Need a manual for FMV156DSB microwave oven

[AmTec Services]

Original call found this unit with no heat/fan or turntable. Found the lower door switch not closing (no continuity). Jumped it out and fan/ table  both worked so I ordered the switch thinking that was all! Installed switch today and found everything runs, but no heat!

No diagram in this unit so I need the masters help! 

......................AmTec

[appl.tech.29501]

dont think we have a manual...while the unit is running you need to check voltage to the primary side of the HV transformer. This will be the 2 small wires coming from the board...leave the wires connected..should have 120V

[AmTec Services]

So 120v in, but no heat means a bad trans?

[appl.tech.29501]

nope, 120V at the transformer = everything in front doing what its suppose to, door switch, board, wiring.

If you have 120V at the transformer you then have 2 different testing methods

Start with the HV diode unless you have a really good analog meter you will have to use a 9 V battery to properly test the diode.

next you will have to check the Capacitor

followed by the transformer

you can check the leads and the TCO on the magnatron but the magnatron if a filthy liar...its common for it to fail under load only.

you may get lucky and bypass these steps in a more primitive manner.

run the unit for 30 seconds with the 2 wires going to the magnatron disconnected. take a screw driver and short across the terminals of the capacitor...if you get a pop and a spark that tells you all  the HV components are working and the magnatron is the culprit.

However, if you dont get a pop and spark then its back to testing individual components.

[RegUS_PatOff]

FMV156DSB Parts List & Wiring Diagram  :headscratch:

 

[AmTec Services]

Thank Regus!!!  Just what I needed.

Now for a question. What type of test insturments are needed to work on these micros? 

.................AmTec

[appl.tech.29501]

Some people use a digital meter and a battery but I prefer an analog meter but you have to find one that will work properly. An analog is also better for testing micro switches...more responsive when testing a micro switch that may be sluggish to open and close. Its hard to find a meter that will do it all unless you wanna spend about $300. I got mine off of EBAY its probably 25 yrs. Old but was never used and still in the box got luck and paid $30.

Even though typically the requirements to test the various components of a microwave especially a doide is 10K ohm or higher and at least 6 volts, - had to try several meters before I could find one that would would perform as I wanted. Except for the real high end triplet meters the only ones I can find are the old Microntas or the Radioshack equivilant.

[AmTec Services]

Thanks Jerry!

[AmTec Services]

Could you tell me how to use the digital meter and battery to test the HV circuit?

I think I've still got an old micronta meter and possibly a AW Sperry analog. Need to look in the shed tommorrow!

...............Thanks!

[appl.tech.29501]

The Samurai has a picture of the battery test somewhere on here...I'll see if I can find it.

[RegUS_PatOff]

usually 9v battery and volt meter to test HV Diode...

one direction (some voltage) reading

reversed .. no reading..

 

 

[AmTec Services]

Checked out this micro with my new fancy wiring diagram. Foud no power to transformer. Checked back thru circits and found the relay on the circuit board that sends power to the trans is kaput. Price of the board installed is higher than a new unit. Are these hard to install? Never done one, but I know they will ask.

  Thanks for all the good advise you guys give.

  Ya'll rock!!!:rockband:

..........................AmTec

[appl.tech.29501]

The new unit will come with a template for drilling and mounting...there's about 1 in a 100 chance that the new unit will go up without any modification. it's not that bad, just think lika carpenter...measure twice and drill once

Here's a most gracious post from our honorable Samurai on diagnosing Microwaves

How to test a Microwave