Daewoo Fridge (FR-4501W) circuit board fault

[Matthew Hill]

pfofit. When I said coming to life, after the power is turned on I could hear the relay turn on after about 5 seconds then the compressor began running, it stayed this way for about 3 minutes before it began arcing. I didn't get a chance to test any of the dc voltages.

Had a look around but there was no tech sheet unfortunately, I tried calling Daewoo directly to see if there was any related tech sheets they could get me but weren't exactly helpful. ( Got the impression they just want to sell replacement boards)

The core moves around relatively freely. I'll keep in mind what you've said when I inspect the transformer and will get some photos.

Les , I did consider that when I was testing the continuity of the windings so tried to do the test directly from the transformer pins rather than the circuit. However after having a better look this evening I'm not convinced it's not the problem so I'll do as you've advised.

I'm planning on heading into my university shortly where they have some good equipment I can use and I'll try remove the transformer to properly inspect it as pfofit has suggested and do the clean up of the broken traces.

Thanks again for all of your input!

 

[Matthew Hill]

a

 

[Matthew Hill]

I was able to take out the transformer and found one of the wires had become disconnected from it's pin as pfofit suggested may be the case. (see picture) While it was reasonably damaged from the impact and some of the unused pins had cracked off, all the other pins connected to wires were in reasonably good condition.

I re-soldered the wire to the pin, then repaired the cracked sections of the circuit properly with wire.

all the resistors, diodes on the primary side tested okay.

I connected it back up to the fridge and it's now all working perfectly!! Many thanks to everyone who has offered their input along the way.

Would anyone be able to explain to me why the primary side of the transformer has 4 wires/pins? Not just two.. From testing I take it there is two separate primary winding's?

 

[pfofit]

Drum roll time.

nice.
There are in fact two windings on that primary side. One (pins 4 & 5) is run power to the controller chip.
Can be seen on the drawing I made up way back when.

One can see the breakup of the base,. Hope it did not break the core.
Remember that the SMPS pulses that tranny at 50 KHz. 50000Hz not 60Hz. This can cause vibrations, Since the base and core got bashed around I would be putting some small dabs of silicone in key locations to stop the core from rattling around over time.

When it was running for a bit did you hear any rattling or excessive buzzing coming from the tranny? Also check to see if'n it's heating up.

cheers

 

[Matthew Hill]

Some silicon to keep the base attached to the core? (assuming "the base" is referring to the sections where the pins are housed?

Yeah stuck around and let it run for a while, was no buzzing or audible sound coming from the tranny at all, didn't check to see if it was heating up but will check.

Cheers

 

[pfofit]

Normally those things are stuck in place from varnish or glue etc.
I said "base", but not quite what i meant.
I was thinking about just a little drop in the corners where the black bits meet the core to immobilize it from moving around.