LG 70UH6350 (UB.BUSMLJr)

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

no this wrong, need to each time after set the probe on vc power up the PWB and remark the high and low

ok will do now

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

I can't do this very reliably with my meter but the "rush" max voltage is always under 12 on all. Make sense?

[Diah]

Re: LG 70UH6350 (UB.BUSMLJr)

and the low?

[Diah]

Re: LG 70UH6350 (UB.BUSMLJr)

any way... i need to be off

right now i do suspect VC 8 regards yours measurements. so you need to be careful
A- don't use your DC external any more to avoid any overload on BL circuit
B- take out the PWB on the table and in Diode mode test all Reg Q from 1 to 12. see if they are all the same reading.
C- on the socket P802 where VC 8 there... free the legs solder of the Pins. to simulated Open circuit at line VC 8
D put every cable back as it should and power on yours TV see any different. BL ---- T-con 12V.. USB 5V and at last picture in screen.

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

and the low?

Can't really do that; the low would be near zero.

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

any way... i need to be off

right now i do suspect VC 8 regards yours measurements. so you need to be careful
A- don't use your DC external any more to avoid any overload on BL circuit
B- take out the PWB on the table and in Diode mode test all Reg Q from 1 to 12. see if they are all the same reading.
C- on the socket P802 where VC 8 there... free the legs solder of the Pins. to simulated Open circuit at line VC 8
D put every cable back as it should and power on yours TV see any different. BL ---- T-con 12V.. USB 5V and at last picture in screen.

ok thanks 2AM here so I need off too.

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

Also on A... I am only using a 3.5 trigger though and it fed/regulator from onboard 7.8v line (I did not know where I could find a 3.5 from.) But still the same worry?

B what means please "test all Reg Q"

thx

[Diah]

Re: LG 70UH6350 (UB.BUSMLJr)

on PWB back side you have each VC 1-12 took pulse from Gate Transistor Q. 12 pieces.. need to check them specially the one with VC8 if they are same read Value. then continue with test points.

you can also power up the TV as normal .. and each time of powering measure one VC of its high and low. this way better than yours external 3.5V .. at least you have the protect circuit in tact. so any fault at LED BL could find from the measurements reading easily. ( this refer to Black on chassis / Red on VC )

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

on PWB back side you have each VC 1-12 took pulse from Gate Transistor Q. 12 pieces.. need to check them specially the one with VC8 if they are same read Value. then continue with test points.

you can also power up the TV as normal .. and each time of powering measure one VC of its high and low. this way better than yours external 3.5V .. at least you have the protect circuit in tact. so any fault at LED BL could find from the measurements reading easily. ( this refer to Black on chassis / Red on VC )

OK I will try this although I am very tempted instead to immediately try opening Vc_8.

What I am wondering though is if there is some sort of SOS to the motherboard where is this happening and can it be temporarily cut? The other LG's it is marked as safety but on the pinout list here there is nothing like that so how is it possible to tell mobo?

[Diah]

Re: LG 70UH6350 (UB.BUSMLJr)

as i said.. put every things as original and power on... check VC 1-12 up and down.. and check if you have 24V 12V after power on on MB. this is main task.

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

as i said.. put every things as original and power on... check VC 1-12 up and down.. and check if you have 24V 12V after power on on MB. this is main task.

ok so leave diode and Q testing for now just do above?

So everything fully connected, use RC to power on/off each time measure VC 1-12 with meter ground to chassis right?

[Diah]

Re: LG 70UH6350 (UB.BUSMLJr)

So everything fully connected, use RC to power on/off each time measure VC 1-12 with meter ground to chassis right?

YES

Note LOL.. i am afraid now yours TV was used at point some how as spare parts... .... the statement from local repair you told us at 1 post funny .. MB & T-CON defect..

let see what you will have at the test.

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

YES

Note LOL.. i am afraid now yours TV was used at point some how as spare parts... .... the statement from local repair you told us at 1 post funny .. MB & T-CON defect..

let see what you will have at the test.

I don't fully understand exactly what/how you want me to test sorry.

We are hoping to find a backlight fault even though so far nothing has been found odd?

Also I found a wire bridge on the PSU marked "FAULT." Can this be useful for troubleshooting?

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

I don't fully understand exactly what/how you want me to test sorry.

We are hoping to find a backlight fault even though so far nothing has been found odd?

Also I found a wire bridge on the PSU marked "FAULT." Can this be useful for troubleshooting?

OH nvm I didn't see your YES confirmation. I wish I had a table or at least the tv original feet... doing this with TV flat on floor...poor back I am very close to giving up point here If I would buy a new TV today with good specs = 120hz, mini-led, FALD then I will have to lose 5" and go down to 65" due to price. Are all TV brands bad now for parts availability or LG is really bad?

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

Vc2 = 6.7V
Vc4 = 6.5V
Vc1 = 7.4V
Vc7 = 7.8V
Vc5 = 6.4V

Vc6 = 6.5V
Vc8 = 8.0V
Vc11 = 6.4V
Vc9 = 6.5V
Vc10 = 6.3V
Vc12 = 6.4V

[Diah]

Re: LG 70UH6350 (UB.BUSMLJr)

how about 24V & 12V.. if you have them for short time.. then just desolder the pin of VC8 and check

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

how about 24V & 12V.. if you have them for short time.. then just desolder the pin of VC8 and check

24V and 12V @ mainboard right? As far as I tested before in first post they lways seem fine but I will re-check.

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

24V and 12V @ mainboard right? As far as I tested before in first post they lways seem fine but I will re-check.

Yes same as original all voltages correct on except DRV_ON.

I also cut the Vc_8 pcb = no diff.

[nonsub]

Re: LG 70UH6350 (UB.BUSMLJr)

24V and 12V @ mainboard right? As far as I tested before in first post they lways seem fine but I will re-check.

Sounds like you thought that "SOS" was shutting off power to mainboard? This was never the case.

I think it is time to give up on this one as almost for sure all mainboards are bad either bad luck buying OR every time I powered up something killeded them even though we don't see a definite reason how happens

[Diah]

Re: LG 70UH6350 (UB.BUSMLJr)

never left only the light eye section on the IR board could be shorted.. it share the 3.5V which MB DC to DC convert to use for eye and DRV_ON.. IR / Wifi / BT so you check if there at eye 3.5V or it dead some where