Power Supply only showing STBY 5V - What could this mean?

[doug35]

I'm a newbie and would like to fix my TV myself.

I get 4.47v from the standby pin. All other pin-outs to the Logic board have 0 voltage.

Could anyone please help me understand what this may mean?

[vinceroger69]

Re: Power Supply only showing STBY 5V - What could this mean?

what is the psu part number (tv make model number) as some psu s you need to force on to test if theres a fault on the main board etc

[doug35]

Re: Power Supply only showing STBY 5V - What could this mean?

PANASONIC TC-P60GT50

POWER SUPPLY MPF6915

Thank you.

[anmol]

Re: Power Supply only showing STBY 5V - What could this mean?

This may help you,
Regards.

[budm]

Re: Power Supply only showing STBY 5V - What could this mean?

BTW, 4.47V for regulated 5V is not right, that is about 10% off. Your meter is good, right?

[doug35]

Re: Power Supply only showing STBY 5V - What could this mean?

That's what I thought.

I ordered a new but used Power Supply from ebay and got the same 4.47v result? I'm thinking the problem is either the Main Board (even though I get no voltage to it?) or the Sub Power Board.

I get a LED 3 blink code.

I wanted to troubleshoot the cause with skilled members here on badcaps before consulting a TV maintenance repair technician.

[vinceroger69]

Re: Power Supply only showing STBY 5V - What could this mean?

Have you got a diffrent multi meter too try just incase yours is reading voltages low you maybe able to check using a new 1.5 battery and maybe a 9v battery too see what reading you get.

[dskall]

Re: Power Supply only showing STBY 5V - What could this mean?

When you push power button do you get any voltages on any pins even briefly?

[doug35]

Re: Power Supply only showing STBY 5V - What could this mean?

Have you got a diffrent multi meter too try just incase yours is reading voltages low you maybe able to check using a new 1.5 battery and maybe a 9v battery too see what reading you get.

No I only have one multi meter and it's brand new. A new 9v battery reads 9.30v.

Cheers.

[doug35]

Re: Power Supply only showing STBY 5V - What could this mean?

When you push power button do you get any voltages on any pins even briefly?

No the power button on the remote doesn't respond at all. Once I switch on the TV at the wall I don't get any brief voltages on any pins.

Cheers.

[vinceroger69]

Re: Power Supply only showing STBY 5V - What could this mean?

Maybe start by uploading some good clear pictures of the boards used in your tv one showing how all the boards are connected up, and then one of each of the boards

[Moreno83]

Re: Power Supply only showing STBY 5V - What could this mean?

5v goes into the mainboard to a small ic ( IC5000 if im correct ) which turns on the 5v STB ON rail and 15V rail. 15V goes back into the power supply and turns on the tv.

You got a bad mainboard , either because of heat or lightning/power surge.

Search for the TNPH0988 1A mainboard and watch out for the suffix sticker , it starts with TXN/....... otherwise you might buy a 50ST50 mainboard. ( Will work ).

[Hombre]

Re: Power Supply only showing STBY 5V - What could this mean?

Did you try to disconnect cable that is going prom P board to A board and then check 5V stand by?

[Moreno83]

Re: Power Supply only showing STBY 5V - What could this mean?

I don't think it is the sub board. Mains go into sub board --> into power supply --> 5V is coming from the power supply and goes into the mainboard and mainboard turns on the led and 5V STB + 15v rail. 15v goes back into the PS and turns the rest of the set on , i had the same problem with my VT50.


Disconnecting the cable from the mainboard won't help because 5V will still be there. Its called EV5V and not STB5V so don't get confused!!
Please look in the service manual on page 30 and search for EV5V. This is the only voltage on the power supply when the mains are plugged in and its on P6 of the white connector.

3 blinks is the 3.3v error which is the mainboard. ( EV5V goes into IC8712 and turns on 3.3v ).

My feeling says its mainboard

[Hombre]

Re: Power Supply only showing STBY 5V - What could this mean?

My point was to disconnect this because he has now 4.4V and he should have 5V, so maybe something on mainboard is causing this voltage drop
I would put my money also on mainboard, but first he has to be sure that PS is functioning properly.

[doug35]

Re: Power Supply only showing STBY 5V - What could this mean?

Search for the TNPH0988 1A mainboard and watch out for the suffix sticker , it starts with TXN/....... otherwise you might buy a 50ST50 mainboard. ( Will work ).

Really appreciate your help Moreno

TNPH0988 1A mainboard seems extremely difficult to find.

I think I should go ahead with TNPH0989 2A mainboard from the 50ST50 as you suggest. Will it work fine without any problems? May you advise me on which mainboard to purchase, I would hate to get the wrong one

http://www.ebay.com/itm/PANASONIC-TX...YAAOSwIWVY~1MK

http://www.ebay.com/itm/Panasonic-TX...gAAOSw-3FZDkmL

http://www.ebay.com/itm/TXN-A1SQUB-T...YAAOSwSlBY17yl

Thanks again.

[Moreno83]

Re: Power Supply only showing STBY 5V - What could this mean?

I know Hombre but my power supply also measures 4.48v , can be resistance issue with some meters.

Im not sure if it will work 100% but the panels are the same. The ST50 board might have less HMDI or USB etc.

Make sure you got the same connectors on the replacement board.
It's best to search for the SUFFIX sticker on the mainboard.

Could you please take a picture of your mainboard? Especially the white sticker , it will say something like TXN/A ....
This because the tuner in the board might be different and your board might not find any cable channels.

So its best to get the exact board!

[doug35]

Re: Power Supply only showing STBY 5V - What could this mean?

could you please take a picture of your mainboard? Especially the white sticker , it will say something like txn/a ....

tnph0988 1a
txn/a1pauavv60

[budm]

Re: Power Supply only showing STBY 5V - What could this mean?

If you look at the diagram STBY5V on pin 6 of the connector P6 is EV5V which goes to connector A6 pin 6 and it is then called STBY5V, so there is nothing to turn on the STBY5V because it IS the 5V standby Voltage which is always present on that pin 6 of P6 which is labeled as STBY5V on the board. Bottom line: STBY5V = EV5V= Always on 5V = It does not have to be turned ON.
F15V, Sound15V and P15V are switched, they also have Low Voltage Protection (LVP) and Over Current Protection (OCP).
Since other command signals on connector P6 are not present from the main board then you have to look at the main board, but you should run the power supply board by itself first to see if the Voltage on connector P6 pin 6 (STBY5V/EV5V) will come up to 5V or not.

[budm]

Re: Power Supply only showing STBY 5V - What could this mean?

If the POWER MICOM on the power supply board does not sense any problem then it should send out STB5V_SW_ON signal on P6/A6 PIN 5 to turn on the switch in side the IC5000 so the STB5V can feed the STB+1.1V and STB+3.3V regulators to produce those two regulated outputs which the main board will need to run.
So you should find out if you do have STB5V_SW_ON signa or not, I expect it to be >2VDC.