Philips PLCD190P5 power supply

[The Performer]

Re: Philips PLCD190P5 power supply

If you look at the PLCD300P3 schematic, on page 2 is the PFC circuit, just like yours except it drives two fets instead of just one.
On the L6562 pin 8 vcc. the supply is VCC_PFC . looking to the left is T100, its Collector gets voltage from V_PFC (which is supplied by the standby circuit) and when the base gets turned on supplies the voltage to: VCC_PFC.
transistor T101 is the stby switch, it recieves the on command from the main board and turnes on, lighting the led in the optocoupler turning on T100
Since there is no schematic for your board, these parts need to be identified on your board.

There should be a power on/off command coming from the main board, that MUST be there for the power supply to turn on.
without that command the power supply will sit in standby forever
Being that this is a %&*# Philips, it could be something on the main board that has detected a fault and not allowing the tv to come out of standby.

R_J thank you for both of your replies, I will do further probing around and find the standby transistor. The schematic you are speaking of for the PLCD300P3 pg. 2 is I am assuming in the available service manual. On another note, what is common practice to test an optocoupler that is in circuit? I understand the concept but have never tested one in circuit.

[R_J]

Re: Philips PLCD190P5 power supply

If you look at the PLCD300P3 schematic, on page 2 is the PFC circuit, just like yours except it drives two fets instead of just one.
On the L6562 pin 8 vcc. the supply is VCC_PFC . looking to the left is T100, its Collector gets voltage from V_PFC (which is supplied by the standby circuit) and when the base gets turned on supplies the voltage to: VCC_PFC.
transistor T101 is the stby switch, it recieves the on command from the main board and turnes on, lighting the led in the optocoupler turning on T100
Since there is no schematic for your board, these parts need to be identified on your board.

There should be a power on/off command coming from the main board, that MUST be there for the power supply to turn on.
without that command the power supply will sit in standby forever
Being that this is a %&*# Philips, it could be something on the main board that has detected a fault and not allowing the tv to come out of standby.

[R_J]

Re: Philips PLCD190P5 power supply

NO the standby drive is working just fine. These are complicated power supplies, I suspect that when IN standby, the PFC circuit (L6562) is not powered. When the main board tells the power supply to turn ON, thats when a transistor, somewhere, applies the Vcc to the (L6562) and the PFC circuit boosts the b+ from 160 volts to 400 volts.
When the pfc voltage is at 400 volts, the circuit that supplies the +12-16 & -12-16 volts gets turend on.
There are 3 seperate power supplies on this board
one: is the standby +5 volts which is working.
two: is the PFC boost supply, which is not being told to turn on.
three: is the supply for the other voltages, and needs the pfc to working for it to operate. It too is likely controlled by the on command.

[The Performer]

Re: Philips PLCD190P5 power supply

R_J I am measuring .1v on pin 8 of the L6562, and there is indeed a wire jumper coming from pin 8 and it goes towards that smd transistor you are describing.

Are you possibly suggesting that I may need to look into what is going on with the standby drive ic?

[R_J]

Re: Philips PLCD190P5 power supply

So the standby circuit is working, the L6562 is for the PFC circuit. What voltage do you get on pin 8 (VCC) On some power supplies the pfc runs all the time, on some they are switched on and off. On the PLCD300p3, the pfc, which uses the same ic, has its vcc turned on and off by a transistor. That plcd300 pfc circuit looks very close to yours, It drives 2 fets where as yours only drive 1
If the pfc circuit is not running, the circuit for the +12 may not run either as the supply for it would be too low.
There is a green wire that runs beside the main filter, does one end connect to pin 8 of the L6562 and the other end connect to a small transistor
That 14 pin ic to the left in the picture I believe is the standby drive ic

[The Performer]

Re: Philips PLCD190P5 power supply

This power supply is a bit rare and not much information is available. the other plcd150,170,190P1 schematics are different. I am guessing that the circuit you repaired is for the standby +5, correct. If pin 11 is the control line (ON/Off) for the power supply does it change if you press the power button? It could be that the line needs to be taken low, try what budm said, place 100Ω from that pin to ground and see if the other voltages come up

Yessir, am sitting in front of it now, tried both ways, no luck. I am probing around in the l6562 part of the circuit (from what I understand about power supplies is this area should provide the high voltage via the P20NM50FP mosfet by switching on and off through a transformer?) anyway, I am not seeing any drive waves in this area coming from the L6562 I replaced, my question is should I?

[R_J]

Re: Philips PLCD190P5 power supply

This power supply is a bit rare and not much information is available. the other plcd150,170,190P1 schematics are different. I am guessing that the circuit you repaired is for the standby +5, correct. If pin 11 is the control line (ON/Off) for the power supply does it change if you press the power button? It could be that the line needs to be taken low, try what budm said, place 100Ω from that pin to ground and see if the other voltages come up

This should be the path from pin 11 that controls a couple transistors that control an opto isolator, That opto should be the one that turns on the main power supply, again no schematic so its a bit of a guess.

[The Performer]

Re: Philips PLCD190P5 power supply

Did you have 5 volts standby before the repair? If it is the standby section that was repaired, then you should be able to connect the main and it should turn on the 12 volts, I believe pin 11 is the standby ON pin to turn on the rest of the power supply, check this pin to see what the voltage is.

Thank you for the response R_J, I verified that pin 11 does indeed show 5.1v at rest.

To answer your first question, I do not know if the 5v was present before I replaced any parts, I was given the set by my brother and went from his word that nothing was powering on. I immediately pulled the supply and started visual inspection. Saw the handful of resistors completely burnt, and began meter checking near by obvious mosfets and drive controllers that might be shorted. Not until after I replaced the found bad parts have I powered it on.

I am using a 25w incandescent light bulb as a current limiter while testing and immediately plugging it it the filament glows VERY dim quickly then goes off and little to no current is flowing.

Im having fun trying to learn more but have gotten myself at a roadblock, not familiar with this power supply function and obvious fixes.

[The Performer]

Re: Philips PLCD190P5 power supply

Some of the Philips power supply use Active low (PS-ON to GND = ON) to turn on the rest of the power supply, some is ACTIVE HIGH (PS-ON > 2VDC = ON, <1V = OFF).
You need to test the power supply board by itself but using 100 Ohms resistor between GND and the PS-ON (STBY) pin of the power supply to see if the rest of the power supply will come on or not, if not, then use 1K resistor between standby 5V and the PS-ON to see if the rest of the power supply will come on or not.

Thank you for the response sir! Doing both of those tests did not turn on the 12v output...

[R_J]

Re: Philips PLCD190P5 power supply

Did you have 5 volts standby before the repair? If it is the standby section that was repaired, then you should be able to connect the main and it should turn on the 12 volts, I believe pin 11 is the standby ON pin to turn on the rest of the power supply, check this pin to see what the voltage is.

[budm]

Re: Philips PLCD190P5 power supply

Some of the Philips power supply use Active low (PS-ON to GND = ON) to turn on the rest of the power supply, some is ACTIVE HIGH (PS-ON > 2VDC = ON, <1V = OFF).
You need to test the power supply board by itself but using 100 Ohms resistor between GND and the PS-ON (STBY) pin of the power supply to see if the rest of the power supply will come on or not, if not, then use 1K resistor between standby 5V and the PS-ON to see if the rest of the power supply will come on or not.

[The Performer]

Re: Philips PLCD190P5 power supply

So as an update, i have installed a temporary .1 resistor to do some testing and upon powering up the board both in and out of tv I get 5v output and no 12v output. With these power supplies do I need to short standby pins or anything to get the supply to power on? There's no schematic for the PS board to be found, the only thing I have to go off of is the service manual shows the pinouts of the connector that comes from the ps board. I've attached a screenshot below.

[The Performer]

Re: Philips PLCD190P5 power supply

Get some .68 Ω resistors...

What is the odds that I can use 1x .1 ohm resistor? If im understanding correctly, the 4x .68ohms in parallel have a total of .17 ohms?

Could i use a single .1ohm to do testing while I order 4x .68 ohms or am I wrong assuming this will work?

[R_J]

Re: Philips PLCD190P5 power supply

Get some .68 Ω resistors...

[The Performer]

Re: Philips PLCD190P5 power supply

It is not a "G" ohm, that would be 6.8 gigaohm. Just 6.8Ω
they use 4 resistors to spread the current instead of one large resistor. They are 6.8 Ω. it can also be used to fine tune the current through the fet by changing one or more of the resistors for different size tv's

R_J, I Have now looked closer at the resistors and it looks like I was wrong, the colors are blue, grey, silver, gold... So .68 ohm... The funny thing is the parts I ordered, the resistors that I thought I ordered 6.8 gigaohms ended up being 6.8 ohm... So even though the order was wrong, Im still wrong again...

I was reading the colors as blue, grey, grey, gold, and putting it into my electrodroid app.

Now what do I do... haha.

[R_J]

Re: Philips PLCD190P5 power supply

It is not a "G" ohm, that would be 6.8 gigaohm. Just 6.8Ω
they use 4 resistors to spread the current instead of one large resistor. They are 6.8 Ω. it can also be used to fine tune the current through the fet by changing one or more of the resistors for different size tv's

[The Performer]

Re: Philips PLCD190P5 power supply

Most of the circuits using that L6562 ic either connect it directly to the fets source resistor or use between 10 ohm and 1K.

Ok I guess that makes some sense. Can anyone tell me what is up with the 4 resistors all running in parallel? They are 6.8g Ohm. Did they just need a 1.7g ohm value and that is the only way to get it? Im not used to seeing that.

[R_J]

Re: Philips PLCD190P5 power supply

Most of the circuits using that L6562 ic either connect it directly to the fets source resistor or use between 10 ohm and 1K.

[The Performer]

Re: Philips PLCD190P5 power supply

Well, put it this way, if a resistor fails, it goes higher in ohm value. I did have a look at the board from SJ and I couldn't identify one color ring. So I got either 1k ohm or 100M. So I'd start with the 1k ohm resistor.

Sold american.

Parts are on order, updates as soon as they arrive.

[CapLeaker]

Re: Philips PLCD190P5 power supply

Well, put it this way, if a resistor fails, it goes higher in ohm value. I did have a look at the board from SJ and I couldn't identify one color ring. So I got either 1k ohm or 100M. So I'd start with the 1k ohm resistor.