LG 60PA6500 - blank picture wont boot

[skyver]

Hi all glad i found this forum bit of an odd one

My switches between either

* constant relay click

or

* stuck in some standby mode where the screen is on but blank , power LED is red and control board D101 LED blinks fast, then slow, then pauses

weird thing is every now and again the TV works fine for a few days then back to this and there was no precursor to this occuring

when its in its constant relay click boot, it will do this with just the power and main board connected with all other boards unplugged

when its stuck in the blank screen mode i have completed an auto gen test and the screen cycles through different colours, so from what ive read that means its a mainboard problem?

what can i test on the main board?

POWER SUPPLY EAX64276701/11 EAY62609801

Mainboard is an EAX64696607 (1.0)

[tom66]

Re: LG 60PA6500 - blank picture wont boot

You can check the voltage regulators on the board. Posting a picture of the board would help us help you...

[skyver]

Re: LG 60PA6500 - blank picture wont boot

Thanks for the reply. This is the main board

Where are the voltage regulators on here? I'm only aware of one on the smps board and don't know how to test that .

[skyver]

Re: LG 60PA6500 - blank picture wont boot

Symptoms have now changed to a 3rd one with no intervention.

* Just a contant standby light and relay doesn't click when the power point it turned on (is it meant to?)

No blinking led on control or constant red on main board

[skyver]

Re: LG 60PA6500 - blank picture wont boot

I tested the power board by jumpering the pins on the power lead that goes to the main board

Relay clicked once and screen was on just black , so looking more and more like hte main board

[tom66]

Re: LG 60PA6500 - blank picture wont boot

Your test of the control board confirmed the main board is the cause of the fault. I don't see any obvious voltage regulators you can check.

[skyver]

Re: LG 60PA6500 - blank picture wont boot

Your test of the control board confirmed the main board is the cause of the fault. I don't see any obvious voltage regulators you can check.

if i get a new main board for overseas i presume i will have to swap over the tuner EBL61120001 component?

Ive found a few voltage regulators but they are tiny and only one specifies the volts in and out 2.5 > 2.5

[skyver]

Re: LG 60PA6500 - blank picture wont boot

found schematics for the circuitry for this TV 60pa6500-TM

starting to go through the voltage regulators

eg IC601

+3.3 in
+2.5 out

Is there anyway i can supply just 5 volts to this board of the TV for testing these?

[tom66]

Re: LG 60PA6500 - blank picture wont boot

You should test in situ, i.e. board powered in standby by main board. If it is not coming out of standby, it does not matter if a main voltage regulator is unavailable, that will not be causing it.

[skyver]

Re: LG 60PA6500 - blank picture wont boot

mmm all the voltage converters appear to be doing their thing is there anything else common on this board that breaks ? i redid any solder joints that didnt look exact and no differnet, Its stuck in the relay click mode at present and again with main board disconnected its no problems

[skyver]

Re: LG 60PA6500 - blank picture wont boot

cant find my version of main board anywhere, as mine is a 60pa6500-TM

[skyver]

Re: LG 60PA6500 - blank picture wont boot

ok so ive come back to this and its now in a new fault state the TV is just in standby now.

I still haven't been able to source another main board yet.

If i bypass main board i can power on and do the test image display so i know power and control is still OK they havent changed.

With main board in when i power on at the wall:

> No relay click
> No LED on main board
> No LED on control board

> power button on remote does nothing
> power button on TV does noting
> Front standby LED is on

any idea what this fault should be leaning towards?

If not i might just get the only other main board that looks suitable the 60pa6500-UG ill need to remove the remote in plug and swap tuners though

[skyver]

Re: LG 60PA6500 - blank picture wont boot

When I bridge the connectors on the lease whilst plugged into main board relay clicks on and off so that to me says something is actually shorting out on the main board. I tried a full reflow with a heatgun no change.

I'll keep updating this till I work it out

[skyver]

Re: LG 60PA6500 - blank picture wont boot

Can someone help with this

So with present scenario its just in standby with no relay click.

These are the readings from the power waver (input cable)

Are these correct?

These are taken directly of the pins on the board

I have no voltages on any of hte voltage regulators but presume this is because its in standby?

[skyver]

Re: LG 60PA6500 - blank picture wont boot

so these 3 are:

-----------------
17 - M_On
15 - RL_ON
13 - STDBY 5V
-----------------

in standby they are meant to be the following according to LG doco

-----------------
17 - 0V
15 - 0V
13 - 3.49v
-----------------

Im getting the following when reading this off the mainboard or SMPS.
-----------------
17 - 3.29v
15 - 2.54v
13 - 3.43v
-----------------

I also noted the incoming [Error_Det] has 3.41V

Does this indicate anything in particular?

So this should indicate the main board is sending the RL_ON command to the SMPS?

But im thinking because its also sending Error_DET to SMPS its not coming on?

Anyone got any ideas? any other places i should be taking readings?

[tom66]

Re: LG 60PA6500 - blank picture wont boot

If you have >2V on RL ON, 5V ON, etc. the power supply voltages should be OK. I think the main board is turning on the PSU ok (whether or not it should - some LG sets will turn on immediately as power is applied but others will only turn on when commanded via the remote) but it's not sending any video output over the LVDS cable...

[skyver]

Re: LG 60PA6500 - blank picture wont boot

ye it wont get out of standby though, relay will never click on, with power button or remote. I know the button section is working as 3.3v is supplied there and red LED on front is on. Would an issue with sending over LVDS only be if it was actually powering on ?

i can get the relay to click for a second and led comes on main board if i bridge - RL_ON and M_ON , did it by accident, guess this would result in sending 5+ volts over RL_ON.

Tracking down voltages at the moment only odd thing ive notived is what i think the eprom has voltages of 5.5V & 5.4V instead of 5V, unsure if this means anything

[tom66]

Re: LG 60PA6500 - blank picture wont boot

MAX3232 is not an EEPROM (or flash memory IC), it is a logic level driver for computer control of the TV. Connects to RS232 port. If you are unsure on what a part does take its part number and google it.

Do you have Vs/Va?

[skyver]

Re: LG 60PA6500 - blank picture wont boot

MAX3232 is not an EEPROM (or flash memory IC), it is a logic level driver for computer control of the TV. Connects to RS232 port. If you are unsure on what a part does take its part number and google it.

Do you have Vs/Va?

no va vs On the output cables off the powerboard.

There is if I remove the mainboard and it powers on automatically.

[tom66]

Re: LG 60PA6500 - blank picture wont boot

you may have to jumper VS ON/RL ON/5V ON signals.