Phillips 47PFL3603D/F7 No Power

[budm]

Re: Phillips 47PFL3603D/F7 No Power

That T701 is the high Voltage backlights inverter transformer.
Does the buzzing sound change with the change in the backlights level?
The inveter circuits run off the high Voltage (>360VDC) generated by the PFC Voltage booster. You may have to check the DCV between the two legs of the main filter cap to see if it is steady, it is dangerous because you will need to get to the bottom side of the board while the board is powered up plus it is in the HOT Deadly side of the circuit.

[Gorrillasnot]

Re: Phillips 47PFL3603D/F7 No Power

Unless I am doing something wrong I cant tell that the brightness level adjustment is doing anything at all. From 0-100 the screen looks the same to me.

C670, C671 Measured 405V pretty steady. It would fluctuate between 404V and 405V, but stayed mostly steady at 405V.

Something odd, when I would go into the menu of the TV the buzz would go away. Exit the menu and the buzz would start back up.

The first 3 pictures are of the startup sequence. Pic1. Immediately after pressing power button no buzz, Pic2. buzz starts, Pic3. TV is fully on and buzzing away.
Picture 4 is after pressing the menu button and the buzz is gone.
The last 3 pictures are the brightness level adjustments. No buzz while on these screens.
I exit the menu and the buzzing returns.

If it's not a cap that's that's causing the buzzing do you think the transformer itself is going bad?

thanks

[Terryfictv]

Re: Phillips 47PFL3603D/F7 No Power

If it's not a cap that's that's causing the buzzing do you think the transformer itself is going bad?

thanks

Did you change out the two caps of wrong value ?
Transformers usually don't "go bad"...they are usually good or bad.

[budm]

Re: Phillips 47PFL3603D/F7 No Power

Not the Brightness adjustment, there should be another adjustment on the user menu for the BACKLIGHTS level.
Most TV will have CONTRAST, BRIGHTNESS, and BACKLIGHTS adjustment. Your TV may not have that function for the Backlights level adj.

[Terryfictv]

Re: Phillips 47PFL3603D/F7 No Power

Did you change out the two caps of wrong value ?

Please ignore ! I just read your response !

[Gorrillasnot]

Re: Phillips 47PFL3603D/F7 No Power

I don't see any option for backlights adjustment.

Could it be the panel itself (or CCFLs) causing the trasnformer to buzz?
In post #9 I attached a pic showing some problems with the picture at the top of the screen.
I'll attach a pic here on a lighter screen so hopefully it shows up better.

thanks

[Terryfictv]

Re: Phillips 47PFL3603D/F7 No Power

Next step = remove transformer from board and examine...
Then re-solder wire wrapped lugs...then re-install on board.
Test =

[Gorrillasnot]

Re: Phillips 47PFL3603D/F7 No Power

If I am doing this right with my dmm set on 200ohm scale I get 22.2ohm on the primary side and 1.3ohm on the secondary. (see pic1 for test points I used)
Does this sound about right?

In pic2 are those the places that I should re solder? Then do the same on the secondary side?
If so, thsoe spots look to be covered with resin..whats the best way to remove it?

thanks

[Gorrillasnot]

Re: Phillips 47PFL3603D/F7 No Power

Do you think my transformer is good? I couldn't find any info when searching google to see what ohms it should be.
(BTW in the above post I think I have the primary and secondary backwards. primary is the thicker wire right?)

I read that Optocouplers is another component that can make a psu board buzz. Do you think that's a possibility in my case and if so how do you test them?

thanks

[Terryfictv]

Re: Phillips 47PFL3603D/F7 No Power

Solder primary wire wraps then inspect secondary....
BTW, MY transformer measures the same.
Smell it....does it have any physical problems?

[Gorrillasnot]

Re: Phillips 47PFL3603D/F7 No Power

Doesn't have any smell that I can tell and no damage that I can see.

Just so I am clear on where to solder, I should solder across the whole top and bottom primary side (thicker) wires as circled in the pic?

if that doesn't fix the buzz is there something else I should test?

thanks

[Terryfictv]

Re: Phillips 47PFL3603D/F7 No Power

DO NOT solder anything !
TTYL

[Gorrillasnot]

Re: Phillips 47PFL3603D/F7 No Power

ok I will wait for further advice.

I was doing some searching and came across a thread on another forum where a guy said he adjusted a pot on a 37" Philips and it fixed 90% of his buzzing.
He said it dropped the transformer voltage from 1060V down to 730V without affecting brightness. He said he adjusted fully counter clockwise.
I looked on my board and it also has 2 pots covered in glue. 1 is at VR401 and the other is VR402.
I believe VR401 is the one he adjusted.
Here is the link to the post http://www.avsforum.com/forum/166-lc...-contrast.html

Do you think this is something I should try?

thanks

[azza1234]

Re: Phillips 47PFL3603D/F7 No Power

them marks might be caused by the casing screws maybe? try undoing them and seeing if the dark patches go

[Gorrillasnot]

Re: Phillips 47PFL3603D/F7 No Power

Thanks azza1234..I will check the screws a little better.

About the buzzing..Looking at the back of the TV when I press the menu button and the buzzing stops I can see the backlight is considerably brighter then when not on the menu screen.
Is there a way to adjust the backlight brightness level other than in the menu which doesn't have that option?

[Gorrillasnot]

Re: Phillips 47PFL3603D/F7 No Power

I reinstalled the transformer and put the board back in the TV.
I ended up not messing with VR401.

I read that turning off auto backlight dimming from the service menu might help.

My chassis is Philips LC8.1U LA and I think this is the correct service manual http://www.s-manuals.com/tv/philips_lc8.1u_la_chassis
In the alignments section of the manual for Byte OP2 it says Bit 3, Dec. Value 8.
My default value for option 2 in the SAM menu is 123 so to turn off the backlight dimming would I subtract 8 from 123 = 115?
I have tried to enter 115 for option 2 but every time I restart the TV it reverts back to 123.
What am I doing wrong?

thanks

[Gorrillasnot]

Re: Phillips 47PFL3603D/F7 No Power

The buzzing is gone..woohoo!

Here's how I fixed it encase it might help someone else.
First download a service manual for your TV.
With the TV powered on (but not on any menu screen) press the following keys on the remote "062596" followed immediately by pressing the Info key.
This should bring up the SAM (Service Alignment Mode) menu.
Scroll down to the options section.
Look in the service manual you downloaded and under the Alignments section find where it mentions "BACKLIGHT_DIMMING" and look for the location and value. In my case it was option 2 and the value was 8.
In option 2 on the SAM menu my value was 123 and I needed to subtract 8 so I changed the value to 115. Go back 1 screen and scroll to the bottom and press "Store" and the setting will be saved.
This turned off the Automatic backlight dimming and fixed my buzzing noise.
As always proceed at your own risk.

Now on to see if I can fix the dark spots at the top of the screen. I dont see any screws to mess with..I probably need to take the front bezel off and get into the metal frame to see if there are any hidden screws.

thanks again everyone

[budm]

Re: Phillips 47PFL3603D/F7 No Power

Thanks for the info, so your TV do not have user BACKLIGHT level control for the user to set the backlights level, can only be done in service mode. They should have put that in user mode like other brand.

[Gorrillasnot]

Re: Phillips 47PFL3603D/F7 No Power

I agree budm..why put something that could potentially fix an annoying (buzzing) problem in the service menu where the average consumer would not know how to get to.

The last issue for me on this TV is those dark spots at the top of the screen. the Op Hours on the TV are 35,534..with that many hours I'm guessing that its some kind of panel issue or burn in spots..I've checked the screws and it didnt make any difference...is there anything else I could try?

thanks

[Terryfictv]

Re: Phillips 47PFL3603D/F7 No Power

Call it a day ! Glad you came to a nice ending !
The old Doctor's motto prevailed on this one =
"Above all else,do no harm!"