Samsung plasma pn50B550t2f wont turn on

[Ryckmav]

Re: Samsung plasma pn50B550t2f wont turn on

I took out those 3 cap (#2 on picture) and test them
1 read 134uf,other 2 read 131uf,would this be enough to stop all from working?

or I if I change this main board is best option?

[martino]

Re: Samsung plasma pn50B550t2f wont turn on

I somehow missed this thread.....
Let me put my TV on the bench(exact same TV) and I will take some pic's for points of measurement to get you going on this trouble shooting,I'm no expert like tom66 or budm,tw2005 etc but can help you in comparing voltages etc...
On mine the Y-sus board is defective,but we'll get to that later...
Meanwhile,can you take a pic of that mark on the back cover,and also a pic of that part of the y-board that matches up to the spot on the back cover??

[martino]

Re: Samsung plasma pn50B550t2f wont turn on

OK,see picture....I marked 2 components...

Component 1:
With TV plugged in,meter on 200volt AC,what voltage do you get between the 2 legs of vx803s(marked as #1),careful when measuring,don't slip or you will have fireworks,don't touch or you will have hair like boy george...
You should see about 120 volt AC .....

If you do keep reading.....

Component 2:
UNPLUG TV and let sit for 10 for a bit...
Put your meter on the OHM scale,measure between legs of NT801S(marked as #2)
You should see about 20 OHM....

Report findings...

I put the TV I have on the bench,it's normal to see 0 volts on those 3 caps you marked #2,when TV is in standby..

[martino]

Re: Samsung plasma pn50B550t2f wont turn on

Re reading this thread.....see pic....
meter on 20 volt DC,black probe on chassis of TV,red probe on pin by arrow...What do you get there for voltage?

**when on my TV,ALL connectors are plugged in and I plug powercord in,the PSU will click twice,pause and click once more....
When I unplug main and logic board plugs,and plug powercord in,NO click at all....***
Hence me now asking for this voltage...

[Ryckmav]

Re: Samsung plasma pn50B550t2f wont turn on

vx803s(marked as #1) read 120 volt

NT801S(marked as #2) read 25.5 Ohm

I'll do the other test soon on the 5V pin


this is the back cover and it's probably nothing,the zoom pic show a shiny spot that could be cause by an arc,but they is nothing in this area but a big plastic mount for optional wall mounting.

[Ryckmav]

Re: Samsung plasma pn50B550t2f wont turn on

Re reading this thread.....see pic....
meter on 20 volt DC,black probe on chassis of TV,red probe on pin by arrow...What do you get there for voltage?

I get 0.44 to 0.79 and never stable,it just keep moving between them 2 value

[martino]

Re: Samsung plasma pn50B550t2f wont turn on

0.44 o 0.79....you measured that with mainboard unplugged??? (just to be sure)

[Glitcher]

Re: Samsung plasma pn50B550t2f wont turn on

Okay I skimmed through the thread a little bit.
So the TV is just dead, and with no red light in the front correct? This is most probably a problem in the PSU itself. (mainboard is rare to cause this problem but I have seen one)

If there is no red light, I'm mostly sure that the PSU is not outputting the standby 5v. Check if you have the Standby 5v. If YES than your problem is the main board. If NO than the problem is in the PSU.

[martino]

Re: Samsung plasma pn50B550t2f wont turn on

He's getting 0.44 volt on the standby....

[martino]

Re: Samsung plasma pn50B550t2f wont turn on

see pic...
CX820,meter on 20volt DC,what voltage do you measure between the 2 legs?

[Ryckmav]

Re: Samsung plasma pn50B550t2f wont turn on

0.44 o 0.79....you measured that with mainboard unplugged??? (just to be sure)

all was plug except for this one I tested (CN801)

did the same test with only 120VAC plug and I get 5.23VDC

[Ryckmav]

Re: Samsung plasma pn50B550t2f wont turn on

see pic...
CX820,meter on 20volt DC,what voltage do you measure between the 2 legs?

5.26 Vdc and this cap is loose,not the the soldering but the lead going into
the cap

all but the 120V ac was unplug.

[Ryckmav]

Re: Samsung plasma pn50B550t2f wont turn on

Okay I skimmed through the thread a little bit.
So the TV is just dead, and with no red light in the front correct?

correct;I got no red light,all is dead.

I took a chance and order a new (used) board for 56$ all included.

[martino]

Re: Samsung plasma pn50B550t2f wont turn on

With only ac plugged in you DO get 5.26 volt on the standby pin...
With only CN801 unplugged,you get 0.43 volt on the standby pin...

That would mean that CN802 is dragging down the 5volt line...Can you test and confirm that?

[martino]

Re: Samsung plasma pn50B550t2f wont turn on

I took a chance and order a new (used) board for 56$ all included.

.......

[Ryckmav]

Re: Samsung plasma pn50B550t2f wont turn on

this is weird,hold on, doing some test because I dont get same reading again

[Ryckmav]

Re: Samsung plasma pn50B550t2f wont turn on

With only ac plugged in you DO get 5.26 volt on the standby pin...

I dont get this no more since I wiggle CX820,the test I did was the standby pin was done before I wiggle CX820

so this would mean CX820 also lost is 5Vdc now, let me check

test done and CX820 still have 5VDC and this Cap is loose as hell so I tried to wiggle again while testing
the standby pin = 0.43 VDC , and did this with 2 different multimeter to make sure,this cap should not be so loose
and as soon I touch it; I got different result.

[martino]

Re: Samsung plasma pn50B550t2f wont turn on

If CX820 has a loose leg like you indicated,you might wanna solder it of the board and see if it's shorting out at that loose leg? It's the filter cap,right after the 5 volt(ac) get's rectified,before it get's regulated in IC QB810. It would also drag down the 5.3 volt DC for the logicboard voltage...

[Ryckmav]

Re: Samsung plasma pn50B550t2f wont turn on

the solder is good martino; it's inside the caps that is very loose

[martino]

Re: Samsung plasma pn50B550t2f wont turn on

the solder is good martino; it's inside the caps that is very loose

Yes,I understand that
What I'm trying to say is that if that cap is shorted(inside cap) it WILL kill the 5volt standby voltage...