Panasonic Plasma TV LED blinking 12 times

[tw2005]

Re: Panasonic Plasma TV LED blinking 12 times

No real idea, just wild guesses. Is there 15V at pin 8 of MC701 . Micro fuse IP351 on the underside, ?

[PaulF]

Re: Panasonic Plasma TV LED blinking 12 times

Typo: Should have been 15v at D and no 15v at S

[PaulF]

Re: Panasonic Plasma TV LED blinking 12 times

TP2302 does indeed go high to flag the SOS.
I nonitored the G-S voltage of mosfet Q351 with a scope, this never rose above a fraction of a volt during switch on & just looked like noise. This obviousy isn't sufficient to turn the device on hence 15v at D and no 15v at D.
I then monitored pin 4 of MC351 which is marked 15V_ON, which i assume is the signal to turn Q351 on, this remained constantly 0. This in turn comes from MC701.
I am probably at the point now where I am beginning to condider that I'll have to replace the power board, unless anyone has any suggestions.

[tw2005]

Re: Panasonic Plasma TV LED blinking 12 times

Doh,
Sorry, will have to get some glasses. even when I saw it in your message I read it as 5 instead of S. Good job there is someone around to put me right.

I stopped short of suggesting that, all I know is once you have them , they never seem strong enough.

Don't worry, someone else would have pointed it out. The fact 2 of us posted 2SK2510, you had me wondering especially with the , can't find the datasheet comment.

[PaulF]

Re: Panasonic Plasma TV LED blinking 12 times

Doh,
Sorry, will have to get some glasses. even when I saw it in your message I read it as 5 instead of S. Good job there is someone around to put me right.

[tw2005]

Re: Panasonic Plasma TV LED blinking 12 times

The voltage increases gradually over a couple of seconds and reaches a max of 1.56v which is steady for probably about a second then shuts off. Will do the test again and take better note of what happens. tw2005 I agree with what you are saying, I'll check out Q2301.
I did identify the FET as 25K2510, I just can't seem to find a data sheet for it to see it's spec in case it is faulty and need to find an equivalent.
Thanks for the help guys.

if you keep typing 25K2510 when it's 2SK2510, you won't. i get a page full of hits, the first being a spec sheet.

One would think if it takes 2 secs to get to 1.56v, holds for a sec then shutdown, PSU fault is looking likely.

Did a quick search here for equivalents http://alltransistors.com/mosfet/crs...024&caps=MP45F

2SK2498, 2SK2512

Type Designator: 2SK2510

Type of 2SK2510 transistor: MOSFET

Type of control channel: N -Channel

Maximum power dissipation (Pd), W: 35

Maximum drain-source voltage |Uds|, V: 60

Maximum drain current |Id|, A: 40

Maximum junction temperature (Tj), °C: 150

Maximum drain-source on-state resistance (Rds), Ohm: 0.024

Package: MP45F

[PaulF]

Re: Panasonic Plasma TV LED blinking 12 times

The voltage increases gradually over a couple of seconds and reaches a max of 1.56v which is steady for probably about a second then shuts off. Will do the test again and take better note of what happens. tw2005 I agree with what you are saying, I'll check out Q2301.
I did identify the FET as 25K2510, I just can't seem to find a data sheet for it to see it's spec in case it is faulty and need to find an equivalent.
Thanks for the help guys.

[tw2005]

Re: Panasonic Plasma TV LED blinking 12 times

Further tests show that I have 15v at TP7 which is upstream of Q351 FET which appears to switch the 15v to P6 pins 1-4. I plan to investigate further at the weekend when I can borrow a probe from work which is small enough to get onto the gate to see if the gate drive is ok.
I have not yet been able to identify the FET from it's number NEC 25K2510.

Don't forget you have the SM. As per Tom's response. Q351 search in the PDF gives you 2SK2510.

There's actually a lot of true part numbers in there unlike the later manuals where they get Panasonic coded numbers which are meaningless most of the time.

[tw2005]

Re: Panasonic Plasma TV LED blinking 12 times

[tom66]

Re: Panasonic Plasma TV LED blinking 12 times

(error on my part, please ignore)

[tw2005]

Re: Panasonic Plasma TV LED blinking 12 times

I was wonder looking at the diagrams, looks like this PSU has those modules (MC351)similar to that in the 46PZ800 and others which had 2 & 10 blink issues generally due to a bad ceramic cap on the module?

I believe they were loss of 15V related too.

Edit: but then you did say you have 15V, keep digging, hope you find the culprit.

[tw2005]

Re: Panasonic Plasma TV LED blinking 12 times

I've done the tests as you suggested and at H3 pins 21-23 & P6 pins 2-4 the voltage only rises to 1.56v max before it is tripped off. Looks like it could be the +15v from the P board? I assume this voltaage is reference to the chassis ground?

Maybe, how long after the 1.56 does it shutdown? Is it a steady 1.56 or rising when it kills.

The other thing I'm looking at is Q2301 and test point TP2301, I suspect gose high on the SOS.

I guess what we really need is either to figure a way to test the voltages from the PSU as if the TV was running or I'm thinking if TP2301 if it's high on the trip, earthing that out and see if the TV powers up with no blinks.

Then recheck the voltage.

There's probably a more correct way, is there anything in the other post that helps.

Both H boards are doing the same assuming both are good suggesting the problem is elsewhere.

I don't want to say it's the PSU unless it's proven the 15V_S can't be generated.

[tom66]

Re: Panasonic Plasma TV LED blinking 12 times

Try 2SK2510.

[PaulF]

Re: Panasonic Plasma TV LED blinking 12 times

Further tests show that I have 15v at TP7 which is upstream of Q351 FET which appears to switch the 15v to P6 pins 1-4. I plan to investigate further at the weekend when I can borrow a probe from work which is small enough to get onto the gate to see if the gate drive is ok.
I have not yet been able to identify the FET from it's number NEC 25K2510.

[PaulF]

Re: Panasonic Plasma TV LED blinking 12 times

I've done the tests as you suggested and at H3 pins 21-23 & P6 pins 2-4 the voltage only rises to 1.56v max before it is tripped off. Looks like it could be the +15v from the P board? I assume this voltaage is reference to the chassis ground?

[PaulF]

Re: Panasonic Plasma TV LED blinking 12 times

Thanks for the reply, yes you are absolutely right about the boards. I'll do the checks you suggested and hope I can trace the board where the fault is. Thanks for the link to the manual, it's a great help, was trying to use a manual for a similar set but had an A board instead of the H & DG boards which is why I replaced them both.
If it's the P board I can get a replacement but want to be sure before I go ahead, looks like I've already replaced 2 unnecessarily.
Thanks again for taking the trouble to help.

[tw2005]

Re: Panasonic Plasma TV LED blinking 12 times

I've just replaced the A board (2 boards to be exact TNPA4177 and TNPA4226) and the problem is still the same, ie 12 blinks. Any ideas where the problem can be now?

So there is no A-board, but DG(TNPA4226), H (TNPA4177), D (TNPA4133), PA(TNPA4178).

Maybe download the service manual

See if you can check +15V_S is going to the H board at H3 pins 21-23, delivered from PSU P6 pins 2-4 via PA board, in PA6, out PA3 , in H3

H board IC2301 needs Sound15V, Sound12V. Sound12V is generated from the Sound15V(+15V_S) by the voltage regulator IC2303.

It appears IC2301 generates the SOS, and a high is operate, a low is SOS so i guess if there was no 15V that would mean a low from that and trip the SOS12.

I've got no experience with this generation so I'm just going by the schematic since there's no mention of any voltage checks.

It may be the case that you will have to hook up the probes first and then power on to detect the 15V because I expect SOS12 will kill the 15V when tripped.

There was another post for similar problem with no result unfortunately.

https://www.badcaps.net/forum/showth...hlight=50PX70B

Manual shows P or H board as first checkpoints in the blink chart.

[PaulF]

Re: Panasonic Plasma TV LED blinking 12 times

I've just replaced the A board (2 boards to be exact TNPA4177 and TNPA4226) and the problem is still the same, ie 12 blinks. Any ideas where the problem can be now?

[EIEIO]

Re: Panasonic Plasma TV LED blinking 12 times

TW2005,

You are correct that the part number is TXN/A1EFUUS and the board number is TNPH07861A. There is no suffix that I can tell. Pictures are attached of the board numbers I find and the panel info.

[tw2005]

Re: Panasonic Plasma TV LED blinking 12 times

I'd stick to

TXN/A1EFUUS or TNPH0786 no suffix. There's a matrix on the PCB above the TNPH0786 number. The suffix is determined by the placement of 5 jumpers above that table which you decode looking at the dots labelled in the matrix.

SJ says yours has no suffix which I suspect means there'll be no jumpers.

The AF is a 46" panel.
42U1, version AE I suspect would work however A30 is missing for the fans.
So it should work as they have the same panel, you won't have fans running.

That's what I see at a glance.