Philips 42PFL3704D/F7 Dead

[budm]

Re: Philips 42PFL3704D/F7 Dead

That should not stop AC from being at the bridge rectifier unless the main fuse is blown, there is/are open trace/traces from the AC input to the Bridge AC pins some where.

[kevinm34232]

Re: Philips 42PFL3704D/F7 Dead

That's what I thought, I think Tom said the relay had to kick on first though..

[kevinm34232]

Re: Philips 42PFL3704D/F7 Dead

Will this block diagram help determine where I need to look at?? I'm stuck here, I would go from the fuse to the bridge rectifier normally but something in between here... I see RL1201 sending back to main bridge rectifier but goes to standby circuit first looks like..

[budm]

Re: Philips 42PFL3704D/F7 Dead

OK, there are more than one bridge rectifier, one has AC fed through the relay for the main power supply which I believe that the shorted out transistors are in or they are in the standby power supply section. The standby power supply is always on, the main board will turn on the relay to run the main power supply instead of using PS_ON to turn on the IC. . So if the standby does not work, the relay will not turn on.

[kevinm34232]

Re: Philips 42PFL3704D/F7 Dead

Is the standby the 3.3vL?

[kevinm34232]

Re: Philips 42PFL3704D/F7 Dead

What DC voltage should I have at the transformer T1201? I checked pins on primary side and getting about 76v.

One more thing before bed, R1217 is a 820k resistor as is R1218 and R1219. R1217 measures about 860k the others around 824k. Is that one out of spec?

[budm]

Re: Philips 42PFL3704D/F7 Dead

You need to measure the DC voltage right across C1201 (47uF 350V), it should be around 170VDC, as you can see the negative leg of this filter cap is not the primary ground for this standby power supply. So this is the section that you had replaced the blown transistor/MOSFET.

[kevinm34232]

Re: Philips 42PFL3704D/F7 Dead

Yes it has 166v

[kevinm34232]

Re: Philips 42PFL3704D/F7 Dead

I finally just replaced this power board and I got the TV to power on only to find the screen was cracked... It comes on for a few seconds and then shuts down. Is it normal for some TV's to shut down if panel is cracked or do I have another issue??..

BTW the problem was defientely in the standby power section. I was never able to isolate it, and finally 2 legs on the transformer burned up and that's when I gave up on it..

[tom66]

Re: Philips 42PFL3704D/F7 Dead

You probably have cracked bulbs in the panel from something hitting the screen pretty hard.

[MisterD]

Re: Philips 42PFL3704D/F7 Dead

I finally just replaced this power board and I got the TV to power on only to find the screen was cracked... It comes on for a few seconds and then shuts down. Is it normal for some TV's to shut down if panel is cracked or do I have another issue??..

BTW the problem was defientely in the standby power section. I was never able to isolate it, and finally 2 legs on the transformer burned up and that's when I gave up on it..

Just out of curiosity does it still shut down if you unplug the connector going to the T-Con Board? since the screen is cracked I was wondering if this could be a test for others dealing with a possible cracked screen but not knowing because it shuts down too fast to see, I realize that doing this is also eliminating the T-CON Board as well. Thanks.