Philips 42FD9954/17s dead

[postrich]

Re: Philips 42FD9954/17s dead

Ooops, another newbie mistake. I failed to reconnect 0306 when I put it together. Now the TV is back to the normal bad behavior of taking 10 minutes to turn on. I guess I will go and replace all the capacitors in RYAN74's post #54. It would be great if I could pin down the problem to the specific capacitor(s) though...

[ryan74]

Re: Philips 42FD9954/17s dead

if I remember correctly the only cap that was visibly bad(bottom blown out) was the one I circled in yellow. I don't have proper testing equipment so i replaced all surrounding caps also.

[postrich]

Re: Philips 42FD9954/17s dead

I finally pulled out the power supply board to get an even closer look at all the components and found a 'surprise' resistor (white, gray, red, gold - see attachment for picture) on the underside (loc2121 - 100v 2200uF) that does not appear to be in the specifications (pages 38-39). It looks like a post fabrication add-on so either the TV was "repaired" before or modified at the factory to work. What does adding a resistor to the leads of a capacitor do ?

Here is what I think I know... When a circuit is off and the cap is charged, a resistor works to more safely drain the caps energy into heat. I don't know what it would do while under power except perhaps reduce the total charge it could take ? Perhaps the unit was over voltage and needed a drain of some kind ? Could the resistor explain why I have about 340-350v on my 400v lines. I'm just guessing at some of this now... :-)

[budm]

Re: Philips 42FD9954/17s dead

That is just a bleeder resistor to discharge that big cap.

[postrich]

Re: Philips 42FD9954/17s dead

I replaced the loc4700 cap as was bad on RYAN74's TV. That one is easy to get at. The schematic shows that cap on the Fan related power page.

Since I am not a super guru and it still works after a 1-2 minute warm up, I decided to close it up and use it before I do damage to it or electrocute myself. Hopefully it will either work like this forever or a cap will show itself and pop.

I wonder if the bleeder resistor is not enough Ohms and that is why the TV takes so long to come on. It does look like something put on afterwards...

I wish I had the knowledge to test different points and find where voltages are wrong and do all the detective work you guys do to find the bad part. Without that, I would just be replacing all the caps on the board, and with my luck, it wouldn't work afterwards. :-)

[sdinelli]

Re: Philips 42FD9954/17s dead

Back from the dead again.

I am getting standby red light, and no voltage at main fuse.(fuse is good)
the three blue film caps are rated at 470n but are only around 400n.
on the first mains filter, the magnet is loose, that doesnt mean its bad does it?
im not very good at reading schematics im just a PC tech.
how can i test the filter? put the leads on pins 1 and 3(the two bottom) ? or pins1 and 2 (the two left)?

you can reference the second pic in post #2

i dont see any noticeable damage.
im afraid to poke around with the power on.

Thanks

[sdinelli]

Re: Philips 42FD9954/17s dead

looking for some help here.
i have pretty much all my standby voltages except the 9v stby is only 6.7
anywho, when i pres power i get no replay click at all, i pulled the relay and tested with my supply and both function correctly.

taking voltages of the first relay,
pin1 = 120v
2 = .8v
3=6.73v
4.6.73v
so i think based on this datasheet it should turn on with the 6.7 provided. is this correct? or does it not have enough?
http://www.digchip.com/datasheets/pa...-109DM_000.php

thanks

[sdinelli]

Re: Philips 42FD9954/17s dead

any one have any ideas?

[ReeceyBurger123]

Re: Philips 42FD9954/17s dead

Heat it with a hair drier see if that brings the 9v back up.

[sdinelli]

Re: Philips 42FD9954/17s dead

Heat it with a hair drier see if that brings the 9v back up.

the specs of the relay say
Coil Voltage 9VDC
Turn On Voltage (Max) 6.75 VDC
Turn Off Voltage (Min) 0.9 VDC

so shouldnt it turn on? what exactly does coil voltage mean?

[budm]

Re: Philips 42FD9954/17s dead

The relay has coil that when it is energized to actuate the relay contact, the DCV for the relay is rated at 9VDC, the 6.75VDC is the lowest Voltage on the relay coil for it to be able to actuate the relay contact. 0.9VDC is the dropout Voltage once the relay was actuated.
Your post 67:
'taking voltages of the first relay,
pin1 = 120v
2 = .8v
3=6.73v
4.6.73v

To me you are not getting the DCV across the relay coil if you read 6.73V on both legs of the relay coil, the Transistor or what ever being used to drive the relay coil is not turned on otherwise one of the relay coil pin should be 0VDC for the relay to actuate, but right now the Voltage is also at the border line. The relay is not actuated that is why there is no 120VAC on pin 2.
You also need to get the 9V power supply working.

[sdinelli]

Re: Philips 42FD9954/17s dead

The relay has coil that when it is energized to actuate the relay contact, the DCV for the relay is rated at 9VDC, the 6.75VDC is the lowest Voltage on the relay coil for it to be able to actuate the relay contact. 0.9VDC is the dropout Voltage once the relay was actuated.
Your post 67:
'taking voltages of the first relay,
pin1 = 120v
2 = .8v
3=6.73v
4.6.73v

To me you are not getting the DCV across the relay coil if you read 6.73V on both legs of the relay coil, the Transistor or what ever being used to drive the relay coil is not turned on otherwise one of the relay coil pin should be 0VDC for the relay to actuate, but right now the Voltage is also at the border line. The relay is not actuated that is why there is no 120VAC on pin 2.
You also need to get the 9V power supply working.

Thanks for the info, so i had an idea from one of the previous posts in this thread.
this tv didnt come with the remote, so i tried turning it on with my phone by searching the code and i hear the relays click on!
it turned on for 20secs and before i got to get some measurements it clicked again and turned off but not all the way, i still had 80 v on the second fuse.

[budm]

Re: Philips 42FD9954/17s dead

Thanks for the info, so i had an idea from one of the previous posts in this thread.
this tv didnt come with the remote, so i tried turning it on with my phone by searching the code and i hear the relays click on!
it turned on for 20secs and before i got to get some measurements it clicked again and turned off but not all the way, i still had 80 v on the second fuse.

What second fuse? The second fuse in the Primary side of the circuit? What did you use for the GND ref for your meter black probe?
Pictures provided by shopjimmy.

[sdinelli]

Re: Philips 42FD9954/17s dead

What second fuse? The second fuse in the Primary side of the circuit? What did you use for the GND ref for your meter black probe?

i was referring to the fuse in the middle, on the cold side. i just used chassis for ground. i turned it back on and got 340V on that fuse.
va= 59.5
vs=79.7
relays click off in 10-15 secs

[budm]

Re: Philips 42FD9954/17s dead

Are you talking about the fuse sitting in the socket next to the big blue cap? That fuse is in the HOT side. Or you are talking about the red round fuses (10 of them that I can see in the cold side) that are soldered into the board.
When you make the DCV measurement in the primary HOT side of the circuit, you do not use chassis GND as the GND ref for the meter, you will use the negative leg of the main filter in the primary side for the GND ref. for your meter. You can use chassis as the GND for the cold side of the circuit.
Pictures provided by shopjimmy.

[sdinelli]

Re: Philips 42FD9954/17s dead

Are you talking about the fuse sitting in the socket next to the big blue cap? That fuse is in the HOT side. Or you are talking about the red round fuses (10 of them that I can see in the cold side) that are soldered into the board.
When you make the DCV measurement in the primary HOT side of the circuit, you do not use chassis GND as the GND ref for the meter, you will use the negative leg of the main filter in the primary side for the GND ref. for your meter. You can use chassis as the GND for the cold side of the circuit.
Pictures provided by shopjimmy.

shoot your right, i knew that. dumb mistake on my part.
what happens if you use cold ground for the hot reading??

[sdinelli]

Re: Philips 42FD9954/17s dead

so when turning set on my
9V stby comes up to 8.3V from 6.7V
25Vhot comes up to 20V from 18v
400Vhot come up to 360V from 160V

then after 10 secs set goes back into standby
any ideas?

[sdinelli]

Re: Philips 42FD9954/17s dead

FIXED!.. well actually nothing had to Be fixed.
this stupid tv/monitor whatever it is, if there is no source video, immediately goes into standby.
i realized this after turning it on, i was pressing button on the remote to see if teh volume/channel woudl come on the screen and it wasnt turning off, and when i stopped it then went into standby.
picture looks pretty good for being a 2004 model. too bad the resolution is only 1024* 768 haha
so in the end i replaced a bunch of caps cause i thought it wouldnt turn on but just didnt know how to work the damn thing.
i guess it probably needed them anyways

[ReeceyBurger123]

Re: Philips 42FD9954/17s dead

Derp It would have probably needed them anyway