• ** 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 JMV8208BA/BC Jenn-Air blowing line fuse

hugo1969

Premium Member
Joined
Mar 20, 2017
Messages
6
Location
California
Model Number
JMV8208BA
Brand
Jenn-Air
Age
6-10 years
Hi,

On a different post i had confirmation from Rick on my transformer being defective, due to low resistance on the secondary wire to ground.
I purchased a new transformer and finally had the time to install it.

After installing the new transformer and connected all components, the main line fuse (20A) blew seconds after hitting start. Then power to the whole unit is lost.
Checked all connections, re-checked door switches to assure they were engaging, replaced capacitor with working one from another unit (same mfd value)

Hit start and fuse went out again.

So far i have replaced the following new components:

Transformer
Diode
Magnetron

I am about to toss this thing out the window but the wife is very attached to it. Any help is much appreciated as I am at a loss with this thing.

Hugo

schem.JPG
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
34,007
Location
Murray, Utah 84107, United States
Disconnect the wires on the primary side of the transformer and tape the ends so they don't touch anything. You have disconnected the entire high voltage side of the machine. If the microwave doesn't blow the fuse when you start the microwave, the problem is with one of the high side components or the wiring. If the microwave does blow the fuse when it's started with the high side disconnected, the problem is elsewhere. Be sure to check the door switches by opening and closing the door and not just pressing the button on the switch.
 

hugo1969

Premium Member
Joined
Mar 20, 2017
Messages
6
Location
California
HI Rick,

With the primary side of the transformer disconnected the fuse did not blow. I then connected the transformer's primary but left the secondary disconnected, fuse did not blow.
As soon as i connected the capacitor/diode conbination the fuse went out.
The same thing happened with a secondary set of capacitor/diode combo.

I visited a local appliance parts store, they tested the capacitors and diodes. They all seem to be good, all they could tell me was to check the switches, which I have multiple times with door open or closed.
I think there is something else damaged on this thing.

Hugo
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
34,007
Location
Murray, Utah 84107, United States
With the primary side of the transformer disconnected the fuse did not blow.
OK, If the cap and diode check good, the problem is either the mag tube or it's misswired.
 

hugo1969

Premium Member
Joined
Mar 20, 2017
Messages
6
Location
California
You nailed it, I was following a picture i had taken of the connections to the cap/diode. I must of taken this picture at one point when i was troubleshooting the defective transformer.
Now that you mentioned it I looked at the diagram and noticed the red and white wires to the cap were swapped on the photo.

No wonder it wasn't making any sense.

Thanks, it's fixed now.
 
Top