repairguy : My name isXXXXX will assist you tongiht
repairguy : Im assuming that you have a meter since you said you know the fuse is good.
repairguy : Were you able to follow the wire from the fuse to the main control board?
Customer: The orange wire from the fuse appears to go to a large box on the right side and attaches to a round black connector with a red wire on the other contact (the connector is attached to the box with 2 philips screws. The black wire appears to go to the left side and plugs into one of three small rectangular boxes.
repairguy : let me see if i can find a wiring diagram
repairguy : Give me a second
Customer: I have one but I am not good at reading it. It was in an envelope inside the microwave.
repairguy : So you can see the 120 volts on both sides of the fuse
Customer: I only checked continuity.
repairguy : if you take one lead to ground and the other to the fuse you should see 120 volts on each side
Customer: The needle doesn't indicate any power when I check continuity. Ususally it will shoot over quickly if there is power. Give me a few minutes and I'll try to check voltage. I have an old meter.
Customer: Yes, I am getting 120 volts on each side of the fuse
repairguy : if you follow the wire to the door switches do you get it there?
Customer: The top door switch appears to have the black wire from the fuse, but I don't get a reading when the door is either open or closed. I used one wire for the ground and tried contact with all of the wires on the switch.
repairguy : Im not sure what that black box is you are talking about
repairguy : I am unable to obtain a wiring diagram, can you take a picture of what you have and email it
Customer: Each switch has a black box behind it that opens or closes the circuit when the door is open or closed. There is another black box in the middle and I don't know what it does.
Customer: If you want a picture, I'll go to my car and get my camera and try to get an actual picture of the wiring diagram.
repairguy : that would help I think you may have a bad board, but I would like to be reassured
Customer: What email address should I use?
Customer: I am sending the pictures now. Forgot to mention that there is no 120 reading for the red wire in the connector next to the orange wire.
repairguy : Do you see the relays on the board?
repairguy : In the picture you sent me of the inside, there are two other type of fuses. They are black and round, the top one has white wires going to it, and the lower one has red it looks like. unplug unit and check these two thermals for continuity.
Customer: The one with the white wires has continuity when they are disconnected.
repairguy : thats good that is right
Customer: However, the one with the red on the left and the orange on the right (this is the one from the fuse) does not have any continuity.
repairguy : Are you able to jump them together?
Customer: You mean connect the red and orange wires to each other? When I tested the orange one with the circuit breaker on I got 120 volts, but not from the red one.
Customer: Do you want me to hook them together and then do what?
repairguy : yes turn circuit breaker off connect the two wires and see if it restores power to the unit, that is all I want you to do dont try to cook
Customer: I hooked them together and the vent fan went on, but no lights and no controls. The control board is still dead.
repairguy : ok that is the thermal for the vent fan ok
repairguy : but them back like normal
repairguy : Do you see the relays on the control board
Customer: Problem: when I went to hook up the orange wire to the vent fan thermal the tab on the thermal broke off. I'm going to need to get a new one--there's nothing left to hook the wire to. There are 2 larger relays on the back of the control board. One is labeled on the board as the main relay, and the other is labeled as a power relay. There are also 3 smaller boxes labeled as relays.
repairguy : On the power relay or the main relay you should be able to put one lead on ground which is the cabinet, and the other lead to the terminals on the relay
repairguy : let me know if you have 120v on either one
Customer: When I tested the power relay, there does not seem to be any power. When I tested the main relay with the black wires, I happened to touch the two wires (disconnected) thru the meter and the lights and fan went on for a moment. Then the fuse blew.
Customer: Don't forget that I do not have the orange wire connected to the vent fan thermal because I broke off the contact. I don't know whether that affects anything else.
repairguy : It does matter but not for what we were checking. from everything we have tested I would say you need a new pcb board, fuse and thermal
repairguy : Would you like me to locate these for your?
Customer: I put in a new fuse. I only get 120 from one black wire on the main relay, but no power from either wire on the power relay. I know I need a new thermal, but you haven't told me if the tab that I broke for the orange wire from the fuse is related to the problem now or not. Why did lights and fan go on when I accidentally connect the two wires from the main relay? And are you telling me I need an entire new pcb board that is on the back of the control board?
Customer: Orange wire is from the fuse to the thermal. The tab on the thermal broke.
repairguy : the orange wire is not part of our problem right now, nor is it affecting it.
repairguy : yes the pcb needs to be replaced, somehow you shorted something that sent voltage to the the other components
Customer: I'm going to connect the two wires from the main relay without the meter in the way and try to see what goes on. Should I be getting a reading from the power relay also?
repairguy : I would think you would, but the wiring diagram does not show us how the pcb is working
Customer: I just connected the two wires from the main relay together (black) and the light goes on inside with the door open. When I shut the door the microwave actually starts running, but the control board shows no lights at all.
Customer: I meant control panel, not control board.
Customer: I would like you to locate a board if you are pretty sure that it is the problem, and a thermal. However, the machine was running fine yesterday and there were no power surges that I know of.
repairguy : i understand what you are saying but i see customers everyday that say the same thing, electronics just go when they want it is hard to figure
repairguy : Goive me a minute and I will get you the info
repairguy : I have tried two different suppliers for your parts, the board is no longer available. I am not sure who you could contact I can give you the two part numbers, but like i said my suppliers do not have them any longer WB27X451 is the board and WB21X393 is the thermostat
Customer: Okay, enough for tonight. Thanks for your help. I
Customer: I'll have to look around some more.
repairguy : Thank you!