urgent help 50pk550-so desperate here

[ramirachamim]

Re: urgent help 50pk550-so desperate here

first kind of transistors(k3667-two pieces) reads 2.014 and 1.975 megaohms
second kind of transistors(fdpf51n25-four pieces) reads 2.32, 2.04, 1.9, 2.32 megaohms

[Alastair E]

Re: urgent help 50pk550-so desperate here

Personally--I never test 'em like that!

Its Extremely Rare, (read Ive never had one in 35 years) that IGBT's/MOSFETS fail by going O/C, ie, 'Wont Turn On'--even if the test applied above indicated its not working--
That would be because that particular IGBT/MOSFET has a high-ish threshold voltage--Above that applied by the test instrument used-- 6V Gate threshold voltage isn't unheard of, but unusual, its more normal in the 2-4V range.

(Threshold Voltage is that required to make the device start to turn on and is quite a variable between parts even of identical type and batch number)

Test-meter/DVM in diode mode usually only outputs 3-5V depending on Make and Model My ancient Beckman its 5V....

(You Could use 9V battery for the test to put 9V on Gate with ref to Source/Emitter while monitoring Emitter/Collector with meter on 'Diode' range)

Test first the middle leg to the Right Leg on lowish ohms ranges. (Can be done with parts still in board--saving Lots of work and removing risks of part/board damage)

Usual failure mode of MOSFETS And IGBT's is by going Short-Circuit or Very Leaky--Practically Never O/C.
--If it passes Low Ohms range test, seeing you have 'em out--Try on Meg-ohm range. Should be around 10-20M, or even 'OL' (O/C)

[ramirachamim]

Re: urgent help 50pk550-so desperate here

Ok alastrir,
From what you wrote i understand that All igbt's and mosfets are probably fine...(will varify according to your reply with 9v battery)
If so, what else can be the problem?
I mean what would be the next step?

[ramirachamim]

Re: urgent help 50pk550-so desperate here

New ysus board on its way...
I will update accordingly

[ramirachamim]

Re: urgent help 50pk550-so desperate here

ok guys,
the new y-sus board has arrived and installed.
unfortunatly-didn't changed a thing
now that we know that the y-sus is not the problem, any further insights please?

[Hamie]

Re: urgent help 50pk550-so desperate here

OK so 2 things.

1.does the new board work?

2. Have you checked vsc and -vy voltages on the new board are they accurate?

[ramirachamim]

Re: urgent help 50pk550-so desperate here

OK so 2 things.

1.does the new board work?

2. Have you checked vsc and -vy voltages on the new board are they accurate?

Dear hamie,
When checking the voltages on y sus, what exatly should be connected to it besides main power plug? Do i disconnect z sus?

[ReeceyBurger123]

Re: urgent help 50pk550-so desperate here

It needs to be plugged in yes, I think your buffer is at fault here tbh. If VSC is low and pulsing on and off the buffer could be shorted too.

[ramirachamim]

Re: urgent help 50pk550-so desperate here

[QUOTE=Hamie;705838]OK so 2 things.

1.does the new board work?

2. Have you checked vsc and -vy voltages on the new board are they accurate?[/QUOTE
hi hamie,

checked the new y-sus board,
when z-sus is disconnected from psu.
the voltages i read in -vs and vsc are according to the label (-190,150) after minor adjustments.
so i guess it means that the new y-sus is OK and it's voltages are accurate now.
which component would be our next suspect?
thanks buddy!

[ramirachamim]

Re: urgent help 50pk550-so desperate here

[QUOTE=ramirachamim;706373]

OK so 2 things.

1.does the new board work?

2. Have you checked vsc and -vy voltages on the new board are they accurate?[/QUOTE
hi hamie,

checked the new y-sus board,
when z-sus is disconnected from psu.
the voltages i read in -vs and vsc are according to the label (-190,150) after minor adjustments.
so i guess it means that the new y-sus is OK and it's voltages are accurate now.
which component would be our next suspect?
thanks buddy!

By the way,
Is there a method to checking if the PANEL is ok?

[ReeceyBurger123]

Re: urgent help 50pk550-so desperate here

Panels almost never ever fail, as Vsc is up does the screen glow in a dark room ?

[Nick's Tvs]

Re: urgent help 50pk550-so desperate here

If the panel was bad, (highly unlikely as ReeceyBurger has mentioned) it would probably short out a few transistors either on your y or Z sustain board. If it was shorted, you would also get a 2 seconds to dark type of symptom on screen. Meaning your panel would glow for 1 maybe 2 seconds and then go dark again. At least that's how the failed samsung plasma panels have been behaving when the panel goes out.

What are the part numbers of your buffer boards. This will be helpful so we can look up pictures and then let you know how to test them.

[ramirachamim]

Re: urgent help 50pk550-so desperate here

Ok guys,
Thank a for you affort.
The screen never glows it is absolutly dark regardless any voltages.
Rare that panels go bad-pretty comforting..
Well the buffer board are divided, one up and one down.
The numbers are
Up or top-eax61307501
Down-eax61307601
Photos can be uploaded if neccesary.
Thank again!

[Nick's Tvs]

Re: urgent help 50pk550-so desperate here

This video is showing how to test a Y-sustain buffer combo for samsung, which obviously we don't have. However the beginning of the video, he shows how to test the IC's on the buffer board portion by using the ground pad on the back side of the IC which no one else does. it is the best way to ensure you are using proper ground for your black pin.
Check your IC's and let us know if you get anything.

[vinceroger69]

Re: urgent help 50pk550-so desperate here

This video is showing how to test a Y-sustain buffer combo for samsung, which obviously we don't have. However the beginning of the video, he shows how to test the IC's on the buffer board portion by using the ground pad on the back side of the IC which no one else does. it is the best way to ensure you are using proper ground for your black pin.
Check your IC's and let us know if you get anything.

No video link?

[ramirachamim]

Re: urgent help 50pk550-so desperate here

Ok guys,
Tested buffers( on continuity 1 lead on floating ground and the second lead racking throw PANEL connectors)
Both didnt beep for short, however lower board buffers did showed a lot of kiloohms resistances unlike the top buffers which were All on megaohms.
Any insights?

[Nick's Tvs]

Re: urgent help 50pk550-so desperate here

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

[ramirachamim]

Re: urgent help 50pk550-so desperate here

Ok guys,
Tested buffers( on continuity 1 lead on floating ground and the second lead racking throw PANEL connectors)
Both didnt beep for short, however lower board buffers did showed a lot of kiloohms resistances unlike the top buffers which were All on megaohms.
Any insights?

guys?

[vinceroger69]

Re: urgent help 50pk550-so desperate here

did you retest them using the above video nick included?

[ramirachamim]

Re: urgent help 50pk550-so desperate here

did you retest them using the above video nick included?

yea i did and still no continuity,HOWEVER:
when looking closely underneath the ic chips, i've noticed that part of the tiny holes there looks as if something might have happend there...
ot was only on the upper buffer, the lower was flawless.
pictures attached,maybe it's worth removing the suspicious ic's heat sinks and see any signs on the top of them?
your opinions please...