JVC lt-32hg35e (Vestel) blinking LED

[unimatrix93]

Dear forum,

I'm stuck with this old TV unit.
PSU: 17PW04-1
MB: 17MB62-1
Symptoms:
- Blue LED constantly blinking when connected to AC.
- Only sigh of life is beeping when touching the capactive buttons on the front.

Diagnostics so far:
Checked the PSU output voltages:
12V present
5V present altought its only around 4.2V
3V is present measured 3.4V.

I check TP 202 which is for the short circuit protection: 0.606V on diode mode

Since I met with some vestel models before with similiar symptoms I tried to flash U158 with different bin files.
Sadly nothing changed, the led were blinking the same altough I'm not sure if the bins I tried were for these exact model.

Does anyone have some tips or matching bin file for this unit?

Thank you!

[yokoono]

Try:

[unimatrix93]

Try:

Thank you,

Flashed it on but sadly same results.
Constantly blinking led.

[yokoono]

It means that the problem is in nand or it is a hardware problem.

[Diah]

could be led BL issue

[unimatrix93]

could be led BL issue

I disconnected everything from the board, so only the PSU - MB - IR control panel is connected. Yet it still do the same.
The PSU has a audbile chirping sound when connected to power.

Maybe there is a problem on the PSU, every voltage are present on output but 5V is a bit low.

[unimatrix93]

I found the schemtics of the power board and it looks like 24V is missing from PL205 (MB connector output) and 5V is missing on PL305 (Backlight inverter connector).

[vinceroger69]

I found the schemtics of the power board and it looks like 24V is missing from PL205 (MB connector output) and 5V is missing on PL305 (Backlight inverter connector).

you may have to jump some pins to get the missing voltages if your just bench testing the psu (im not sure which pins though)

[unimatrix93]

you may have to jump some pins to get the missing voltages if your just bench testing the psu (im not sure which pins though)

What is wierd is that it looks like the 24v rail is disconneted on purpopse. Yet the schematics (both the PSU and the mainboard mentions it for the 32inch model)

[vinceroger69]

can you take some pictures of the top and bottom sides of your psu and upload them thanks

[unimatrix93]

can you take some pictures of the top and bottom sides of your psu and upload them thanks

Sure,

[Diah]

seem you didn't understand my post#5 yours set just 32 take the screen out and there you will find the issue at LED BL

[vinceroger69]

seem you didn't understand my post#5 yours set just 32 take the screen out and there you will find the issue at LED BL

As diah ritely says yes remove screen and check the backlights (98% of my repairs lately have just been failed backlights)

[unimatrix93]

seem you didn't understand my post#5 yours set just 32 take the screen out and there you will find the issue at LED BL

Sorry, I just removed the display and checked the backlight.

Backlight LEDs seems to working fine, however they light up in sections with my led tester.

This tv has edge backlight.

Maybe I should check with my bench PSU too?

[EazyBone]

Take picture of lights when lit. Sometimes to blinding to see one is dim or out when they close together on edgelit maybe

[Diah]

if the edge LED are double LED then there are zener diode build in.. if it get open or short PSU turn off but the tester light them on...
test each with DMM in diode mode

[unimatrix93]

if the edge LED are double LED then there are zener diode build in.. if it get open or short PSU turn off but the tester light them on...
test each with DMM in diode mode

I took out the backlight modules and tested each led diodes one-by-one with my PSU and with my DMM in diode mode. The LEDs are 6V and the voltage drop in diode mode were 0.775V so I guess they are fine.

[vinceroger69]

I took out the backlight modules and tested each led diodes one-by-one with my PSU and with my DMM in diode mode. The LEDs are 6V and the voltage drop in diode mode were 0.775V so I guess they are fine.

Can you power each strip seperatly and see what each strip is using voltage and amps wise

[unimatrix93]

Can you power each strip seperatly and see what each strip is using voltage and amps wise

My bench PSU only do 30V/5A maximum. However I can measure the voltage of the 3 segments with my tester.
I can turn on the segments one by one by touching the black probe to the 3 test points on the board.
Each segments uses 90-91V.
I test the other 3 board in a minute.

[unimatrix93]

Can you power each strip seperatly and see what each strip is using voltage and amps wise

All of them uses the same voltage.