⟐ Commented April 11, 2026 at 17:59 MST

When you switched it on , it go off and on

Best and thanks in advance for your help

⟐ Commented March 26, 2026 at 13:06 MST

⟐ Answered March 17, 2026 at 10:54 MST

, image apeared, but with some distortion. When starting color calibration, those lines appear clearly as white ones. If i lower color from 255 to 229 (10% darker, lines dissapear. Adding photos:

. So is it tcon (or its riborn cable) or panel driver? Is it worth to invest 20eur more for new tcon?

⟐ Commented February 26, 2026 at 17:46 MST

It has no indication and in its power supply I have only 3.5V and nothing else.

TV Philips 42PFL3403D/12 with PSU DPS-279BP What links do I need to make to function fully after I have left it from the main body of television to have a complete indication of the voltage measurements it has to give.

⟐ Commented February 22, 2026 at 9:21 MST

I opened the back panel and measured if the voltages feeding the motherboard were present.

So at the output I have 3.3 and 12 volts and the standby voltage goes to 3.3 then to zero every time the switcing starts because when the TV is on I hear a very faint hissing of the switcing transformer and the processor touching it gets warm, after a while it cools down, the very faint hissing is heard again, the processor gets warm again, everything continues until the led starts blinking.
The voltage measurements I made on cn4 of the attached schematic.

Do you think the fault may be in the power supply or the mainboard ?

⟐ Answer accepted January 18, 2026 at 21:40 MST

⟐ Answer edited January 01, 2026 at 21:06 MST

I've taken of the back and measured the voltage at - VLED (5.34v) and + VLED (25.5v) measure against ground.

How can i find out if it is the board that need's to be replaced or the LEDs?

⟐ Commented December 09, 2025 at 5:28 MST

⟐ Commented December 08, 2025 at 9:50 MST

I've been noticing the screen on my 2019 tv getting a bit darker on the upper and lower edges of the screen, but hardly noticeable unless on a bright equal picture, so thought its normal (tv never had uniform white either way).

Then yesterday the backlight gave up while on. A full power cycle has it turn back on for a second and it shuts itself off again. Picture and sound are working.

I opened the back panel to see if there's something looking off but it appears fine. I can do a voltage reading but I'm not sure what values I'd be looking for.

Thanks in advance!

Sorry, couldn't upload photos in a comment so adding an answer.

@uwn8r5maruubj3n the first thing I would do I measure the DC voltage on the Backlight LED connectors on the power board.

Post a picture of what your screen is actually showing. It would be good to see the differences in lighting.

@oldturkey03 thanks again man! The differences in lighting are no longer visible as the entire backlight panel turns off a fraction of a second after a full power cycle where you can only see the logo centered so even if I capture it it won't show. I mentioned it as it looked potentially relevant that I noticed parts of the screen have gotten ever so slightly dimmer days before it died entirely.

Here's DC readings of the LED connection on the power board. Positives around 25V and negatives around 2V, no exceptions.

@oldturkey03 R8619 is probably under one of the heatsinks unfortunately, or I'm blind and can't see it...

I think I'll take the risk and order backlight strip replacements though. Let's see if I can disassemble a full screen, it will be a first. 😅

@oldturkey03 you are a LEGEND!

Replacement backlight arrived this week and I changed it today. I was overwhelmed with joy once the lights stayed on!

Later however it soured a bit when I saw a dark area on the screen. Now I'm not sure if it's something I've messed up in the reflector sheet or diffuser or if it's the chinese backlight strips fault. Any thoughts? The darkening is at the beginning of the strip so I don't think it's voltage related, but it looks like two of the strips are affected.

⟐ Commented December 01, 2025 at 20:12 MST

Thank you for taking the time to look at this question. I was cleaning around my TV, Moved it and cleaned only on top of the tv and with a damp cloth not wet went aross the front bottom part of the tv so the edge between the screen and the trim. After placing it back the TV would not turn back on, the normal red light indicator does not turn on at all. This would indicate a power issue, so i tried the cable with tv around the house and the plugs that do work for other things like charging my phone don't work for the TV.

Checked the end of the cable that goes into the tv with a testing screwdriver and its lighting up so it gets power. I opened up the TV and i see the board where the power comes in and a fuse, so plugged the powercable in and checked both sides of the fuse and both sides lit up the screwdriver so it got power.

Now i am at the end of what i can test. If i could attach pictures i would. Maybe i have the option later.

Thank you and i hope to figure it out as i dont want to need to buy a new tv as this one was working perfectly

⟐ Answer accepted November 19, 2025 at 15:52 MST

⟐ Commented October 25, 2025 at 7:00 MST

I have tried to buy the spare part from Phillips, they refuse to sell spare parts, I will never ever buy a Phillips product again that is more complicated than a light bulb.

I have tried for years to find the spare part on ebay.

It is such a shame as it was a great and expensive display.

The power board part number is 715g9412-p01-000-003m

the product is https://www.philips.co.uk/c-p/436M6VBPAB...

Photos of damage:

https://ibb.co/4Zbc7bn6

https://ibb.co/HTyQ3yvQ

https://ibb.co/tMqp6x20

https://ibb.co/Qyzd01f

⟐ Answered October 21, 2025 at 6:51 MST

I purchased this brand New out of the box and haven’t been able to use it. Please help.

⟐ Commented October 17, 2025 at 20:56 MST

Philips TV Model 55PFL5402/F7 . Reset to factory settings no help. Unable to change color with Blue, red or green on screen controls. What is the TVs problem??

⟐ Commented September 08, 2025 at 21:55 MST

Decided to order a new T-con board to see if that would fix it without success.

I stumbled on a "Tape fix" video, decided to give it a shot. Ended up taping pin 1-13 from the right and hey, it works (with a few picture flaws)

My question is this:

What would be the reason this tape fix works, is it it the mainboard that needs replacing?

Thanks in advance!

⟐ Edited August 31, 2025 at 1:51 MST

⟐ Commented July 30, 2025 at 15:04 MST

⟐ Edited by author July 22, 2025 at 8:49 MST