Samsung PN51D530A3F - Has Sound, No Picture

[ECU_Techie]

Hello all!

So this is a 51" plasma tv I picked up from some one to try and fix. Thought it would be a good learning experience. I suppose a LCD/LED TV would have been easier to troubleshoot then a plasma! Oh well, diving in head first.

So here is the story, I tested the current on the VS and VA test points on the main power board with the Y-Main board disconnected and the voltages they read are actually double what the sticker reads before they both drop down to around 22 and 12.

The logic board green LED flashes every 5 seconds with it connected to the Y-Main board, but once disconnected it will flash every second, thus telling me there is an issue with the Y-Main board.

With the Y-Main board connected I read around 22V at the VA test point and 0V at the VSCAN test point. The sticker on panel says the VSCAN should be reading -190 I believe.

This is a replacement Y-Main board I just got in the mail. Looks like all caps were replaced and no sign of a bulge in the slightest.

What should I do next to further isolate issue? Thanks in advance!

[ReeceyBurger123]

Re: Samsung PN51D530A3F - Has Sound, No Picture

Hello do you know how to check for short circuits ?

[ECU_Techie]

Re: Samsung PN51D530A3F - Has Sound, No Picture

Maybe, haha. Since I am looking to do this type of repairs for a while, I am going to be buying a capacitor tester and ESR tester for ease of use in testing capacitors out.

From my understanding, with the digital multimeter I currently have, I can only test capacitors out for shorts by unsoldering it out of circuit and running it through Ohmns of 10K or less?

As far as other components on the board, i'm not sure of the exact steps to test them out. Any input on what to do would be great!

[ECU_Techie]

Re: Samsung PN51D530A3F - Has Sound, No Picture

Ok, sorry for not uploading pictures in the first post, but here are pictures of the TV's boards.

From the left: Overall board layout, (Excluding the Y-Buffer which is out for testing.) - The Main Power Board - The Y-Sus Board - The Logic Board - The X-Main Board - The Main Board.

[Moreno83]

Re: Samsung PN51D530A3F - Has Sound, No Picture

You don't really need a capacitor tester to be honest. It's always useful of course but on these boards either the IGBT's or diodes fail or the panel/mainboard fails. Same for other tv's. The older lcd tv's have problems with capacitors , if they are not bulging they most of the time are fine.

[ECU_Techie]

Re: Samsung PN51D530A3F - Has Sound, No Picture

Ok, good info to know! I was looking at buying the Fluke 87V multimeter or would that be overkill for most TV troubleshooting?

Also, on a side note, I tested the two Y-Buffer boards I have, I believe both might be good and not shorted. Upon throwing 200k Ohmns at the test points, I read 150K ohmns on both.

I still am suspecting a fault with the Y-Sus board. Going to return the replacement to the seller and try a different vender.

[ozzy214]

Re: Samsung PN51D530A3F - Has Sound, No Picture

Try power on tv without the buffer hooked up. Just the y sustain and see if your readings aright. Make sure to have y bolted down, but buffer unhooked from it.

[ECU_Techie]

Re: Samsung PN51D530A3F - Has Sound, No Picture

Ok, so I went back to test the Y-Sus board and started with the main power board instead. I actually noticed something I don't think I realized before, the VA test point reads the correct value of 57V on the sticker, but when I go to test the VS point, it will read around 199V for a second and go back to reading just the starting value of 1. The sticker says VS is 207V. This is with the power connector to the Y-Sus board disconnected. As expected, when I test the two VS pins going to the Y-Sus board, I get the same reading. Something shorting out the VS line on main power board?