Hisense 65P7 Blank screen

[Hisense65P7]

Hi,
I have a 65 inch Hisense 65P7 LED TV which has suddenly decided not to show any picture or sound.
The TV still has the standby red light on when connected to power and when turned on either with the remote or power button, the TV screen will turn from Black to a dark Blue and the red LED will flash a total of 17 times and stop blinking.

I have removed the back cover and with the TV turned on, the LED backlights are all working.

I have noticed a hum and clicking coming from the Power Board and also a flashing red light (picture attached) on the Power Board close to the Back Light connections.

I am new to this Forum and just trying to rule out which components will need to be replaced in order to have the TV working again.

Thank you.

[nomoresonys]

Re: Hisense 65P7 Blank screen

Check all solder joints on power board, look them over very closely, reflow any that look suspect, careful not to bridge any, examples of bad joints there: https://www.google.com/search?q=bad+...ih=607&dpr=1.5

[Hisense65P7]

Re: Hisense 65P7 Blank screen

Thank you nomoresonys.

Given that there is 4 LED's in a row to which one is the blinking red light in the picture, will this represent which section maybe faulty?
The detail next to this LED is 'VD701'

[Hisense65P7]

Re: Hisense 65P7 Blank screen

Hi, Sorry, I have managed to rule out the Main, Power and CON-T boards.
Does this mean it is only the panel left? Is there an easy way to make sure that the panel is the issue by testing it somehow?

[howardc64]

Re: Hisense 65P7 Blank screen

Hi, Sorry, I have managed to rule out the Main, Power and CON-T boards.
Does this mean it is only the panel left? Is there an easy way to make sure that the panel is the issue by testing it somehow?

How did you rule out main+PSU+tcon? Did you replace with known good boards?

[Hisense65P7]

Re: Hisense 65P7 Blank screen

Hi Howsrdc64,
I found used parts on eBay for all boards with no change to the issue.

[howardc64]

Re: Hisense 65P7 Blank screen

Hi Howsrdc64,
I found used parts on eBay for all boards with no change to the issue.

Did some search for you but unfortunately can't find much info. But can share some observations

TV has local dimming backlight array. Can't find how many. These backlights require more wiring than the non local dimming backlights. Obviously need to drive each LED individually. Individual LED voltage rails are on the LED strip with additional flex cable connecting the strips.

There are total of 4x6 lines coming out of PSU to drive backlight array, printed label on PSU suggest LED flex cable has 4/6 lines for LED+ 2/6 is probably GND (V0?)

I believe your picture shows only a single LED on the daughter board on the PSU near the LED flex cables. Maybe someone knows LED on means good or failure? I'd imagine the daughter board is a switch matrix to pump proper voltage and current to the individual LEDs. Main board surely calculate each LED's brightness and sent to PSU on the smaller of the 2 cables between PSU/main.

Searched for the service manual and didn't find any. Googled result says high # of blinking standby light on HiSense usually means backlight. Don't know if true given many designs over many years.

If know the local dimming wiring circuit, then maybe an LED tester can reveal which one/section is bad. Searched for LED strips for 65P7, didn't find any. Seems local dimming LED replacements are quite rare?

[Hisense65P7]

Re: Hisense 65P7 Blank screen

Thank you so much Howardc64.

I can confirm that when the TV is turned on, that the LED back light turns on, blinks once and then stays on until the TV is turned off.

Upon removal of the front panel, I did test each LED strip (4) which are positioned at the bottom the the TV and only shine upwards and they all worked but I am wondering if they need to be brighter?

[howardc64]

Re: Hisense 65P7 Blank screen

Thank you so much Howardc64.

I can confirm that when the TV is turned on, that the LED back light turns on, blinks once and then stays on until the TV is turned off.

Upon removal of the front panel, I did test each LED strip (4) which are positioned at the bottom the the TV and only shine upwards and they all worked but I am wondering if they need to be brighter?

ah interesting, edge lit so it will be simpler than 2D dimming zones.

Did you use LED tester? All consistent voltage? Were you able to figure out how many zones (Since its 4/6 LED+ per flex and 4 flex, 16 zones?) and tested each zone?

blinking light on that daughter board would suggest failure by conventional wisdom (blinking = alert) but no idea without service manual or prior experience.

Does the TV boot if disconnect the panel flex (or each one individually) from main?

[Hisense65P7]

Re: Hisense 65P7 Blank screen

Hi Howardc64,

I have not used an LED tester.

When the TV is turned on, the 4 x LED strips turn on, gently fade and then stay on.

I have not tried to disconnect the 4 connections to the LED strips one by one to see if the TV turns on, but I will certainly try this tonight.

I have also noticed a faint humming sound coming from both the power board and main board while the TV is in stand by mode and the noise disappears when the TV is turned on.

Thank you again for your help.

[howardc64]

Re: Hisense 65P7 Blank screen

Hi Howardc64,
I have not tried to disconnect the 4 connections to the LED strips one by one to see if the TV turns on, but I will certainly try this tonight.

Not these 4 LED flex cables. Disconnect the 2 from main that goes to the panel. Also try just 1 removed at a time..

[Hisense65P7]

Re: Hisense 65P7 Blank screen

I have tried disconnecting the flex going from the main board to the T-con board one by one without any luck.

[Hisense65P7]

Re: Hisense 65P7 Blank screen

Hi Howardc64,

I did try a few things last night with the TV without success.
The LED edge lighting is definitely working but the LCD panel just turns a dark blue colour when the TV is turned on.
I can press the remote buttons such as 'INPUT' which will alter the colour of the blue screen slightly.

I am stumped and would have to say due to changing all panels, it is now working due to a bad panel.

[howardc64]

Re: Hisense 65P7 Blank screen

Hi Howardc64,

I did try a few things last night with the TV without success.
The LED edge lighting is definitely working but the LCD panel just turns a dark blue colour when the TV is turned on.
I can press the remote buttons such as 'INPUT' which will alter the colour of the blue screen slightly.

I am stumped and would have to say due to changing all panels, it is now working due to a bad panel.

I can see how you conclude its bad panel

• Swapped all the board set
• Backlight turns on and stays on

About only thing left is the panel which is of course not worth swapping.

One handicap is not so many of your TV getting repaired so google finds nothing. No service manual freely available online which might tell what 17 LED blinks mean.

Next step would be to probe panel voltages with a multimeter. This require probing the main board side driving the panel and/or the buffer boards attached to the panel. Also a bit more understanding of LCD.

[Hisense65P7]

Re: Hisense 65P7 Blank screen

Thank you very much for your help howardc64.

I will try and have a look at how to probe the panel for voltages.

[howardc64]

Re: Hisense 65P7 Blank screen

Thank you very much for your help howardc64.

I will try and have a look at how to probe the panel for voltages.

This channel has some basic explanation of how LCD panels work and the voltage supplies.

https://www.youtube.com/@elearningelectronique/featured

I'm not so expert but my basic understanding is you need to have vgh, vgl, vcom, clocks, and voltage supplies for any digital chips on the buffer boards (3.3?V) Finding or not finding these may help with narrowing problem area.

[lotas]

Re: Hisense 65P7 Blank screen

I have tried disconnecting the flex going from the main board to the T-con board one by one without any luck.

You disconnected the wrong cables, you need to disconnect from the T-CON to the panel strips (left and right). You have two cables coming from the motherboard to T-CON and two short cables go out from T-CON to the left half of the screen and to the right half, these are the ones you need to disconnect in turn.
Do you have such a T-CON?

[howardc64]

Re: Hisense 65P7 Blank screen

You disconnected the wrong cables, you need to disconnect from the T-CON to the panel strips (left and right). You have two cables coming from the motherboard to T-CON and two short cables go out from T-CON to the left half of the screen and to the right half, these are the ones you need to disconnect in turn.

Ah, didn't catch this and unfortunately internet doesn't provide many picture of this TV's boards. Saw 2 flex coming out of main and assumed they went to the panel. But looks like t-con maybe integrated on main. Here is pic of 65P7 main from ebay



@HiSense65P7, can you provide pics according to the following forum customs?

• Pic of entire back of TV showing how boards are connected
• Pic of each board in good lighting and highest resolution possible
• Pic of model # sticker on back of TV

[Hisense65P7]

Re: Hisense 65P7 Blank screen

Hi Howardc64,

Not a problem. I will be able to take some more pictures tonight.

Thank you lotas. I will certainly try this also tonight.

[Hisense65P7]

Re: Hisense 65P7 Blank screen

Hi howardc64 and lotas,

Please find attached pictures as requested.