HISENSE H55B7500UK has backlight no picture

[Diah]

Re: HISENSE H55B7500UK has backlight no picture

we don't know the history of this TV.. actually when you do testing the T-CON and panel standalone should display color pattern ,

[Diah]

Re: HISENSE H55B7500UK has backlight no picture

i would suggest start from Zero to trouble shooting... start with LED BL... yes you can see light... but you have 2 Group need to measure the currents of both and compare them

[snowangel27]

Re: HISENSE H55B7500UK has backlight no picture

Do you mean 2 groups of led backlight?

[Diah]

Re: HISENSE H55B7500UK has backlight no picture

Do you mean 2 groups of led backlight?

sure,,, there are 2 way to measure..
do first put yours DM on 250V DC. black probe on TV chassis.. and the Red Probe of the Red wire of each Group... turn on and notice the high V and the low at start up .. write yours result here

second method of measurements... DM at same Level DC ... each group black on black as well the Red on Red.... then turn on

[snowangel27]

Re: HISENSE H55B7500UK has backlight no picture

High vol 1p and 2p 144-130v in 10s when i plug into wall socket.
Low vol 1p and 2p 126.8v when turn on the tv

[Diah]

Re: HISENSE H55B7500UK has backlight no picture

do the measurement method 2... P1 N1 .... and P2 N2 at plug in wall socket.... record the high and low

[snowangel27]

Re: HISENSE H55B7500UK has backlight no picture

When i plug into wall socket
1p 1n 15-11v
2p 2n 34-29v
When i turn on the tv
1p 1n 103v
2p 2n 104v

[Diah]

Re: HISENSE H55B7500UK has backlight no picture

the reading not normal.. because the amount of LEDs at each Group are same amount.

i think now this happen.. at time the TV on. there are error at BL... main boards didn't complete the booting normally... but after at start up script of BL ON order the BL turn on... but its little late maybe in 1-2 second....

i never faced such issue .. its really interesting to discover the reason and terminated it..

so i will suggest the following to try... as you are not expert at electronic,,, so i will make it easy DIY
take any Normal house Flammable Lamp... ( like table lamp ..etc ) doesn't matter the watts.. but not less 20 ..... each group cutting the N of them and put the lamp in between... to act as as Resistances .. ( it will dummy the power boards as the group working fine )... if our thought correct... you will see at least Hisense start up Logo on screen

[Diah]

Re: HISENSE H55B7500UK has backlight no picture

you first start trying with N1 group.... if no result bring back the cable as original and try N2

[snowangel27]

Re: HISENSE H55B7500UK has backlight no picture

Can I use real resistor(how many ohms?) to connect into line 1n and 2n?

[Diah]

Re: HISENSE H55B7500UK has backlight no picture

Can I use real resistor(how many ohms?) to connect into line 1n and 2n?

NO

Lamp will take any off current caused by fault LED in case there are.. and Generate it to Heat / light... so its Resistances will be fixable ,,,,
Normal Resistor cant do this Job because its Value fixed

[snowangel27]

Re: HISENSE H55B7500UK has backlight no picture

Unfortunately, i don t have any flammable lamps because all my house's lights are led. I will try to find one and let you know the result later.
And the lamp will be connected like this, right?

[Diah]

Re: HISENSE H55B7500UK has backlight no picture

Unfortunately, i don t have any flammable lamps because all my house's lights are led. I will try to find one and let you know the result later.
And the lamp will be connected like this, right?

correct

[snowangel27]

Re: HISENSE H55B7500UK has backlight no picture

correct

https://drive.google.com/file/d/1s3T...w?usp=drivesdk

I already connected the lamp on N1 and N2 but the tv s still nothing on the screen. The only thing changed s the blinking led gone(see video)

[Diah]

Re: HISENSE H55B7500UK has backlight no picture

i wrote before... while you do the lamp test.. you need to look on the screen front.... to see if Hisense start Logo can be seen for short time

[lotas]

Re: HISENSE H55B7500UK has backlight no picture

https://drive.google.com/file/d/1s3T...w?usp=drivesdk

I already connected the lamp on N1 and N2 but the tv s still nothing on the screen. The only thing changed s the blinking led gone(see video)

I don't understand the meaning of such a connection, what it can give.

[snowangel27]

Re: HISENSE H55B7500UK has backlight no picture

I don't understand the meaning of such a connection, what it can give.

I just do as diah say^^

[snowangel27]

Re: HISENSE H55B7500UK has backlight no picture

i wrote before... while you do the lamp test.. you need to look on the screen front.... to see if Hisense start Logo can be seen for short time

I will do it again and watch the screen more carefully

[Diah]

Re: HISENSE H55B7500UK has backlight no picture

I will do it again and watch the screen more carefully

i think yours N1 & N2 share same line on the power boards,, so take out the power boards and check from the down side at the socket,, if they are connected together... in case yes they are sharing same line... then do the lamp test with P1 P2 and always check screen if there any start logo..

LOTAS trouble shooting for normal user with out background of electronic or he/ she lack with equipment like any who had workshop...... i give them easy way to terminated issues by easy test... lamp test for by passing any error of BL if exist.. and let the MB go forward to complete the starting script. this tested on Hisense over here many time

[lotas]

Re: HISENSE H55B7500UK has backlight no picture

LOTAS trouble shooting for normal user with out background of electronic or he/ she lack with equipment like any who had workshop...... i give them easy way to terminated issues by easy test... lamp test for by passing any error of BL if exist.. and let the MB go forward to complete the starting script. this tested on Hisense over here many time

I understand that it is necessary to break one channel, but why hang the two ends of the lamp on one wire, what is it?