Can you dignose from the photo ? . Toshiba 65S2650EV

[Ancient1]

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

OK
The other PSU , from which I took 1P and Y5 , works fine, fully, including Backlight.
So the Opto line was OK all along.

Ordered 2x IC2 ( to be on the certain side ). Paid extra for est. arrival on 01.Mar .

[Ancient1]

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

Hi . I'm back on track

New IC2 installed.
Vcc ( Pin8) is 16V .
Drv ( Vout , Pin7 ) is 0V !
What Pin should I investigate first

Preparing to power-up , I measured continuity on PS-On (jumpered with 5VSB, the connector ends are not mirror wired , so I needed to avoid not actually auto-starting ) and saw what looks like a short, I just verified again with an old analog DMM that makes a clear noise :
5VSB / PS-On is SHORTED

I found myself trying to discharge the Main Caps while Plugged in, TWICE. Warning sign, I don't feel 100% atm. So I'll avoid electrocution today

P.S I bought 2 ICs. But I don't think the new IC I soldered is defect.

[Davi.p]

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

Hi, i saw new post yesterday but too late to answer, check R37 again, maybe it blew due to lower wattage

Preparing to power-up , I measured continuity on PS-On (jumpered with 5VSB, the connector ends are not mirror wired , so I needed to avoid not actually auto-starting ) and saw what looks like a short, I just verified again with an old analog DMM that makes a clear noise :
5VSB / PS-On is SHORTED

measured continuity of which points? you told only one.. this block is very unclear for me..
which tension you have on bigger caps?

[Ancient1]

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

Hi

R37 is fine : 5.6k in-circuit.
R38 " " . 680k ""

When I found "short" , PS and 5VSB were jumpered. I removed it now.
(When the 2 probes touch : volume is 100)
PS - GND is silent
5VSB - GND : Beeps in a diminishing way : medium beep , 66 , which drops in ~one second to ~15 and stays so.
Measured to the nearby Plated Screw-Hole GND2.

I took new V measurements of the new IC2 : Pin 5 deserves attention.
Nearby tracks are fine. Though this is a low grade board it seems , the tracks layer bulges easily

[Davi.p]

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

Your measurements on ps/5vsb pins shows no errors, please lets focuse on pfc part so ic2, please measure on bigger caps, i recall this is an old photo that you re-edited with right square, in that the measurements are ok, so let's discover if PFC is ok..

[Ancient1]

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

"Your measurements on ps/5vsb pins shows no errors," OK
"please lets focuse on pfc part so ic2," Sure
"please measure on bigger caps," What do you mean "bigger caps" ?
"i recall this is an old photo that you re-edited with right square," YES, Brown is new IC, I added so we can compare.
"in that the measurements are ok," New IC look fine ?
"so let's discover if PFC is ok.." definitely

P.S I took out, previously, all heatsinks and checked the ICs there

[lotas]

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

Check this garland of resistors, the resistance has not changed in them, and where does the second output of the resistor R37 go?

[Davi.p]

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

Bigger caps.. sorry... my english..biggest caps...the electrolitics that levels the pfc out so the ones rated at 450v...
i answer to lotas without watching the photos, R37 as always when connected to CS, goes to a node between the big PFC mosfets and a very low ohm sense resistor/s, that one could be broken,togheter with the mosfets... so good question lotas..

[Ancient1]

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

All resistors measure as printed on them.
R37 connects to the Wire-Resistor . see image

Main Capacitor measure 307V ( I want to measure all 3 , just in case, mehh)

I don't know where to check next, because I don't have a clear image in my mind on how such a PSU work. As I understand, 5VSB part is fine, but the PS-On line does not activate the high V ( 24 12 etc). I assume PFC starts to work from the PS-On line but how ? does Vcc presence mean High V or another pin is needed to turn it On ?

[Davi.p]

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

Vcc on IC2 makes the PFC to start, as i have told PFC mosfets are suspected, you told you've tested it but i insist because since the sense resistor can't burn well , the mosfet can go open with a pleasant hole, the fact that the wire resistor burnt its ends stays there to demonstrate it..

[Ancient1]

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

I'm on it: under the black long heatsink.
But, is it possible to measure the output of this stage instead of the components in it ? If so where ?

What do you think is under the aluminum heatsink ?

I need a simple description , block diagram, not too technical, of such PSU - do you know ?

[Davi.p]

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

i cannot explain on a forum the working method of a power supply complex like this, the output of the pfc is the big cap at 450v, must mark 390v approx, under the heatsink there must be at least 1/2 mosfets and maybe a diode, check them so we can come back home..

[Ancient1]

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

I wanted to attach this to the results message but I see that checking the mosfets is delayed and delayed. so:
I did not ask you to write description yourself of course, because messages are not a methodological scripts, they are composed quickly. I asked if you know of a pdf

and "by the way" , "big cap" here are 3 (long) capacitors that I measure 307V on them.
I think 390V is typical to CCFL or Plasma ? I don't recall seeing such high V (390) on LED TVs.

[vinceroger69]

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

390v is correct when pfc is working correctly on led tvs

[lotas]

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

To do this, they put power capacitors at 450v so that they have a voltage margin = 380-400v. (PFC operation).

[Davi.p]

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

Sorry Ancient, your last message is unclear to me, this evening i try to read it by new..
i can't post you a text guide because it is in Italian..

[lotas]

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

Maybe something will help to figure it out (without the denominations of the components).

[Davi.p]

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

what about checking mosfets/diodes? Aren't you able? diode must not show 0v in diode mode both ways, mosfet the same but in 6 ways.. especially D-S

[Ancient1]

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

I got the heatsink out and will check later. I will make a detailed result for double-check.

with regard to the other part : I did not ask you to write anything. A course in PSU design has different sections/levels. from electrons to broadest level like tracks length maybe etc.
When you said the PFC Mosfets must be faulty, you use a level of this course that describes the purpose and reason for every sub-section of the PSU. Black box logic like : the TV On button shorts the only V available - Standby V - and this signals the CPU to direct it to the PSU-ON pin/wire and this turns on the PSU, check if the button is dirty and so does not send its signal out. If I know this for PSU, than I can troubleshoot better. Many words on a simple thing really The problem is that if you google you get confusing results , like the PDF Lotas posted ( maladyetz. nyet, ya nye panimayet ruski ).

[Davi.p]

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

My limited language prevents me to catch the core of your discussion, i can only give you some few clues on the specific part, i am also writing wih cellular and you don't even know how many times i correct errors.. the pfc is a dc dc switching converter with boosted output, the reason of why this is not important for you, after this there are two flyback switching psu, one for standby, one for main, since the wire resistor blew , too much current flowed into it, that one came from the mosfets that are in parallel and short circuits the big tension 320v to gnd briefly, this to "charge" the big inductor..