Lg 70uh700v

[hhanoem]

Has someone the service manual or the schematic for the LG 70UH700V?

regards, Henk

[Diah]

Re: Lg 70uh700v

LED TV are just view known boards with same principle function ,, what will the schematic in this case help.!!! are you going to repair MB ??
so its better to have others mind sharing.. tell the fault and with photos...

[nomoresonys]

Re: Lg 70uh700v

Yes always pictures: https://www.badcaps.net/forum/showthread.php?t=39740

[hhanoem]

Re: Lg 70uh700v

The backlight of the tv is only lit for a few seconds. de backlights are oke, tested with a backlight tester. al led-strings has the same voltages and stays on when i use the tester. No voltage dips on de led-strings, also tested it with a fluke recorder for hours. I want to measure some signals on the driver chip. Its a BBH5YF. I can't find any datasheets for this driver. There is an MCU (MC93F55168B) that controls and operates the led driver. All voltages of the power board are present.

[Diah]

Re: Lg 70uh700v

1- first you need to clean yours PSU from top the dust. and from downside the moisture on it with alcohol 99%
2- BL turn on at start up only to show LG logo then turn off and TV remain on with sound and can see the picture with tourch light its 99.9% LED BL fault.

LG INVOTEK LEDs used at BL each LED unit contained build in zener Diode at the reserve way to A G for limited currents and protection. LED Tester cant handle this and know if this zener open or shorted however the LED lit on.

this mean only LED with DMM one by one in Diode mode to test the lit on and the reserve zener. in yours case the edge LED even if one turn off you will not notice the light of it on screen.

[hhanoem]

Re: Lg 70uh700v

1- first you need to clean yours PSU from top the dust. and from downside the moisture on it with alcohol 99%
2- BL turn on at start up only to show LG logo then turn off and TV remain on with sound and can see the picture with tourch light its 99.9% LED BL fault.

LG INVOTEK LEDs used at BL each LED unit contained build in zener Diode at the reserve way to A G for limited currents and protection. LED Tester cant handle this and know if this zener open or shorted however the LED lit on.

this mean only LED with DMM one by one in Diode mode to test the lit on and the reserve zener. in yours case the edge LED even if one turn off you will notice the light of it on screen.

If the zener was shorted, the total string voltage should drop 1 led-voltage. all strings has the same voltage.

[Diah]

Re: Lg 70uh700v

If the zener was shorted, the total string voltage should drop 1 led-voltage. all strings has the same voltage.

there are many scenario
LED out zener in tact
LED ON zener open
LED OUT zener shorted
LED ON zener shorted

[Diah]

Re: Lg 70uh700v

put yours DMM - to Tv chassis and + each time at start to LED group LED+ .... write down all one by one each at start up.

of course after you clean your PSU