Philips 32PFL3403d/27 LCD NO POWER

[PlainBill]

Re: Philips 32PFL3403d/27 LCD NO POWER

Sorry I was gone for a while....I didn't detect much of a voltage drop across R931,932 and 943. So I unplugged wire 10 from CN902, tested the voltage of #10 pin on CN100, (to pin 6 for gnd) with 2.1V.

Well, I hope you enjoyed your vacation, because I almost lost the trail on this one. Let's see if I can dig up the service manual.

Got it. This is driving me nuts; it's like trying to swim in quicksand. On the main board CEC_PWR goes low, turning off Q107, which allows CEC_PWRSB to go high. R140, a 2.2K resistor pulls CEC_PWRSB to 3.3 volts. Holding it low is the base of Q102, which has an internal 10K resistor and the base of Q101 via an external 10 K resistor. Through the wizardry of a modern calculator, I come up with the voltage at pin 10 of CN100 should be a minimum of 2.5 volts.

Now let's list possible culprits. C138 and C140, Q101 and Q102 seem to be the only possible candidates. C138 and Q101 can be tested by measuring the voltage at the base of Q101. If it is 0 volts, one of them is shorted and it would explain the discrepancy. The voltage at the base of Q102 can't be measured directly, but the voltage at the collector can. C140 can only be tested by removing it and seeing if the voltage rises.

Another possibility would be to bridge R140 with another resistor. I'd suggest starting with about 5.1K, and dropping no lower than 2.2K.

PlainBill.

[John-NZ]

Re: Philips 32PFL3403d/27 LCD NO POWER

What a fascinating piece of diagnosis to follow - I would say that a serviceman's charge-out hours would be up to about $350 by now? Fortunate that they are not all so difficult to trace. I was about to buy the same Philips model (used for 6 months), but it is a worry about the quality of components inside the cheaper LCD TVs. Best service manual that I have seen so far. It seems that all the low-price LCD TVs in known and unknown brand names tend to be assembled in China or elsewhere in Asia, while the expensive sets with LED backlighting, 3D and other features may come from Europe, Korea or Japan. You take your chances on whether you buy the item that was assembled on Monday or Friday, perhaps!

[mkemre]

Re: Philips 32PFL3403d/27 LCD NO POWER

Has this problem been solved. I have a similar TV having similar issue.

[PlainBill]

Re: Philips 32PFL3403d/27 LCD NO POWER

Has this problem been solved. I have a similar TV having similar issue.

Not that I know of. But you have some key points to check, good luck,

PlainBill

[sscs]

Re: Philips 32PFL3403d/27 LCD NO POWER

SOLVED: mine had no power as well.

I did some testing around on the power supply board and looked for shorts and all. Well, I found it. The Schotty diodes (901/902 of SP10150) were reading short. I pulled the caps around them with no change. still shorted. I then pulled the diodes and one of them was fine and the other was shorted out. I was brave and put in a Schotty diode that was of the same basic spec and now it works!