Vestel 17PW26-4 V.1

[rafa805]

Hi all, so I had a friend who gave me a bad TV that is using this Vestel PS, and the TV is stuck at stand by, will not power.
I took it a part and immediately saw a few bad capacitors, I replaced them all right away but no change.
I've checked my output voltages, and the problem is 12V and 24V are 0, so i basically only have 5V and 3.3V.
I've looked around in the forum for similar problems and checked everything I read that could be the issue but couldn't find anything.
I've looked for shorts around the PFC controller chip, nothing there that I could find.
All the diodes are ok, I couldn't find any shorts, so now I really don't know what else to check. To be honest I love electronics but unfortunately my troubleshooting skills need to be perfected and that's what I'm looking for, hope someone can help do just that.

Thank you.

[arizanotlari]

Re: Vestel 17PW26-4 V.1

Hi.
what is mainboard name?

[rafa805]

Re: Vestel 17PW26-4 V.1

Hi.
what is mainboard name?

It's a Vestel 17MB36-2 (020309)

[arizanotlari]

Re: Vestel 17PW26-4 V.1

in standby mode, chassis activated only 5V and 3V3. try turn-on set via rc or local keys.
if led not blinking or other voltages (12V&24V) not regulated, rewrite SPI.
If led blinking or other voltages regulated but cut off suddenly, check capacitors of U121 U144. There may also be a short circuit on the chassis

Diagram : https://yadi.sk/i/dCNi9uSatOpTCA

[rafa805]

Re: Vestel 17PW26-4 V.1

in standby mode, chassis activated only 5V and 3V3. try turn-on set via rc or local keys.
if led not blinking or other voltages (12V&24V) not regulated, rewrite SPI.
If led blinking or other voltages regulated but cut off suddenly, check capacitors of U121 U144. There may also be a short circuit on the chassis

Diagram : https://yadi.sk/i/dCNi9uSatOpTCA

According to what you're saying I should now rewrite the SPI, the problem is I do not know what that is and I don't know how to do that, can you elaborate please?

[budm]

Re: Vestel 17PW26-4 V.1

Can we see good clear straight shots pictures of the boards so we can see what we are dealing with?

What is the power supply board number?

[SMDFlea]

Re: Vestel 17PW26-4 V.1

vestel_17pw26-4 not sure if its the right one .

[rafa805]

Re: Vestel 17PW26-4 V.1

Can we see good clear straight shots pictures of the boards so we can see what we are dealing with?

What is the power supply board number?

Sure, here they are.

[rafa805]

Re: Vestel 17PW26-4 V.1

Does anyone have any ideas?

[dick_barton]

Re: Vestel 17PW26-4 V.1

With the mainboard disconnected from power supply jumper ST_BY to +5V using a 1K resistor. Then check for +12V & +24V.

[budm]

Re: Vestel 17PW26-4 V.1

If the schematic in post #7 is matched to this power supply board, the ST_BY (PS-ON) is active low, so if you run the power supply board by itself without any pull-up resistors, all the switched power supplies output should be present.

[rafa805]

Re: Vestel 17PW26-4 V.1

With the mainboard disconnected from power supply jumper ST_BY to +5V using a 1K resistor. Then check for +12V & +24V.

Well I can tell you that doing this in pins 11 and 12 I get 12.1V and in pin 26 I get 24.5V. what does this tell us? Main board issue?

[dick_barton]

Re: Vestel 17PW26-4 V.1

So it looks like your power supply is working.

[budm]

Re: Vestel 17PW26-4 V.1

Well I can tell you that doing this in pins 11 and 12 I get 12.1V and in pin 26 I get 24.5V. what does this tell us? Main board issue?

If that is the case, then the switched power supplies section are working, but the schematic does not match your board.
If you have all the board connected back together, what DCV do yo have on the ST-BY (PS-ON) pin when TV is off and when TV is turned on?

[rafa805]

Re: Vestel 17PW26-4 V.1

Let me rectify that. Those values where when I plugged the resistor between ST_BY and GND. Now I did it again but this time like you said the second time, between ST_BY and +5V and now I get 22.47 on pin 26, and on pins 11 and 12 it keeps changing constantly from 0 to around 5/6 volts, it almost feels like it's increasing and then suddendly it drops to 0.

[budm]

Re: Vestel 17PW26-4 V.1

Let me rectify that. Those values where when I plugged the resistor between ST_BY and GND. Now I did it again but this time like you said the second time, between ST_BY and +5V and now I get 22.47 on pin 26, and on pins 11 and 12 it keeps changing constantly from 0 to around 5/6 volts, it almost feels like it's increasing and then suddendly it drops to 0.

I am confused, so if you put the resistor between ST_BY and GND you will get steady output from all the switched power supplies, correct?

But if you put resistor between ST_BY and +5V then the switched power supplies output are not on steady, correct?

[rafa805]

Re: Vestel 17PW26-4 V.1

I am confused, so if you put the resistor between ST_BY and GND you will get steady output from all the switched power supplies, correct?

But if you put resistor between ST_BY and +5V then the switched power supplies output are not on steady, correct?

Precisely!

With the resistor in ST_BY to GND in pins 11 and 12 I get 12.1V and in pin 26 I get 24.5V;

With the resistor in ST_BY to +5V I get 22.47V on pin 26, and on pins 11 and 12 it keeps changing constantly from 0 to around 5/6 volts.

[dick_barton]

Re: Vestel 17PW26-4 V.1

If the supplies are correct when ST_BY is connected to ground then that will be correc way. I had it the wrong way round. So Budm has given the correct method for testing.


Edit
Found some notes I made in the past.

[rafa805]

Re: Vestel 17PW26-4 V.1

If the supplies are correct when ST_BY is connected to ground then that will be correc way. I had it the wrong way round. So Budm has given the correct method for testing.


Edit
Found some notes I made in the past.

Yes I've checked again and the values are the same, but the TV does not power. The local keys are touch and I think they.might be working because they beep when I press, the remote control I don't know whether it's working or not. Is there a way I can jumper something to force her to boot up?

[dick_barton]

Re: Vestel 17PW26-4 V.1

Here is the schematic for your mainboard.
I would check all the voltage regulators as shown on page 10 of 20 for the correct output voltages.