Z50PJ240 Powers on then back off clicks but no picture

**tw2005** · 10-24-2013, 04:27 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

For all intended purposes the LG 50PJ350 is the same layout, even the mainboard in the Zenith is a LG produced board.

I just so happen to have a complete set of boards stripped from a 50PJ350 if at some point you want to compare something like buffer boards.

I had a FHD 50PK550 which had a shorted out lower buffer which caused it to click on and then off & shutdown straight away.

some manuals if you have not already found these.

Attached Files

**soog35** · 10-24-2013, 05:56 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

I see STBY and RL ON, M ON

Attached Files

**tom66** · 10-24-2013, 06:21 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

Ah OK on this set STBY to M ON and STBY to RL ON

**soog35** · 10-24-2013, 08:15 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

I will have to get some resistors.
When I jump these pins do I disconnect it and jump it on the power board, or disconnect it and jump it on the plug and what am I looking for test test to do?

**soog35** · 10-24-2013, 08:36 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

TW, thanks for the info. I can't seem to view those on my phone right now. Will have to wait til I get home.
How did you find out it was the lower buffer on yours?

**tw2005** · 10-24-2013, 03:17 PM

Re: Z50PJ240 Powers on then back off clicks but no picture

Originally posted by soog35

TW, thanks for the info. I can't seem to view those on my phone right now. Will have to wait til I get home.
How did you find out it was the lower buffer on yours?

Well, it had some help from a cockroach which actually got lodged and literally shorted out the bottom buffer ic, took that board out.

Even if I did not find that, i would have eventually. Just so happens after I found nothing shorted on the ymain, the bottom buffer was removed next.

Bit of luck having visible evidencr in this case.

Whenever I suspect the TV has gone into protect mode I start sniffing around the sustain boards and buffers for short ICs or shorted FETs/Vsus etc.

Don't get me wrong here, I'm just sharing thoughts, I have not seen where they've been checked yet.

It's a habit of mine with plasmas to check these out if it goes to turn on and shuts down.

Bad ctrl boards/ main boards of course could cause similar issues and that's something I've not had to deal with but Tom's an ace with these . Panasonic stuff i prefer to mess with.

Like I said, I have every board if needed for comparison.

Don't let me distract you from what Tom's trying out, I just throw in the little info I find just in case it helps.

**soog35** · 10-25-2013, 05:35 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

I picked up some 100 ohms resisters 1/4v . Does it matter on the voltage? Also when I jump these pins do I disconnect it and jump it on the power board, or disconnect it and jump it on the plug and what am I looking for test test to do?

**tom66** · 10-25-2013, 06:20 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

You mean 1/4W? And no it doesn't matter.
You disconnect the connector from the main board end, and leave it attached to the power board. The main board is the board with the video inputs on it.
With the EXT AUTO GEN jumpered and LVDS disconnected, the set will power up and show test patterns if the main board is the cause of the fault.

**soog35** · 10-25-2013, 07:39 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

Sorry, I did mean watts. Ok I will test tonight and give you the results.

**soog35** · 10-26-2013, 12:50 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

When I did the resistor test, the tv still would not power on and had no test pattern. I even found a nice diagram in the manual that TW sent me and even tried the ground jumper that it shows. So does this rule out the main board and can you tell from that test which board is causing the problem? I do have to say after being unplugged for 2 days it powered on when I first plugged it up it and stayed on for about a couple of minutes, then clicked off and back to the same trouble. That's just like it did when it sat for a week and I put that diode and voltage reg in on the power board. Another thing I noticed that I seemed to hear a quick little pop or crackle sound around the big copper coil on the Y-sus board, when it did power up. Noticed it the other time too. Don't remember hearing that when it was working normal. So I don't know if that tells you anything.

Attached Files

**tom66** · 10-26-2013, 04:56 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

OK, at this point, please leave the resistors connected and check the VS, VA voltages from the power supply. Are they good or bad?

**soog35** · 10-26-2013, 07:15 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

Do i use the test point or just touch a pin and ground?

**tom66** · 10-26-2013, 07:24 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

You place red probe on test point, black probe on ground. Meter on DC volts highest scale (500, 600, 1000V.) Do not use AC scale "~".

**soog35** · 10-26-2013, 09:02 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

When I plug it up and the tv clicks quickly its getting voltage but starts dropping back down to zero. I did this about 10 times and twice the green light powered on the control board stayed on for a minute and the voltage stayed steady 203.6volts on the VS and 59.6 volts on the VA then clicked off the voltage started draining. Also since it stayed on a minute I checked to see if any test pattern was on and it was not. So what does that tell us.

**soog35** · 10-26-2013, 01:10 PM

Re: Z50PJ240 Powers on then back off clicks but no picture

Any idea yet? Don't mean to bug and rush you. Its just that I'm off today and can work on it.

**soog35** · 10-27-2013, 08:21 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

Can anyone tell me from doing the resistor test above, what board my problem is or if I need to try something else? Not sure if Tom has given up on me or just to busy. The help would be greatly appreciated.

**tom66** · 10-27-2013, 08:23 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

Sorry missed your posts completely, but it seems to indicate the power board is bad.

**soog35** · 10-27-2013, 08:37 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

Do you feel like if I replace the power board it would solve the problem?

**tom66** · 10-27-2013, 08:44 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

From the readings shown, yes.
Just to confirm, that is with all boards unplugged from power board, Z- and Y-sustain, main board, control board, etc?

**soog35** · 10-27-2013, 08:52 AM

Re: Z50PJ240 Powers on then back off clicks but no picture

Are you asking if I unplugged everything from the power board when I was testing it? Because I did not have the Z and Y board unplugged.

Z50PJ240 Powers on then back off clicks but no picture

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