Philips 47PFL4606 No Power Fuse Keeps Blowing

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello

Tested the two boards across. and came to the next result
Color green is for working board and red for the not working
All is tested without the 1K resistor

IC905
1= 2.85V 1.30V
2= 1.3V 1.26V
3= 5.92V 5.5V
4= 0V 0V
-
5= 317V 315V

IC907

1-2 = 1.10V 0.31V
3-4 = 2.21V 4.80V

C946 = 8.16V 0.70V
D916 = 8.22V 0.70V

What Voltage do you have on pin 3 and pin 4 of IC907 with ref to negative leg of C946?

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Those readings as in all the readings given today do not show any obvious fault.
I have to bow out at this point since with all the checks made the fault has still not been found.
Perhaps others can spot something I've mssed.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello,

IC905 was an new unit.. which came from ebay, So probably from china ?
https://www.ebay.com/itm/3pcs-T0P264...53.m2749.l2649

When i measure R959 on both boards iam getting on one side 5.11ohm and the other side 0.15ohm

Ordered the TOP264 at farnell (Sinuss) now and ill see if that fix the problem

EDit used the top264 form the working board and no difference

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Other than changing IC905 once more I can't see what else there is to check.
You have definately checked R959 and replaced D907 with a 9.1V zener diode.
One side of R959 to hot ground should measure 4.7 ohms (plus winding resistance) and the other side of R959 should measure just the winding resistance. This will eliminate the transformer winding as a problem.

Was IC905 replacement a new device, Chinese purchase or from a donar board?

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Got the next

IC905 to hot ground both boards measure almost the same

1 = 9.595k 1 = 9.677k
2 = 10.346k 2 = 10.416k
3 = 6.620k 3 = 6.744k
4 = 0.11ohm 4 = 0.10ohm
5 = 2.7271k 5 = 2.7436k

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

The voltages for IC905 are not too dissimilar to your test board. They will be for the Opt since there is no 5V on the secondary.

Check the solder joints on IC905 since I feel that this is where the fault lies.

Can you measure the resistance to hot ground of all the pins of IC905 between the good/bad board, power off.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

IC905 Pin2 is 13V or 1.3V for the working board???

Looking through threads on this power supply and the problem tends to be either IC905 or ZD907.

Sorry Typo its is 1.3V

Changed IC905 and ZD907 and still the same results

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

IC905 Pin2 is 13V or 1.3V for the working board???

Looking through threads on this power supply and the problem tends to be either IC905 or ZD907.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello

Tested the two boards across. and came to the next result
Color green is for working board and red for the not working
All is tested without the 1K resistor

IC905
1= 2.85V 1.30V
2= 1.3V 1.26V
3= 5.92V 5.5V
4= 0V 0V
-
5= 317V 315V

IC907

1-2 = 1.10V 0.31V
3-4 = 2.21V 4.80V

C946 = 8.16V 0.70V
D916 = 8.22V 0.70V

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

If you have twp identical boards, one working and one not working perhaps you could give the voltage readings of each around IC905, IC907 & C946/D146 junction.

Also can you use your meter set to ohms to compare resistance readings against each other at the above points.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

On that board i have 8,1V on C946,
also
The voltage on pin 3 rises to 5.9V of TOP264 !
No difference when 1k resistor in place

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Where is the link to show me the power supply board of the 37"?
This one, correct?
https://www.badcaps.net/forum/showthread.php?t=85509
That 37" board is still not fixed, correct?
That 37" board standby power supply is working, correct? So what Voltage do you have on C946 (no need to use resistor to turn on the power supply), just power up the board by itself.

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello

I have two 47 inch and one 37 inch, The fixed 47 inch is gone now,
And the 37inch board is almost exact the same as the 47 inch except for the CCFL part
So i did compare it with that board. Also the 47inch tv starts with the 37inch board only no BL

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello

C946 = still reads 0.75V,
T904 = Measured along with the 37inch board and reads the same!
R953 = 100 ohm
C952 = 100.2 nf
R956 ,R954 ,R957 ,Q908 ,R952 = Compared them with an other board and they both read the same

37"?
We worked on the 47" same model on this Thread: https://www.badcaps.net/forum/showthread.php?t=85971

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

Hello

C946 = still reads 0.75V,
T904 = Measured along with the 37inch board and reads the same!
R953 = 100 ohm
C952 = 100.2 nf
R956 ,R954 ,R957 ,Q908 ,R952 = Compared them with an other board and they both read the same

[budm]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

"When i measure the 5V its only 2.7V, When i connect an 1K to S/B-5V iam getting 1.9V on the 5V"
I am confused as to why you are getting Voltage on the cold side of the 5VSTBY power supply but you report this in post #21 "1. On C946 i get 0.7V ?! seems low to me !". C946 which is the filter cap for the rectifier D916 which rectifies the AC from the AUX winding of the STBY transformer T904, having 0.7V on that filter cap means the transformer AUX winding is bad or R959 (4R7 Ohms) is open. The Voltage on that C946 should be around 15V (see your thread of the same TV on another thread) when PS-ON is present, and lower when PS-ON is not present. If you look at the other thread, you will see that you will have around 4.6V output on the 5VSTBY pin, then it will jump up to 5V when PS-ON is present.
The 15V ON C946 is used for runninng the SMPS ic's and PFC IC

BTW, post 22 by dick_barton
"Those results don't seem right. C946 is connected to the Opto isolator (IC907) which has 4.7V across it. It can only get that voltage from D916/C916 which you say is at 0.7V"
I think he means C946.

Bottom line, you need to check the Voltage on C946 again.

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

So at switch on it rises to 5.5V and stays at that voltage?

The data sheet says the initial operating voltage needs to reach 5.8V on the Control pin before the mosfet kicks in and drive the transformer so long as the Control voltage doesn't drop below 4.8.V

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

The voltage on pin 3 rises to 5.5V of TOP264 !
No difference when 1k resistor in place

[dick_barton]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

The voltage on Pin 3 (Control) of the TOP264 should rise to 5.8V. The capacitor connected to this pin is charged up by the voltage on pin 6 (Drain). When it reaches 5.8V the internal circuit providing the charging current from the Drain supply to the capacitor switches off and the voltage across the capacitor connected to Pin 3 is then maintained by the feedback winding of T904

Can you check that the voltage on Pin 3 rises to 5.8V

[trunks81]

Re: Philips 47PFL4606 No Power Fuse Keeps Blowing

The voltage across D916 is 0.7v and C916 0.3V