Can you dignose from the photo ? . Toshiba 65S2650EV

[Ancient1]

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

I already bought new LED Strips set.
I don't want to spend more on a TV with bad Panel ( I hope not), remember ?

Anyway, I found the two 11N60E are strange. While I don't see any short , I can't "turn them on" , like , I get 0.L everywhere , only D-S shows 0.5V ( one way ). Maybe I have replacement, we'll see

[Davi.p]

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

if you are sure all power semiconductors marks ok then try to replace the TL431..

[Ancient1]

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

Tl431 ?

I have a new 19N60E, and it behaves the same as those 2 11N60E , so I assumed they are fine and soldered back.
I put the board back in the TV : Main Caps have just 50V , So it looks like I need to go back to the Mosfets you mentioned before : those under the removed heatsink by the Bridge.

[Davi.p]

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

yes my suspicion was all there, the pfc is broken and is composed by the items: 2 big mosfets and diode, coils, surely ok, and pwm ic. If the mosfet are ko one low ohm resistor connected to them is open

[Ancient1]

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

What is ko mosfet ?
How do I check the IC ?
open resistor = SMD I assume ? I did a quick test , in circuit, and I don't see any open, 0.L, resistor

I upload a photo of both side in one , note that I fliped one photo so that it would be easy to know where is what and under/above what

I really appreciate your continued help ! Merry Christamass and Happy 2022

[Davi.p]

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

Mosfet ko is the opposite of ok, then broken, the resistor i mentioned is on the source of both mosfet (paralleled), maybe tht, maybe multiple smd..

[Davi.p]

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

the ic is not easy to test, needs datasheet but usually is been changed.

[Ancient1]

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

I marked the Source Legs in the image
The problem is I don't see any common resistor ? Each Mosfet has its own Transistor and SMDs

[Davi.p]

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

ok, this design is one that i've never seen, the current sense resistor for the pfc is the big wire resistor, but the tension read is negative unusually, that is why it exploded, one or both mosfet gone short, i don't understand why you don't see a short on them..the mosfets are paralleled like i said..

[Ancient1]

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

220AC . 298VDC on Bridge and same on Main Cap.
I re-soldered the Current Sense Wire/Resistor - I think this was the issue.

But .. : I do have Front LED now, but TV won't start = must be High V missing.
Front Led stays Red - it turned dark when TV worked.

I took some random V readings in the Hot side and saw about 110V ? ( forgot how much exactly ) : where should I measure on to see if Cold side High V area gets the juice ?

[3DIL]

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

At some time I will isolate a part of the tape that comes out of Tcon towards the display of the side that is affected, it will work until today 6 months later

[Ancient1]

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

At some time I will isolate a part of the tape that comes out of Tcon towards the display of the side that is affected, it will work until today 6 months later

We did that. Now we try to power the TV because the PSU blew as I was trying to test the Panel after I RIPPED a side Tab off.

[Davi.p]

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

to properly test the power board you must isolate it and give the on command to turn on pfc circuit and the rest.. then test outputs..

[Ancient1]

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

Of course. I forgot to mention that I did that PS<->5VSB .
Didn't see High V, so I tried in the TV.


I measure , installed PSU ( but also alone), 5.2V on 5VSB and 3.8V on PS i.e looks like this isn't the ON signal , I also measured 0V on 5V and 12V pins.
strange

[Davi.p]

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

need clear photo of entire backside of the board

[Ancient1]

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

Because I assume that I Auto-Started the PSU correctly ( and it didn't work) what worries me is the presence of 3.8V on PS pin/wire.
Did jumpering those pins damage the ON button circuit ..? oh NO !

Both sides in one Hi-Rez photo. I marked with RED to help orient and added the Pin/V of the connector ON TOP of it

[Davi.p]

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

No the jumper can't damage board, locate q14 near the optocoupler, the pin of opto that is connected goes to gnd when PSU is fully on, first connect only PSU then check voltage on the secondary pins of the opto, if there are 2v approximately then command on is lit, otherwise make a jump from the gnd pin of the opto and gnd, for example i think that the q14 pin down-right in photo is gnd, then check outputs..

[Ancient1]

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

Hi

Yesterday I noticed a ball on 1 leg of the Q14 Transistor ( Marked : 1P ), I think the leg might have over heated , since I don't see ANY solder ball elsewhere.
I reflowed and :
I did make a photo of what I did thus far. There is no change before and after Power ON button press ( Front LED remains Red , does not go dark)

What I understand from what you wrote is :
Q14 is on Cold side
Q14 and Opto have one track connecting them, to a Opto Leg
This Leg/Track should be GND with PSU-On signal. and the other Leg should be ~2V ( I see 1.135V regardless of On or Off)
If there is no V on the other Leg than connect the GND Leg to other board GND

I will investigate Q14/Opto GND later ( need to take the board out )

[Davi.p]

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

Sorry, not 2v, 1,2v is correct, so is correctly working the optoisolator, but we do not know if 3v is the correct state for the on command since i do not see a pull up resistor on the PS line.. Can you test on the primary the IC3 pin1? (bigger ic).. try also to pull down PS with a jumper to gnd and test again IC3..

[Ancient1]

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

Hi

This is the White thermal paste trick. the surface is clean but the marking full of paste

I want to understand what you want to do:
"Can you test on the primary the IC3 pin1? (bigger ic).. try also to pull down PS with a jumper to gnd and test again IC3.."

1. Please see the Pin Table: What do you mean by test ?
2. Pull down = connect PS to GND ??? and test what ?

Do you want to see if IC3 is connected with GND ? please explain.

btw - what is the Red stuff at the bottom of the image ?

Thanks