Toshiba 40E200U1 turn ON but no backlight, no video

[budm]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

I'm agree with you but that's the reading from pin1, thru pin5 = -165v dc

If the DCV readings on pin 1 ~pin 5 of the IC with ref to the negative legs of the main filter cap are showing MINUS 165VDC then it has to be error in reading.
I do not know what else to tell you, I cannot help with wrong Data.
Show us where you put the meter's black probe, it should be on the NAGATIVE leg of the main filter cap as instructed in my post #17.

[Diah]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

please post photo of yours meter, you may have the black probe at wrong place

[CapLeaker]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

+1 on budms comment.

I think the meter is alright, but he measured form GND on the secondary to the negative of the main filter cap.

He should have had the negative lead on the negative pin of the main filter cap and the positive lead on the positive pin on the main filter cap.

Any DC voltage that is measured in the primary section, the NEGATIVE lead of the DMM goes to the NEGATIVE pin of the main filter cap and stays there.

[alfredomfr1]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

Guys look at the pictures

[budm]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

https://www.badcaps.net/forum/attach...7&d=1472849856
OK, I see why now, the power supply uses two filter caps connected in series to form Voltage Doubler circuit to create 320VDC output to run the power supply, so the Black probe has to be on C2 Negative leg.
Sorry for the confusion, I should have spend more times tracing out the connections on the bottom side of the board to see how it is setup.

[alfredomfr1]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

You right budm now pin 1: 0v

[budm]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

OK.
1) TV no power applied, check the resistance between pin 1 and Negative leg of C2 to see if it shows low resistance.
2) I need good clear pictures around the IC to see where pin one is connected to.

This one is not sharp enough to trace out the connections.
https://www.badcaps.net/forum/attach...1&d=1472672662

[alfredomfr1]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

7k

[Diah]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

https://www.badcaps.net/forum/attach...0&d=1472851460
you can see there short contact by soldering U! pin 5-6-7

[alfredomfr1]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

That's a piece of silicon

[budm]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

Isn't that the grey Silicone RTV?

[budm]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

BTW, that pin 1 reading is done with PS-ON signal present, right?
OPTO PC2 looks to be the one used for controlling the Voltage to Vs pin 1.

[Diah]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

never saw before silicon apply on smt ic which placed by robot

[alfredomfr1]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

How can i check pc2?

[budm]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

https://www.badcaps.net/forum/attach...1&d=1472852671

put the two probes of the DCV meter on the two pins (Photo Transistor side) on the right side of the PC2, polarity of the probes do matter since we are looking for the change of the Voltage when PS-ON is not present and when it is present.

[budm]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

https://www.badcaps.net/forum/attach...1&d=1472852671

put the two probes of the DCV meter on the two pins (Photo Transistor side) on the right side of the PC2, polarity of the probes do matter since we are looking for the change of the Voltage when PS-ON is not present and when it is present.

Also check DCV of those two pins against Primary circuit ground (- leg of cap C2).

[budm]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

I need you to zoom out the picture to see what the marked Transistor in the attached photo is used for.
It may be the switched Transistor for supplying the Vs Voltage of the IC.

[alfredomfr1]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

on the right side of pc2 between pin 1 and pin 2: 0.2v with ps-on present
: 0.1v without ps-on
between pin 3 and pin4: 7.1v with ps-on present
: 6.3v without ps-on

[budm]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

Hmm, basically not much action, I will need to see what that transistor in question is for when I see the updated picture.

[alfredomfr1]

Re: Toshiba 40E200U1 turn ON but no backlight, no video

ps-on present
pin1 and c2 : 0v
pin2 and c2 : 0.24v

ps-on not present
pin1 and c2: 0v
pin1 and c2: 0.1v