LG w2241s 2sec and then black

[rippergr]

Re: LG w2241s 2sec and then black

ok I tried with the resistor but I still have the same problem. Lamps just light for 2 seconds then off.

[selldoor]

Re: LG w2241s 2sec and then black

OK Well if you have re flowed every high voltage pin and the transformer is good and
you tried with a set of new lamps one of the few things left is the high voltage blue caps.
They are not easy to test and replacement is the usual way forward.

[rippergr]

Re: LG w2241s 2sec and then black

So you exclude transformer , mosfet and you say that I should change all the blue caps.
I attached a picture with the resistor just in case I did something wrong.
I didn't put any battery.

[selldoor]

Re: LG w2241s 2sec and then black

That looks ok - some boards also need a similar resistor across from 5v to DIM
If you want you could move that resistor from pin 3 to DIM (Pin2) and use the battery
from ground to pin3.
Budm said to check the blue caps - I am not sure what he meant. Inspect them for
cracks , bad joints and discoloration. Unless you have cap tester I dont think there
are more tests- they dont test for resistance - at least not on my meter so I suppose you could do a resistance test to check if any were shorted.

[rippergr]

Re: LG w2241s 2sec and then black

I think I will go to hange all the blue capacitors just in case. Can you give me a picture of which capacitors should I change (all blue or just the ones near the transformer)

[budm]

Re: LG w2241s 2sec and then black

Those blue ballast cap when they are bad, the body will have light tinted brown or turn black if it is really bad:http://s807.photobucket.com/user/bud...tml?sort=3&o=1
http://s807.photobucket.com/user/bud...ml?sort=3&o=10
What I look for is to test and see if it show any resistance reading using the highest Ohm scale, good cap with no resistance leakage will show infinite resistance, but since the meter does not put out 1000 of Volts as the cap is exposed too, this test will not be 100% verification.

[rippergr]

Re: LG w2241s 2sec and then black

I set my multimeter to 200M ohms.
All blue caps show infinitive except 3 (c102, c208 and c201) that are near the big capacitor that shows 01.0 and 01.1 .
the one writes LY HR1KV 222K(C102) and the other two(c201 and c208) write HRR 102K 1KV SHM

[selldoor]

Re: LG w2241s 2sec and then black

Did you take them off the board to test them ?

[rippergr]

Re: LG w2241s 2sec and then black

Sorry I didn't remove them
I removed them and recheck them and all show infinitive.

[selldoor]

Re: LG w2241s 2sec and then black

Ok - can you have a look at PC201 on the power supply top -it looks as if it has been hot and may even have a piece off the case?
On the bottom of the board there is an 18 legged IC can you get the part number off it.

[rippergr]

Re: LG w2241s 2sec and then black

The IC is DT8211 T830
The PC201 seems ok. Can I check it somehow?

[selldoor]

Re: LG w2241s 2sec and then black

The PC201 seems ok. Can I check it somehow?

Its not an easy one see here
http://preher-tech.com/documents/optoisolators

The diode side can be tested just as any diode with a digital meter.

[selldoor]

Re: LG w2241s 2sec and then black

Here is the data sheet for the DT8211 all we need now is someone who fully understands it

[rippergr]

Re: LG w2241s 2sec and then black

I changed the opto PC201 but the problem remains.
I noticed that the one lamp doesn't light all the way. I mean it seems to light only the half for a second and the shutdown.
I changed the order of the lamps and the lamp that is on the same output does the same.
Maybe this means something?
P.S. The lamps are both new and working

[selldoor]

Re: LG w2241s 2sec and then black

Thought you had tested the lamps and they were good before I came on the thread.

Which socket is bad

[rippergr]

Re: LG w2241s 2sec and then black

It lights but not all the way .
I attached the bad side.

[vinceroger69]

Re: LG w2241s 2sec and then black

if it was me as that transormer looks like its overheated at some point if its chaep enough change it imo if it still does not work its always handy to have a spare.

[selldoor]

Re: LG w2241s 2sec and then black

Can you post a new picture of the back of the board close up of that corner

[rippergr]

Re: LG w2241s 2sec and then black

I had all those blue caps resoldered when I test them, maybe some seem with black spots. It's because of the solder wick.

[selldoor]

Re: LG w2241s 2sec and then black

I have been trying to draw a pic but it is too messy.
First can you examine the pins in the sockets. Then do a continuity /ohms test from the actual pin to the next solder joint on the back of the board - on the end pin of the socket the next pin is close by but for the other pin the next joint is around the other side
of the section on D401 and /or resistor R412. Do that for each of the 4pins - more I look at it i am not sure that is going to work - I think you can only do from the 1 and 3 pin to the blue cap joint then from the other side of the blue cap joint to the transformer pin.
If nothing appears wrong then you are going to have to resolder again - perhaps removing all the solder and cleaning up the pads then applying new solder. In which case it may be worth getting some new blue caps and replacing them at the same time.