMBER! **The microwave can still shock you even unplugged!!

    ALWAYS discharge the high-voltage capacitor first if you even think your hands will come close to any HIGH VOLTAGE components.

    Jeff mentions this: Anything in the high voltage ( magnetron, capacitor, diode, wires to and from ):
    ...Use a metal ( not the shiny chrome type ) screw driver with a insulated handle to short across ( touch both at the same time ) the terminals of the high voltage capacitor to discharge it.

    From Jeff's site: http://www.applianceaid.com/component-testing.php

    Jake

FIXED LG LMV2073 Micrwave dead

larrywick

Premium Member
Joined
Nov 21, 2010
Messages
22
Location
Novato, ca
Model Number
LMV2073WW
Brand
LG
Age
1-5 years
LG LMV2073WW Microwave


Hi, there is power to unit, but it is completely unresponsive, no light when door is opened, no display. Line cord is plugged into noise filter circuit board which has fuse on it. Fuse is good. A black and a white wire are plugged into board, white goes to oven thermostat and black goes to M.G.T. thermostat. If I am reading the circuit diagram correctly the black should always be hot, 120volts. It is not. I am thinking that a component on the noise filter board has failed and it needs to be replaced. Do you agree?


all Microwave Display Repair Sharp Dacor GE General Electric
service manual for similar machine

Thanks for any help
Larry
 

jeff1

Appliance Tech - Moderator
Staff member
Joined
Oct 10, 2004
Messages
23,817
Location
Ontario, Canada
Hi,

If I am reading the circuit diagram correctly the black should always be hot, 120volts. It is not. I am thinking that a component on the noise filter board has failed and it needs to be replaced. Do you agree?
Unless the polarity of the outlet is backwards.

Hi, there is power to unit
What was the readings? Where was this taken?...and how?

Dead....often the fuse, fuse holder, flame sensor/thermostat, wiring between.

jeff.
 

larrywick

Premium Member
Joined
Nov 21, 2010
Messages
22
Location
Novato, ca
Thanks Jeff1 for your thoughts,
Polarity at outlet is correct, voltage there and at both sides of the fuse holder is 122.9 using a digital multimeter.
Could I temporarily bypass the noise filter without harming the microwave to see if that is what is keeping it from operating? I am assuming that the noise filter is there to condition the input voltage.

Thanks
Larry
 

jeff1

Appliance Tech - Moderator
Staff member
Joined
Oct 10, 2004
Messages
23,817
Location
Ontario, Canada
voltage there and at both sides of the fuse holder is 122.9 using a digital multimeter
That would indicate the fuse is good. Leave one needle on the neutral ( white ) and if you get 120 volts AC with the other lead on both sides of the fuse holder the fuse is good.....a bad one will have 120 volts on one side and 0 ( zero ) on the other. Can also remove the fuse and ohm meter test it.

ohm-meter-how-to.jpg

Could I temporarily bypass the noise filter without harming the microwave to see if that is what is keeping it from operating?
Usually yes.

jeff.
 

jeff1

Appliance Tech - Moderator
Staff member
Joined
Oct 10, 2004
Messages
23,817
Location
Ontario, Canada
Thankx for the update :)

jeff.
 
Top