Philips 47PFL4606 No Power Fuse Keeps Blowing

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

1. i did place an part from an other donor board.
2. i did not put back R947 and R966,Q906
3. Yes iam going to leave it out.
4. Q907 = 9,8 to 10.5V on all the legs to hot ground

1) We still want to leave R966, Q906 for the Brownout protection circuit out for now. R947 is not part of the brownout circuit, I had you removed to isolate the standby power supply from the PFC and the 12V/24V circuit.

2) R947 (4.7 Ohms) is for supplying Voltage to the PFC IC and the 12V/24V SMPS IC, so without having it in place you will have switched 15V Vcc to run those two IC's. You will leave it out for now until we finish checking the parts in the PFC section.

3) Q907 is used as a switch to provide the switched 15V to run the PFC and 12V/24V SMPS IC'c. It is turned on when 1K pull up resistor is connected. Did you replace Q907 since the old one was shorted?

4) You need to check R929 (47K) which is connected between Gate and Source pin of PFC MOSFET Q902, we want to make sure it is not damaged.

5) Did you verify if R916 is 4R7 or not on the good board? That is important, you must verify that.

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

I just read the thread below about the board used in the 37" which is what you say it is the good board?
https://www.badcaps.net/forum/showth...695#post977695

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Q907 is changed and the measurements in previous post where with an 1K in place
Q907 = 9,8 to 10.5V on all the legs to hot ground

4. R929 is damaged getting an reading of 28/k ohm and reverse 8.2K ohm
Soldered R929 out of the pcb and now its reading 47K ohm
5. R916 reads 123K ohm and reverse 133K ohm !! the bad board reads 4.7 ohm in both directions

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Q907 is changed and the measurements in previous post where with an 1K in place
Q907 = 9,8 to 10.5V on all the legs to hot ground

4. R929 is damaged getting an reading of 28/k ohm and reverse 8.2K ohm
Soldered R929 out of the pcb and now its reading 47K ohm

5. R916 reads 123K ohm and reverse 133K ohm !! the bad board reads 4.7 ohm in both directions

4) Since R929 reads 47K as it should be then it was not damaged.

5) R916 is part of the Gate drive circuit for MOSFET Q902, the circuit will not work with that high if the resistance present on the Gate drive circuit OF THE GOOD BOARD. Can I see the picture of the good board and the bad board around the resistor and Q902? Are you sure you good board is good?

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Yes the (good) board (37 inch) is partially working problem now is that the CCFL are flickering but the board gives an 5/12/24V and the tv starts

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Yes the (good) board (37 inch) is partially working problem now is that the CCFL are flickering but the board gives an 5/12/24V and the tv starts

Both pictures show R916 markings of 4R7, so I do not understand by the reading of the good board is over 100K that you reported "R916 reads 123K ohm and reverse 133K ohm" on the 37" good board.

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

BTW, we still need to find out why we only have about 10V on C946 when 1K pull up is connected, the PFC IC FAN6961 and SMPS ICNCP1271 need 12.5V for the circuit to start running.
We know that IT should have about 15V based on the board that we fixed for 47" in the link below.
https://www.badcaps.net/forum/showthread.php?t=86061
https://www.badcaps.net/forum/attach...6&d=1594984130
So we need to figure out why we are only getting around 10V.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello Budm

My measuments of Q907

https://www.badcaps.net/forum/attach...1&d=1596089841

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

We know that we have those Voltages at Q907 (or C946), we need to find out why the Voltage generated by the 5VSTBY transformer is so low, it should be closed to 15V like we had in other thread, that is what we need to figure out.
Right now 10V to too low to run t he PFC IC and the 12V/24V SMPS IC.
If you check the Voltage on your 37", you will see that it is higher than this 47" board we are working on.
We know that the 5V output is OK, we have 5V when 1K is connected but we do not have the 15V from AUX winding when 1K is connected, something is loading down this Voltage. We need to get correct Voltage at this section first before working in the PFC and the 12V/24V section.
Check the Voltage of Q907 (or C946) on your 37" board with and without 1K and see what you get.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

C946 = 8.15v / 9.8v (37)
c946 = 7.8v / 10.5v (47)

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

.

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

C946 = 8.15v / 9.8v (37)
c946 = 7.8v / 10.5v (47)

The 37: board is actually working with that low Voltages, 9.8V? 9.8 is not enough to run the PFC and the SMPS IC.
That does not look right at all.
What DC Voltage (measured between the two legs of the cap) do you get on the main filter cap of the 37" board with 1K in place?
The picture attached is from your working 47" board.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Ive got 311V on Filter cap of the 37 inch with 1K in place. (Strange when i place this board back into the tv ive got 300V on the filtercap and 14,6V on C946 tv is running only backlight is flickering)
Also gor 311 on the filter cap of 47 inch

[ivtec]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Ive got 311V on Filter cap of the 37 inch with 1K in place. (Strange when i place this board back into the tv ive got 300V on the filtercap and 14,6V on C946 tv is running only backlight is flickering)
Also gor 311 on the filter cap of 47 inch

Flickering maybe bad caps on
inverter board.

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Ive got 311V on Filter cap of the 37 inch with 1K in place. (Strange when i place this board back into the tv ive got 300V on the filtercap and 14,6V on C946 tv is running only backlight is flickering)
Also gor 311 on the filter cap of 47 inch

That means the PFC Booster circuit is not working on both boards! That 37" board is not fixed.
The Voltage on the main filter cap should be around 380 ~ 400V when PFC is working.
The schematic shows 395V.
The inverter circuit will not work properly at 311V, it should not even come on if it has low Voltage protection circuit.
BTW, is your AC Voltage is 230VAC? Measure it.if it is 230VAC, then the Voltage on the cap should be around 325VDC when in standby.
BTW, you do know how to read schematic, correct?

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello Budm

Oke good to know need to find out then what is causing it!
what else can i check ?
What section in the schematics is the PFC Booster circuit ?

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

I updated my reply.
The cause of both board not working is due to low voltage on C946.
So the seller of the 37" board sold you bad board.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

That correct it is 230V and when i measure it is 230 exactly
Iam trying to learn how to read schematic i understand a little but still not enough

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

That correct it is 230V and when i measure it is 230 exactly
Iam trying to learn how to read schematic i understand a little but still not enough

OK, that explain why you did not understand what Voltage you should get and why.
At this we cannot use the 37" board as a good board since the VCC Voltage is too low to run PFC and the SMPS IC's.
We need to get hat 10V up 15V first but I do not know yet why it is not working when the 5V output is correct at 5V when 1K is present.
So are you going to return that defective 37" board?

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

What sections can i check more to find an error in the pfc ?