LG 37LC46 power on problems

[selldoor]

Re: LG 37LC46 power on problems

Hieton - he doesnt do soldering

clarksters - post again when you have a meter.

[tom66]

Re: LG 37LC46 power on problems

Bad caps on both boards? Or only on old board?

[clarksters]

Re: LG 37LC46 power on problems

There are no obvious bad caps on the new board, it did come "fully tested", I just find it too coincidental that the TV is displaying the same fault regardless of which board I use, but I don't know where else the fault could lie.

[tom66]

Re: LG 37LC46 power on problems

Oh I did not realise the TV had the shutting down problem with both boards. I thought one board worked when heated. It sounds like an inverter fault or a bad bulb in the LCD panel which could be tricky to repair.

[selldoor]

Re: LG 37LC46 power on problems

Well tom66 did mention the inverter boards were a common fault but you dont seem to have followed that up. - Perhaps post a picture see if we can spot anything. Needs to be good and clear -difficult I know as its dark - perhaps wait til tomorrow -as near to 2 mb as you can get it

EDIt there you go - hes just mentioned it again

[tom66]

Re: LG 37LC46 power on problems

This set has integrated inverter on PSU I think?

[clarksters]

Re: LG 37LC46 power on problems

There are 3 boards on the back that I can see, the power board, the main board and a smaller board above the main board that I can't identify, it has a small blue LED on it which lights briefly before the backlight comes on.

[vinceroger69]

Re: LG 37LC46 power on problems

in post 1 there are slight differences between the old board and the replacement board so what are the differences?

[clarksters]

Re: LG 37LC46 power on problems

The main difference is that there's a black cable on the board, you can see it at the bottom of the 3rd photo in post 18.

I think I've identified the third board as the t-con board, I can't see a separate inverter board.

[budm]

Re: LG 37LC46 power on problems

Per post 1, the new board he got from E-BAY is combo board (PS + INVERTER) for the version of the TV he has.

[vinceroger69]

Re: LG 37LC46 power on problems

all what i can suggest is you try to borrow a multi meter then we can talk you through some basic tests to do safely.

[selldoor]

Re: LG 37LC46 power on problems

Perhaps something has happened to the lamps? I see the main inverter transformer is on the main board but how does that connect to the lamps? Is there a distribution board
can you get to where the lamps are and post a picture. The board you found is probably the Tcon . You could try disconnecting it and see if the backlights come on and stay on.

[clarksters]

Re: LG 37LC46 power on problems

Disconnecting the t-con didn't help.
There are two cables from the board that power the lamps, disconnecting either or both of these doesn't stop the TV turning off.
I don't think I'll be able to post a pic of the lamps, but they don't seem any less bright than before, although I don't know if you'd be able to tell if they were.

[clarksters]

Re: LG 37LC46 power on problems

Ok, managed to get my hands on a multimeter, hoping to test tonight if anyone can give me some pointers.

[selldoor]

Re: LG 37LC46 power on problems

It was not a picture of the lamps, although we could see how black they were on the ends or if we thought the wiring was bad, not that its easy to tell.
I am interest in knowing what is between the lamps and the power supply.
Each lamp might have a wire or two - what do they plug into?

The fact that they flash does not mean they are good and perhaps you should make up some test bulbs, though at the moment im not sure how or where you would connect them. See Budms signature files for how to make them.

[truep]

Re: LG 37LC46 power on problems

I wonder what that black cable does? If the part numbers of the board are not identical, the new board might have done some damage elsewhere.

[clarksters]

Re: LG 37LC46 power on problems

I wonder what that black cable does? If the part numbers of the board are not identical, the new board might have done some damage elsewhere.

I think you might be right.
I've done a bit of testing with the multimeter and all the voltages on the psu match what they should be, I think the TV's past the stage where I might be able to save it.