samsung ue40d5520 flashing red light

[wreksta]

Hi all just got a sdt in there cheap £55 the standby light is flashing
I disconnected the led cable and tuner board cable from the power supply board and measured voltages from the power supply to the tuner board connection I get no voltages at all on any pin until I hear the power supply pulse then the voltages rise then drop within 2 seconds and it repeats

any ideas there is on pin that gives a steady 5v all the rest are fluctuating

power supply board is bn44-00422b
http://www.google.co.uk/imgres?clien...bwYDoDg&zoom=1

[tom66]

Re: samsung ue40d5520 flashing red light

There's a thread on here regarding the 55" D5000 series which is more or less the same as yours, with same symptoms. Bad main board.

[wreksta]

Re: samsung ue40d5520 flashing red light

Tom when all boards disconnected I get fluctuations on the connector lead that leads to the main board but disconnected only 1 pin is a steady 5v the rest are from from no volts up to mm 10-12v then back dosn to mm no volts within second ill see jf I can get a videonfor you

[tom66]

Re: samsung ue40d5520 flashing red light

Yes, that TV has the same symptom which makes it look like main board bad. Thread:

https://www.badcaps.net/forum/showthread.php?t=34566

(My error, that's a D6000, but I think the only major different is the D6000 is a Smart set.)

[wreksta]

Re: samsung ue40d5520 flashing red light

He got a start up screen I dont mate

[tom66]

Re: samsung ue40d5520 flashing red light

Do you get stable 5V standby? Or is that varying too?
I'm SURE I saw one about D5000 which was similar, but I might be getting mixed up...

[mmartell]

Re: samsung ue40d5520 flashing red light

There seems to be a plague of these lately

[wreksta]

Re: samsung ue40d5520 flashing red light

With all boards disconnected and the led cable all disconnected running only the psu with ac cable in
I get pulsing noise from psu and only one pin on the white connector is showing 5v and the rest of the pins fluctate

[tom66]

Re: samsung ue40d5520 flashing red light

What voltage do you see across the 450V caps?
No schematic, Samsung stopped releasing them I think, so we're kind of working blind...

[mmartell]

Re: samsung ue40d5520 flashing red light

Are the BLON, PSON and PWM lines oscillating as well ?

[wreksta]

Re: samsung ue40d5520 flashing red light

A5v is the only voltage I can read steady

[mmartell]

Re: samsung ue40d5520 flashing red light

Right but you said the others are oscillating. Does that include the ones I asked about ?

[wreksta]

Re: samsung ue40d5520 flashing red light

What voltage do you see across the 450V caps?
No schematic, Samsung stopped releasing them I think, so we're kind of working blind...

About 360v ramping up 390 every time it pulses then drops again go 360v

and all except grnd and a5v fluctuate

[wreksta]

Re: samsung ue40d5520 flashing red light

Mmartell all ps on bl on and power sw are all 0v until hear the power supply pulse then ramp up to 3v then down to 0v again


I have ordered a replacement power supply but wont come for a week

so hoping to try and narrow this down

[tom66]

Re: samsung ue40d5520 flashing red light

Sounds like PFC fault - I'd focus on startup capacitor for PFC section or main run section.

[wreksta]

Re: samsung ue40d5520 flashing red light

Any ideas tom where exactly to start ive tested all mosftes and diodes all check out etc so on my diagnosis do you all agree my psu is fuxored

[tom66]

Re: samsung ue40d5520 flashing red light

Knowing how complex some of these PSUs are, in newer Samsung LED that is, I could not say for sure. It does SEEM like it, though.

[johnboy1313]

Re: samsung ue40d5520 flashing red light

Just an FYI, I stripped a 55D6420 Monday. At one point, I tried to power it up with the LEDs unplugged from the PSU which resulted in a flashing red light and a pulsing power supply. My power supply would click about every second if I remember correctly. Your symptoms make me wonder if you have an LED out.

[wreksta]

Re: samsung ue40d5520 flashing red light

My psu pulses with led strip plugged in or out and if im corrsct those startup caps are power Ed in line before then led section so should have higher voltages on those caps ks that right tom

[tom66]

Re: samsung ue40d5520 flashing red light

The 450V caps are primary side. In a 40", the LEDs will work on around 100 to 200V end to end. I have an LED driver from a 40" Technika LED (fell off a wall...) which is rated 130V. It used a Samsung FHD panel from 2011, similar to yours. The LEDs will be driven off the secondary.

Not enough experience with these I'm afraid to give much help. My only big LED TV fixes have been unrelated to backlight or PSU.