Question about Philips 42FD9954 42 in. Plasma HDTV

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Philips 42FD9954/17 Power Problem, will not turn on.

The DC power relay will not energize when the on button is pushed. I have two monitors that act this way.
Have made some ac and dc voltage checks with the units off and compared them with a good monitor in the off position and they look good. Have ordered a service manual but would like to know if this is a common problem with this model. If so, what component should I look at ?

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Re: Philips 42FD9954/17 Power Problem, will not turn on.

I repaired this model TV for a friend. The red standby LED would take about a minute to come on, and most of the time the TV wouldn't turn on even after it, and the relays would engage/disengage rapidly when it did try to turn on. After reading about the capacitor problems, but not finding any obvious physical issues with them (and not having a way to readily test capacitances) I went ahead and replaced all the Rubycon branded caps on the power board. This solved the problems - the red standby LED comes on immediately and the TV turns on like normal with a single click engagement of the relays. It seems the problem is just the low quality/defective/bad run of capacitors. I spent about $40 on capacitors at a local electronics supplier, but probably could have spent half of that if I hadn't wanted them right away and ordered online.

Posted on Nov 01, 2009

Re: Philips 42FD9954/17 Power Problem, will not turn on.

Hello: I'm having the same problem, Your voltages can't be good . the issue is on the standby power supply, that is the TYN256 IC, but that IC is not the problem, something else cause the voltages go all wrong, where it's suppose to have 24V i read 12V, on the 9V, reads 6.8V , the 5V reads 3.8 , the 3.3 seems to be good, the problem is you need 9V to energize the relays, I've checked for shorts and nothing, all components look good, this IS a common problem, and I'm pretty sure it's cheap to repair , just nobody seems to have the right clue that what's the faulty component.

Posted on Dec 19, 2007

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Push on and off button, you can hear the click like it is coming on, and you can also see the yellowish light like it is on, but it is not. I own a 50' philips flat tv


The problem is that there is a bad capacitor on the power supply board of the television, it is still turning on because it is not yet completely bad. While it tries to respond is when you get the clicking sound, therefore it is going to keep acting that way until the bad capacitor is replaced.

Run a check on the power supply board, you will definitely see the bad capacitor, have it replaced and the television will turn on after reassembling the television back together.

Thank you for using fixya

Jun 29, 2011 | Flat Panel Televisions

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37PF9731D/10 - when turned on the tv power light remains green but no picture or sound. Just a clicking sound - like it does normally when swiching on from being on standbay. It reapts the attempt to turn...

The clicking sound is from the main power supply relay being turning on and off, it is driven by hte main board and it gets the power from the standby power supply board.
You need to check the main powwer supply board and the standby power supply board voltages.
Check the resistor in the main power supply board also
Please see my pictures here:

Basic LCD monitor and TV troubleshooting guide:
Failed TV and Monitors pictures:
Learn about bad caps:
Capacitors kit: he can make you a set of caps.
Or, just make sure to use caps with low ESR, 105c, high ripple current and long life rating such as PANASONIC FM or FC series.

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3 Answers

I have a phillips flat screen tv and to repair man say that it needs the power supply board ! the tv does not turn on but when you hit the power button on the remote a red light blinks in front of the tv !

There's a good chance you have failing electrolytic capacitors either in the power section or the inverter section or both.
Any caps in these sections that look bulged at the top, or bulged/leaking at the bottom need to be replaced.
If you repeatedly turn it off and on, eventually it'll probably stay on, but every time you turn it off, the TV will get harder and harder to start up until one day it just won't.
Sometimes you have to do the opposite to start it up and unplug it for some time and then try again.

If you aren't tech savvy, don't worry, read the rest of this solution and watch the videos.

If you are handy with a soldering iron and can identify the power supply and inverter / FM section for the backlights, an inexpensive handful of capacitors will likely fix you right up.
Match the capacitance on the capacitors. Go over voltage if you can, and still have them fit.
IE - it's not a bad idea to replace a 10V cap with a 16V or 25V or even a 50V, but don't replace a 680uF cap with a 500uF or a 1000uF (unless you are positive it's only doing ripple filtering, and even then, you should go OVER, not under the uF rating).

Most of the caps that go are 10V 1000uF or 3300uF.

I found some great videos of the procedure (for many Samsungs with the same issue) on youtube.

As you can see, this issue spans plasma TVs, as well as large and small LCD TVs and monitors.
The parts are cheap, and skill required is minimal.

May 30, 2011 | Philips 42FD9954 42 in. Plasma HDTV

1 Answer

My sva lcd (vr-2600w) recently will not power on. The red light in the corner is still lit up red, but when I push the power button it doesn't turn on. I've already replaced the power board almost a year...

Right now you only have 5vdc standby power supply working. It can be the main board, power supply module (bad DC filter caps). You need to open it up and do in-depth troubleshooting.

Basic LCD monitor and LCD TV troubleshooting guide:

Failed TV, Monitors, Caps :

Learn about bad caps:
Capacitor kits: he can make you a set of caps for you.
Please post back what you find.

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1 Answer

Power light blinks red

Hello, If you can turn it back on with the s momentary key or power button:
When it shuts off, do you need to push the power button once or twice to get it back on? Also, does anything else about the picture or sound change as it warms up?
If once, then the controller is shutting the TV down either as a result of a (thermally induced) fault in the controller or it sensing some other problem. Monitoring the voltage on the relay coil (assuming these is one) could help determine what is happening. The controller thinks it is in charge.
If twice, then the power supply is shutting down as the controller still thinks it is on and you are resetting it. A couple of possibilities here would be low voltage or high voltage regulation error (excessive high voltage is sensed and causes shutdown to prevent dangerous X-ray emission). A partially dried up main filter capacitor could also cause a shutdown but there might be other symptoms like hum bars in the picture just before this happened. Clipping a good capacitor across the suspect (with power off!) would confirm or eliminate this possibility.
If it uses a pull-knob (or other hard on/off switch), then this may be like pulling the plug and would reset any abnormal condition.

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2 Answers

Magnavox 15mf605t/17 15'' LCD HDTV won't turn on

Have similar TV. If it is set to the PC source, it goes into standby when there is no signal, like a regular monitor. Even though the monitor is in standby, you can still press the Source button to change to, say, HD input, and will use the familiar on/off action when pressing Power on the remote.

A little weird, but I've gotten very used to it.

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Does the remote have one power button for on/off .... or, does it have separate buttons ?

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42pf9956/37 philps plasma

I don't know why but this got my TV on.
I took off the back cover and found the source of the clicking.
Two blue plastic rectangular relays in the exact middle.
When I pushed the power button, I felt the top relay click, and I saw a flash from the bottom one. (they are right next to each other)
I took a hair dryer and placed it over the two relays for about 1 minute and tried the power.
It clicked only 4 times and then came on!!!!!!!!!
For some reason heat helps the relay.
If anyone is a tech and can explain this, please do.
Good luck!!!!
My tv is on and it didn't cost me anything.
I just can't turn it off now!!!

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1 Answer

15-inch Phillips LCD FlatTV

It could be the AC adapter. That is easy enough to check with a DMM. Turn on the meter, set to volts dc, push red probe into the hole in the output power jack and touch the black probe to the outside of the same jack. Have someone plug the AC cord into a good outlet(one you know has power). If the adapter is working you should see 12 vdc displayed on the meter. There still could be a problem as I recently found an adapter which displayed the correct voltage with no load but little or no voltage with a load. Testing with a load is a problem if you are not familiar with the procedure. Odds are if you have 12 vdc the adapter is fine and you have a short somewhere in the monitor. If you are handy with tools and feel confident, remove the back of the unit and check the fuses in the power supply. If they check OK you probably can't do much more. Unless you are an electronic tech you will need to take the unit to a shop for repair by a qualified tech. Good luck.

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