need help to test inverter transformer

[woaimi]

Re: need help to test inverter transformer

What same readings 1 and 1 or 1 and 597 ?

the readings were 1 and 597 consistently. I have not solder it back, planned to replace it just in case.

[woaimi]

Re: need help to test inverter transformer

Yes those are diodes some examples are here
http://www.westfloridacomponents.com...ierDiodes.html

Can you make out any part numbers on them?

they are
1x EN220A
2x W2206

they all indicate having common cathode in the middle lead

[woaimi]

Re: need help to test inverter transformer

I found this testing method from Tomm66 in this forum to test EN220A
<<<<<<
Number pins 1-3 left to right.
Labelled (pos/red) (neg/black) respectively (use diode test.)
Test 1-2 should read ~150 - 700.
Test 2-1 should read single "1" or "OL".
Test 2-3 should read single "1" or "OL".
Test 3-2 should read ~150 - 700.
Test 1-3 should read single "1" or "OL".
>>>>>>
and the result
1-2= 159
2-1="1"
2-3="1"
3-2= 159
1-3= "0.00"

meanwhile from a user name multimeter's suggestion on that same thread
<<< set your meter if dmm to 200 ohm,or 10k ohm anologue, pin 1 and 2 should show reading one way ,pins 2 and 3 should show reading one way >>>>
it shows reading only one way 1-2 & 2-3 as I flipped the probes, i got "1"

couldn't find any info for pair of W2206 diode.

[woaimi]

Re: need help to test inverter transformer

well I de-soldered all 3 schottky diodes (photo attached) and test them using the diode test and they seems to be working. The primary and secondary filter capacitors were also de-soldered and test using capacitor test mode, them too were fine. I have not test the transformer and the "optoisolator" (guessing) as some reading material point out.

Can anyone suggest how to test the transformer and the "optoisolator"? Other than that I run out of option, might just give up.

the 1st photo is EN220A
the 2nd photo is W2206, the 2 diodes that I couldn't find any info.
the 3rd photo is from what I'm guessing is the "optoisolator"

[woaimi]

Re: need help to test inverter transformer

Well, I decided to mounted the board back in place and try since I pretty much run out of option. Plugged in AC and power it on. It actually came on and screen went away after about 5 seconds. The standby led is on still after the screen went away. I can turn it off and on and the screen would be on again for about same amount of time.

Replacement parts so far:
2 x inverter transformers (burnt)
1 x diode (nothing wrong but since I got it off the board might as well replace it)
2 x radial fuses
and all filter capacitors got de-soldered and re-soldered back in.

any suggestion are much appreciated. Thank you

[retiredcaps]

Re: need help to test inverter transformer

any suggestion are much appreciated. Thank you

Plug in a source and see if it stays on.

[woaimi]

Re: need help to test inverter transformer

It would stay on with the standby light but the screen goes away after a few seconds, may be I should replace the last of the 3 inverter transformer as well.

[woaimi]

Re: need help to test inverter transformer

any other idea? I get the correct voltages from the connector as the stamp on board indicated.

[selldoor]

Re: need help to test inverter transformer

I cannot see that we have ruled out the bulbs or wiring being bad? Have you any spare bulbs or any old lcd screen.


Can you re check the secondary winding resistance on the 3 transformers report result as
T1 s1>s2 = xxxohms
T1 s3>s4 = xxxohms and so on

[woaimi]

Re: need help to test inverter transformer

I have many old lcd screen to be used just nothing with that size. I don't think the bulbs or lcd is bad though, because the whole screen actually came on for a short time and went away. My guess is the transformers but I couldn't find any info about this transformer. My is a little different than the one on your photo; it has 9 pins. I replaced 2 out of 3 because they look like they melted but even those 2 gave me the same reading as suggested by lcdparts.net
i will have the transformers measurement later tonight.

[selldoor]

Re: need help to test inverter transformer

Please measure as per my diagram - ignore the other pins.
I have to go out now but you can get a panel that might have good bulbs in
thet would be great - even better if they have the sme connectors- doesnt usually matter about the size of the bulbs for a short test.

[woaimi]

Re: need help to test inverter transformer

I measured the transformers according to your diagram and got "OL" on all pairs
s1-s2=OL
s3-s4=OL
p1-p2=OL
p3-p4=OL

I have not get a chance to test with light bulb but will follow up and keep you posted
thanks

[selldoor]

Re: need help to test inverter transformer

I measured the transformers according to your diagram and got "OL" on all pairs
s1-s2=OL
s3-s4=OL
p1-p2=OL
p3-p4=OL

Can you test your meter - is battery ok- it is very unusual for all 4 windings
to be open. Was it on 2000 ohms Make sure you are testing on bare metal.

[budm]

Re: need help to test inverter transformer

Yes I wonder about those reading too, pretty hard to break the primary winding since they are pretty good size wire gauge compared to very fine wires on the secondary side.

[woaimi]

Re: need help to test inverter transformer

yeah, all 3 meters gave me the same result, 2 of them on auto, the other was set to 2000 ohm. the thing is i don't think the winding goes in that pattern cause I get the same reading from all 5 transformers (3 existing and 2 new)

[selldoor]

Re: need help to test inverter transformer

Ok - you will have to do it the long way
1>2 1>3 1>4 1>5 1>6 1>7 1>8
2>3 2>4 2>5 2>6 2>7 2>8
3>4 and so on - Just record the high numbers.

[woaimi]

Re: need help to test inverter transformer

wow, it'll be lots of numbers to play with

[woaimi]

Re: need help to test inverter transformer

ok this what i got out of 1 transformer. I labeled the pins in the photo.

1>2=1.77k / 1>all other 8 pins = OL

2>all pins = OL

3>4= 1.77k / 3> all pins = OL

4> all pins = OL

5> all pins = OL

6>7= 2.9 ohm; 6>8=5.3 ohm; 6>9= OL

7>8= 2.9 ohm; 7>9= OL

8>9= OL

[selldoor]

Re: need help to test inverter transformer

Well, that is a bit different - can you do 1>2 and 3>4 on the other transformers ( Leave them on the board)

[woaimi]

Re: need help to test inverter transformer

I get 1.7K -1.8K ohm on all 3 transformers on board