Toshiba 22EL833G with Vestel 17PW05-3

[Gogan]

Hi everyone

After years of lurking its my time to come for help

Got a Toshiba 22EL833G with Vestel 17PW05-3 PSU - TV powers on, sound OK, no picture or backlight.

With PSU disconnected - humming/pitching sound on transformer

PL706
Pin 1 - 20.8/22.5
Pin 3 - 0V
Pin 4 - 0V

PL703
Pin 7 - 11.25V
Pin 9 - 5V
Pin 11 - 5.5V

With PSU connected to other boards, on boot - horrible pitching/screaming sound on transformer

PL706
Pin 1 - 20.8/22.5
Pin 3 - 0V
Pin 4 - 3.3V

PL703
Pin 7 - 11.25V
Pin 9 - 5V
Pin 11 - 5.5V


With PSU connected to other boards, ON state - transformer silent

PL706
Pin 1 - 5.5-9V
Pin 3 - 3.1V
Pin 4 - 2.2V

PL703
Pin 7 - 11.25V
Pin 9 - 5V
Pin 11 - 5.5V

C371 - 11.25V
C735 - 29.6V


No visible damaged on boards besides transformer pins (see picture)

No shorts found between transformer coils/ferrite, no shorts found on diodes, transistors or capacitors

Small differences from PSU schematics:
IC700 not ICE3BR1765J but ICE3BR10665J
D715 not present
D712 and D713 not UF5402 but SB5100
C734 not present

I'm missing the obvious or could it something else?

[Andrew F. Ali]

Re: Toshiba 22EL833G with Vestel 17PW05-3

Seems like you have a HV Transformer short and/or bad CCFL causing this problem.

[Gogan]

Re: Toshiba 22EL833G with Vestel 17PW05-3

Seems like you have a HV Transformer short and/or bad CCFL causing this problem.

The obvious them. Ordered a new transformer, will update when it arrives

[Andrew F. Ali]

Re: Toshiba 22EL833G with Vestel 17PW05-3

How did you test the transformers before ordering?

[R_J]

Re: Toshiba 22EL833G with Vestel 17PW05-3

This seems to be an led backlight tv, I think you have a open led in the panel
PL706 has lines like PWM_DIM and BL_ON/OFF which tells me it is controlling another board

Is this what the WHOLE back of the tv looks like? If it does I believe there is a led driver board under the tin.

[Gogan]

Re: Toshiba 22EL833G with Vestel 17PW05-3

How did you test the transformers before ordering?

I guess it was a precipitated leap of faith

How can I do it?

[Gogan]

Re: Toshiba 22EL833G with Vestel 17PW05-3

This seems to be an led backlight tv, I think you have a open led in the panel
PL706 has lines like PWM_DIM and BL_ON/OFF which tells me it is controlling another board

Is this what the WHOLE back of the tv looks like? If it does I believe there is a led driver board under the tin.

Yes it is. Will post a picture of the whole back with cover of asap

The PSU noise, disconnected. It's not "normal" is it?
Also 24V and 12V seem a bit off. 23.25V and 11.25V reading (PSU disconnected)

[Gogan]

Re: Toshiba 22EL833G with Vestel 17PW05-3

This seems to be an led backlight tv, I think you have a open led in the panel
PL706 has lines like PWM_DIM and BL_ON/OFF which tells me it is controlling another board

Is this what the WHOLE back of the tv looks like? If it does I believe there is a led driver board under the tin.

Here they are

[Andrew F. Ali]

Re: Toshiba 22EL833G with Vestel 17PW05-3

So this is a LED TV after all. I was expecting to see pictures of the Main Bd and PSU on the TV also. I was thinking HV Transformer that supplies the CCFLs. Guess I guessed wrong. Those voltages, though not spot on to what the legend says, are good. Look for cracks in the soldering especially the Transformer legs. Test the ESR of those e-caps. Tighten the boards hold-down screws.

[ducky29]

Re: Toshiba 22EL833G with Vestel 17PW05-3

Test the ESR of those e-caps. Tighten the boards hold-down screws.

Sorry to hijack the thread but I wanna ask you what tool do you use to test the ESR of the caps. I used those T-4 (6$ on aliexpress) but they usually fail after some time.

[Gogan]

Re: Toshiba 22EL833G with Vestel 17PW05-3

So this is a LED TV after all. I was expecting to see pictures of the Main Bd and PSU on the TV also. I was thinking HV Transformer that supplies the CCFLs. Guess I guessed wrong. Those voltages, though not spot on to what the legend says, are good. Look for cracks in the soldering especially the Transformer legs. Test the ESR of those e-caps. Tighten the boards hold-down screws.

Tested all ecaps ESR, all seems good, replaced anyway

The C375 24v rising to 29v when PSU is connected and PL706 Pin1 dropping from 22V bellow 9V seems good?

[R_J]

Re: Toshiba 22EL833G with Vestel 17PW05-3

Check F401 on that top board, It might be open (2.5A/63V) Looks like thats what supplies the 24 volts to the led driver, That would also explain why 24 volts is a bit high, no current being drawn.

[Gogan]

Re: Toshiba 22EL833G with Vestel 17PW05-3

Check F401 on that top board, It might be open (2.5A/63V) Looks like thats what supplies the 24 volts to the led driver, That would also explain why 24 volts is a bit high, no current being drawn.

Fuse is good. Can't find any shorts on transistors, diodes and capacitors either

[R_J]

Re: Toshiba 22EL833G with Vestel 17PW05-3

Have you ever tried shining a flashlight or other light at the screen to see if there is any video on the screen? you may need to press the menu to get something, It does seem like there are no backlights and you do have the BL_ON signal on PL706(3) I would check the voltages on the pins for the backlight leds, CN402, (the thin white cable)

Did you also check F1 (2A/32v) on that board? that fuse supplies voltage to the t-con part of that board.
Here is the panel pdf

[Gogan]

Re: Toshiba 22EL833G with Vestel 17PW05-3

Have you ever tried shining a flashlight or other light at the screen to see if there is any video on the screen? you may need to press the menu to get something, It does seem like there are no backlights and you do have the BL_ON signal on PL706(3) I would check the voltages on the pins for the backlight leds, CN402, (the thin white cable)

Did you also check F1 (2A/32v) on that board? that fuse supplies voltage to the t-con part of that board.
Here is the panel pdf

Yes, flashed a light, can't see anything

CN402
CH1 - 3.5/4.5V
COM - 5/7V (?)
CH2 - 2.5/4V
CH3 - 2.5/4V
CH4 - 3.5/4V

PL706 Pin 1 - 5.5/9V coming from PSU shoudn't be 12-24V?

Fuse F01 is OK

[R_J]

Re: Toshiba 22EL833G with Vestel 17PW05-3

Pl706 pin1 should be 24 volts, I would not suspect the backlight inverter on the panel to be loading it down as F401 would likely have blown. You can disconnect CN401 to see if the 24 volts comes up when the tv is turned on.
It could be the power supply can't supply the current on the 24 volt line.

Usually it is one of the diodes for the 24 volts that shorts on these power supplies

Does the 12 volts on L702 stay up?
Does the 24 volts appear at D712/13? if it does see if those resistors R781/782 are used and if they are that they are ok.
+12 & +24 are from the same transformer so if one drops the other should also drop.
Have you removed the power supply and checked the connections on the transformer, Can you provide a clear picture of the bottom of the power supply board so we can see the traces.


I hate these type of schematics

[Gogan]

Re: Toshiba 22EL833G with Vestel 17PW05-3

Pl706 pin1 should be 24 volts, I would not suspect the backlight inverter on the panel to be loading it down as F401 would likely have blown. You can disconnect CN401 to see if the 24 volts comes up when the tv is turned on.
It could be the power supply can't supply the current on the 24 volt line.

Usually it is one of the diodes for the 24 volts that shorts on these power supplies

Does the 12 volts on L702 stay up?
Does the 24 volts appear at D712/13? if it does see if those resistors R781/782 are used and if they are that they are ok.
+12 & +24 are from the same transformer so if one drops the other should also drop.
Have you removed the power supply and checked the connections on the transformer, Can you provide a clear picture of the bottom of the power supply board so we can see the traces.


I hate these type of schematics

Hi

Got a few updates

- Image is displayed, no backlight

- Horrible noise on PSU was solved with the new transformer, don't now if it was related to the problem or how long its been that way (TV's from my in-law).

- If PSU is disconnected from from TCON (CN401) 24V stays up

- If PSU is connected to TCON (CN401), with backlight (CN402) connected or not, 24V drops.

From what I understand BD9261EFV (U401) is a safety chip, if it detects a problem in one of the 4 led arrays it enters safe mode, dropping the 24V, correct?

[R_J]

Re: Toshiba 22EL833G with Vestel 17PW05-3

That circuit takes the 24 volts and then boosts it to provide a higher voltage to light the led's. If it detects a problem, the boosted voltage will drop back to 24 volts. At no time would it just short the 24 volts, Check that the fet Q401 and the diode D401 are ok and not shorted, BUT if there was a short the fuse f401 would open. It looks like the power supply can not supply a solid 24 volts.
If you check the +24 volts right at the cathode of the diodes on the power supply does it drop also?

[budm]

Re: Toshiba 22EL833G with Vestel 17PW05-3

So how low does the 24V power supply drop down to?

[R_J]

Re: Toshiba 22EL833G with Vestel 17PW05-3

budm, in post #1 he measured 5.5 - 9v on PL706(1) which should be the +24v line