Can you dignose from the photo ? . Toshiba 65S2650EV

[Davi.p]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

I made a mistake watching the pins because under side photo is mirrored, so the test become so:
Test in volt on the IC3 pin12 with psu alone.. try also to jumper PS with to gnd and test again IC3 pin12
the red glue doesn't matter..

[Ancient1]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

I am just curious about that red .. paint ?

I can check Pin 12 V with PSU alone, in standby of course. This means the IC gets VCC ( maybe not proper V

than you suggest I short PS pin to GND ? directly or with 1kOhm ? and check #12 again . Like, sounds a bit strange to short PS Pin to GND . Is this is like the ON signal ? because as I understand, if PS is PSU-On line it should get Voltage, not GND

[Davi.p]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

Red thing is glue as i said. Since PS is not gnd with PSU alone then is pull-up-ed by a resistor to 5v somewhere, so no need for resistor..

[Ancient1]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

In both states , #Pin12 ( vs #Pin10 ) I measure ~20mV .
PS Line was shorted with GND Line

[Davi.p]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

in both states you mean with/without jumper on PS pin?
So you know now why the main smps doesn't turn on, both main smps and pfc ic are not fed, now i want you to force its feeding, watch the poor picture below.. i've marked UF1 the turn on command optocoupler, first try to short it's primary side pins, this puts the Q10 base to low (it's probably a PNP) and making primary vcc rail goes to the said 2 ic, then check outputs, if there aren't, check tension on pin 1 of q10, it must be something around 12v-16v, now you can also short pin 1-2 (collector-emitter), check pin12 of ic3 again and check outputs..(12v-led-out)

[Ancient1]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

"in both states you mean with/without jumper on PS pin?" - Yes. of course.

Just a quick note :
I do have ~290V on Main Caps so I think PFC is powered ? and I do have 5.2V on 5VSB.
And ~2V on PS... this is suspicious as I did see previously 1.35V , maybe because Main is not connected.

Backlight LED output is 24V . Mainboard gets 12V. different connectors.

* From what you say , it is obvious that you focus in the Q10 transistor : I will take it out and test it.

[Davi.p]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

i was happier if you did what i had suggested, the pfc is on when you get about 400v on big caps

[Ancient1]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

OK

I want to write what I understand the steps are :

1. Connect Opto.HotSide Pins
2. Check Pin12 on IC3
3. No VCC ? -> Check Q10 Pin1 ( as you marked ) : If 12-16V ? -> Connect Pin1 and Pin2 ( As you marked ) on Q10
4. Do 2. again and Check if Outputs exist ( 12V, 24V)

The only thing unclear is " making primary vcc rail goes to the said 2 ic, " , because the smaller IC is IC2 . I assume you mean VCC Rail goes to Pin12 of IC3

[Davi.p]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

steps are ok, the last question i was meaning that the auxiliary of the standby transformer can provide vcc power to pfc ic and main smps ic (ic2, ic3)

[Ancient1]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

All bad

with Pins 1,2 connected , I get fluctuating ~0.6-2.5 on Pin12 and fluctuating to 1.5 on Q10. High V do not exists , 5VSB and PS are as before but a bit lower and not stable.
I verified continuity after jumpering, and separation to pin #3.
Uff .. TV from Hell

Can I use another PSU to provide 12V and 24V ? might be different GND .. I think I can find a TV PSU board than does provide those and jumpstart it with this PSU.

[Davi.p]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

I guess there is a problem in the standby stage, the output doesn't support the load, changing PSU is not an option as you said, you could lost time in tests, you have only to correct the feedback items, then locate and change the TL431 chip under the heat sink, is type To92 package, near the border of board, if it isn't enough change optocoupler U1

[Ancient1]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

All this is on the boundary of my understanding, since I know very roughly how a PSU works.

I assume by "feedback" ( you have only to correct the feedback items ) you mean the Opto which, being triggered by the PSU-On signal opens Q10 transistor to power IC3.
I see 3 AZ431 Transistors near the heatsink on the Cold Side. But TL431 ?

Is it a Standby PSU issue or signal issue ? because if the Standby PSU isn't working properly than perhaps the area near the small , yellow , coil should be investigated ?

I forgot to upload Q10 photo, so here it is : A684

[Davi.p]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

These are the two that must be changed, AZ431 is the same as TL431, them are IC:

[Ancient1]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

You mean "replace" , yes ? put new of the same

I can test & compare 2 of the AZ431 . How about testing the Mosfets under the big heatsink on the cold side ?

[Davi.p]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

you can compare but it's a bit time consuming, replace them and stop

[Ancient1]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

found : ( each line one board )
AS431 , PC123
431A , NEC 2561A
AZ431 , EL 817
TL431 & KA 431AZ , PC817 & cosmo 1010 PC817

our board :
AZ431 , 817c

[Davi.p]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

i don't understand this message.. i have said to you which one to change..
i have forgot one reply, for change i mean replace..

[Ancient1]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

I have 4 bad PSU boards , and I list what they have.

I assume any 431 and any 817C will be good replacement ?

[Davi.p]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

yes, pc123 and 817 the same

[Ancient1]

Re: Can you dignose from the photo ? . Toshiba 65S2650EV

OK :
Replaced with AS431 , PC123 .
Tested in TV : same as before - Red LED does not go dark . No BL nothing.
BUT
Measured PSU alone :
1. IC3 Pin12 = 9.8V !
2. Q10 : #1 = 13.57 ; #2 = 13.25 ; #3 = 12.6 . ( #Pin as you wrote ).
3. Opto.ColdSide = 1.12V

So you were again correct : replacing on Cold Side made a big change.

Isn't Pin12, Vcc, too much ? Specs say it can take up to 20V