no picture on my samsung 50 inch plasma

[jose6326]

Re: no picture on my samsung 50 inch plasma

I still have the scope

I can retest and take pics if you want

[tom66]

Re: no picture on my samsung 50 inch plasma

Can you repeat the Y-main test? Except this time also turn the intensity/brightness thing down, as that will make the image sharper.

[jose6326]

Re: no picture on my samsung 50 inch plasma

Tom please look at pics
Im not sure if I set the time/div in the correct position

The dial has a tab and 2 black hash marks
Is the 5ms supposed to be in between the hash marks or is the tab supposed to be over the 5ms?

[jose6326]

Re: no picture on my samsung 50 inch plasma

I went ahead and tested it with the 5ms in between the hash marks

Please see pics

[jose6326]

Re: no picture on my samsung 50 inch plasma

Here is the test with the tab over the 5ms

[tom66]

Re: no picture on my samsung 50 inch plasma

The waveform looks OK except it looks to be like the SUSTAIN portion is missing! I am not sure why... A missing SUSTAIN portion will cause no image. Can you go over to testing the X-main?

[jose6326]

Re: no picture on my samsung 50 inch plasma

how do i test the xmain?

[tom66]

Re: no picture on my samsung 50 inch plasma

Here -- I think end nearest the connector.

[jose6326]

Re: no picture on my samsung 50 inch plasma

Hey tom I been really busy and haven't had a chance of testing my tv

I will get to it tonite or tomorrow

Hopefully you haven't given up on helping me

Thanks

[jose6326]

Re: no picture on my samsung 50 inch plasma

Hey tom I want to give it another shot at this problem child of a tv lol

I put the test lead on the xmain and this is what I got

[capkid]

Re: no picture on my samsung 50 inch plasma

I don't want to derail you from your testing, but can you post the current panel voltage readings?

[jose6326]

Re: no picture on my samsung 50 inch plasma

Vs 205.1
Va 54.1
Vsc -195.2
Ve 72.5

[capkid]

Re: no picture on my samsung 50 inch plasma

I haven't read the whole thread thoroughly, but the service tips point to a bad X-main (see page 3):

http://www.toms-service-manuals.com/...&Search=Submit

If Ve is low or missing and Vs is OK, the failure is with the X-Board since the Ve is generated by the X-Board from the Vs supplied by the SMPS. Please note in some rare cases the Ve may be generated by the Y-Board feed to the X-Board.)

I'd remove the X-main from the TV to see if you can locate a bad component. Check the heat sink components first. I'd be careful with this TV, since the Y-main and X-main are chained; you risk damaging your Y-main.

[jose6326]

Re: no picture on my samsung 50 inch plasma

I actually replaced the xmain and buffer

I still have the original one

[capkid]

Re: no picture on my samsung 50 inch plasma

Ok. I saw a mention of the X-main, but I wasn't sure if you'd gone ahead with a purchase: https://www.badcaps.net/forum/showpo...8&postcount=25

Was that the last thing you changed in the TV?

[jose6326]

Re: no picture on my samsung 50 inch plasma

The xmain was the last thing I changed
Before that I changed the psu, the ymain ,y buffer, and logic board in that order

[capkid]

Re: no picture on my samsung 50 inch plasma

Strange. One thing I didn't get about that last sentence from the service guide, and maybe Tom can shed some light, is that it says that Ve is generated by the Y-main feed to the X-main in some rare cases. Since many of these Samsungs have the Y-main and X-chained without a connection from the PSU to the X-main, I don't understand why this is rare.

If Ve is low or missing and Vs is OK, the failure is with the X-Board since the Ve is generated by the X-Board from the Vs supplied by the SMPS. Please note in some rare cases the Ve may be generated by the Y-Board feed to the X-Board.

[jose6326]

Re: no picture on my samsung 50 inch plasma

The only thing i havent changed is the main board and the e and f buffers

[jose6326]

Re: no picture on my samsung 50 inch plasma

i might just order the main board
but i will test the mosfets on the heat sink first on the xmain

[jose6326]

Re: no picture on my samsung 50 inch plasma

Strange. One thing I didn't get about that last sentence from the service guide, and maybe Tom can shed some light, is that it says that Ve is generated by the Y-main feed to the X-main in some rare cases. Since many of these Samsungs have the Y-main and X-chained without a connection from the PSU to the X-main, I don't understand why this is rare.

If Ve is low or missing and Vs is OK, the failure is with the X-Board since the Ve is generated by the X-Board from the Vs supplied by the SMPS. Please note in some rare cases the Ve may be generated by the Y-Board feed to the X-Board.

So does that mean there might be something wrong with the y board if it is feeding Ve to x board?
Im just throwing stuff out there