Z50PJ240 Powers on then back off clicks but no picture

[soog35]

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

D304 is the diode that I already replaced. So you have to take them out to check them?

[tw2005]

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

Ok, you got me. Flipped the board over and found the answer. That one sits across 0.26ohm resistor so you'd have to remove it to find out. My leads are about 0.3, reads between 0.5-0.6 on my old fluke.

[tw2005]

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

This power supply of mine is good, I've struck this before on another power board thinking it was bad. Can't read the part number, schematic would be handy.

See if I can find some info.

[tom66]

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

A diode will -never- read shorted if it is working.

[tw2005]

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

D304 is short on mine, I think this is one of those special diodes that measure like this . TVS ?? Tom will know.

[tom66]

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

I don't know much about repairing these, unfortunately.

[soog35]

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

pic

[soog35]

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

I tested it again with the cable unplugged, same results.
I have a few question.
1. Should i just replace the complete board?
2. If i do, some boards I've seen with my part number have 2 or 3 of those white resistors in the right hand corner. Mine has 3, does it matter?
3. Testing all the diodes on the board seem to be all open except for the one I replaced (D304) and one other one. Is that normal or are they all bad?
4. The Q802 transistor on the center heat sink, right above the IC301 voltage reg is where it was popping and a spark when it first clicks on. Could that be the problem?

[tom66]

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

Can you retry with all disconnected, except leave the resistors connected? If it still goes out, then it would appear to be a power board fault.

[soog35]

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.

[tom66]

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]

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]

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]

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.

[soog35]

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]

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.

[tom66]

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]

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]

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]

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.