How to run the self test on a plasma display control board / logic board

[tom66]

Why?
A plasma TV is a lot like an LCD TV, in that they usually share main boards and cases. Only the display panel technology is different. Very few LCD TVs come with built in self-tests for the panel. However, most plasma display panels do -- this is because the main display processor (T-con) is almost always running software, instead of being a custom ASIC, and it costs very little -- if anything -- to include a self-test mode.

These tests rule out the plasma panel, sustain boards, power supply, control board and most other parts and are becoming increasingly necessary as

You may/will need:

• a hard-disk drive configuration jumper (0.1" pitch) or piece of wire
• 100 to 470 ohm through-hole resistors (at most 3 typically, the values do not have to match)
• the original remote or one compatible with the TV that is known to be capable of entering service mode
• a soldering iron

How to find the test method
You need to find who made the plasma panel in your model then look below for the methods available. This is on the panel sticker. The panel sticker will be on the back of the plasma panel, and may also mention the Vs, Ve, Va etc voltages which may be used in other repair and diagnostic procedures.

Control board location
The control board location often varies. Some example positions are shown in the images below. The control board always connects to the main board, Y-sustain (Y-main/SC), Z-sustain (X-main/SS), and horizontal buffers. In some cases it also has a connection to the power supply.

Some images shamelessly copied from ShopJimmy.

[tom66]

How to test a Samsung control board

• Turn off the TV (all power disconnected)
• Locate the 4 pin connector block (see below)
• Place a wire or HDD jumper across pins 3-4
• Unplug the LVDS cable (see below)
• Turn on the TV

Note: On some newer Samsung sets there are pads in place of the connector. To do the self test you have to solder a jumper in place.

Control board location
In general the control board is located below the power supply and to the right of the main board. Sometimes the main board is on top of it. In such a case, you will need to remove the main board, apply the jumper, install the main board again then test.

PS42B450


PS42Q97HD


Test locations
PS42B450


PS42Q97HD

[tom66]

How to test a Panasonic plasma D board

If the TV powers up and the panel is primed (glowing slightly), but there is no video, you can verify the D board (on sets using a separate board) using a button sequence on the remote control and TV.

• Power the TV on.
• On the TV, hold the VOL- button.
• Press the numeric zero button three times on the remote in quick succession.
• Wait approximately 10 seconds.
• Press the red button on the remote control twice.
• A pattern should appear. Press red again to cycle through each.
• Then power the TV off.

This does not work with all failures as it requires the A board to process inputs and send the commands for generating the patterns to the D board. However, it can eliminate some failure modes. (Note the A board itself does not generate the patterns; it simply sends the command to generate them to the D board, so this test will work if the A board can't generate video.)

[Ltank]

Is there a test similar to this that can test tcon board s in a LCD TV? What about main board/tcon combination boards. Need to rule out a bad panel or main board?
Thanks
Ltank

[tom66]

For the majority of sets, no. Some newer Samsung LED-LCDs and LCDs with 240Hz processor have separate tests for FRC (motion upconverter/T-con) and main board from service menu, but no access if TV won't power up and menus aren't usable.

[newtothis]

Deleted

[Ashroyer05]

How do we verify the test results after jumping pins 3 and 4?

[Ashroyer05]

Is it to state that the main board is the problem?

[tom66]

Please ask your question in your own thread not here.

[tonyuk]

Originally Posted by tom66

Please ask your question in your own thread not here.

tom can you om me many thanks

[Ashroyer05]

I was asking the question to hopefully get an answer to help people understand what had previously been mentioned. We are or at least should be here to learn from each others experiences.

[tom66]

Originally Posted by Ashroyer05

I was asking the question to hopefully get an answer to help people understand what had previously been mentioned. We are or at least should be here to learn from each others experiences.

But it clutters the thread. This thread is about how to do the self test only. Ask questions relating to this thread elsewhere, please.

[catalin004]

Hy , I have a problem with an Samsung PS42C450B1W Plasma, when I turn it on, I don't have image on screen...it's black, I foun to X-main 2 IGBT transistors bad, and I change them....but doesn't work...I don't have a schematic diagram..
I'm sorry for my English, but I'm from Romania....

[Poor Flick]

catalin004,
You will need to ask your question in the "troubleshooting tv" section.
Those reading it will want all available info of your tv and good pictures.
I'm not much help on tvs, but there are some here that are great at this!
Welcome aboard!

[de_bronzeprince]

hi.. thanks and apologies if I broke protocol...but I do have a question that I cant seem to find the answer to...at the top of this post this sentence.."These tests rule out the plasma panel, sustain boards, power supply, control board..."..what test and where can I find them...and lastly what does the control/logic board test test???and what do the results no how do you interpret the results of the test??? I only ask because I see the test I have even done the test on one tv it went thru the color thing and on another tv...nothing happened...no one states what either result means..apologies opnce more..thanks for your time..

[tom66]

Originally Posted by de_bronzeprince

hi.. thanks and apologies if I broke protocol...but I do have a question that I cant seem to find the answer to...at the top of this post this sentence.."These tests rule out the plasma panel, sustain boards, power supply, control board..."..what test and where can I find them...and lastly what does the control/logic board test test???and what do the results no how do you interpret the results of the test??? I only ask because I see the test I have even done the test on one tv it went thru the color thing and on another tv...nothing happened...no one states what either result means..apologies opnce more..thanks for your time..

The test documented in this thread rules out those parts as being the cause of the fault (the control board can still be faulty but it is very unlikely; everything else is guaranteed to work.) One TV working = main board likely fault. Other TV not = not sure of fault, would require further tests.

[jellentz]

how come i can,t make a threads. jellentz

[flexy123]

Hello, THIS one is related.

Some Samsungs, as far as I know, require that you connect pin PS_ON to GND on the power connector which goes from the SMPS to the main board. (To force the PS on). (Correct me if I am wrong).

I did the self-test of my Samsung logic board as you described, but did not jumper the PS. I disconnected the LVDS, jumpered 3+4 on the logic board, turned the TV on but I got the same garbled screen as with unjumpered logic board.

Since I got a picture, although garbled, can I assume that I didn't need to "force on" the SMPS? (Because I got power, after-all) How do you know that for a proper test of the internal display patterns of the logic board you need to jumper the PS_ON pins..and how do you know you have a model where you don't need to do this?

** Edit: Not not wanting to appear picky, but you might want to add that the purpose of this test is to generate the "internal" test patterns of the logic board and display them, with the main board out of the loop. I am saying this since I was confused at first seeing your thread where your describe how to do the self-test, but did at first not know what is supposed to happen.

[Ltank]

I have a Samsung PN59D6500F that will not self test with the cable between the Control Logic Board and M.B. disconnected.
If the cable stays in place, it will self test just fine.? Normal for this TV or do I have other issues with the Logic , M.B. or both?
Thanks

[DrBWG]

Flexy123, did you ever fix your garbled image?