Philips 47PFL4606 No Power Fuse Keeps Blowing

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

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

So is the boost voltage back up to +390V

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Boost inst back yet. But we are missing the next components so i dont know if boost can be back

R947
ZD907
R966
Q906

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

OK, I see, no boost without those components and I see that you are still working on finding the missing 15V

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

OK, I see, no boost without those components and I see that you are still working on finding the missing 15V

I had him remove R947 (and other not needed parts for the STBY 5V power supply to run) for now so there will be no PFC and SMPS IC loading down the 15V power supply from AUX winding of the STBY power transformer.
Right now he has only about 10V on C946 instead of 15V like the other 47" that I helped him fixed. The IC's need 12.5V startup Voltage for them to run.
He also has only about 10V on c946 of the 37" board for the 37" TV he is working on in the 37" thread and that is why he does not have PFC boosted Voltage on the 37" TV either..
If we can figure out why we are only getting only 10V and fix it then we can fix the 37" board at the same time.
What does not make sense is that 5V (4.6V in standby mode) is at 5V when 1K force on is present, so the 15V winding should also be 15V but it is not.
The other 47" board for the other TV (we do not have that TV any more) that I helped him fix shows 15V as it should but not these two boards.
The 37" board that he sent out for repair is also not fixed either. I wish I have the board in front of me instead of trying to do remote troubleshooting due to some time we get wrong data.
And now we just found out that there is solder bridge on pin 5-6 of the PFC IC, frustrating, I am glad I did not have him put the R947 back in yet..
Once we get he 15V back, he will have to check 12V/24V section real well too for any solder bridge before putting R947 back in place.

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

He mentions swapping T803 in one of the threads so I wonder if this is a link to the problem.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

i did swap T803 from the 47 to the 37 inch, And powered the 37 inch with the other T803

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

i did swap T803 from the 47 to the 37 inch, And powered the 37 inch with the other T803

So did you swap the transformer back so everything is back to original condition?
T803 is inverter transformer, it will not cause low Voltage at C946, beside, we remove the resistor that feed the switched VCC for the PFC IC and the 12V/24V SMPS IC.
BTW, so did you buy the 37" replacement board or you sent the board out for repair?

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

i did swap everthing back to normal, the 37 inch board i did send out for repair by accident.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

When i connect mainboard in the tv iam getting 11.18V on C946

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

BTW, do you remember this thread of the other 47" that we fixed, you took the Voltage readings for me after the board was fixed?
Do you remember if the Voltage readings of Q907 was done using 1K resistor or it was done when the main board is connected?
This thread here: https://www.badcaps.net/forum/showthread.php?t=86061
https://www.badcaps.net/forum/attach...6&d=1594984130

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Readings where done when 1K resistor is connected.
red is without and green is with

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Readings where done when 1K resistor is connected.
red is without and green is with

OK thanks, more thinking to do.
So it jumps from 11.5V to 14.1V when 1K is connected which is correct because the standby also jumps from 4.6 to 5V, but the two bad boards are not jumping up to 14V.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Both IC901&IC902 measure to ground high ohmage

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Both IC901&IC902 measure to ground high ohmage

We remove R947 for testing so those two IC's are not drawing any power from C946 so Voltage on C946 should be close to 15V, but it is not.

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

I have a question, did you replace D916?

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello Budm

No i did not replace D916 because it measered oke,

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Lets put R947 back in place and see if the PFC Boost Voltage will be present.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

put R947 back in and i see an strange thing happening with the boost
its start at 410 and goes back to 312

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

put R947 back in and i see an strange thing happening with the boost
its start at 410 and goes back to 312

That means the Voltage on C946 did go up close to 15V so the PFC starts up, but then PFC drops out.
Now we need to find out why.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Checked C946 again and that one does not climb to 15v it stays at 9.91V