no picture on my samsung 50 inch plasma

[jose6326]

Re: no picture on my samsung 50 inch plasma

So how do I test the tv boards

[jose6326]

Re: no picture on my samsung 50 inch plasma

Hey tom66 so what is the step by step process

[tom66]

Re: no picture on my samsung 50 inch plasma

Sorry; missed your posts.

Here is the Y-main output, it is on the lead of the capacitor which is closest to the connector going to the buffer board.

I am going to assume you know NOTHING about a scope; tell me if I am wrong...

On this model you have two channels.

Connect the hook probe to CH1. Set the probe to 10X. Left of CH1 you have a VOLTS/DIV control. Set this to the 10V position (not the 10mV position.) On top of CH1 voltage control you have a VAR knob. Turn this until it clicks, this puts it in the "CAL" position (no significant force should be required.) To the left of the CH1 volts knob, press the CH1 button to turn it on. Below the CH1 volts knob, move the AC/GND/DC selector to the GND setting. Now, set the position knob for CH1 so the trace is in the vertical centre of the display. This position is known as "0V". Each division will be 10V x 10X probe setting = 100V from the ground point, which means the scope can display a waveform +/-400V around ground.

Now, move the AC/DC/GND setting to DC. On the right hand side of the scope, set the TIME/DIV to 5ms and HORIZ DISPLAY to "A".

In the A TRIGGER area, set SOURCE to LINE, and COUPLING to DC. Mode should be AUTO.

Now hook the probe on the previously mentioned and highlighted capacitor, and the black probe on a part of the metal chassis.

Turn the TV on.

Take a picture of what you see.

[jose6326]

Re: no picture on my samsung 50 inch plasma

I know very little about the scope
I haven't used a scope since 2005 when I was in automotive school

But with what you just typed it seems simple enough

[jose6326]

Re: no picture on my samsung 50 inch plasma

Tom the knob will only let me select 5v even though it has 10, 20, 50v but it will not turn any further for some reason

Also when I push the ch1 button should it stay down or up

When the ch1 button is pushed down the 5v is illuminated see pic
When the ch1 button is pushed and stays up the 5v illumination goes off and the green line shows up on the display see pic

[jose6326]

Re: no picture on my samsung 50 inch plasma

Tom I figured out that the ch1 button should be pressed down
And I positioned the trace line to 0v

But I still can not select 10v only 5v

Can I still test it on 5v?

[tom66]

Re: no picture on my samsung 50 inch plasma

You can test for now on 5V. Do you have a horizontal line? CH1 should be depressed, if that switches CH1 on (there may be a label nearby telling you what it should be for ON but it's usually depressed for ON.)

Perhaps there is a 10X button somewhere on the scope which allows the selection of the other ranges.

[jose6326]

Re: no picture on my samsung 50 inch plasma

there is an "X10MAG" button but not sure if this is what you mean.
you can see this button in the center of the scope at the bottom of the display

i went ahead and tested on on 5v yesterday
i followed your step by step process

i took several pics of the waveform when i turned on the tv

please excuse the barefoot in the pics lol

[tom66]

Re: no picture on my samsung 50 inch plasma

Try with X10MAG off?
Also, turn the FOCUS control to make the display sharper (easier with no signal input or GND position.)

[jose6326]

Re: no picture on my samsung 50 inch plasma

i belive the x10mag was off when i tested it yesterday

where is the focus control?

i will do this today when i get home

thanks

[tom66]

Re: no picture on my samsung 50 inch plasma

Focus is directly below the CRT in this photo.
https://www.badcaps.net/forum/attach...7&d=1370456969

[jose6326]

Re: no picture on my samsung 50 inch plasma

ok i should be able to figure it out

but what type of wave form are you looking for when i focus it?

i will take more pictures to make sure i selected everything correctly as you instructed

[tom66]

Re: no picture on my samsung 50 inch plasma

Right now the waveform looks almost right, but it's not quite right... Just need sharper, also perhaps try at 10ms/div for the TIMEBASE?

[jose6326]

Re: no picture on my samsung 50 inch plasma

ok i will do that today when i get home

thanks

[jose6326]

Re: no picture on my samsung 50 inch plasma

Tom I tested the tv at 10ms like you instructed and I focused it as sharp as possible with x10mag off
Here are the pics

Also the tv started to flicker as you can see in the pics
It goes to steady waveform then kind of erratic

Sorry about the angke of the pics I uploaded from my phone
I wish I could upload a video directly to this site

[jose6326]

Re: no picture on my samsung 50 inch plasma

Here are pics with x10mag on

[Clydeuk]

Re: no picture on my samsung 50 inch plasma

Looking at your picture there I notice you say you had .00v at either side of the marked fuse? Can you clarify there is no voltage there (should be VA when the panel is on). If it is 0V with the panel on remove the connector (circled) and check resistance to ground. You can also see if you get the same effect powering up with this connector removed, and test for VA on the wire with it disconnected. Illumination from the panel suggests that the sustains are working to some degree. Missing VA at that connector would give you this problem, as would a CTRL fault as either way there will be no data going to the address lines.

[jose6326]

Re: no picture on my samsung 50 inch plasma

Tom I tested the fuse at both ends with the tv powered on and I got 0v
I tested one end of the fuse with the positive lead and the negative lead to ground and I got 2.7v

I disconnected the connector on the E buffer board as you circled in the pic with the tv powered on and the panel stayed illuminated and I got 54v for Va

While the E buffer was disconnected I mistakenly tested the Vsc test point on the y main and it caused this board to shut down and the panel shut off as well

I got scared for a moment thought I blew something but I didnt I powered off and reconnected the E buffer and everything is back as usual

[tom66]

Re: no picture on my samsung 50 inch plasma

0V either end of Va? I missed that completely.

[jose6326]

Re: no picture on my samsung 50 inch plasma

Which fuse did you want me to test?

I tested the fuse on the E buffer board
The fuse that is located next to the connector that you circled

I put one lead on one end of the fuse and the other lead on the other end of the same fuse with the tv powered on and the voltage reading was 0v
I wasnt sure if that is what you meant for me to test I just did it anyways

It didnt make sense unless im going to actually put my meter in the circuit