Samsung 51" Plasma PS51D450A2M

[s_henya]

Hey guys,

Found this one, with no power symptom,
With power connector, i have one little red blink.

Opened up it and i can see that i have a green light on on the tcon board.

(The light on the Tcon board randomly turns on and off)
and i can hear small ticking as there is a load or a short to the psu.

I have very little experience fixing plasma tvs.

Visual inspection showed heating signs on 2 boards (not the psu, main, tcon, buffer board) im sorry but i don't know their technical names (YSUS VSUS maybe).

I searched the forum and found Tom66 post, (he had a bad mainboard)

Some testing tips on plasma would be great,

PSU Board :BN44-00443B
Main Board: BN94-04644A

I have 5.21v Stby voltage, and 395vdc on 2 main filter caps.

I don't know how to force start a plasma psu, is it the same as in LCD?

Use a 1k resistor from 5v to pson with nothing connected to psu but the ac?

[newtothis]

Re: Samsung 51" Plasma PS51D450A2M

Yes same as LCD.

IGBT maybe ticking? Use an insert from a toilet roll to narrow down where it is

[tom66]

Re: Samsung 51" Plasma PS51D450A2M

Control board LED should flash in operation about once every 1-2 seconds. If fault is detected, it will be 5-7 seconds.

Boards from 3rd image: X-main, Y-main, control/T-con/logic, main AV board

These sets can be easily upgraded to the 3D model, although the 3D performance in my case was lacklustre (but I've never seen a 3D TV I liked to be honest.)

[s_henya]

Re: Samsung 51" Plasma PS51D450A2M

So...

I should test the psu first right?

using 1k resistor between b5v to ps_on in the first picture?

with all other cables disconnected, but power cable?

afterwards test all of the other voltages out of the psu?

[s_henya]

Re: Samsung 51" Plasma PS51D450A2M

After playing with it some more,

I found to have a quick flash on the screen when i plug it to the power, and counted 6 red blinks.

I guess its an error code,

anyone knows what it means?

[sordids999]

Re: Samsung 51" Plasma PS51D450A2M

on your power board try testing your VA/VS voltages to see if you have any readings it should match up with your panel sticker

[tom66]

Samsung sets use PS_ON low, so you want to use 1k from PS ON to GND.

Then if lower voltages come up, jumper VS ON to 5V and check Vs/Va (200V and 60V each, approximately, exact values on panel sticker)

I found to have a quick flash when i plug it to the power, and counted 6 red blinks.

I guess its an error code,

Samsung plasmas don't use error codes, so I'd ignore it for now.

[s_henya]

Re: Samsung 51" Plasma PS51D450A2M

https://www.youtube.com/watch?v=JjrwTZC5nVg

found this video on youtube, maybe it will be of help.

i will now try to force start the psu, so it's staring low not high.

i will try and update right away!

[s_henya]

Re: Samsung 51" Plasma PS51D450A2M

So,

I disconnected the cable from the psu to the AV board from the AV board side,

plugged a 1k resistor between pin 1 PS_ON to pin 3 GND.

It didn't start.

But if i jumpered it without the resistor the psu started and i could hear the high voltage whining as i have a short or load.

Is it safe to start it without the resistor,
if i understand correctly, the resistor acts as a voltage divider or a current limiter?

should i disconnect the cable from the psu to the tcon? ( i left it connected)

[tom66]

Re: Samsung 51" Plasma PS51D450A2M

1k might be too high. I use 100 ohm. I recommend using a resistor in case the power board does not have a resistance built in. Most of these sets do... but it's better to be safe rather than sorry...

You will need to check the B5V, etc to see if they work rather than just listening to whining sound, whining could mean anything.

[s_henya]

Re: Samsung 51" Plasma PS51D450A2M

OK with the 100ohm the psu kicked in. (still whining but i will leave it aside for now)

B5V to tcon=5.27vdc steady
VS=180vdc and dying very quckliy till almost few volts in less than a minute
VA=58vdc and dying very quckliy till almost few volts in less than a minute

I did that with all boards connected but the cable from the PSU to AV board.
is that the right way?

[tom66]

Re: Samsung 51" Plasma PS51D450A2M

Ok, all boards connected? If Vs/Va rise then fall, there is a fault detected. Is 13/15V OK?

Can be damaged plasma panel (crack on screen), bad Y-main, bad X-main, bad buffers.

Check panel very carefully for cracks, especially on the edge.

[s_henya]

Re: Samsung 51" Plasma PS51D450A2M

As always you are correct, sadly the panel is cracked.

at least i learned a thing or two on the way..

Thank you for teaching!

Sad ending :-(

[tom66]

Re: Samsung 51" Plasma PS51D450A2M

It's a shame I actually quite liked the 2D picture from this panel, even if only 720p. They are very fragile. Much more fragile than they should be.

Is it an edge crack, or a small "spiderweb" crack near the centre of screen?

[s_henya]

Re: Samsung 51" Plasma PS51D450A2M

Its a tiny spiderweb at the left side.

I didn't notice it yesterday when i picked it up at 24:00 in the dark.

I will try to sell it as is.

Thank you again.

[gadget78]

Re: Samsung 51" Plasma PS51D450A2M

Ok, all boards connected? If Vs/Va rise then fall, there is a fault detected. Is 13/15V OK?

Can be damaged plasma panel (crack on screen), bad Y-main, bad X-main, bad buffers.

Check panel very carefully for cracks, especially on the edge.

sorry for digging up old thread, but it seems there is only couple of threads with this TV/PSU on !?
so thought be nice to keep it all together!?


ok so fault on this TV (which has no cracks) the screen does nothing
red LED flashes when you try to power up
(think its going staight to power on state anyhows??)

it has 5v ok, and will go, it seems, straight to power on state when plugged in to 240v, were the (PS_ON) is low...
so 15v is (stable) live, but with NO voltage VS, or VA ..

if i disconnect PSU board from mainboard, it then goes to a 'powers off' state, relay clicks out, then has no 15v, (and of course still no vs/va), PS_ON voltage go's to 3.7v, and your left with just the 5v on the 5v rail.

connecting mainboard, but disconnecting everything else ...
get a stable 15v still, and some unstable LOW voltage on VA/VS ..

theres no real 'cold' joints, and all the main gates seem to check out ok with meter, no bulging of caps, Fuse, and the 5WR017J is ok too .. i did re-flow all the main joint to be sure, but didn't alter anything ...

any help to guide or focus on would be great .. Cheers Mick ..

[tom66]

Re: Samsung 51" Plasma PS51D450A2M

Check the green LED on the control board.

No light = fault with control board or no 5V
Flashing light once a second = Working, so check video input (or do test pattern)
Flashing light once every 5-7 seconds = Fault, with sustain boards, buffer/scan drive, no Vs/Va, etc.

[gadget78]

Re: Samsung 51" Plasma PS51D450A2M

first off, thankyou for replying!!

the green light on the control board is flashing once a second;
video input/test pattern... the screen doesnt switch on attall how do i do these in that case?..
i was thinking its some kinda PSU fault, as not outputting Vs/Vs voltage ? so if Vs/Va are not stable/present doesnt actually mean the psu is at fault?.. was going to test PSU "on bench" separate ...

cheers Mick .

[tom66]

Re: Samsung 51" Plasma PS51D450A2M

Sounds like it may be a main board issue

Try jumping PS ON to GND and VS ON to 5VS using a 470 - 1000 ohm resistor. (You can try without a resistor but we prefer it because it reduces the risk of damage if the power supply is different. Usually it is fine without.)

Then if Vs/Va stay stable and control board light still flashing once a second, we can activate the test patterns (there is no need to use the menu to do it...you will see)

[gadget78]

Re: Samsung 51" Plasma PS51D450A2M

arrrr... never realised there was a Vs-on on that bottom connector ! DOH !

ok so with them manually activated..
can confirm stable standby, 5v, 15v, and now a stable 200v Vs, and stable 60v on Va

so that rules out the power supply ...
from the 1 second flash from control board rules that out so yeah think you gonna be right on the main board !! ...

Thankyou for this... im normally a forum lurker, as i can normally get by from just reading whats already been posted when helping others on same/similar boards/TVs
but coudnt find anything similar enough to this board ! hopefully this can help others too ..