LG M2262D TV is not turning on

[tibimakai]

I have got this small LG TV for very cheap and I may and up keeping it for my "shop".
When I turn on the TV, only the power button LED turns on.
I have checked for 400V, but course there is only 162V as usual.
TV can be turned on and off from the sensor button. I assume that the mainboard it's fine then.
I'm not sure where to check for the 400V?
There are two components on the PS board(which I suppose they matter the most), one is STR W6252(which gives 15V/2A)which is like a FET on a heatsink, but has multiple legs and there is only one chip on the bottom of the board OZ9938GN(this one is the inverter IC.
I haven't done much measurements yet.
Any input would be appreciated.
The service manual fom elektrotanya (Hungarian site as I am ) does not show diagrams.

[drpj23]

Re: LG M2262D TV is not turning on

What's the output on the pins when it is turned on?

The 400v will be present when the ps is on. Measured across those 2 big filter caps.

[budm]

Re: LG M2262D TV is not turning on

This power supply/inverter board does not have PFC Voltage booster, so the 160V DC reading is OK, it does not even have Standby power supply. The power supply is always on. Since the main board in functioning, it means the power supply is working as you can see that it only has one main transformer.
Did you check any DC voltages in the inverter circuits yet? It is basically a 22" Monitor with TV Tuner and input circuits for other Video source. More likely to have problem with inverter circuits.

[tibimakai]

Re: LG M2262D TV is not turning on

Thanks budm, I didn't have time to measure anything yet, maybe in the next couple of days.
I have worked on the 52" Philips, which looks good, doesn't turn off in the "torture room" (garage it's very hot). I have picked up another similar model number Philips(7403) and I'm using that TV's stand and remote, plus I have a set of good boards, all for $40(had a broken screen and other then that only one blown glass fuse on the master inverter).
A couple of days ago I have picked up a 12M/pixel Olympus camera with a bad screen. Tonight I have replaced the screed and now is good as new.
Trying to fix other devices also. Thinking about trying to repair cell phones.
Hopefully tomorrow I will pick up a HTC HD2 for $35 with broken digitizer.

[tibimakai]

Re: LG M2262D TV is not turning on

I have checked the PS voltages and are as follows:
15V= 15.39V
5.2V= 5.24V
OLP= 0.004V
ON= 3.32V
DIM= 0.83V
M/S= 2.82V
Not sure which one is the inverter circuitry since I couldn't find any schematic
for this TV.
Those two 8 pin IC's would be the inverter circuitry?
Transformer reads at both secondaries ~1k and 0.6Ohm on primary, that to me it looks OK.

[tibimakai]

Re: LG M2262D TV is not turning on

Those two ICs are APM4550. I can't find a typical diagram for this IC.
It seems like it's a specialized FET.
I have seen some other repairs on the net and some stores in UK that they say that other versions can be used as well, like APM 4546, AM4511GM.
Not sure how to check these components.

[tibimakai]

Re: LG M2262D TV is not turning on

Since the inverter traf looks good, should I replace the two APM ICs?
There is a 1000V warning on the inverter output, can I measure the output?
What else can I check before I open up the LCD? I don't have a tube tester.

[tibimakai]

Re: LG M2262D TV is not turning on

Any more inputs?

[tibimakai]

Re: LG M2262D TV is not turning on

I have just ordered the inverter IC and I'm researching the APM FETs.
It looks like it's very hard(read expensive and hard to find) to get these FETs, but there is one place iccfl.com, where is available for $24 shipping.
On this site shows some other ICs that are compatible with this APM4550 IC(4546, 4511).
The other ones are available even on Ebay for a couple of bucks.
I will go ahead and order at least a pair.
I know I shouldn't be doing this, by ordering parts before I know that are actually needed, but usually it takes forever to get these parts in from China, so I'm just ordering them just in case that I might need them.
I will oder the APM4546.

[tom66]

Re: LG M2262D TV is not turning on

You should be able to substitute them with equivalent devices, no need to match them directly.

[tibimakai]

Re: LG M2262D TV is not turning on

Do you mean that I could use separate FETs(2x2pcs)?

[tom66]

Re: LG M2262D TV is not turning on

Yeah, if you have the datasheets for the mystery devices, it should be possible.

[tibimakai]

Re: LG M2262D TV is not turning on

I don't have the data-sheet for the exact same part that I need, but it seems that this one is equivalent.

[budm]

Re: LG M2262D TV is not turning on

Here is the spec sheet for the APM4550. You may be able to use the part from ALPHA-OMEGA Semiconductor., AO4614 from EBAY, I just order 50 pieces for $20 for fixing VIEWSONIC N3252W inverter board.

[tibimakai]

Re: LG M2262D TV is not turning on

I had a couple of minutes and tried out a bit the TV.
It actually has a two seconds to black and it has sound too.

[tibimakai]

Re: LG M2262D TV is not turning on

Bud, found these ICs on Digikey also, 0.79/each.
I have got the OZ chip in, and I'm ordering now the two other chips from Digikey.

[tibimakai]

Re: LG M2262D TV is not turning on

I had some time and got back a bit to this.
I have replaced the OCZ IC and I have picture. It's pretty dim and there is a scratchy sound coming from the PS board.
The screen it blinks(dims & brightens) as the scratchy sound.
I can't replace the FET ICs because I have ordered the wrong package. I have SMD chips and it needs through hole ICs.
Any input on what could be that sound?

[tom66]

Re: LG M2262D TV is not turning on

Use a toilet roll tube to locate the sound.
Suspect the primary capacitor(s).

[tibimakai]

Re: LG M2262D TV is not turning on

It sounds like it's coming from the inverter transformer.
I have ordered the main capacitors, just to exclude them.

[tibimakai]

Re: LG M2262D TV is not turning on

Replaced the two main capacitors with no change.
I have the two double FETs in SMD format, but the board requires through hole ICs. How could I install these?
Backwards on the underside of the board and bend the pins toward the board?
It seems that only this SMD package is available. This FET is an equivalent transistor. The original is not available.