Philips LCD 42PFL5432D/37 - Bad PSU

[trixter]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Don't know what the numbers mean with my DMM, but with one diode I get 11 both ways and the other 29 both ways.

[trixter]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

New diodes came in. They measure 300 and only going one way.

[Dgtech]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

I'm glad you see a difference. Replace them, test it and report back.

[trixter]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

I soldered the two new diodes in. Turned the tv on and no more chirp. Then all the sudden the white lights came on. I looked at the screen and it was back to normal. Yay!!! I screwed everything back together and three of us picked up the tv to mount it on the wall and plugged in all the video cables and power. Turned it on and nothing. It started chirping again. Darn. All that work. There must be something still wrong that caused it to go bad again. I took it all apart and tested the diodes. They are still good. The power must have gone beyond that now and now something else could be bad. Got to do some more testing.

[gdinon]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

I soldered the two new diodes in. Turned the tv on and no more chirp. Then all the sudden the white lights came on. I looked at the screen and it was back to normal. Yay!!! I screwed everything back together and three of us picked up the tv to mount it on the wall and plugged in all the video cables and power. Turned it on and nothing. It started chirping again. Darn. All that work. There must be something still wrong that caused it to go bad again. I took it all apart and tested the diodes. They are still good. The power must have gone beyond that now and now something else could be bad. Got to do some more testing.

What did you find? I am in a similar situation. Replaced the 3 caps, powered it on, and 1 blew. The diodes are bad but I would like to know what you found that caused it before I replace them.

[Xeniczone]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

I concur.
The other clue that gives this away is that there's only 2 transformers in this power supply (one of them being the broken one you mentioned) and each has a single output only.

So what's next?...
Remove J5 and R974. This will disable the primary side of the standby circuit. Then finally wire in 12v from an external power supply (see attached image below). Note that ground (GND) from the external PSU also needs to be connected.
I suggest a PSU capable of at least 2A. Also if there's any loose solder like in the pictures you posted, make sure to clean it up.

Very interesting. I too have had problems with our Philips 42 inch TV. I traced the chirping back to the same transformer, T904. I started by replacing the 4 larger capacitors because they looked swollen and all that jazz. After nothing I tested came back bad or nothing I replace made the PSU work, I decided to try this idea out.

It does seem to work but there is a problem with the backlight. It flickers. I believe it has something to do with the PWM not functioning correctly, but I'm not sure 100% how it works because I can't find it in the wiring diagrams. The reason I think it is the PWM is because when first turning the TV on the backlight doesn't flicker until the software initializes (shows HDMI in the corner and such) then it starts flickering. Plus trying to turn the brightness up/down in the menus has no effect on the TV.

I will keep at it and try to find a solution. Plus try to make the solution look better so you don't have a computer psu sitting next to your TV.

Just to note, I'm doing this for the thrill of it. My dad has already bought a new TV to replace this.

[momaka]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Very interesting. I too have had problems with our Philips 42 inch TV. I traced the chirping back to the same transformer, T904. I started by replacing the 4 larger capacitors because they looked swollen and all that jazz. After nothing I tested came back bad or nothing I replace made the PSU work, I decided to try this idea out.

It does seem to work but there is a problem with the backlight. It flickers. I believe it has something to do with the PWM not functioning correctly, but I'm not sure 100% how it works because I can't find it in the wiring diagrams. The reason I think it is the PWM is because when first turning the TV on the backlight doesn't flicker until the software initializes (shows HDMI in the corner and such) then it starts flickering. Plus trying to turn the brightness up/down in the menus has no effect on the TV.

Interesting results.
When I wrote that suggestion for the external power supply, I did spend a good chunk of time observing the circuit in order to make sure an external power supply can be inserted without having to have anything on the primary of the standby circuit function. Now that I look at it again, though, it seems that there is indeed a voltage line derived from the auxiliary winding on the standby transformer. It goes through SMD resistor R977, then gets rectified through SMD didode D929, filtered through cap C958 and then goes out to optocoupler IC909 and surrounding circuitry.

See if the voltages on the main power supply pulse with the same frequency as the backlights. If they do, then I think this may be the problem - i.e. missing auxiliary voltage on the primary side of standby transformer.
Possible solutions...
Pin 1 of IC907 is Vcc. According to the TEA1507P (IC907) datasheet, Vcc can be up to 20V. So if there is a way to get a voltage inserted at the positive leg of C958, I think the power supply may then function properly. Unfortunately, you cannot insert any external voltage source for this because everything on the primary side has a hot ground. Perhaps one of those unregulated, ungrounded 9-12v chargers may do the trick.
I'm also wondering if a voltage divider from the primary would work. Perhaps if the current required for IC909 and the surrounding circuitry turns out to be fairly low.

I will keep at it and try to find a solution. Plus try to make the solution look better so you don't have a computer psu sitting next to your TV.

Yes, I agree that this solution is not very pretty at all. More of a last-resort type of thing. And if the above turns out to be true, you will have not one, but two external power supplies! Now that's a bit too much, even for me .

Just to note, I'm doing this for the thrill of it. My dad has already bought a new TV to replace this.

Yeah, that's fine. It's normal to see other folks here (including myself) fix things that are usually not worth fixing.

*EDIT*
I think I may have figured it out...
It looks like the purpose of optocoupler IC909 is to send a signal to the PFC controller in order to run the PFC circuit. There's a wire from pin 8 on IC902 (the PFC controller) that goes to IC909 and the transistors around it.
Get a voltage inserted on C958 and you may have a working power supply. (Again, just make sure it's an ungrounded power supply like one of those cheap, linear wall-warts.)

[Xeniczone]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Good catch, but I'm not sure I understand the purpose of the aux coil there. Based on the wiring diagram it doesn't look like the coil does anything couldn't pin 5 and 6 on T904 be shorted out and receive the same result. Forgive me on this one, I don't know as much as I should about transformers.

Also, I have trouble understanding why this would cause the backlight only to flicker once the firmware has booted.

Pin 8 on IC902 got to IC910 (also an opto-isolator) not IC909 that you're referring to.

[momaka]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Good catch, but I'm not sure I understand the purpose of the aux coil there. Based on the wiring diagram it doesn't look like the coil does anything couldn't pin 5 and 6 on T904 be shorted out and receive the same result. Forgive me on this one, I don't know as much as I should about transformers.

Pin 6 on T904 supplies IC907 (the standby circuit PWM controller) with power. Without it, IC907 would not work and there would be no standby power.
Initially, when the TV is plugged in, IC907 receives power through pin 6 (Drain) and charges capacitor C957 (which is connected to pin 1, VCC, of IC907). Once C957 reaches a certain voltage, IC907 uses that to "pulse" Q908 (the standby MOSFET). This pulse generates a voltage in the auxiliary winding of T904 (pin 6), which then gets rectified through D908 and charges C957 and thus provides IC907 with constant power. IC907 then again pulses Q908, and the whole cycle keeps repeating. Meanwhile, the pulses from Q908 also generate a voltage on the secondary of T904 - this is what produces the 12v standby voltage.
All of this is relevant to your next question...

Also, I have trouble understanding why this would cause the backlight only to flicker once the firmware has booted.

Well, at least from what I traced, the PFC controller seems to be controlled by a bunch of SMT transistors (Q914 particularly) which are located near opto-isolator IC909. It also seems that IC909 is "supplied" with power through R975, which if you trace back comes from the standby auxiliary coil. Moreover, what I just found out, based on this schematic,
https://www.badcaps.net/forum/attach...6&d=1298647899
it seems that IC904 (the PWM controller of the main power supply) is also supplied by power from the standby auxiliary coil through Q912. This would explain the pulsing of the backlights, since the backlights are powered from the main 24v power supply, whereas the firmware and other logic-related power is likely supplied from the 12v standby power supply. The main PWM controller pulses because it too initially starts up like IC907 (i.e. it charges C921 through pin 6, Drain).
Also, when the PFC is not working, the voltage across the big 220uF, 400v primary capacitor is likely only about 170 volts (if you live in a country where the line voltage is 120V rms, of course). With the PFC circuit enabled, this voltage should be ~385v. Feel free to check me on this by measuring the voltage across the primary cap (be very careful, though!). If it's close to 170v when the TV is powered on, your PFC is not working.

Pin 8 on IC902 got to IC910 (also an opto-isolator) not IC909 that you're referring to.

Okay, let's make sure we're on the same page here. I'm using these pictures as a reference when I determined that IC902 (the PFC controller, supposedly) is connected to opto-isolator IC909:
https://www.badcaps.net/forum/attach...3&d=1298297504
https://www.badcaps.net/forum/attach...6&d=1298206864
If I'm not mistaken, one of the pins on IC902 should be connected to SMT transistor Q914.

Double check me on all of these items and let me know what you find.

[momaka]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Okay, apparently power to the IC904 (main PWM controller) also comes from pin 5, the auxiliary winding of T905 (the main transformer). Not quite sure why there would be two supply circuits for IC904. Either way, it seems possible for IC904 to draw power from both standby and main transformer auxiliary windings. Perhaps one of them is for when the TV is in standby mode.
Diode D907 is for main transformer aux. power, whereas D910 is for standby aux. power. Interesting...

Anyways, I still think this missing voltage is the cause for the main power supply not starting up. The standby auxiliary winding is connected to a lot of things, so it really must be important, otherwise the designer(s) wouldn't have bothered.

[Xeniczone]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

I will test some of your suggestions out tomarrow and report back, I got a day off tomorrow.

Here is the datasheet I'm using, it looks a lot better than those pictures you have.

[momaka]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Here is the datasheet I'm using, it looks a lot better than those pictures you have.

Ah, what a difference. I can see things much better now .
Thank you.

I looked at the schematic you posted, and everything I posted above seems to be correct.
Pin 8 of IC902 (the PFC controller) is VCC, and it is connected to SMT transistor Q914, which is controlled by optocoupler IC909, and Q914 is supplied with power by the auxiliary winding of the standby transformer, T904. Without it, you get no PFC, which too could mess up the operation of the PWM controller.

I think the idea of feeding a positive voltage to the positive terminal of electrolytic capacitor C958 should solve the problem. But again, the voltage you feed to that spot needs to come from an ungrounded power supply only. Otherwise you can do a lot of damage to both the external power supply and the TV power supply.
I *think* a 12v power supply should work for this. Perhaps try and start with 5v first, and if that doesn't work, then go up in voltage. Technically, IC904 can take up to 22v, and IC902 can take up to 25v. However, it's the other components in the circuit that may be of limited capability, so that's why it's better to start with something low.

By the way, for the power supply to work, you will also need that 12v computer PSU you had connected to the standby output before.

[Xeniczone]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Ah, what a difference. I can see things much better now .
Thank you.

No problem. You're helping me remember.

I looked at the schematic you posted, and everything I posted above seems to be correct.
Pin 8 of IC902 (the PFC controller) is VCC, and it is connected to SMT transistor Q914, which is controlled by optocoupler IC909, and Q914 is supplied with power by the auxiliary winding of the standby transformer, T904. Without it, you get no PFC, which too could mess up the operation of the PWM controller.

You're correct, I was wrong what I stated in the post above about where Pin 8 connected. I jump lines.

I think the idea of feeding a positive voltage to the positive terminal of electrolytic capacitor C958 should solve the problem. But again, the voltage you feed to that spot needs to come from an ungrounded power supply only. Otherwise you can do a lot of damage to both the external power supply and the TV power supply.
I *think* a 12v power supply should work for this. Perhaps try and start with 5v first, and if that doesn't work, then go up in voltage. Technically, IC904 can take up to 22v, and IC902 can take up to 25v. However, it's the other components in the circuit that may be of limited capability, so that's why it's better to start with something low.

By the way, for the power supply to work, you will also need that 12v computer PSU you had connected to the standby output before.

Before I tried that, I gave this a try. In theory, it should have worked right? I connected the Aux coil from the transformer back into the power supply, but no luck the light still flickers.

I have a 12v 1500mA linear power supply that should do that trick if not. It is unregulated so the power that comes out of it is generally 14-16v, but as you stated that shouldn't be an issue since the two ICs can handle far beyond that. I guess if push comes to shove, I can always stick a regulator IC on the end of it. Unfortunately, I don't have any 5v power supplies that fit the bill. Most of the ones I do have are cell phone chargers, but they only put out 300-500mAs, I'm not sure if that is enough.

[momaka]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

I connected the Aux coil from the transformer back into the power supply, but no luck the light still flickers.

Right.
That's because on T904 (the standby transformer), the auxiliary winding gets its power from the main winding. Basically IC907 (standby PWM controller) "tells" Q908 (the standby MOSFET) to pulse on and off very fast. The pulses (ac voltage) of Q908 are sent through the main winding of T904, which results in an output voltage at the secondary side of T904 and the auxiliary winding.
But we already have disabled the primary side of the standby circuit, remember? (the removal of J5 and R974 disables Q908 and IC907). Therefore, you don't need T904 connected at all for this mod, just two external power supplies - one is the 12v computer PSU feeding the standby output, and the other is the ungrounded power supply feeding the positive side of electrolytic capacitor C958 (this makes it seem as if the voltage is supplied from the auxiliary winding of T904).

I have a 12v 1500mA linear power supply that should do that trick if not. It is unregulated so the power that comes out of it is generally 14-16v, but as you stated that shouldn't be an issue since the two ICs can handle far beyond that. I guess if push comes to shove, I can always stick a regulator IC on the end of it. Unfortunately, I don't have any 5v power supplies that fit the bill. Most of the ones I do have are cell phone chargers, but they only put out 300-500mAs, I'm not sure if that is enough.

Well, I looked through the TEA1507 (IC904) datasheet again, and it says that the minimum start-up voltage is 10.3v. Therefore, use the 12v, 1500mA linear power supply. I don't think a regulator IC will be needed.

You're correct, I was wrong what I stated in the post above about where Pin 8 connected. I jump lines.

No worries. I do that too sometimes .
I think this is why I didn't see the potential problem that was caused by the missing auxiliary winding voltage.

By the way, those capacitors you used for the replacement are huge! What brand and series are they?

[Xeniczone]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Right.
That's because on T904 (the standby transformer), the auxiliary winding gets its power from the main winding.

Ahh, okay may bad. Again, I apologize, I should know more about transformers, but I never learned anything about them in school and never did any research online about them. I need to find me a good book. Is the Aux winding just a 1:1 winding or something like that?

Well, I looked through the TEA1507 (IC904) datasheet again, and it says that the minimum start-up voltage is 10.3v. Therefore, use the 12v, 1500mA linear power supply. I don't think a regulator IC will be needed.

Alright I will give this a try right now.

By the way, those capacitors you used for the replacement are huge! What brand and series are they?

They are ones I bought at radio shack, so I'm not sure of the actual branding or anything because I'm sure radio shack just buys them and places their logo on the them.

The reason for the size difference compared to the original caps is because of the ratings. C955 was original a 2200uF @ 16v. I replaced it with a 2200uF @ 32v, and because it is an axial-lead cap doesn't help with the sizing. C951, C952, and C953 were each 1500uF @ 32v and I replaced all of them with a 4700uF @ 32v. Sure the replacement is 200uF larger than the original ones, but since they had a 20% tolerance, I didn't think it would make much of a difference. I assumed it would be fine based on the wiring diagram. I'm not sure why they used 3 small capacitors when they could have just used one large one.

I will update with results.

[Xeniczone]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Lol, seems that you're the man of the hour in my book. I wired in that separate 12v linear PSU and the turned the TV on and it worked perfectly. I played Killzone 2 on it for 40 mins didn't see a problem. My dad doesn't like me playing games on the new 55" Sony because he is worried about Image Persistence, but I don't think new LCDs are affected by this. The Philips had image persistence problems, but I think it is because of the CCFL heating up the LCD panel which causes it.

I would like to turn this TV into a LED TV by replacing the CCFL backlight, but I'm not sure if it would be worth it. It would fix the image persistence if my theory is correct, but The LCD panel is already 4 years old, but then again, the TV wasn't worth fixing the first time. 40" TVs cost about 400-500 dollars. A new PSU is 130-240 dollars. :/

Would it be possible to run all this of one power supply. I would need to test the amperage being pulled by both the 1500mA PSU and the PC PSU, but I see that there are two different grounds so this wouldn't be possible correct?

[momaka]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Ahh, okay may bad. Again, I apologize, I should know more about transformers, but I never learned anything about them in school and never did any research online about them. I need to find me a good book.

No need to apologize here. Two years ago, I knew very little electronics as well.
Transformers are pretty simple actually. Think of it as two or more coils (or windings) wound on a piece of iron. Wherever you input an AC voltage on one of the coils, you will get an AC output voltage on the other coils. The size of the output voltage of each coil is proportional to the number of turns on that coil to the number of turns on the coil you're inputting the voltage.
Say we have an ideal transformer with two windings - one with 100 turns and another with 10 turns. If you put 200 VAC on the 100-turn winding, you will get 20 VAC on the 10-turn winding ( [200 * 10]/100] ). If you put 5 VAC on the 100-turn winding, you get 0.5 VAC on the 10-turn winding. And so on...
The winding on which you input the AC voltage is called primary, whereas the winding on which you get an output is called secondary. Then you can use the following formula to calculate the voltages on a transformer:
V1 * N2 = V2 * N1
where V1 and V2 are the voltages on the primary and secondary windings respectively, and N2 and N1 are the number of turns on the secondary and primary windings, respectively.
Also, transformers work only with AC voltages, and not DC.
That's pretty much all of the basics on transformers. Not like you need to know any of that for the PSU mod, though.

Is the Aux winding just a 1:1 winding or something like that?

Most likely not. But we don't really need to know, anyways .

They are ones I bought at radio shack, so I'm not sure of the actual branding or anything because I'm sure radio shack just buys them and places their logo on the them.

Well, I don't mean to rain on your sunshine here, but Radio Shack capacitors are not very suitable for this application and will need to be replaced with something better.

There's two other very important parameters besides the capacitance and voltage rating of each cap. Those two parameters are ESR (equivalent series resistance) and Ripple Current handling capability (or just Ripple Current).

In almost all modern switch mode power supplies (like the one in this TV), the AC voltage fed to the transformer is switched at relatively high frequencies (40 KHZ to 120 KHz or even more). When the output voltage from the transformer is rectified (turned into DC), there are undesirable high frequency voltage spikes and dips (called ripple and noise). The ripple and noise needs to be filtered out, and this is where the electrolytic capacitors come in: basically, the electrolytic capacitors function like little batteries, charging quickly when there are voltage spikes (thus suppressing the voltage spikes) and discharging when there are voltage dips. This makes the output DC voltage much smoother.

Unfortunately, like everything else, capacitors are not perfect and they have an internal resistance called ESR. At high frequencies, the ESR starts to become an issue because it doesn't allow the capacitor to charge/discharge as quickly as it should. Therefore, the capacitor is not able to filter out all of the noise and ripple.

And this is exactly where the Radio Shack capacitors are lacking - they have too high of an ESR and therefore cannot filter out noise and ripple.

As for the Ripple Current rating, this is a rating of how much ripple a capacitor can filter before it begins to overheat.

When buying new capacitors, you first want to look up the brand and series of the original ones in your circuit, then find a datasheet for them and see what their ESR and Ripple Current characteristics are. Then, based on that, you buy new capacitors that have the same or lower ESR and same or higher Ripple Current rating.

With that said, what were the original capacitors on your PSU (brand and model)?
This also raises the doubt - what if your power supply is working fine but you concluded that it's not because you used inadequate Radio Shack capacitors? In this case, you may be just $10 or so away from a perfectly working power supply again without all of those external power supplies.
I would certainly give it a try. Hope you haven't thrown away any of the removed parts yet.

You can order capacitors from here (badcaps.net), digikey.com, or mouser.com. Let me know what the originals are so I can suggest a replacement.

=============

**** EDIT ****

Oh nice, you got it working!
(lol you fixed it faster than I could type my post ).

Well, I would still encourage a complete recap - maybe we can get your PSU running properly with good caps and no external power supplies again.
(and if not, you can always keep it the way it is, now that you know that it works).

As for integrating the PSUs into one - I do have a few ideas, but they may or may not work, and now that you have a working power supply, I'm not willing to suggest them that much, just in case they don't work (but I will if you really really want to).

[Xeniczone]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

No need to apologize here. Two years ago, I knew very little electronics as well.
Transformers are pretty simple actually. Think of it as two or more coils (or windings) wound on a piece of iron. Wherever you input an AC voltage on one of the coils, you will get an AC output voltage on the other coils. The size of the output voltage of each coil is proportional to the number of turns on that coil to the number of turns on the coil you're inputting the voltage.
Say we have an ideal transformer with two windings - one with 100 turns and another with 10 turns. If you put 200 VAC on the 100-turn winding, you will get 20 VAC on the 10-turn winding ( [200 * 10]/100] ). If you put 5 VAC on the 100-turn winding, you get 0.5 VAC on the 10-turn winding. And so on...
The winding on which you input the AC voltage is called primary, whereas the winding on which you get an output is called secondary. Then you can use the following formula to calculate the voltages on a transformer:
V1 * N2 = V2 * N1
where V1 and V2 are the voltages on the primary and secondary windings respectively, and N2 and N1 are the number of turns on the secondary and primary windings, respectively.
Also, transformers work only with AC voltages, and not DC.
That's pretty much all of the basics on transformers. Not like you need to know any of that for the PSU mod, though.

O yeah, I knew all that. I just didn't understand the concept of an aux. coil or how one coil (in this case on the primary side) can have 4 connectors.

Well, I don't mean to rain on your sunshine here, but Radio Shack capacitors are not very suitable for this application and will need to be replaced with something better.

There's two other very important parameters besides the capacitance and voltage rating of each cap. Those two parameters are ESR (equivalent series resistance) and Ripple Current handling capability (or just Ripple Current).

Now that I didn't know. Good information, thanks!

With that said, what were the original capacitors on your PSU (brand and model)?

The 1500uF is CapXon GF series

Did a little research and found the datasheet that lists the Ripple Current and the impedance.

This also raises the doubt - what if your power supply is working fine but you concluded that it's not because you used inadequate Radio Shack capacitors? In this case, you may be just $10 or so away from a perfectly working power supply again without all of those external power supplies.
I would certainly give it a try. Hope you haven't thrown away any of the removed parts yet.

I would give it a try, but I don't want to get my hopes up. I'm not even sure if the original caps were ruined in the first place, and like I mentioned before the chirping sound was coming from the transformer (T904). I know this because I used a microphone and stuck it on each component in the area to measure the loudest sound, aka where the chirping was coming from.

Nope, I haven't thrown anyway anything.

Oh nice, you got it working!
(lol you fixed it faster than I could type my post ).

Well, I would still encourage a complete recap - maybe we can get your PSU running properly with good caps and no external power supplies again.
(and if not, you can always keep it the way it is, now that you know that it works).

Yeah, I would still replace those RadioShack Caps with something else. I was just trying to fix that PSU in one day and RadioShack is the only place to get things local. Those caps weren't all that cheap though about $5-$6 dollars a piece, but that is RadioShack for you.

As for integrating the PSUs into one - I do have a few ideas, but they may or may not work, and now that you have a working power supply, I'm not willing to suggest them that much, just in case they don't work (but I will if you really really want to).

I didn't necessarily mean to combine it all into one, I was thinking of using just one power supply to piggy back the TV's power supply, rather than having two.

[momaka]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

The 1500uF is CapXon GF series

In that case, proper replacements would be any of the following:
United Chemicon KZE, Nichicon HD, Panasonic FM, and Rubycon ZL.

If you can't find these caps 25v, 1500uF for those series, try United Chemicon KY, Nichicon HE, and Panasonic FR.
Technically, they are not as good as the CapXon GF, but they are very close, and still way much better than the Radio Shack capacitors.

Most of these can be found at digikey.com and mouser.com. I checked the BCN store, but there are no 25v caps with 1500uF capacitance, unfortunately.

I would give it a try, but I don't want to get my hopes up. I'm not even sure if the original caps were ruined in the first place, and like I mentioned before the chirping sound was coming from the transformer (T904).

Right. But chirping is also somewhat common when a power supply cannot start due to a bad start-up capacitor, and the chirping in those cases also comes from the transformer.

Besides, CapXon doesn't have a really good reputation around here. Most people usually just replace them on sight, especially in LCD TVs and monitors, because they are known to fail over time (they don't last in hot places at all).

Nope, I haven't thrown anyway anything.

Excellent! Keep them. When you get the new caps, install everything the way it was originally.

Yeah, I would still replace those RadioShack Caps with something else. I was just trying to fix that PSU in one day and RadioShack is the only place to get things local. Those caps weren't all that cheap though about $5-$6 dollars a piece, but that is RadioShack for you.

Ouch, that is quite expensive for a capacitor. Good quality, low ESR capacitors usually cost under $1 each (and only around $10 for the whole order + shipping).
The Radio Shack capacitors cannot stay because it's very likely that they are not filtering noise and ripple very well right now, and this may damage other capacitors and components in the TV over time.

In addition to that, also replace C957 (10uF, 25v - this is the standby supply startup capacitor - very important), C958 (47uF, 25v), C955 (2200uF, 16v - this is the standby output filter capacitor, also important), and C921 (100uF, 25v).

For C957, C958, and C921, you may also use any of the following caps in addition to the caps I listed above:
United Chemicon LXY and LXZ, Nichicon PW and PM, and Panasonic FC.

Let me know if you need more help finding the replacements.

I didn't necessarily mean to combine it all into one, I was thinking of using just one power supply to piggy back the TV's power supply, rather than having two.

Should be possible. I can think of a few ways, but they are pretty complex. Changing the capacitors is still easier.

[revenger681]

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Hey guys,

My Philips 48" t.v. went out Monday (3 days ago). I searched all over google for "my philips t.v. keeps turning off" and etc. And I found your great forums here. I did some searching through this thread. Through this one and other posts on your forums I was able to find all the information I needed. I'm a network technician, but know nothing about other electronics and how they work as far as t.v.'s and etc. go.

Through reading your forum posts: I was able to get my t.v. up and running via over-night shipping my new caps, and soldering them in place of the old ones... My t.v. works GREAT now!

I just wanted to visit this site and thank all of you guys for providing such an informative and helpful forum here. I ended up fixing my t.v. for $9.00! My t.v. is the same model/kind as the one here: 42PFL5432D/37. Seems like a common problem with this model. Everything else about this t.v. is great though, for it's price.

Again: thank you all for your informative posts!