Philips 47PFL4606 No Power Fuse Keeps Blowing

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Now the big question is how can we get the 9.9v back up to 15v

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

With 20K resistor, it went up to 382V which is good enough for testing but I do not see why it drops off as if the circuit is turned off after that, It should have stay up. 19K will probably bring it up to 395V.
I think it is related to 9.9V power supply.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Did an test with an R223 (22K) and with an 20K
Looks like it 19,?? k is the sweetspot only i cannot find one

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello

This is the chart without the 820K resistor.
Looks like it the voltage is like 3 a 4V lower as before.
Still find it strange that C946 keeps hanging on 9.91V

Good, so it is going in the right direction. I would try replace R911 with 20K first to see how much it drops down, you can use through hole resistor for testing.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello

This is the chart without the 820K resistor.
Looks like it the voltage is like 3 a 4V lower as before.
Still find it strange that C946 keeps hanging on 9.91V
did not read correctly about an chart with 820k and one without.. sorry

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

I did more research about PFC FAN6961 and found application circuit, see page 2 and page 4, it looks like they just copy the circuit, according to the notes, the PFC Voltage is 398VDC. They use the same resistors values for the output Voltage sensing network.

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

The currrent resistors measure like this (off the board)

0.9977Mohm
1.0013Mohm
1.0058Mohm

Just for reference:
The total resistance of the 3 resistors above is 3.0048 M Ohms.
The design is based on 3M +/- 1 % = 3 M +/- 30K Ohms, so 3.0048 M Ohms is higher than 1% tolerance.
I rather see it at 3M or less since higher resistance will cause higher Voltage.
We can trim the PFC Voltage by varying the value of R911 instead, the higher the resistance of R911 the lower PFC Voltage.

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello

Its an 1872 resistor, that should be 18,7K.
Looks like they added an 820kohm on the 47 board
Should i remove the 820k and then test again ?

It looks like some one tries to trim the Voltage by adding the resistor, since this basically the same board used in the 37", did you look at it to see if they add resistor like this board?
Is this the picture of 37"? https://www.badcaps.net/forum/attach...6&d=1597529098
Yes remove it then you should see slightly lower PFC Voltage, you should do the same C907 Voltage readings that you did before which is great because you can see what is going on with time stamp without removing the resistor first, then after resistor is removed.
I like that Voltage charts you makes, it helps a lot.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello

Its an 1872 resistor, that should be 18,7K.
Looks like they added an 820kohm on the 47 board
Should i remove the 820k and then test again ?

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Soldered in the new resistors, still pfc is hitting the 420,
Only thing i noticed that there are two 18,7k resistors

Lowering resistance of the R911 by parallel with another resistor will cause the PFC Voltage to go up. It looks like it was added on later by someone.
The 1M resistors have opposite effect, the higher the resistance the higher the PFC Voltage.
Can you look at the same R911 on the 37" board that you have?
I look at the pictures fo the 37" board and I do not see the added on resistor. See what value of the R911 is on the 37" board.
https://www.badcaps.net/forum/attach...5&d=1592909026

https://www.badcaps.net/forum/showthread.php?t=85509

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Soldered in the new resistors, still pfc is hitting the 420,
Only thing i noticed that there are two 18,7k resistors

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

The currrent resistors measure like this (off the board)

0.9977Mohm
1.0013Mohm
1.0058Mohm

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

It is 2AM here, I am going to bed, I think we are getting close.
Good night.

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Are they 1%? They do not have to be SMD if you have the room for through hole resistors.
As you can see, they values have to be pretty tight tolerance, that is one of the reason R911 is 18.7K 1%, they did not put in 18K 1% since that extra 700 Ohms makes difference as to what the PFC Voltage will be.
You can try new 1M resistors first and see what the PFC Voltage will be, see if it gets higher or lower with the new 1M resistors, we may be able to trim it to get what we want, 390 ~ 395Vdc.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

i have three 1M resistors over from the NR1504 repair, They are not smd
And ive got the 1M smd resistors from an donor board

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Those resistors are 1% so 1M Ohms will be +/- 10K Ohms.
So what does the meter actually show when you measure those 1M off the board?
if the those 1M resistance go up it will cause the PFC Voltage to go up.
We need to get the PFC Voltage back down to 390 ~ 395VDC range
Do you have high Ohm value resistors in stock?

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Measured R907,R908,R909 and R911 on the board iam getting these results
See pdf for that.. but when i reverse the leads iam getting different result
And when these resistor are desoldered they are 1M exceot R911

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Did an new measurement please see attachments

You refer the PFC Voltage of C908, but the main filter cap is C907 (120uF 450VDC), please check. C908 is X safety cap connected across the AC line.
It does not make any sense to me at all to see PFC IC FAN6961 starts up at 9.9V.
Look at the Voltage of main filter cap C907, it looks like at6:22:21 the Voltage went up to 421.04VDC and then it starts dropping down, that may have been over Voltage condition. The PFC Boosted Voltage is supposed to be 395V according to the schematic.
Please check the 1M resistors R907, 908, 908 to see if the resistance has gone up >1%.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Did an new measurement please see attachments

Edit C908 is C907 my bad

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

tested again waited like 15min an then connected the board.
only the boosted voltage drops from 410 to 312
and the voltage on C946 stays at 9,91 no drop of climb
5v is still present

If you leave the board unplugged again for 15 minutes, leave the meter on C946 then watch the meter to see how high it goes up to when you apply the power to board..
No way for PFC to run at 9.9V, it needs 12.5V to start.