no picture on my samsung 50 inch plasma

[tom66]

Re: no picture on my samsung 50 inch plasma

Can you check with your black probe on the chassis of the TV, red probe on one end of fuse, then other, and record both readings for us?

[jose6326]

Re: no picture on my samsung 50 inch plasma

Tom66 I was speaking with the electronics guy at my job

He said I put the lead on the wrong ground
That I should of put the negative lead on the ground of the connector not on chasis ground

Is this correct?

[tom66]

Re: no picture on my samsung 50 inch plasma

It may be correct for some systems but for TVs I've always used the chassis ground and that always works for me. You can wire it to the ground of the connector... but you're going to need a length of wire to do so.

[jose6326]

Re: no picture on my samsung 50 inch plasma

Thats exactly what I did

Negative probe on chasis ground and positive probe on one end of fuse with power on and I got 2.7v

I will do it again when I get home and I will take a pic

[tom66]

Re: no picture on my samsung 50 inch plasma

Check both ends.

[jose6326]

Re: no picture on my samsung 50 inch plasma

Tom here is what I did

First 2 pics

Power on
Positive probe on one end of fuse negative probe on chasis ground
Fuse Reading: 4v
Fuse reading: 3.92v

[jose6326]

Re: no picture on my samsung 50 inch plasma

Here are pics with board disconnected

Not sure if I tested it correctly on this one

[jose6326]

Re: no picture on my samsung 50 inch plasma

Tom im not sure if this will help

on pg 3 in the pdf it looks like it is saying to jumper the connector to the logic board or main board to get the test pattern

Am I wrong?

[tom66]

Re: no picture on my samsung 50 inch plasma

You tested correctly, on the first one. But can you please check the connector on the Y-main side too?

[jose6326]

Re: no picture on my samsung 50 inch plasma

Tom I got 54v on the ymain board from the connector that goes to the E buffer

[jose6326]

Re: no picture on my samsung 50 inch plasma

you think it is the E buffer or F buffer board?

[tom66]

Re: no picture on my samsung 50 inch plasma

If you connect Va to the buffer board, does the Va collapse? Measure the Y-main side.
(Don't connect it with power applied to the TV. Allow the TV 10 seconds to discharge before plugging it in.)

[jose6326]

Re: no picture on my samsung 50 inch plasma

what do you mean by collapse?

right now the tv has been unplugged for a whole day or two

you want me to reconnect the connector to the E buffer board
then power on the tv
then test for VA at the connector on the y main board that goes to the E buffer
is this correct?

[tom66]

Re: no picture on my samsung 50 inch plasma

Collapse = drops to the 3~4V measured previously.

What you have said is correct.

[jose6326]

Re: no picture on my samsung 50 inch plasma

do you want me to test Va as the tv is being powered on?
or it does not matter if it has been powered on then i place the probes at the connector?

[tom66]

Re: no picture on my samsung 50 inch plasma

I want you to measure the Va on the Y-main board end with everything connected.

[jose6326]

Re: no picture on my samsung 50 inch plasma

Tom I tested the va at the ymain as you instructed

I could not take a pic of the reading because I needed both hands to probe the connector since I dont have alligator clips

But I took a pic to show you how I tested it
I got 53.8v for va

I also retested the fuse at both ends with negative probe on chasis ground with powrt to tv and this time I got 53.8v on either end of the fuse

The last time I tested it was 4v

Do you know why it is doing this?

[tom66]

Re: no picture on my samsung 50 inch plasma

You might have a dodgy multimeter lead or the fuse connectors may have been corroded. Since you now have good Va, the control board is a likely suspect, but it's hard to be certain.

[jose6326]

Re: no picture on my samsung 50 inch plasma

So is there anything else to test?

I keep forgetting to mention that the y main is buzzing and it tends to get a low buzz and then goes back to the same level buzzing as it started
Is this normal?

[tom66]

Re: no picture on my samsung 50 inch plasma

The scope tests were somewhat inconclusive about Y-main functionality, the waveform did not look quite right.