LG 32lc46 totaly dead

[vinceroger69]

Re: LG 32lc46 totaly dead

right just restested it still 2.00 volts board marking says 3.4-on so any ideas guys the remote turns it on and of ok light flashes when change channel button pressed etc screen does not flash on at all no sound only slight speaker pop when turned on.
board came of flat tv parts co.uk all number match up.
just to clarify its the mainboard i have now fitted which has solved the no led issues but now have no picture no sound looks like 24volts to inverter board is spot on just cant figure out why only have 2 volts on the 3.4-on board socket marking just going try with 1 k resistor as a load and see what the voltage is then

[vinceroger69]

Re: LG 32lc46 totaly dead

right placed a 1k resistor as a load no voltage to that pin so voltage must come from the mainboard?
page 27 in manual socket p900 number 13 in the power section if anyone can figure it out no good a following circuits lol

[tom66]

Re: LG 32lc46 totaly dead

right placed a 1k resistor as a load no voltage to that pin so voltage must come from the mainboard?
page 27 in manual socket p900 number 13 in the power section if anyone can figure it out no good a following circuits lol

No voltage comes from DC-DC on PSU. May be on bottom of PSU.

[vinceroger69]

Re: LG 32lc46 totaly dead

so are you saying i should have voltage when loaded with a 1k resistor also whats dc-dc on psu? there are 4 caps i have not changed in the primary side of the psu by the small ls-003 transformer could that be the problem?

[tom66]

Re: LG 32lc46 totaly dead

so are you saying i should have voltage when loaded with a 1k resistor also whats dc-dc on psu? there are 4 caps i have not changed in the primary side of the psu by the small ls-003 transformer could that be the problem?

From the 42LC46 it's a synchronous buck converter, it has two MOSFETs on the bottom and an inductor and capacitor.

[vinceroger69]

Re: LG 32lc46 totaly dead

this psu defently out of a 32lc46 same as tv model could there be a difference in the 42lc46 your mentioning?
bottom left in the picture is the underside of that area

[tom66]

Re: LG 32lc46 totaly dead

this psu defently out of a 32lc46 same as tv model could there be a difference in the 42lc46 your mentioning?

Big difference in 42LC46 (onboard inverters, bigger output power) but probably still has a dc-dc. Most older LG TVs do. Post clear pics of top & bottom.

[vinceroger69]

Re: LG 32lc46 totaly dead

see pic above thats all i have at the minute.

[tom66]

Re: LG 32lc46 totaly dead

see pic above thats all i have at the minute.

Can't see anything in pic do you have a bigger one?

[vinceroger69]

Re: LG 32lc46 totaly dead

edit sorry no camera at the minute but page 1 and page 2 have good pics i saved these pics i just posted wrong sorry
so are you saying this pin should have voltage to it when loaded with a resistor

[tom66]

Re: LG 32lc46 totaly dead

If you find a camera let me know- can't really work with blurry photos.

[selldoor]

Re: LG 32lc46 totaly dead

Convinced myself it was a jumper but now not sure as I have noticed the connectors are numbered Jxxx

[tom66]

Re: LG 32lc46 totaly dead

Convinced myself it was a jumper but now not sure as I have noticed the connectors are numbered Jxxx

Jxxx means connector. I see it on boards sometimes, or "CN" or "CONN", depending on how the manufacturer is feeling, there seems to be no standard.

[vinceroger69]

Re: LG 32lc46 totaly dead

right a little update as i was in a rush to fit the board yesterday i only glanced at the main board ebr numbers although the first 13 mumbers match up ok the end few dont
my new board is 7NEBR3702950812 the old board is 7NEBR37029508006 so this may be the issue i have just emailed the company to see if they have the correct board do you guys think because its the wrong ebr number thats my problem?
also whilst i have the boards out side by side i took some ohm readings from the regulators on both boards (what you guys thought was the initial problem eith my old board) i have 2 different readings on a voltage regulator old regulator is
pin 1
pin2
pin3 gnd
pin4 66.7
pin5
new board regulator
pin1
pin2
pin3gnd
pin4 01.8
pin5
both these items are sc156515m 0724 regulators do you guys think this is the problem on my old board if so anyone got any ideas where to get 1 from in the uk.cheers
http://pdf1.alldatasheet.com/datashe...CH/SC1565.html

[tom66]

Re: LG 32lc46 totaly dead

Probably not. The 3.4V is your problem. Start by checking that with pull up on PSON.

[vinceroger69]

Re: LG 32lc46 totaly dead

Start by checking that with pull up on PSON. can you explain a bit more please.

[tom66]

Re: LG 32lc46 totaly dead

Start by checking that with pull up on PSON. can you explain a bit more please.

1k from 5Vstby to PSON.

[vinceroger69]

Re: LG 32lc46 totaly dead

1k from 5Vstby to PSON.

yes done that 0 volts on that pin but are we sure it should have voltage on it or does it take its voltage from the mainboard says 3.4_on psu unit says 3.3_on the mainboard but when the tvs green leds on it has 2.0 volts to the pin thats whats making me think the voltage comes from the mainboard?
cheers tom for your advice

[tom66]

Re: LG 32lc46 totaly dead

yes done that 0 volts on that pin but are we sure it should have voltage on it or does it take its voltage from the mainboard says 3.4_on psu unit says 3.3_on the mainboard but when the tvs green leds on it has 2.0 volts to the pin thats whats making me think the voltage comes from the mainboard?
cheers tom for your advice

I expect it is a signal from mainboard to PSU.  There should also be a 3.4V output pin is this around 3.4V?

[vinceroger69]

Re: LG 32lc46 totaly dead

yes that other 3.4 v pin is spot on cheers guys for your help i have just been offered a good price for just the screen i get to keep the invertor board psu and tcon so going to let the set go its a pity but have got a full refund for the mainboard coming so not out of pocket at all. but for a novice like me the procedure for testing items and fault finding has been great so thanks for all you help and advice guys be back soon with another project no doubt shortly as just of to my local recycling center may see what they have.