Hisense H6750G stumped on this

[EazyBone]

Picked up another free one. The original owner replaced power board to try and fix them gave up gave to me

Problem: Red led standby light blinks once every 5 seconds repeatedly for ever.power button does nothing. Nothing turns on.

PSU, 12v are all 12v to main, 18v are all 16.6 stby is 2.6
Disconnect main and 12v is 10.5 and 18v become 14.4.
This is the same for BOTH psus.

Backlight tester turns on backlights at 105v each strand and work properly.

I cannot get ANY voltage to backlights on either power supply. They remain zero always.

I am stumped. I put pictures. Is there any way to jump this on or does anyone have any insight. The main is getting some voltages as it should.

Does the main tell the PSU to turn on backlight voltages? Should I have some sort of voltages at the PSU for LEDs? Help lol

Also thanks everyone whose been helping me! I've fixed many many tvs now and it's going great 👍👍👍💯💯💯

[EazyBone]

Re: Hisense H6750G stumped on this

Also is 75 inch.

As a note w833,832,830,834,835 are all at -5v (checking in DC with chassis ground) and start and -5 and drop all down to zero, if that means anything.

[nomoresonys]

Re: Hisense H6750G stumped on this

Check XP901, voltage on the BRI pin, check it in standby then power on tv, what voltage do you get in both situations?

[Diah]

Re: Hisense H6750G stumped on this

105V by LED tester sound to me not good.... how about when you start the tv did you have any up and down V, u need to put the probe in place then turn on

BTW STB 2.6V very low

so you need to do the first test and second leave the PSU alone with out MB connected and check V on the its socket we want to know STB

[EazyBone]

Re: Hisense H6750G stumped on this

Check XP901, voltage on the BRI pin, check it in standby then power on tv, what voltage do you get in both situations?

Bri is 0.151volts, mashing power button does no change as TV won't power on at all.
BSW is .105v, mashing power button jumpers it to .109 and right back down immediately, that's all that's happening.
PSON never gets any volts

[EazyBone]

Re: Hisense H6750G stumped on this

105V by LED tester sound to me not good.... how about when you start the tv did you have any up and down V, u need to put the probe in place then turn on

BTW STB 2.6V very low

so you need to do the first test and second leave the PSU alone with out MB connected and check V on the its socket we want to know STB

TV doesn't start. Voltages never change when hitting power button for LEDs they always remain zero. StB v is the same on Both power boards. Will get back in couple min without StB MB connected

[EazyBone]

Re: Hisense H6750G stumped on this

StB is zero with MB disconnected

[Diah]

Re: Hisense H6750G stumped on this

read other pins at socket psu what v u have and where

[nomoresonys]

Re: Hisense H6750G stumped on this

Do test on backlights as Diah described, if that looks ok maybe test the powerboard as stand alone.

[EazyBone]

Re: Hisense H6750G stumped on this

read other pins at socket psu what v u have and where

PSON zero
18v's 16.6
12v's 12.14
Bri 0.152
BSW 0.105
StB 2.6

Led drivers all zero

Disconnect from mb


PSON zero
18v's 14.6
12v's 10.14
Bri 0
BSW 0
StB 0

Led drivers all zero

Sony the LEDs both have 105v and do turn on with tester

All steady voltages also

[EazyBone]

Re: Hisense H6750G stumped on this

Also I have two psus and they both give these voltages

[Diah]

Re: Hisense H6750G stumped on this

so you have step down circuit on MB.. work on it,, and check if u have spi on it if it shorted

[nomoresonys]

Re: Hisense H6750G stumped on this

Like Diah said 105 seems quite low for a 75 inch tv, does this powerboard have a label for expected backlight voltages? not sure tho, maybe it's normal if it's edge lit.

[EazyBone]

Re: Hisense H6750G stumped on this

so you have step down circuit on MB.. work on it,, and check if u have spi on it if it shorted

I really don't know what this means. I tried to look up step down circuit. Don't know what spi is either.

Here are some pictures, one component gets 220degree fahrenheit which I circled on MB.
And here are some pictures of it.

Sony, they are not edge lit and for some reason my last Hisense was only 2.5 v per light and looked dim. So 105v for 2 sets. Also here's the expected voltages picture which says 98vAre we thinking this is a MB problem?

[Diah]

Re: Hisense H6750G stumped on this

disconnect the blue LVDS cable from MB side and turn n see if backlight come on

[EazyBone]

Re: Hisense H6750G stumped on this

disconnect the blue LVDS cable from MB side and turn n see if backlight come on

No backlight, nothing changes

Edit, the backlight voltages come up to 0.200v and drop to zero.

This is with everything connected and MB lvds cable disconnected

Also with lvds cable connected the voltages come up and down like that now also, must of missed this earliwr

[R_J]

Re: Hisense H6750G stumped on this

The led supply voltage for this power supply is 98V@510ma. You could have a bad led in the panel causing the problem, your led tester likely only provides about 10ma, when the led draw a higher current they can fail.

Using W842 as ground, check the voltage on W702 as you turn on the tv, see if this voltage comes up and drops, It may be tough to check with a meter.

[R_J]

Re: Hisense H6750G stumped on this

Also is 75 inch.

As a note w833,832,830,834,835 are all at -5v (checking in DC with chassis ground) and start and -5 and drop all down to zero, if that means anything.

All these jumper wires are in the primary (hot) side of the power supply, you can NOT check these points using chassis ground.

[nomoresonys]

Re: Hisense H6750G stumped on this

That does seem very hot for a voltage regulator, check those little caps right by it, are any shorted, also what do you get measured in ohms?

[EazyBone]

Re: Hisense H6750G stumped on this

The led supply voltage for this power supply is 98V@510ma. You could have a bad led in the panel causing the problem, your led tester likely only provides about 10ma, when the led draw a higher current they can fail.

I can hit about 100ma, and they still turn on. Not saying this is wrong but is what I got.