neff microwave 10 amp fuse blown

[tiv48]

Phone call do you repair microwaves ?
Well i used to and i have a day off so bring it along and i will take a look.
when they turned up all they had was a board!
my heart sunk what they had was inverter board.
The story was that they had taken the microwave to a neff dealer who told them that the board was faulty and needed replacement at a cost of
over £120!
The fact that the 10 amp fuse had blown i was expecting to see blown tracks ect but it all looked fine.
out with the meter and sure enough a dead short across the mains input .
first inline from the mains was a hefty bridge rectifier which was short all the way round.
i fitted a 1000 volt 25amp job   £1.46 from radio spares http://uk.rs-online.com/web/p/bridge-rec...s/7514436/
went with them to try the board works well.
this the first microwave inverter i have repaired .
made a charge of £25 every one happy.
Rob T

[AlanBeckett]

Well done. I've never been brave enough to take one to bits.

Alan

[Paraguayo]

I have the same problem but in ma case was the HV capacitor in short circuit.. sorry for my bad english

[Old Sparky]

Your English is better than my (non-exsistant) Spanish, Paraguayo. I've seldom attempted repairs to Microwave Ovens, but I'm sure that there are Hazards to be aware of, if and when a microwave oven is opened or dismantled.

[tiv48]

On an old school microwave there is no reason to work on one with the eht circuit live .
What i mean by old school is a mains tx a diode a cap and a magnotron .
to save costs microwaves now use an inverter which is not that much different than a tv line/eht stage .
As i have yet been unable to find a circuit of a microwave inverter i am left with checking the obvious .
that is to say the mains input circuit (the mains filter/the bridge rec) and the output stage the diodes and caps in the voltage double circuit and the output transistors.
WARNING the eht in a microwave can KILL you.
Rob T