philips 55pft5500/12 Backlight issue. What am I doing wrong?

[DoOm86]

TV philips 55'' no backlight (image ok).
I tested the backlight with my led tester from the unplugged connector cable and it lights up. I had voltages at the motherboard connector, but anyway I order a new psu. Same problem, same voltages. Disassembled the TV and checked every strip with my led tester, they all light up, same voltage for every pair of strip (they go two by two).
What am I missing?

And something else I don't understand. I checked and I have 3v Leds, 10 per strips. Why every pair of strip (so 20 Led) take about 32v when powered up with my led tester 🤔

[EazyBone]

Sometimes main board is culprit. I am not familiar with this TV at all, but I hav seen some tvs backlights not working because of main board. Main board sends signal to turn on BL and it doesn't. What is the legend for the PSU to MB show. One of those pins may be missing voltsge

[SMDFlea]

Put make and model number in thread title ! ! !
https://www.badcaps.net/forum/troubl...n-thread-title

[DoOm86]

Sorry. Model: philips 55pft5500/12. I can't edit my title.

EazyBone I didn't think to check the return signals, assuming everything was alright since the TV worked fine (backlight apart). I'll check the signals, hoping that is a problem, at least I can try to work it out.
One thing I know for sure. When the TV is in standby I don't have voltage at the BL connector. If I turn on the TV I have it instead.
When the TV is on I have 76v on the positive lines and 48v at the negative ones, comparing with ground. While checking with my led tester, it takes 125v on the positive lines, if I am not mistaken.

[Diah]

you need to messure the LED socket... between LED- & LED+ on each Group.. then compare

[EazyBone]

Give us a pic of the PSU legend to mb

[DoOm86]

Diah oh yeah, I forgot to mention. I don't know why, but if I measure the connector LED + and LED - with my multimeter I don't have a reading (voltage DC mode) but if compare them to ground I have 76v and 48v respectively. If I use my LED tester on the connector (connector disconnected, testing from the Led side of course), LED + and LED -, i have around 30v (if I am not mistaken) and the backlight is fully present.
EazyBone ok, I upload the pic now.
If needed, I upload also the schematic of the psu

[EazyBone]

What does bl/on / dim/ 3d(?)on voltages show when turned on

[lotas]

Check these areas from the back side to see if the tracks are damaged...

[Diah]

Diah oh yeah, I forgot to mention. I don't know why, but if I measure the connector LED + and LED - with my multimeter I don't have a reading (voltage DC mode)

this mean there are no signal on pins BL_OFF/ON.... or as Lotas mentioned... you have damage on the track of the left side which its belong to LED BL circuit

[DoOm86]

Hello again.
Sorry I didn't update you guys before but the TV was in test at the client's house and I wanted to be sure it was working.
So at the end the tv had a double fault. A problem was in the power supply board, which I couldn't understand which component was faulty. The TV at that point turned on but after just a week of working intermittently, I found out a motherboard problem as well. I had one and I changed it to save time, even though I was curious to know the problem.
Now it's working great.
Thanks