LG 32LE7500 - Standby on, No Sound/Picture

[RickyZA]

Hey everyone,

I got this set from a friend recently, when you apply power to the set the red standby led comes on & you hear a

click, when you push the power on button the led disappears and a buzzing sound appears from the small transformer

on the powerboard, according to my friend this would work if switched on and off several times although when you

push power off after you have switched it on the set wont switch off and go back into standby mode.

I replaced 2 x 330uf 35v Caps (blue markings on top) on the power board just to see what would happen but i got the

same result although now i could hear a buzzing sound from the bigger transformer before even turning on the set.

I then resoldered some joints on the powerboard which seemed to look bad, after resoldering it seems the set is now

going into standby and immediately switching on by itself carrying on with the buzzing sound.

I measured all voltages on the outputs of the power board. This is what i found.

N.C ERR-OUT
12v - My reading 11.84v P-DIM
12v - My reading 11.84v N.C
12v - My reading 11.84v DRV-ON
GND N.C
GND GND
3.5v - My reading 3.41v 3.5v - My reading 3.41v
3.5v - My reading 3.41v 3.5v - My reading 3.41v
GND GND
GND GND
20v - My reading 17.94v 20v - My reading 17.94
PWR-ON - My reading 2.18V 20v - My reading 16.10v

Could this be cap related as my voltages on the 20v line are quite low ?

There was also a SWS100 Button i pushed on the logic board which seemed to have bypassed something and switched on

all the backlights. It seems that the buzzing sound went away when i pushed it and the lights came on.

The buzz sound on the logic board has been the same since i tested the set first, buzzing along aswell when i pushed

the power on.

I have tried getting schematics for the power board but unfortunately i havent found any.

Codes on Powerboard : E247691, C/pn - EAY-60802701 , Model LGP3210SLPBLD

Logic Board : LB03D , LJ03D , LL03D , LTO3D
EAX61682903 (0)

Any help tracking down the source of the problem would be very much appreciated. Thank you all !

[RickyZA]

Re: LG 32LE7500 - Standby on, No Sound/Picture

Replaced some more caps but still the same problem, getting 17.1v on the 20v rail now so ive got a drop in voltage from doing that.

[dick_barton]

Re: LG 32LE7500 - Standby on, No Sound/Picture

Your attachments produce the following message

"Invalid Attachment specified. If you followed a valid link, please notify the administrator"

[RickyZA]

Re: LG 32LE7500 - Standby on, No Sound/Picture

Not too sure what that means, it was working when i made the post, anyway i made a imgur for better viewing. Thanx man !

https://imgur.com/a/U5hXl

[dskall]

Re: LG 32LE7500 - Standby on, No Sound/Picture

I would disconnect cable to main board jumper your PWR-ON to standby with around 1k resistor and see what your voltages are.

[RickyZA]

Re: LG 32LE7500 - Standby on, No Sound/Picture

Hey bud, which one would be standby ? Thanx

[dskall]

Re: LG 32LE7500 - Standby on, No Sound/Picture

The one that reads 3.5v and see if your 20v comes up.

[dick_barton]

Re: LG 32LE7500 - Standby on, No Sound/Picture

Attachments added for others to view

[RickyZA]

Re: LG 32LE7500 - Standby on, No Sound/Picture

The one that reads 3.5v and see if your 20v comes up.

Hey bud, 20v voltages were low from the start as mentioned above, i was reading 17.9v and 16.1v on the 20v rails, standby was reading about 3.18 at first but i think everything has pretty much changed now, replacing those capacitors caused even more voltage drop.

i was slightly moving some of the RED box type capacitors looking for any loose joints while there was power on,probably a stupid idea as this was early hours of the morning tired but adamant to try get his set working with my limited knowledge.. the top left RED Capacitor upon slightly moving it caused the big transformer right next to it to make some crazy high pitched noises, after that testing the backlights didnt work.... Im really keen to find out whats going on here. Appreciate the help guys.

[dskall]

Re: LG 32LE7500 - Standby on, No Sound/Picture

You need to check that 183j red cap for capacitance. I think this is a capacitive coupled transformer

[RickyZA]

Re: LG 32LE7500 - Standby on, No Sound/Picture

Ok will do man, ill get back to you on what i find.

[RickyZA]

Re: LG 32LE7500 - Standby on, No Sound/Picture

So upon finding out that the Peak ESR70 doesnt measure below 1UF it seems my best bet is replacing those red dipped caps unless i buy a ESR meter that can measure such caps, it seems the red one is a 18nf 800v DC Cap ( Code: 183js800v | NP A28 PP ) , is it possible that these can fail before lytics ? Thanx

[dskall]

Re: LG 32LE7500 - Standby on, No Sound/Picture

Haven't seen the circuit, but I believe it is the coupling capacitor for the transformer. You may be able to use another cap in parallel to read it.

[budm]

Re: LG 32LE7500 - Standby on, No Sound/Picture

LG EAY60802701 (LGP32-10SLPBLD) Power Supply / LED Board
http://www.shopjimmy.com/lg-eay60802...pply-unit.htm#
Pictures provided by shopjimmy.

[RickyZA]

Re: LG 32LE7500 - Standby on, No Sound/Picture

LG EAY60802701 (LGP32-10SLPBLD) Power Supply / LED Board
http://www.shopjimmy.com/lg-eay60802...pply-unit.htm#
Pictures provided by shopjimmy.

Thanx Budm, those are some great close up photo's, i didnt include the backside fortunately you did , appreciate it man !

Looking at that 18nf 800v capacitor, is that meant solely for the led driver ?
Seems weird because im getting lower voltages on every pinout since i changed most of the lytics, i did use the same rating but higher voltages though, from what ive learnt there is no problem using higher voltages as long as you have the same ratings.

[budm]

Re: LG 32LE7500 - Standby on, No Sound/Picture

That big transformer on that power supply board produces three Voltages:
D221~224 are the rectifier and filter caps C221~222 to produce the Voltage to feed the Voltage booster circuit for the LED backlights. Check the DCV between the two legs of either one of C221, or C222. Also the dcv between the two legs of the Boosted Voltage output filter cap C313.
D225 is the rectifier and C224, C223 filter caps for the 20VDC for the main board.
D226 is the rectifier and C201~203 filter caps for the 12VDC for the main board.
The regulation of those three power supplies are done by using the feeding back from the 20V power supply section.
Post #1 DCV readings:
"N.C ERR-OUT
12v - My reading 11.84v P-DIM
12v - My reading 11.84v N.C
12v - My reading 11.84v DRV-ON
GND N.C
GND GND
3.5v - My reading 3.41v 3.5v - My reading 3.41v
3.5v - My reading 3.41v 3.5v - My reading 3.41v
GND GND
GND GND
20v - My reading 17.94v 20v - My reading 17.94
PWR-ON - My reading 2.18V 20v - My reading 16.10v"

At this point I am not worrying about the 20V reading, but we do need to find out what the DRV_ON and the dim Voltages are.

[RickyZA]

Re: LG 32LE7500 - Standby on, No Sound/Picture

Hey budm , thank you once again man.

It seems the connection i made for the D222 rectifier isnt as good as it needs to be, there is continuity but its touching not actually attached, ill have to redo that.

I want to check out the voltages although im unsure which pins exact pins i need to use to jump the pwr_on , drv_on and pdim_on ? Also too hard to measure while the logic board/Main board connector is on and ive already made a incredibly stupid mistake trying to measure voltages at the early hours of the morning with the main board attached... i shorted pwr on with the 20v, this lead to one of the transistors on the logic board to burn out, i have the schematic for the main board and this is the transistor that i completely out and turns out there is continuity on all 3 pins now..

RT1P141C

Service Manual / Main board Schematic
I burnt out the Q8002 Transistor.

I cant really seem to find a exact match for a replacement, emitter to base voltage is only 5v compared to 10v on this one, do you possibly know what specs are important to match ? I want to get a replacement asap and get that transistor back on. Hopefully this hasnt burnt out anything else.

Back to the power board, upon trying it with the logic board.. the LG light on the screen bezel came up and i saw the white leds on the power button, it seems something cooled down dramatically and has decided to function, that i can find out once i jump the pins and measure those voltages. Appreciate the help Budm !

[RickyZA]

Re: LG 32LE7500 - Standby on, No Sound/Picture

Any insight guys ? I have found these two replacements, my only worry is that a previous data sheet stated a input voltage of -40 on the RT1P141C, a newer one it seems doesnt state a input voltage , the DDTA seems fine at +10 to -40 , the PDTA seems like it has a input voltage of +40 only though ?

DDTA114ECA-7-F - PDTA114E

Thank you !

[RickyZA]

Re: LG 32LE7500 - Standby on, No Sound/Picture

I managed to get the transistor replaced with the above mentioned PDTA114E , unfortunately im still getting the same problem, standby comes on red , when i push power on standby red light goes off and i hear buzzing from the transformer on the power supply, im rooting towards a loose joint somewhere as i get different results upon cooling, could also possibly be a cap problem though or i may have even broken the logic board as pushing the button which previously made the backlights come on doesnt work anymore.

Could anybody help me with what pins to jump to get the power supply on without the logic board ? Im confused as there are more than one 3.5v supply and im pretty afraid of damaging anything again.

[dskall]

Re: LG 32LE7500 - Standby on, No Sound/Picture

Did you replace cap as in post 12?