Samsung PN51D550 unable to power on

[hatechildren]

The TV turned off yesterday in the middle of watching it and now wont turn back on (no sound, no image, no response from remote/buttons). There is a 5 double blink LED light flashing where the power button is.

Unplugging and plugging back in makes the 'on' click that repeats 5 times then stops. A green LED on one of the boards flashes in sync with this.
I checked the caps and everything looks normal. My guess is a bad power supply, but TVs are far from my specialty. Any help would be appreciated!

Here is an album with pictures and close ups.
http://imgur.com/a/1NWxW

[tom66]

Re: Samsung PN51D550 unable to power on

A very common failure on this set is the X-main:
http://i.imgur.com/GImFfG3h.jpg

Unplug all connectors from it, except the two brown ones going to the plasma panel.

Then re-attempt power on.

[awyatt2]

Re: Samsung PN51D550 unable to power on

look on the heatsink rail you will find a pair of diodes they have three legs in a to220 case. the symbol is on the case dont remember if they are common anode or commom cathode and may be one of each. check it with ohm meter in diode setting. u may find the problem here. had three of them in three different samsungs same model, to fail and they have held up since i repaired them.i had a couple of old atx power supplys i borrowed the diodes from, tv is worth more than the powersupply.also you might want to run the caps with an esr meter to be sure. and there is a possibility this is not the problem but it is a weak area. one of them i am currently using now it is the 55d550. been using for over a year now. wife has it on most of the time.

[hatechildren]

Re: Samsung PN51D550 unable to power on

OK, I will try both of these when I get home and let you know how it goes. Thanks!

[hatechildren]

Re: Samsung PN51D550 unable to power on

It looks like I've misplaced my multimeter, so Ill have to wait on that test. But unplugging the xmain still has the same issues. Any other suggestions that wouldnt require a multimeter?

[tom66]

Re: Samsung PN51D550 unable to power on

Try with Y-main disconnected -- opposite board to X-main.

[hatechildren]

Re: Samsung PN51D550 unable to power on

Try with Y-main disconnected -- opposite board to X-main.

Unplugged, and still has a clicking relay. I tried with only the main-logic and main-misc connected and it still clicks. With the main unplugged, no clicks.

[hatechildren]

Re: Samsung PN51D550 unable to power on

any other suggestions to try? or would anybody recommend which board to just replace and hope for the best?

[tom66]

Re: Samsung PN51D550 unable to power on

Here is one test:
- Unplug main board power connectors
- Disconnect main board to control board LVDS
- There is a four pin square connector on the board. Jumper pins 3-4 of this

Then power on set by plugging in... do you get test patterns.

[hatechildren]

Re: Samsung PN51D550 unable to power on

Here is one test:
- Unplug main board power connectors
- Disconnect main board to control board LVDS
- There is a four pin square connector on the board. Jumper pins 3-4 of this

Then power on set by plugging in... do you get test patterns.

No test patterns. but the relay doesnt click right away (it does once after a few minutes) and the red LED on the power button is responding to the remote.

[tom66]

Re: Samsung PN51D550 unable to power on

Can you check the 5V supply on the control board -- is it steady?

[hatechildren]

Re: Samsung PN51D550 unable to power on

Can you check the 5V supply on the control board -- is it steady?

The control board is this correct? http://i.imgur.com/oqc4rTvh.jpg
Assuming it is, its listed as 5.3v on the board, but im getting a reading of 5.9 when measuring from the power board itself while the 'control' board is unplugged. if its plugged in, im getting a reading of 5.9 breifly before dropping to 0 (this coincides with the relay clicking)

[tom66]

Re: Samsung PN51D550 unable to power on

Yes, that is the control board.
High 5.9V makes me suspicious of your multimeter battery -- can you swap it so we can be sure.

[hatechildren]

Re: Samsung PN51D550 unable to power on

Yes, that is the control board.
High 5.9V makes me suspicious of your multimeter battery -- can you swap it so we can be sure.

Ill have to wait until tomorrow until Im able to get another 9v battery. Anything I should try in the meantime?

[tadziuz]

Re: Samsung PN51D550 unable to power on

look on the heatsink rail you will find a pair of diodes they have three legs in a to220 case. the symbol is on the case dont remember if they are common anode or commom cathode and may be one of each. check it with ohm meter in diode setting. u may find the problem here. had three of them in three different samsungs same model, to fail and they have held up since i repaired them.i had a couple of old atx power supplys i borrowed the diodes from, tv is worth more than the powersupply.also you might want to run the caps with an esr meter to be sure. and there is a possibility this is not the problem but it is a weak area. one of them i am currently using now it is the 55d550. been using for over a year now. wife has it on most of the time.

Did diodes from ATX PSU had the same markings? Just found one bad in my samsung tv and it is 30G124...

[awyatt2]

Re: Samsung PN51D550 unable to power on

they were the same common anode or common cathode. samsung wanted 27.00 each so i used what i had and have been watching it for over a year now. my wife loves this tv. it is only off when she is at work or asleep.

[tadziuz]

Re: Samsung PN51D550 unable to power on

they were the same common anode or common cathode. samsung wanted 27.00 each so i used what i had and have been watching it for over a year now. my wife loves this tv. it is only off when she is at work or asleep.

In my case it seems to be a transistor and I can't find a datasheet for it. Found them on ebay but delivery from China gonna take ages Don't see any other options...

[vinceroger69]

Re: Samsung PN51D550 unable to power on

In my case it seems to be a transistor and I can't find a datasheet for it. Found them on ebay but delivery from China gonna take ages Don't see any other options...

whats the part number on the item you are looking for?

[tw2005]

Re: Samsung PN51D550 unable to power on

I'm confused, are we talking about 30G124? is that the full number on the casing?
If so and it is a transistor, Toshiba GT30G124 IGBT? N Channel, 430V ,Ic=30A Dc, 200A pulsed ,

[tadziuz]

Re: Samsung PN51D550 unable to power on

I'm confused, are we talking about 30G124? is that the full number on the casing?
If so and it is a transistor, Toshiba GT30G124 IGBT? N Channel, 430V ,Ic=30A Dc, 200A pulsed ,

This is the one I found on ebay:

http://www.ebay.co.uk/itm/30G124-Man...item589aec8af7

Anyway Im getting replacement X-Main board tomorrow and see what happens... Also found open fuse on Logic board but afer replacing it relay keeps clicking and front LED flashing even with disconentec x-main...