HV Microwave Oven Rectifier question

Discussion in 'General Electronics Chat' started by Gdrumm, Mar 24, 2010.

  1. Gdrumm

    Thread Starter Distinguished Member

    Aug 29, 2008
    How does an HV Microwave Oven rectifier work?

    I've never seen them before, and today I fixed a microwave by taking the HV-6X2P1 out of the circuit.

    The capacitor had the usual diode coming off on one lead, and going to ground, but it also had this rectifier tied in to both posts of the capacitor. Every time I tried to use the Microwave, it would blow the fuse.

    When I saw it across both posts of the capacitor, I thought that it looked like a direct short. I cut one of its leads, and tried the microwave again, and it worked perfectly.

    It seem like it's sort of a thermal fuse, in reverse?

    Just wondering how its intended to work?

    I looked it up on Alldatasheet, and it mentions that it has High Overload Surge Capability, Controlled Avalanche Characteristics, and Low Forward Voltage Drop. What do those things mean?

    Is it safe to leave it out of the circuit?
    I've repaired numerous microwaves in the past, and I've never seen one of these.

    Thanks for any insights,
  2. JDT

    Well-Known Member

    Feb 12, 2009
    Microwave ovens usually have a voltage doubler type rectifier. This has two diodes and two capacitors.

    The device you are talking about, if it is in parallel with the capacitor is probably a surge voltage limiting avalanche diode. As microwave ovens are built to a (low) price, only essential components will be fitted. So best to replace if you can.

    I have to say that THIS IS A VERY DANGEROUS, HIGH VOLTAGE piece of equipment and should not be tampered with!! FATAL if touched!!!

    The capacitors can retain their charge even after the oven is disconnected from the supply.
  3. Gdrumm

    Thread Starter Distinguished Member

    Aug 29, 2008
    Thanks for the warning.
    I did use a two foot long wooden pole, with a nail in one end, to discharge the capacitor.

    If I choose to use the microwave with that component removed, and it works well, what would be the worst that could happen?

    Is it a redundant feature?