Philips 47PFL4606 No Power

[trunks81]

Hello

I have one other tv only 47 inch, first issue was that the 5V only was 2,8V
After i replaced IC905 it went back up to 4,6Vdc still to short ?
And when i place an 1K resistor between 5V and S/B it falls back to 4V
Also no 12V and 24V!
Do you guys have any ideas ?

[thommyX]

Re: Philips 47PFL4606 No Power

if you replace IC905, then always replace ZD907 9.1V.


I just see the IC801 is a UBA2071. Do you have a low resistance between pin 17 and 22 ??? Then the IC would be defective.

[trunks81]

Re: Philips 47PFL4606 No Power

if you replace IC905, then always replace ZD907 9.1V.

Hello forget to mention that but indeed i replaced both.

[trunks81]

Re: Philips 47PFL4606 No Power

Between Pin 17 and 22 meter says OL so that would be defective ?
Also this IC is for the backlight ?

[dick_barton]

Re: Philips 47PFL4606 No Power

OL on your meter means the resistance is higher than whatever ohm scale you are on. That is its resistance is higher than what you have set your meter to.

[budm]

Re: Philips 47PFL4606 No Power

What Voltage do you have on Emitter, Collector, and Base of Q707 when SB is not connected with 1K pull-up resistor and when connected to 1K pull-up resistor?

[budm]

Re: Philips 47PFL4606 No Power

Between Pin 17 and 22 meter says OL so that would be defective ?
Also this IC is for the backlight ?

Pin 17 (GND) pin 22 (SH) are connected to the Source and Drain of the low side MOSFET, so if that MOSFET is shorted out then it will read as low resistance, so based on your result, there is no low Ohm reading.
The IC is part of the backlights inverter circuit.

[trunks81]

Re: Philips 47PFL4606 No Power

What Voltage do you have on Emitter, Collector, and Base of Q707 when SB is not connected with 1K pull-up resistor and when connected to 1K pull-up resistor?

Can not find Q707 in the schematics ?

[budm]

Re: Philips 47PFL4606 No Power

Can not find Q707 in the schematics ?

What do you mean cannot find in the schematic?
It is shown in the schematic of your PDF in post #1.

[trunks81]

Re: Philips 47PFL4606 No Power

When i look in the schematics adobe can not find part Q707

[budm]

Re: Philips 47PFL4606 No Power

When i look in the schematics adobe can not find part Q707

See pictures.Sorry, it is Q907!

[trunks81]

Re: Philips 47PFL4606 No Power

Hello see attachment for measurement !
With the 1K resistor is Red and without is yellow

[thommyX]

Re: Philips 47PFL4606 No Power

I suspect your mistake is not the power supply. U750 on the mainboard is a voltage regulator LM1117-3.3. I would renew it.

LG Thomas

[budm]

Re: Philips 47PFL4606 No Power

Hello see attachment for measurement !
With the 1K resistor is Red and without is yellow

What did you use for meter ground? The negative leg of the main filter cap?
If that is what you use then 5V is not going to be enough to run the PFC and SMPS IC, it should be around 15 ~ 20Vdc range.
12V/24V SMPS IC901, NCP1271, startup Voltage is 12.6V
PFC IC902, FAN6961, startup Voltage is 12.5V

You may need to put 1A load on the 5V STBY power supply and then make the measurement again.

[trunks81]

Re: Philips 47PFL4606 No Power

I used an 12V 7W halogen to make an load, light wasnt burning btw
On both IC's on the VCC pins am getting 0.3V
In both cases i used the main filtercap or the rectifier negatief as test point

[budm]

Re: Philips 47PFL4606 No Power

I used an 12V 7W halogen to make an load, light wasnt burning btw
On both IC's on the VCC pins am getting 0.3V
In both cases i used the main filtercap or the rectifier negatief as test point

12V 7W lamp will have cold resistance will be quite low, check the resistance of the lamp with Ohm meter, hot resistance will be about 20 Ohms. So with the Voltage do you get on 5VSTBY with 1K forced on resistor and lamp connected? The lamp may load down the 5VSTBY too much due to cold resistance of the lamp..
BTW, looking at the diagram, if no 1K pull-up resistor, the STBY5V will be about 4.5V or so, then it should jump up to 5V when 1K pull-up is connected, this is done by Q908 and R954.

[trunks81]

Re: Philips 47PFL4606 No Power

Hello Budm

After your tip to inspect Q908 and R954 ive found an strange brigde to an opto ?!
After removing that bridge the power supply worked again.
See picture for what i mean !
PS. do i need to open an other topic because ive an other 47PFL4606 supply where the fuse blows ?

[budm]

Re: Philips 47PFL4606 No Power

Hello Budm

After your tip to inspect Q908 and R954 ive found an strange brigde to an opto ?!
After removing that bridge the power supply worked again.
See picture for what i mean !
PS. do i need to open an other topic because ive an other 47PFL4606 supply where the fuse blows ?

1) Did some one work on this power supply before? I look at pictures in post 1, some one did put solder bridge (you can see the flux residue) on the LED side so power supply no longer have feedback to regulate the output. What kind of repair guy do such a thing like that?
2) Please check the 5VSTB when TV is off to see what you get, it should be less than 5V if my calculation is correct and it should jump up to 5V when PS-ON is present.
3) I would start another thread just make sure to put down the model number and the problem on the header, it is always good to put down the chassis number too.
4) So what Voltages do you have now on Q907?
5) So does the TV work now?
6) I wonder now if the original IC905 may be OK.

[trunks81]

Re: Philips 47PFL4606 No Power

1) Did some one work on this power supply before? I look at pictures in post 1, some one did put solder bridge (you can see the flux residue) on the LED side so power supply no longer have feedback to regulate the output. What kind of repair guy do such a thing like that?
2) Please check the 5VSTB when TV is off to see what you get, it should be less than 5V if my calculation is correct and it should jump up to 5V when PS-ON is present.
3) I would start another thread just make sure to put down the model number and the problem on the header, it is always good to put down the chassis number too.
4) So what Voltages do you have now on Q907?
5) So does the TV work now?
6) I wonder now if the original IC905 may be OK.

1.I guess someone did indeed work on it.. dont really know who and why they did make an bridge on that opto.
2.When tv is off the voltage is 4.6V and when PS-ON it is 5V
3. Going to do that.
4. See Attachment !
5.Looks like it going to put the tv on long term test.
6.Iam wondering that to only the parts is allready in the bin

[budm]

Re: Philips 47PFL4606 No Power

1.I guess someone did indeed work on it.. dont really know who and why they did make an bridge on that opto.
2.When tv is off the voltage is 4.6V and when PS-ON it is 5V
3. Going to do that.
4. See Attachment !
5.Looks like it going to put the tv on long term test.
6.Iam wondering that to only the parts is allready in the bin

Great, the STBY Voltage is as I suspect it to be when in standby and when the TV is turned on.
Good to see the TV is working again. This one is tough because I do not have the board in front of me to do real close visual inspection.