PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

[xclusiveplayer]

I have a Philips 32" LCD manufactured in 2007 that have been working for the past couple of years. One day, I turned it off and it wouldn't power on again. When I press the power button nothing happens i.e. no power light, nothing is displayed to the screen. All the electrolytic capacitors are from a reputable brand (Rubycon) which are all flat and shows no signs of wear. When plugged into a power outlet my multimeter shows no DC voltage to the biggest capacitor. Anyone have any ideas what may be the cause to this problem?

[PlainBill]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

I have a Philips 32" LCD manufactured in 2007 that have been working for the past couple of years. One day, I turned it off and it wouldn't power on again. When I press the power button nothing happens i.e. no power light, nothing is displayed to the screen. All the electrolytic capacitors are from a reputable brand (Rubycon) which are all flat and shows no signs of wear. When plugged into a power outlet my multimeter shows no DC voltage to the biggest capacitor. Anyone have any ideas what may be the cause to this problem?

One obvious cause is that big white label right smack dab in the middle of the picture.

But that doesn't really answer your question, does it? This looks like a fairly typical design. The left hand end of the board is a PFC front end, the bottom 1/3 of the remainder is the standby supply, while the upper 2/3 is the main supply.

Have you checked the fuse? If it IS open, find the cause before replacing it.

If the fuse if good, check for AC at the power cord connector. Also, what is the identifier for the large gray block right above the bright blue NTC thermistor? It looks like it could be either a relay or a capacitor.

That very large cap looks like it might be part of the PFC circuit. How about a reverse angle shot so we can see what is under the heat sink in the lower left corner.

PlainBill

[Wizard]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

This is geniune philips SMPS and mainboard is also philips as well.

Time for multimeter and start measuring the fuse (blown fuse is open circuit) and rectifier bridge, and other things for short or opens.

Of this design, this may be 12V standby design. Not 5V. Like I said regarding Philips, they are illogicial.

Cheers, Wizard

[xclusiveplayer]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

Have you checked the fuse? If it IS open, find the cause before replacing it.

The only fuse that I'm able to check is the ceramic fuse and I'm getting an fluctuating reading from "0.00-3.00" ohm. Does that mean that it's good?

If the fuse if good, check for AC at the power cord connector. Also, what is the identifier for the large gray block right above the bright blue NTC thermistor? It looks like it could be either a relay or a capacitor.

Testing the power wire by itself plugged in I get 115VAC. However when connected to the TV, I get 6-7 VAC from the white plug located on the lower left of the power supply. Does this seem odd that the voltage reduces to much? The gray block is a capacitor and it's identifier is C010.

That very large cap looks like it might be part of the PFC circuit. How about a reverse angle shot so we can see what is under the heat sink in the lower left corner.

PlainBill

I appreciate the help Bill.

[PlainBill]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

The only fuse that I'm able to check is the ceramic fuse and I'm getting an fluctuating reading from "0.00-3.00" ohm. Does that mean that it's good?



Testing the power wire by itself plugged in I get 115VAC. However when connected to the TV, I get 6-7 VAC from the white plug located on the lower left of the power supply. Does this seem odd that the voltage reduces to much? The gray block is a capacitor and it's identifier is C010.



I appreciate the help Bill.

That is very strange. It sounds like you may have a defective power cord. You should see 115 VAC at the white connector.

As far as the picture, I am reminded of a saying by Karl Von Clausewitz "An order which can be misunderstood will be misunderstood." I wanted a picture taken with the board right side up, but rotated 180°, so I could see under the heat sink. OF course, if indeed the power cord is bad, it won't be necessary to provide that picture.

PlainBill

[xclusiveplayer]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

That is very strange. It sounds like you may have a defective power cord. You should see 115 VAC at the white connector.

As far as the picture, I am reminded of a saying by Karl Von Clausewitz "An order which can be misunderstood will be misunderstood." I wanted a picture taken with the board right side up, but rotated 180°, so I could see under the heat sink. OF course, if indeed the power cord is bad, it won't be necessary to provide that picture.

PlainBill

The white cord is connected to some sort of relay. Its brand is Hosiden and has rating of 2.5A 250V. Does this has anything to do with the reduction in voltage?

[xclusiveplayer]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

There are only resistors under the heat sink.

[tmwalsh]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

I *believe* PlainBill wanted to see the components attached to the heat sink, in addition to seeing what is under them.
The power cord plugs into the receptacle in the last thumbnail, and there should be 115AC across the wires at the back. You *should* be getting 115AC across the black and white wires in the connector at the bottom left of the board. If the fuse is blown, you would also measure higher voltage when measuring from 'end to end' of the fuse. The fluctuation you were seeing is likely a capacitor in the circuit bleeding and feeding from the battery in your meter. If you are really unsure, take the fuse out of the holder and test it.
I think you may have a bad power cord as noted. Try pressing the cord gently towards the board and away from the board, or wiggle the wire where it goes into the connector while measuring the voltage at the board connector. You can likely put the VOM pins into the connector and they would stay there while you wiggle the wire.
tom

[PlainBill]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

There are only resistors under the heat sink.

That's not a relay, that's the connector for the power cord! Maybe the power cord is defective, there is a bad connection from the receptacle to the internal wires, OR the cord wasn't plugged in completely.

PlainBill

[xclusiveplayer]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

I *believe* PlainBill wanted to see the components attached to the heat sink, in addition to seeing what is under them.
The power cord plugs into the receptacle in the last thumbnail, and there should be 115AC across the wires at the back. You *should* be getting 115AC across the black and white wires in the connector at the bottom left of the board. If the fuse is blown, you would also measure higher voltage when measuring from 'end to end' of the fuse. The fluctuation you were seeing is likely a capacitor in the circuit bleeding and feeding from the battery in your meter. If you are really unsure, take the fuse out of the holder and test it.
I think you may have a bad power cord as noted. Try pressing the cord gently towards the board and away from the board, or wiggle the wire where it goes into the connector while measuring the voltage at the board connector. You can likely put the VOM pins into the connector and they would stay there while you wiggle the wire.
tom

I just did some further testing and it shows that the power wire is not defective. I measured it incorrectly...Now I get 117VAC from the white plug and 117VAC from the white ceramic fuse. More pics of shots under the heat sinks and the logic board below

[xclusiveplayer]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

Picture of all components attached to the heat sinks as requested.

[Krankshaft]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

Well if the fuse isn't blown shorted bridge rectifiers and switching semis can be ruled out.

The next step would be to check if the standby supply is outputting the proper voltage without the standby there is no power to kick the main power supply on. D220 and D223 are the output diodes.

[xclusiveplayer]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

Well if the fuse isn't blown shorted bridge rectifiers and switching semis can be ruled out.

The next step would be to check if the standby supply is outputting the proper voltage without the standby there is no power to kick the main power supply on. D220 and D223 are the output diodes.

I'm a noob when it comes to testing diodes. Do you need a specific tool to test diode? Which selection would I use on my fluke, ie vac,vdc,mohm,kohm? Does it matter which order I put the nagative & positive lead to the diode? Do I have to plug in the power plug? What would be a good and bad reading?

[sam67]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

I prefer to test diodes with analogue meter set at x1 ohm and then x10k ohm ..you should get one reading one way and no reading the other way...oh and make sure you lift one leg if it's in parallel because of back circuits ..unless you know there is nothing interfering with the diode..you can use the diode test function on your dmm but i prefer analogue to see if the diode is leaky.

dmm diode function you should put red probe to anode and black probe to cathode ( usually has a marking for cathode like a stripe) you should get a reading ,then move red probe to cathode (stripy one) and black to anode and you should not get a reading.If 2 readings then diode is considered faulty.

p.s do it with power off.

[sam67]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

oh by the way when set at x1 ohm on analogue meter you test with black to cathode and red to anode and there should be no reading..then reverse the probes and there should be a reading . I then test at x10k ohm also.

pps dmm is a digital multimeter ,some use the term dvm digital volt meter .

man this edit time option needs extending

[sam67]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

This is for testing just diodes not zenor diodes etc.

This quick edit option is really a pain now ..sorry for multiple posts but was also on phone while typing lol.

[sam67]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

Just realised that you were on about the diodes to the heat sinks and here i was thinking you were on about the smaller diodes ,silly me I think i will keep my mouth shut lol.

[Krankshaft]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

Sorry I mean't to say they would be a good measuring point to check the DC voltage of the standby supply.

Trace one of the diodes to it's respective filter cap set the meter to DC volts and measure with the black probe on the - trace and the + probe on the positive.

On testing diodes your DMM should have a diode check function don't use the resistance measurement. Yes in one direction there should be a voltage drop in the other you should measure nothing OL should be displayed.

[xclusiveplayer]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

Testing both D220 & D223, I'm getting .099 when in the correct polarity along with two quick beeps. However, testing them in reverse polarity I'm getting an increasing reading instead of "O.L". Could the diodes be bad?

The strange thing is D600 & D608 are giving the same results for both correct and reverse polarity with a single beep. Both .065 and no OL for reverse polarity.

[xclusiveplayer]

Re: PHILIPS 32" LCD 32PFL7332D/37 WILL NOT POWER ON!

Knowing myself, I could be doing something wrong because all of the other diodes that I test did not give "OL" is reverse polarity. Any chance they all could be bad?