Philips 37MF321D No power no LED

[budm]

Re: Philips 37MF321D No power no LED

Philips does thing in its own way, it may have been made before the mandate comes along, at least they are using PFC.

[tom66]

Re: Philips 37MF321D No power no LED

There is no 5vdc standby in this power supply, it has the always on 16vdc power supply that feeds the main board, this 16vdc will be used in the stepdown switching power supply circuits (5v, 3.3, 2.2, etc.) in the main board to run the main board , see page 20 of the service manual.

Okay. That's strange for a 37". Usually there's a separate standby supply to comply with low power consumption mandates. (Blue Angel, etc.)

[budm]

Re: Philips 37MF321D No power no LED

There is no 5vdc standby in this power supply, it has the always on 16vdc power supply that feeds the main board, this 16vdc will be used in the stepdown switching power supply circuits (5v, 3.3, 2.2, etc.) in the main board to run the main board , see page 20 of the service manual.

[tom66]

Re: Philips 37MF321D No power no LED

If you've got no standby voltage, then that's the first place to start fixing. The rest of the supply probably won't work without that.

[alexanna]

Re: Philips 37MF321D No power no LED

I do not notice 5v on any of the connectors on the power supply.
Do we want to try to turn on the power supply with applying 3v on the standby pin? And if that doesn’t work try grounding the standby pin?

[budm]

Re: Philips 37MF321D No power no LED

Here is the SCH of the power supply.

[budm]

Re: Philips 37MF321D No power no LED

In this case, per SCH, the HI signal from main board will turn on Q7076, which will turn on the OPTO, which will turn on Q7063 which will supply the VCC voltage to the PFC Cotroller IC.

[PlainBill]

Re: Philips 37MF321D No power no LED

One thing to watch out for, Philips often uses the 'Label = function when high' convention. That is, the label (Standby) indicates the power supply is in standby mode when the Standby line is high. BUT they aren't consistent about it.

The best way to test it is to disconnect the main board from the power supply, then use a resistor (anything between 2.2K and 3.3K) between 5V_SB and Standby. If that doesn't bring the power supply to life, try using the resistor to pull Standby to ground.

PlainBill

[flamike]

Re: Philips 37MF321D No power no LED

I too have the same set in magnavox,same problems, I think its signal board too,pricey guess,bought another set ,I can say that even working set has no standby light just green light when working nothing when off

[budm]

Re: Philips 37MF321D No power no LED

Yes, start checking voltages, that is what I will do after board inspection.

[alexanna]

Re: Philips 37MF321D No power no LED

The manual is for the 26 and 32” televisions.
The problem is that the power and main board is different for the 37 and 42”.
They did include a supplement for the 37 and 42” power board but not for the main board.
I see a 5v and 3.3v LDO regulators on the main board, I guess I can hope one of those are bad.

[budm]

Re: Philips 37MF321D No power no LED

At this point, yes, since it is not putting out the PS_ON signal. Since you have the service manual, you can try locating where the signal is generated from in the service manual.

[alexanna]

Re: Philips 37MF321D No power no LED

When you hit the power button on the TV or using the remote to turn on the TV, the main board will send out the logic high to pin9 to turn on the PFC circuit that is when TV will change from stanby mode to ON mode. The main board is always on 24/7 the minute the TV is plugged into the outlets but it will be in standby mode (pin 9 is LO). This TV does not have 5vdc standby, but it uses the 16vdc that is always on.

So it looks like the problem is on the main board?

[budm]

Re: Philips 37MF321D No power no LED

When you hit the power button on the TV or using the remote to turn on the TV, the main board will send out the logic high to pin9 to turn on the PFC circuit that is when TV will change from stanby mode to ON mode. The main board is always on 24/7 the minute the TV is plugged into the outlets but it will be in standby mode (pin 9 is LO). This TV does not have 5vdc standby, but it uses the 16vdc that is always on.

[alexanna]

Re: Philips 37MF321D No power no LED

I still do not understand this,
Should standby voltage on pin #9 be high any time power is applied to the main board? Or does something else have to occur to take the voltage high?

[budm]

Re: Philips 37MF321D No power no LED

I looked at the diagram, the STANDBY PIN is the control pin from the Main board that when it goes high (3.3~5vdc) it will turn on the PFC circuits which will kick the voltage on the that large cap (120uf 450vdc) from 170vdc (when it is in standby mode) to about 400vdc when it is in the ON. Since you are not getting the logic high from the main board on pin 9, you should verify the connection back to the main board.

Failed TV's and Monitors:
http://s807.photobucket.com/albums/yy352/budm/

[alexanna]

Philips model # 37MF321D
I am having trouble figuring what is going on with this television.There is no power and no LED
Following the trouble flow chart has me wondering if it's correct.
The service manual looks like it's for a 26 and 32” model, with a supplement for the 37 and 42” models. The connectors for the scaler board appear to be different, but the supplement for the 37” power board is correct.
The service manual is available at Elektro Tanya.
On connector 1089 I have,
Pin #1 16v
Pin#2 16v
Pin#3 24v
Pin#4 .8v
Pin#5 0v
Pins # 6-7-8 are 0v
Pin#9 0v and
Pin#10 is 0V
Pin # 9 appears to be standby but its not mentioned in the flow chart; I am thinking I should see a voltage on that pin?