Philips 47PFL4606 No Power Fuse Keeps Blowing

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

It is not PFC problem, it is the low voltage (10V) we are getting from the AUX winding of the 5VSTBY power supply transformer, we need to get about 15V form it but we are not getting it. we need 15V on C846 first, that is what we trying to figure out why we are only getting 10V.
We know that the good 47" board was putting out 15V but we do not have that good board anymore to do comparison testing.
So do not do anything in the PFC or SMPS section.

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

BTW, you did not change any transformer on this 47" board we are working on, correct?

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello

If swapped out T803 from the 47 inch to the 37,
and swapped it back to the orginal boards again

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Can you un-solder one leg of Zener diodeZD907 and check the RESISTANCE in both direction of that ZD907?
BTW, did you replace ZD907?

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

I did replace ZD907, when one leg un-solder iam getting 85K ohm in one direction

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

I did replace ZD907, when one leg un-solder iam getting 85K ohm in one direction

OK, leave ZD907 out like that for now.
Power up the board and see what Voltage you will get on C946 again.
BTW, you can leave 1K resistor in place for now.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Oke ZD907 is out, and i have 10.5V on C946
With 1K in place ofcourse

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

OK. I have to spend more time to figure why we are not able to get 15V on C946.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

in the mean time can i check some more components?

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

I am still thinking, i have been staying up late here every night until 2 ~3 AM my time helping you and the other guy in Euro and I am very tire right now, I need to clear my head so I can think straight again.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

I really appreciate it very much !!

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

I want to solve the problem as much as you do, at least we get the 5V on the standby output OK.
Try lifting one leg of the D916 then check the resistance in both directions to see what you get.
There is not much in that 15V section of that STBY power supply, just the transfomer winding, rectifier (D916) and filter cap C946.
BTW, did you ever test the C946 ESR?

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

D916 measure in Diode mode OK and when in resistance iam getting 8K and reverse OL
C946 measure ESR 0.08ohm

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

D916 measure in Diode mode OK and when in resistance iam getting 8K and reverse OL
C946 measure ESR 0.08ohm

OK, that's fine, put them back in.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Strangly i measure over R918 0.17ohm,And when solderd out 47K

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

One side of R819 is connected to ground via L903 and the other side connected to ZCD. The only way it can measure such a low resisteance is that ZCD is shorted to ground or has a very low input resistance. Perhaps the 10V internal zener has gone short circuit.

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Or it could be that pins 5 & 6 are shorted by solder when the IC was replaced.


Edit
Have you fitted an extra resistor along the R907, R908, R909, R911 path??

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Yes someone fitted an extra 18.7k resistor

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Just a reminder, I had OP remove the R947 from the board to isolate the AUX power supply for feeding the PFC and 12V/24V circuit so we can figure why we only getting around 10V on C946.
https://www.badcaps.net/forum/attach...9&d=1595998843

And we also have the same problem with the 37" board, we only have 10V on C946 and the Voltage on the main cap is only a little over 300 V instead of 395V..

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Or it could be that pins 5 & 6 are shorted by solder when the IC was replaced.


Edit
Have you fitted an extra resistor along the R907, R908, R909, R911 path??

Pins 5&6 where indeed shorted ! did not see any bridges when inspecting
Now i have an high ohm reading on those pins