Question about jumpering P.S.-on command

[Ltank]

If a TV P.S. can not be jumpered (470 ohm 1/8 watt resistors) then is the P.S. always bad?(5vdc stdby to PS_On) So if the main board is not sending voltage to the front panel where the buttons are then the standby led power comes from the main board. and it does not light up. (3.3vdc on several pin but not lighting up, then the main board is bad? There are no shorts on any outputs to the Led backlighting or voltages to the main board.
How is the AC-Det signal made and processed? I know the AC comes in on the SMPS. So is it generated and processed on the P.S. board itself? The AC-Det pin has zero volts on it. So The Power Supply is bad?
AC-Det signal is sent to the main board and and gets processed to send back the PS-On command? Can the AC-Det if low be jumpered high to turn on the P.S.? The standby led power comes from the main board. and it does not light up. Then the main board is bad? If there is zero vdc on the AC-Det then the the P.S. is bad? Is the AC-Det signal being sent to main board?
I have two P.S. that jumping the BU5V to the PS_On and the P.S. dont turn on. The original and a New P.S. does same thing. I have jumper on many power supplies in the past and at this point am I fighting two bad supplies?
With LED SMPSthe P.S. has to sense the correct load current draw before starting? Does it have to be loaded? Is it not turning on because it does not have the correct load. Guys please feel free to enlighten me on what I am not understanding to properly test these P.S. Board level repair I have a fair amout of experience but it was a different feild of electronics.
Thanks

[budm]

Re: Question about jumpering P.S.-on command

If you know that this TV standby lamp should be on (some TV may not have any lights on the front panel until power switch is activated) when the TV is not switched on and you do have 5VSTBY feeding the main board processor to run, then yes, there is problem with the main board.
So do remember if this model suppose to have some knid of indicator lights when TV is off?
What is the make and model of this TV? Some TV will have AC DET signal that HIGH= GOOD, some may use HIGH = bad.
Pictures of the boards?

[Ltank]

Re: Question about jumpering P.S.-on command

There is 5vdc on P.S. The universal remote will not turn it on. No PS-On from main board. Substituting the P.S.-ON by jumping at the P.S. will not turn on P.S. So it seems a bad P.S. and Main board? Sharp LC-60LE820UN. I had another post but I had problems trying to understand the AC - DET and trying to jumper on P.S. So I wanted to address this issue that could be applied to almost any TV. I did not know if I have two bad P.S. and bad main board or 2 good P.S. and one bad main board. I hate to spend more money on a main board if not needed. My main concern now is to turn on the P.S..In all other P.S. I had worked on in the past I have been able to jumper them on.

[Ltank]

Re: Question about jumpering P.S.-on command

Pic of P.S.

[budm]

Re: Question about jumpering P.S.-on command

So what brand is this so I can look at SJ to see if he has good clear pictures of the board?
OK, it is a SHARP DPS-141CP

[budm]

Re: Question about jumpering P.S.-on command

OK, so when you said it does not turn on when PS_ON is applied, what do you mean by that? Do you see the DC Voltage on the main filter caps (3 of them laying on its side) go up from 170VDC to > 360VDC?
Do you see 13.2VDC at the PD?

[mmartell]

Re: Question about jumpering P.S.-on command

Some power supplies are not active-high but active-low and so pson needs to be grounded for those supplies to turn on. I cannot tell by looking at the board but budm certainly can tell which type you have here.

@budm the set is a Sharp LC-60LE820UN

[Ltank]

Re: Question about jumpering P.S.-on command

I will try a active high then a low because I was not sure what to do with it. I have never had to jumper them before on other sets. But without jumping what I have is described below.
When jumpered there was no voltages. The main caps were still 170 vdc. There was no 13.2 vdc for audio power. I now suspect either two bad P.S. or that I have a bad LED backlight.
If that's the case the P.S. output to LEDS have no marking as to what the voltage or current rating. This makes it difficult to figure what resistance to jumper across the outputs to fool the P.S. that the LEDS are good.

[budm]

Re: Question about jumpering P.S.-on command

More likely to be active high, if the Voltage on the main cap does not go up to >360V, then the PFC is not working or the force on signal did get through to turn on the PFC Voltage booster.
Shopjimmy does not have good pictures of the board. Can you please take good pictures of the whole bottom side of the board for me?
BTW, the LED driver power supply runs on boosted Voltage and it looks like it has 4 LED strings.

[Ltank]

Re: Question about jumpering P.S.-on command

I jumpered (PD-11 BU5V) to( PD-10 PS-On) and to (PD9-9 AC-Det) with 470 ohm 1/8 watt resistors. I did get 13.2 volts on the (PD audio power pins 1-4).
But across the main filter caps is still 168vdc. I went ahead did some other checks any way. I am unaware of anything else to to to make the P.S. come out of standby and turn on. Odd that I got the 13.3vdc though.
There was no voltage on any pin of LB connector when connected to the main board ot not connected to the main board. There was no voltage out to L1 &L2 to the LEDs.
I did a diode and resistance check on L1&L2 that feeds voltage to the LEDs and all readings any combination were all open. That is higher than my Fluke 87 would read. If they are open the the P.S., does it sense this and does not turn on power to the LEDs? Does anyone know what I should read if the LED strips are good? Or what resistances can safely be used to trick the P.S. to turn on? This would tell me that the two P.S. I have are good.
The other issue is I can not get the TV touch key pad to to work. There is Voltage to the Keypad. Do I also have a bad main board? P2005 to front panel
remote sensor and key pads are. Pin #1 is 3.28vdc #3. is 3.28vdc
#5 is 2.3vdc #7 is 2.4vdc all other pins are zero.

[Ltank]

Re: Question about jumpering P.S.-on command

With the P.S. has only 170 vdc the then both supplies are shot? Unless there is something else to make the main caps come up to 390vdc.
Because I had high resistance across L1 and L2 higher than 3 meg that my meter reads
I tried using 2.2m ohm resistor across the pins. In theroy the parallel resistance will be less than the lowest resistance that are paralleled together. The only readings I got was the 2.2 meg ohm reisistance of the resistor confirms that Both L1 and L2 branches are open circuit? I have a big can of worms here!

[budm]

Re: Question about jumpering P.S.-on command

AC DET is the error siganl that is fed to the main board to tell if there is error, then the main board will determine what to do with that error signal, the power supply will run without AC DET.
"I did get 13.2 volts on the (PD audio power pins 1-4)." So it does detect the PS_ON so the 13V does get switched on.
The LED power supply drive circuit will not run on 170V, you need to get hat boosted Voltage up first for it to run.
I need to see the bottom side of the board.

[Ltank]

Re: Question about jumpering P.S.-on command

Bottom of board

[budm]

Re: Question about jumpering P.S.-on command

OK, you need to get the P/N of that PFC Controller IC so we can find out if we are getting the B+ at the VCC pin.

[Ltank]

Re: Question about jumpering P.S.-on command

There are two PW Controller IC DDA003A and a DDA002C

[budm]

Re: Question about jumpering P.S.-on command

Right now we are interested in the PFC Controller IC that needs to be checked out as I redlined in the picture in post 14.

[Ltank]

Re: Question about jumpering P.S.-on command

The DDA002C Gnd Pin#14 is connected to Gnd of the Main filter cap on the Primary P.S. 450v 68uf cap. Pin #16 VCC of the IC has zero volts. I will try to trace ot the problem. Poer Supply is a Sharp RUNTKA684WJQZ
No visual problems nothing obvious.

[budm]

Re: Question about jumpering P.S.-on command

The PFC Controller IC only has 8 pins, please see my post #14 AGAIN.

[Ltank]

Re: Question about jumpering P.S.-on command

Ok. I took a pic of two 8 pin IC. 16088P is the PFC controller. VCC is zero.
38S3LJ is another PW Controller. VCC is 16.2vdc

[tom66]

Re: Question about jumpering P.S.-on command

Check VCC to GND on PFC controller for shorts (ohm range, power off)