samsung plasma ps50 c580g1k slow tripping relay

[jimbofz]

Hi ,this appears to have 2 faults
black lines on raster and faulty main board ?
let me explain futher
at switch on the relay does a few slow clicks with red led blinking and repeats every 10 seconds .i ran the psu into 2x 100w lamps and it runs fine all day supplies good .
i removed y sus and x sus checked for dry joints and checked all igbt anf fets all ok
next i removed buffer and checked for any s/c buffer ics all ok
so i unplugged feed to main board from logic board and linked test points pin 3 and 4 ,
tv still trips but now i get plain raster with black lines
as shown in pic
for a few seconds
the black lines could be the plasma panel ,so game over
BUT why the main board fault ?
the owner said it was fine before the clicking started .
so my main question is ,
can the lines be caused by any thing other than the plasma panel? and why dont i get the test pattern without the tv tripping off?
theres no short on the main board pulling down the lt supplies

[jimbofz]

Re: samsung plasma ps50 c580g1k slow tripping relay

does anyone hace cct of mainboard please?

[jimbofz]

Re: samsung plasma ps50 c580g1k slow tripping relay

38 views no replies?
i must be jimmy no mates

[R_J]

Re: samsung plasma ps50 c580g1k slow tripping relay

Can you tell which relay is clicking?
If it is RL801S that is turning off it could be that the supply voltage to it is dropping, the relay is supplied D5V3 through QM404 mosfet . This circuit requires a stable Vg voltage (measured across CM419)

NT801S will be warm in standby but does nt801S get hot when the tv is ON running? If it does the relay contacts are likely bad, when the tv turns ON RL801S should short NT801S if it doesn't the tv could act like it is due to the drop in voltage across the thermistor.

2 light bulbs is not enough load so the power supply will run fine. the tv takes much more current.
The lines are likely due to a bad panel, It is possible the buffer ic is bad but unlikely. You would need to scope the signal coming from the buffer is to the panel to be sure.

When you disconnected the main board and jumped the auto_gen pins, you eliminated the main board, the white screen I believe is the first test signal, then black, then the colored rasters.
What are the Vs and Va voltages? The reason it still shuts down is likely due to the power supply.

I had a PN50A450P that had 6 black lines and it was the panel for sure, in fact it started out with just 2 and the next time I turned it on it had another, then another.

[jimbofz]

Re: samsung plasma ps50 c580g1k slow tripping relay

well thanks thats reassuring ,
i assumed that running psu into load and confirming all supplies good
ruled out psu but obviously not .there are 2 relays side by side one clicks then the other clicks 2 seconds later .whilst testing psu all supplies remained stable ,but as you say 2 100w bulbs is not enough load .
in the past i had one of these with bad main board and the test patterns would run happily with the link and feed to main board disconnected .
the va and vs are spot on at 55v and 211v
i have a scope and would like to look at w/f ,
but ive always been afraid of checking around buffer and y sus boards
due to floating ground ,
just as years ago the primary of switch mode psu's was a no go .
im now going to look again at psu vg as you advised and report back if i get a stable test pattern without tripping
if indeed the panel is duff ,at least im learning more
thanks for taking time to reply

[jimbofz]

Re: samsung plasma ps50 c580g1k slow tripping relay

Can you tell which relay is clicking?
If it is RL801S that is turning off it could be that the supply voltage to it is dropping, the relay is supplied D5V3 through QM404 mosfet . This circuit requires a stable Vg voltage (measured across CM419)

NT801S will be warm in standby but does nt801S get hot when the tv is ON running? If it does the relay contacts are likely bad, when the tv turns ON RL801S should short NT801S if it doesn't the tv could act like it is due to the drop in voltage across the thermistor.

2 light bulbs is not enough load so the power supply will run fine. the tv takes much more current.
The lines are likely due to a bad panel, It is possible the buffer ic is bad but unlikely. You would need to scope the signal coming from the buffer is to the panel to be sure.

When you disconnected the main board and jumped the auto_gen pins, you eliminated the main board, the white screen I believe is the first test signal, then black, then the colored rasters.
What are the Vs and Va voltages? The reason it still shuts down is likely due to the power supply.

I had a PN50A450P that had 6 black lines and it was the panel for sure, in fact it started out with just 2 and the next time I turned it on it had another, then another.

i removed the relay covers to see what what, rl802 closes first,then rl801 after 2 seconds ,then 5 seconds later both open
the charge across cm419 is 15.2 v whilst on
the 5.3v drops to 5.18v whilst on
on the z sus the VE volts should be 86v it drops to 72v for the few seconds it is on
qm 404 tests ok,the thermister stays cold ,
its not possible to check in sby as
tv goes to trip mode at switch on ,the power red led will blink faster when you press the remote ,so it is receiving commands but not possible to put in sby ive not got the correct cct diagram but one similar
i wanted to investigate psu futher

[R_J]

Re: samsung plasma ps50 c580g1k slow tripping relay

The power supply should turn on without the main board connected. RL802S is the main relay that turns on the tv. RL801S is there to short out NT801S thermistor.
What is the voltage across CP806 or CP805? It would be around 340vdc in standby then increase to around 380vdc with the tv ON, This will tell you if the PFC circuit is working.

[jimbofz]

Re: samsung plasma ps50 c580g1k slow tripping relay

yep already made sure pfc working fine 390v
in pic 5 the logic board :
to isolate the main board i remove only the flat foil on the far right .
theres 2 green leds the one on the right blinks every second as normal,
then it stops and the left one blinks once this coincides with the two psu relays going open .then the cycle repeats
if i unplug ALL leads to main board the tv wont start at all?
i must be missing something,wish i had correct cct diagram