Philips 42PFL7422D/37 is dead

[tibimakai]

Yesterday, I had a couple of minutes and I looked at this TV and it's a weird one, never had one of these and I'm lost.
It's the one with a small power supply on the main board.
No light, no clicks nothing.
I have measured the bridge and nothing comes out of it(0.056V). Input is 120V.
I have removed it to be able to measure it and it checks out OK. That is weird.
Fuses are OK on PS and on the main board PS also.
The main caps( there are 4 of them) measure 0V. The connectors on the boards are those that are all covered and it's no way that I can measure the voltages this way. I will have to somehow raise the boards to be able to measure them from underneath.
I have took some pictures, but those I can only provide later when I'm home.
At this point I'm looking for opinions, where to start.

[tom66]

Re: Philips 42PFL7422D/37 is dead

Possible a relay or open fuse?

[tibimakai]

Re: Philips 42PFL7422D/37 is dead

I don't understand how does this PS works with relay and a secondary PS on main board. I never even had a power supply with a relay yet.

[tom66]

Re: Philips 42PFL7422D/37 is dead

Relay is for inrush current limit (so it won't blow fuses or trip breakers) or for switching main PSU on or off.

In the first case there's an NTC or resistor in series which limits the current. The TV can't run properly with this resistor so the relay shorts it after a short period of time and the TV works.

In the second case the relay just turns the power off or on to part of the PSU.

Sometimes the two are combined using two relays.

[budm]

Re: Philips 42PFL7422D/37 is dead

I s there a chassis number pirnted on the model numbe label?
http://elektrotanya.com/?q=showresul...oria=&kat2=all

[tibimakai]

Re: Philips 42PFL7422D/37 is dead

If I remember well is Q523-1ULA.

[budm]

Re: Philips 42PFL7422D/37 is dead

OK, I did download the correct service manual then.

[tibimakai]

Re: Philips 42PFL7422D/37 is dead

I have it too, but no time to really look into it. I have a 4 year old daughter

[budm]

Re: Philips 42PFL7422D/37 is dead

Can I see the picture of the board? I have two versions, one is power-inverter board combo, another version is just power supply.

[tibimakai]

Re: Philips 42PFL7422D/37 is dead

The inverters are on the side of the TV.
Soon I will be home and I will post them.

[tibimakai]

Re: Philips 42PFL7422D/37 is dead

Here are the pictures:

[budm]

Re: Philips 42PFL7422D/37 is dead

Do you get anything on that large black cap on the main board, it should have 170VDC on it the minute you plug power cord into the outlet.
Also check R3318 to see if it is open.

[Dgtech]

Re: Philips 42PFL7422D/37 is dead

Replace the bridge rectifier just to take a cheap stab at it. If it were shorted it would take out the main fuse. It may be open. Change it out and go from there. This problem shouldn't be too hard to find. There should be only a few components that power hits before the bridge schematically.

[selldoor]

Re: Philips 42PFL7422D/37 is dead

This problem shouldn't be too hard to find.

Famous last words?

[Dgtech]

Re: Philips 42PFL7422D/37 is dead

Yeah , I hear ya. My boss is always saying stuff like, " Here. Do this job. It should only take you fifteen minutes." Two hours later, I'm pissed.

Here is a copy of the schematic from that PDF. As you can see here, theres a handful of components in the bridge rectifier section. That transformer could possibly need the leads reflowed. It may be open all toghether.

[tibimakai]

Re: Philips 42PFL7422D/37 is dead

Bud, that resistor is good.
I had a bit of time and I have look at the TV.
I have noticed that one of the ~ pins of the rectifier goes to the relay. There is no 5V stby voltage and the relay doesn't kick in. This is the reason that I don't have any voltage at the main caps.
Now why I don't have the STBY voltage? Where is created this voltage. Next step is finding this issue.

[budm]

Re: Philips 42PFL7422D/37 is dead

Th circuits as shown in post15 is the one you need to check, that is where the standby power supply is located, that is I ask you to check the voltage on the large cap of the MAIN board, not on the power supply board.

[Dgtech]

Re: Philips 42PFL7422D/37 is dead

I have measured the bridge and nothing comes out of it(0.056V). Input is 120V.

Am I missing anything? The problem states that he has 120 in to the power board's bridge rectifier and nothing coming out from the bridge rectifier. CHANGE THE RECTIFIER - or did you measure this wrong?

[budm]

Re: Philips 42PFL7422D/37 is dead

I think he has been measuring the voltage on the bridge rectifier on the MAIN POWER SUPPLY board, the rectifier will not get get any AC feeding it until the relay is turn on by the main board. The standby power supply is on the Main board which creates the standby power for the main board (SSB), that is where he needs to check and see if the standby power supply is working or not.

[tibimakai]

Re: Philips 42PFL7422D/37 is dead

On the main board the capacitor measures 2.69V, but it reaches that very very slow. Goes up in tenths at a time. That is weird.