Can you dignose from the photo ? . Toshiba 65S2650EV

[Ancient1]

So
I measured the combined resistance, and every half turn = 10 ohm, powered up, and every 100ohm I powered off/on .
No Luck
I want to inspect the lousy board... tracks get raised off very easily.

I'm going to buy a new board, unless you have some other idea.

[Storyteller12]

I would buy a new board at this point. 17 pages on here of troubleshooting and still no fix. I would waste this much time on a cheap toshiba TV personally

[nomoresonys]

Originally Posted by storyteller12

i would buy a new board at this point. 17 pages on here of troubleshooting and still no fix. I would waste this much time on a cheap toshiba tv personally

+1000

[Davi.p]

+1000

..and so talked the man of the street with nothing to do...

Ancient: we have focused onto pfc, now try to focuse on main switching, have you tested big mosfets QP2, QP3, capacitor C31 the grey square one?
Have you got a frequency meter? If yes with turn on command try to measure an oscillation on the gates of QP2,QP3 if them ok, black probe on primary gnd..

[nomoresonys]

Originally Posted by Davi.p

..and so talked the man of the street with nothing to do...

AND the reply was BLAH BLAH BLAHBY BLAH AND BLAHBY BLAH. How ya doin ONE of the few? did you catch covid yet?

[Ancient1]

Davi.P
You're The Man

C31 marking : 223J1000V . I measure ~27.5 nF In-Circuit. It looks 25% off since 223J means 22,000.

I checked QP2 QP3 once for shorts - none.
I don't have Oscilloscope but my Meter has Hz mode - is that OK ?
I'll get their PDF

[Ancient1]

Guys, I am learning quite a bit from all of this. I think Davi.P is an amazing guy !

[Davi.p]

ehm... wait.. 223 on a mylar cap means 22000 picoF then 22nF. Yes Hz mode means a frequency meter built in the multimeter (DMM), now i'm suspecting ic3, then everything on the standby aux line, that are ic2, ic3, D10 near ic3

[Davi.p]

if you can, test in diode mode between the pins: 10-11, 11-12, 14-15, 15-16, for shorts..

[Ancient1]

"now i'm suspecting ic3, then everything on the standby aux line, that are ic2, ic3, D10 near ic3" - what do you mean ?
"if you can, test in diode mode between the pins: 10-11, 11-12, 14-15, 15-16, for shorts.." - IC3 ?

I'll get C31 out to measure
What about QP2,QP3 and my DMM Hz Mode

thx

[Davi.p]

1. i am suspecting those components
2. ic3
3. no leave c31 there, it is already measured
4. already said, put black on primary gnd and probe the oscillation in those mostets gate, there must be an around 100khz signal..

[Ancient1]

IC3 pins :
Continuity : all pairs NC
Diode Mode : 0.L one way , other way 0.58, but 12-13 , 13-14 0.L

QP2 QP3 : I measured using IC3 #10 GND ( Black on GND ). I think I don't know how to measure ? ( like probes off and I see Hz ? ) , anyway , I measured all pins, no consistant result, But I saw 1K , 3K, 4K but no 100KHz

[Davi.p]

please read previous posts, i have explained the oscillation test, for the gnd is more safe on - of biggest electrolitics, only 2 steps, short on ps-on input, gate probing, don't probe drain or source, it can ruin your tester.

[Ancient1]

I don't get anywhere near 100k
I will test a good TV PSU as a way of testing my DMM.

[Davi.p]

so only on the gates you probed 1k and so on? The datasheet says operation at 50-500khz, so ic3 feels bad to me.. you ment 1khz not 1kohm right?

[Ancient1]

I do measure Hz . For sure.

on another, GOOD TV board , I got 360K on 1st Mosfet and 0 on the 2nd.
So I assume my DMM is OK

I did the Gate , Hz Mode, measurement again :
QP3 Gate = 1.3K
QP2 Gate = 1.69K .

This time the measurements were stable, for few sec, than 0.000.

[Davi.p]

now i think ic3 is good but it goes into protection, this is possible in many situations, two of them are a not working PFC (possible), a not working U2 optocoupler, if you want to try replace it.. but if bad U2, possible bad TL431 connected to it..
if you want to follow the bad PFC circuit you can probe the gate of the mosfet QF1/QF2 if i see well, with the frequency meter

[Ancient1]

Hi. Better late than never. sorry

I don\t quite understand :
* "not working PFC (possible)" - I put new NCP1653A ( Vcc was ~16V with IC off)

* As I recall , I think we replaced UF1 ... with Q10( A684) connected .
But "if bad U2, possible bad TL431 connected to it" . AZ431 is in Cold Side . What am I supposed to do ?

* "probe the gate of the mosfet QF1/QF2 if i see well" - But I just did that in previous post , no ?

I upload a photo of some tests I PREVIOUSLY made of the Optos

[lotas]

TL431 and AZ431 have different pinouts.
https://www.badcaps.net/forum/showpo...52&postcount=8

[Davi.p]

1. There is always a doubt when buying chips from China, especially of non Chinese brands, how do you have received it, in sealed blister or free in an anonymous bag?
2. Sorry i say TL431 just to intend, the type is the same as AZ431, U2 i point at, not U1.. the test does not reveal a sure good part.
3. I see QF1/2 , it's not clear, you tested QP1/2..