Hisense LCD39V77PK Blue led directly no sound no picture

[revenger132]

A Hisense 39 inch model: LCD39V77PK glowing with blue led directly after connecting to power source (no standby red led) and no sound or picture appears with no response to buttons or remote control!!
i checked the power board voltage all of them were Ok. also i checked the control board voltage all of them exist but the flash IC voltage was 4.3 v not 3.3 v so i replaced the voltage regulator with same # and the voltage back to 3.3 v but same issue.i reflashed the flash IC with same model software but same issue.
i checked power signal (5 v) from control board to power board it is always on directly after attaching tv cable to power source.
i disassembled the Flash IC, HDMI IC and sound IC and check all smd capacitors for any short then connected tv same 5 v always on
i disassembled all connected cables from power board to control board and only connected 5 V Standby voltage to control board and i found that the power signal continue to be on!!!

Any suggestion for the problem and how to fix it please

[Diah]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

start to upload photos on whole back of the TV show how they are connected. also photo on the main board and remrk which IC you are talking on and the NO. and which regulator you replaced. also show us clear photo of the PWB especially the socket which feed MB

so we can start trouble shooting..

[revenger132]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

This is the whole back

This is the main board

This is the power board

power board voltage distribution

connecting only 5 v (standby voltage) to main board

measuring pwr switch (pwr signal) pin from main board to power board

IC which have been replaced and disassembled

Voltage regulator

Flash IC

HDMI IC

Sound IC

[Diah]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

okay, the Regulator you changed brought back the 3.3 V to the SPI eeprom. you had just re flashed firmware and no change. mean your SPI Flash in bad condition because of the over load Volts
also i cant tell you take out the SPI out from board to flash it again... flash bin file on eeprom should be done out side the circuit after format the SPI and blank check.. if this didn't bring the set back then change the SPI
could you write the SPI Flash No.?

[revenger132]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

Thank you for your support
SPI flash no MX25L3206E 4 MB flash
But actually i am not suspecting the Flash IC because if it is removed it must bring back the LCD to Standby status with the Red LED lit not the blue led and then the LCD will not respond to remote or fixed buttons.
However the condition also after removing the flash SPI out of the board same issue blue led with power board on for all voltage as if i opened the TV from power button.

N.B.
I have removed the SPI flash and flashed it with the RT809F programmer with same firmware found it from other forums.

[Diah]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

check out of circuit the 2 transistor bridge on the right side near to SPI. they are responsible to switch On PW ON and and Stand by Led signal too.. they should be PNP & NPN type as i call back.

[Diah]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

one things more, the SPI flash MX25L3206E 32Mb not as you mentioned 4Mb. and its operation bus Sock between 2.6 -3V regard Macronix specification

so if your programmer read it just 4Mb mean its diffidently bad

[diif]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

one things more, the SPI flash MX25L3206E 32Mb not as you mentioned 4Mb. and its operation bus Sock between 2.6 -3V regard Macronix specification

so if your programmer read it just 4Mb mean its diffidently bad

32Mb = 4MB

[revenger132]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

Yes already checked both are same type PNP (H1A code).

Yes as you said they are both connected directly to the PWR signal for the PWR board but from where they take the 5 v signal to pass for the power board?
Does it comes from the main IC?

[revenger132]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

32Mb = 4MB

Yes it is 32 Mega bit = 4 Mega Byte
the programmer read erase and write it with now issue so i doubt that the ISP is defected

[Diah]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

32Mb = 4MB

thx ..time to change my glasses

Yes already checked both are same type PNP (H1A code).

Yes as you said they are both connected directly to the PWR signal for the PWR board but from where they take the 5 v signal to pass for the power board?
Does it comes from the main IC?

yes exactly took the order from main CPU. but if you read the specification of the SPI. the STB are not really deep power off. it mean it remain On but as sleep mode.
this can quids us for point. take the set out from wall socket.. leave it for view minutes off then.. press the power on tv side panel and keep it press for 1 minute.. then press with it menu on the tv and keep press then plug it on.. hope the screen will come back

[revenger132]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

thx ..time to change my glasses



yes exactly took the order from main CPU. but if you read the specification of the SPI. the STB are not really deep power off. it mean it remain On but as sleep mode.
this can quids us for point. take the set out from wall socket.. leave it for view minutes off then.. press the power on tv side panel and keep it press for 1 minute.. then press with it menu on the tv and keep press then plug it on.. hope the screen will come back

I will try it and let you know by results.
But what is the effect of this process? Is it like a reset for the TV?

If this is a reset, why when i re-flashed the SPI it doesn't brought back it to normal mode?

[Diah]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

No. this is never being a RESET Process. its Just let other script at firmware to take in place.. in case the glitched and stooped at one script process where it can be saved at Temp within NAND. ..its same way if you connect the set with JTAG and read in & Out script after power on. to know at which step the set hold on.

[revenger132]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

i have done the above process but with no hope same blue led.
is there a possibility that the controller main IC is dead, i found replacement for this IC on Chinese aliexpress site, if i replaced it would it be effective if it was the reason?

[Diah]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

you can try reball the same IC

[revenger132]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

you can try reball the same IC

It is not a BGA IC it a normal SMD IC with terminal from 4 sides and all of them are welded in a good condition

[revenger132]

Re: Hisense LCD39V77PK Blue led directly no sound no picture



This is the IC schematic

[Diah]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

whats the NO of it ? ok read it
well i still suspect the SPI Flash

[revenger132]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

MST6E181VS-LF-Z1

Do the TV will directly operate the power board if i took up the SPI flash out of the board?
I think if the SPI flash is the concern it should keep on the standby mode no 5 v power signal go to the power board with all same symptoms (no picture, no sound, no response to buttons or remote control).

[Diah]

Re: Hisense LCD39V77PK Blue led directly no sound no picture

MST6E181VS-LF-Z1

Do the TV will directly operate the power board if i took up the SPI flash out of the board?
I think if the SPI flash is the concern it should keep on the standby mode no 5 v power signal go to the power board with all same symptoms (no picture, no sound, no response to buttons or remote control).

normally yes. but not the chinese one..LOL.. its to me same Principle of Chinese LCD Projector.
do you have firmware update to put it on USB and check if it will response to USB stick ..