GE microwave JVM1440BH04

[BradE]

Anyone have a manual for this microwave or what the high voltage side specs are? I keep blowing the HV diode after about 2 minutes. Everything else seems to be OK, but oviously something is ary. Any past experience knowledge??

[appl.tech.29501]

I don't think we have a manual for this unit. Have you checked the capacitor for a short?

[BradE]

Capacitor checked OK, tried an extra one I had anyway. Same scenario.

[appl.tech.29501]

Time to check the Transformer

1. UNPLUG the oven.
2. DISCHARGE ALL HIGH-VOLTAGE CAPACITORS. (Procedure)
3. Disconnect the high-voltage lead from the transformer's high-voltage terminal (or tap).
4. With an ohmmeter set to the lowest resistance scale, R X 1, measure the resistance from the high-voltage terminal to the transformer chassis (ground).
   1. Some early models are equipped with two or three high-voltage taps. If this is the case, perform the measurement from each tap to chassis ground.
   2. The meter should read about 55 to 70 ohms, depending on which high-voltage tap is being measured and the model being tested.
      1. A substantially higher or lower reading would indicate that the transformer is defective.

[*] Carefully disconnect the leads from the primary (input) terminals [*] Measure from one transformer primary terminal to the other for a normal reading of less than 1 ohm (i.e., .22 ohms)

1. A substantially higher reading would indicate that the primary winding is open.

[*] Set the meter to its highest resistance scale and check from each transformer primary terminal to the transformer chassis (ground) for a normal reading of infinity (open circuit).

1. Any measurement of resistance would indicate some degree of a short to ground

[*] Set the meter back to its lowest resistance scale. Then carefully disconnect the filament leads and measure from one filament terminal to the other for a normal resistance of less than 1 ohm. [*] Set the meter to its highest scale and measure from each filament terminal to chassis ground for a normal reading of infinity (open circuit).

1. Any measurement that is substantially different from the normal readings would indicate a defective transformer.

[BradE]

Because I don't have the specs, I don't know if this is out of range or not. I am getting 134 ohms on the high voltage lead to ground. Don't know if you have access to this models specified range.

 

thanks

[appl.tech.29501]

that seems high...let me do some more checking

[RegUS_PatOff]

31-9028

lists JVM1440  but doesn' t show that particular schematic

others may be similar

one schematic shows the Transformer resistance values ,,

link PM'd