Philips 47PFL4606 No Power Fuse Keeps Blowing

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

So now you do get 4.6V Standby Voltage?
It should jump up to 5V when using 1K to simulate turn on signal, verify that.
BTW, My typo on R866, it should be R966.

Indeed when 1K in place iam getting the 5V

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello Budm

Done al the steps you asked except remove R965 that one isnt on the board. and R866 is R966.
But now i have 5,9volt @pin 3 of ic905 and 4,6v on the 5v

So now you do get 4.6V Standby Voltage?
It should jump up to 5V when using 1K to simulate turn on signal, verify that.
BTW, My typo on R866, it should be R966.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello Budm

Done al the steps you asked except remove R965 that one isnt on the board. and R866 is R966.
But now i have 5,9volt @pin 3 of ic905 and 4,6v on the 5v

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

1) Leave out R966 and Q906 of the brownout circuit, we do not need them right now for the circuit to function.
2) Remove R947 (4.7R), R965 (2M2).
3) "Still dont understand why D901 and Q902 and R919 exploded when i replaced IC901/902" Something was done wrong or bad parts, but we will deal with that later, right now we need to get the 5V standby working first.
4) I also need high res pictures of the whole bottom side of the board you are working on so I can see the soldering works that were done to the board.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Checked the total brown out circuit on faults !
everthing measure oke in ohms no strange readings

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

i forgot to check them they where the fault.. smps doesnt blow the fuses any more !

Edit smps stil doesnt has power to the M/B so i swapped out IC901 and IC902
After this R919 exploded and D901,Q902 measure very low ohms (these where replaced by me before !)

Still dont understand why D901 and Q902 and R919 exploded when i replaced IC901/902

Also how do i keep the config in an bare minimum ?

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

how do i keep the circuit in minimal config ?

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

I just cannot see what else can stop the C Voltage to rise up to 5.8V for the IC to startup, which at the same time I do not expect to see 2V on the cold side if the IC is not running at all but may be running a little bit on and off, something is amiss here on component that are tested good.
Right now he needs to leave the brown out detection out and keep the circuit in minimum configuration that the IC requires to run.

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

I'm clutching at straws here. It may be worthwhile checking any component that you have replaced and make sure that something silly like a diode fitted the wrong way around or a solder bridge to a pad alongside.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

That is still around 2v to 2,4v

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

BTW, so the 5V standby is still low at this point, correct?

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

it is still 0.55V

That transistor is on as it should be.
I updated my reply of post 49.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

it is still 0.55V

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

i removed R966 first still the V is 5.50 in pin 3, So i also removed Q906 same story.
ZD909 measure in Diodemode 0.68V and V across it is 4.2v and on the good board is 3.2V

ZD909 Vdrops is fine.
So without R866 and Q906 in place, the E-C Voltage of Q913 is still <1V?
Without Q906 in place, I do not see anything else that can load down pin 3, you only have ZD907 (9.1V Zener), C948, R620 in series with C948 connected to pin 3 (C), which you have already tested those parts out.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

i removed R966 first still the V is 5.50 in pin 3, So i also removed Q906 same story.
ZD909 measure in Diodemode 0.68V and V across it is 4.2v and on the good board is 3.2V

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Post 34:
Ic905 good bd / bad bd
1= 2.85v /1.30v
2= 1.3v / 1.26v
3 (C) = 5.92v / 5.5v
4= 0v / 0v

Your post 46 now makes sense.

At this point, it seems to me that the Voltage on pin 3 (C) never reach 5.8V for SMSP TOP IC to start running.
One thing that can load down pin 3 (C) is Q906 (PNP) turned on by the brown out detection circuit, or it has leakage between E and C.

You can try removing R966 (330K) so the Q906 cannot be bias on, this will disable the brown out protection circuit to see if the TOP will run or not.
But if Q906 is leaky, then you will have to remove it.

You also need to check the Vdrops of ZD909 (9.1V Zener).

For the the TOP to work, Q906 has to be off, Q913 has to be on, but if brown out occurs, the Q906 will be on which causes Q913 to be off and shut down the TOP SMPS.

See attached picture regarding to Brown out detection circuit.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello

V between pin 3/4 on IC907 = 4.74V
V between pin 4 IC907 / Hot ground = 0.75V
V between pin 3 IC907 / Hot ground = 5.54V

V Between + /- C946 = 0.75V
V between + C946 and hot ground = 0.75V


On the good board this is

V between pin 3/4 on IC907 = 2.23V
V between pin 4 IC907 / Hot ground = 8.14V
V between pin 3 IC907 / Hot ground = 5.90V

V Between + /- C946 = 8.1V
V between + C946 and hot ground = 8.1V

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

V on pin 3/4 to ground of C946 is 5.50V and 0V,
V between C/E of Q913 is 0.54V

on the good board this is

V on pin 3/4 to ground of C946 is 5.88V and 0V,
V between C/E of Q913 is 0.55V

R965 and ZD912 are not on the board

Your post #24 for C946 Voltage readings:
C946 = 8.16V (good bd.) 0.70V (bad board)
D916 = 8.22V 0.70V

If you look at the schematic, the OPTO IC907 pin 4 (Collector) is connected to the positive leg of C946, so I cannot see how you can have 0V (on good and bad board) on pin 4 of the OPTO IC907. Does that make sense to you?
Are you sure you are probing at the correct parts on the board?
It seems to me we are having some kind of measurement error here that is throwing us off trying to troubleshoot the problem.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

V on pin 3/4 to ground of C946 is 5.50V and 0V,
V between C/E of Q913 is 0.54V

on the good board this is

V on pin 3/4 to ground of C946 is 5.88V and 0V,
V between C/E of Q913 is 0.55V

R965 and ZD912 are not on the board

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

1) Check resistance of R965 (2M2 Ohms), it is located around IC 905.
2) Check the Voltage between the Emitter and Collector of Q913, it is also located around IC 905.