How to use an universal power supply?

[mokie]

Hello, I have a lcd monitor without the power supply board and I am wondering if I could install on it an universal power supply like this one:

http://www.ebay.es/itm/Universal-AC-...3cd86af&_uhb=1


Also I guess I will need something like this for the ccfls:

http://www.ebay.es/itm/1pc-4-Lamp-Ba...112943e&_uhb=1


My problem is that the number of wires doesn't match. The universal power supply has 5 wires and the universal ccfl inverter has 4 wires while I have 7 and 10 wires respectively.
Thanks in advance.

This is what I have:

[mariushm]

Re: How to use an universal power supply?

The inverter has Voltage (+) , Ground (-) , On/Off signal, Adjust brightness.

The power supply of the monitor usually also has the inverter on the same board, so there are no voltage and ground wires (they're on the pcb).

The power supply has to send power to the board with the video connectors (display board) and has to receive from it the on/off and adjust brightness signals from the board with video connectors. So at least 4 of those 10 wires are accounted for. If it doesn't say on pcb by the connector and you're not carefully following the traces from that connector, you're just guessing.

Your universal lcd power supply outputs 12v and 5v but we have no way of knowing if the display board required other voltages as well. It could very well be that the power supply was also providing the display board with 3.3v or 1.8v or some other voltages. So out of those 10 cables at the top, who knows which does what...

The cable with 7 wires goes to that bottom board which seems to be an audio amplifier, if those black things are speakers. Probably the power supply board also had an audio in jack and a small section with an amplifier, in which case those 7 wires could be voltage, ground, audio in left, audio right, audio ground, voltage adjust from display board ... just guesses.

Why don't you tell us the actual monitor model (all I can see is that it's a benq), maybe we can find a service manual and then we can tell you the role of each of those wires?

[mokie]

Re: How to use an universal power supply?

Oh sorry I forgot to mention the model. It's HP 1730

[mariushm]

Re: How to use an universal power supply?

Ok, it seems to be HP L1730. Unfortunately, the only service manual that seems to be out there is for HPL1730R which is made by Philips, not benq.

That HP L1730R has another display board, as you can see in this thread: https://www.badcaps.net/forum/showth...hlight=hp+1730

If you count the wires, they're probably 13, which matches with the connector on page 38 in the service manual:


However, since your board only has 10 wires and a connector with 10 pins, all bets are off. The stuff in the service manual doesn't apply exactly.

BUT... if we look at the power supply connector in the service manual we see there : ground, brightness , enable backlight, panel_idx (?) , ground, 12v x2 , ground , 5v x 2 , ground , 3.3v x 2

and in that display board, there's a voltage regulator that takes the 3.3v and produces 1.8v.
Your display board also has a voltage regulator right there by the connector so it's possible that your display board also needs 3.3v. If not, that regulator that makes 1.8v uses 5v to do it.

Now, searching for the board I also found some images of the backside of your board:



Seeing those two very thin traces near the edge of the board tells me that those aren't used for power, but most likely they're the brightness and backlight enable wires.

The 1st wire on the other side of the connector looks like it's black in your picture, and that's probably GROUND but I can't be sure.

The 3rd and 4th are connected together and there's a thick trace going all the way to the other side of the board and then goes through the board and there's a capacitor there and then it goes into the 30pin panel connector.
The other service manual says there's some mosfet there that helps convert 12v to 5v needed by the panel, so it's possible those two pins bring 12v to the monitor. I can't be sure though.
Red wires are usually for 5v, yellow wires are usually for 12v, orange wires are usually for 3.3v.
I can't tell the colors of the wires from your picture. If you can come back with the colors I can probably try to be more helpful.
Also, say what's written on that small chip by the connector (the voltage regulator). If I know what chip is that, I can tell you the pinout, so if you have a multimeter you can put it in continuity mode and determine what pin in that connector goes to the input voltage pin of that regulator, and then that pin in the connector is for 3.3v or 5v.

Most likely your board also needs 3.3v so you're going to have to provide it as well - there are LM2576 based boards on ebay that can give you that.
But then again, you can find a power supply board for this model on eBay for $40 : http://www.ebay.com/itm/HP-L1730-POW...item19e8683921

[mariushm]

Re: How to use an universal power supply?

by the way, the power supply code is 48.L8802.A01 so you can search for this code on eBay or other parts store and maybe you find the whole power supply board cheaper.

[mokie]

Re: How to use an universal power supply?

Yes, actually the model is L1730 but the power supply that you mention (48.L8802.A01) is not the same that the monitor had. I've already thrown away the old one and i haven't got the number ID.
Here you can see the colors of the wires and the chip ID.
For what I'm seeing, I think that chip is a 2.5v regulator with 5 volt on the input

[mokie]

Re: How to use an universal power supply?

I have checked continuity between the input pin (I think is number 1 because of the datasheet and also because it matches with the letter printed on the board as I) and the wires and there is continuity between input of the regulator and wires white, green and yellow
Also pin 2, which is ground, has continuity with wires purple and blue and pin 3 (output) obviously with anything.

Thanks for your help.

[mokie]

Re: How to use an universal power supply?

I will buy this power supply:

http://www.aliexpress.com/item/100-N...400767569.html

I think it should work althought I don't see where is the cable with 7 wires, I think that is for audio, so the audio won't work I think.

However, the board has a jack input, I don't understand anything.

[mokie]

Re: How to use an universal power supply?

mariushm do you think this board will work?

[mariushm]

Re: How to use an universal power supply?

I have no idea. At 10$ it's worth trying. Anything more and you're better off buying another used 17-19" monitor, they're 30-50$ here.

[mokie]

Re: How to use an universal power supply?

ok, thank you. I've ordered it. I will post the results when it arrives

[mokie]

Re: How to use an universal power supply?

The power board is already here.

I'm trying to connect it. This power board has 1 conector with 10 wires that match perfectly with my display board. But, there's no a conector for the other cable with 7 wires.

I know that this cable with 7 wires is for the audio because I have checked continuity between these wires and the speakers (4 are for the speakers and the other three are black, red and brown, I think it could be for the volume control).

The problem is that the monitor doesnt turn on, even the led i s turn off. The power board isn't working. Can I check the 5v and 12v output from this power board?

Also I have checked that when I push the ON button, there is continuity between red and purple wires.

[Davi.p]

Re: How to use an universal power supply?

You have done a bad job buying that board seen the lack of audio connector (and audio circuitry) and the type of lamps connector. Next time is better to spend a bit more in repairing your old board (if possible) or at least keep it for reference. I've found a possible part number but there's none on sale.

[mokie]

Re: How to use an universal power supply?

But the board has an audio jack input

[mokie]

Re: How to use an universal power supply?

Ok, I have the problem almost solved. The problem is that the cable that I said that matched, actually they don't. Even they have the same colors, there aren't the same voltages.

On the conector of the display board I have identified 5 wires which are 5v, ground and the ON/OFF signal for the inverter. But there are another 4 wires which I don't know their function.

The 4 wires that I don't know their function are orange, red, brown and black.
If I power the display board with 5v and ground but I don't turn on the monitor I get 3.5v on the black one and 0v on the others three.
If I turn on the monitor, I get 3.3 on the brown, 3.45 on the black and 0 on the others two.

Thanks in advance

[Davi.p]

Re: How to use an universal power supply?

"But the board has an audio jack input" It's an optional external power supply jack.
the 3.3v is probably the brightness if you are sure about the on-off, the 3,5 is probably a supply voltage for the audio ampl. section, check if it exits from a voltage reg., if not is maybe one of the on-off / bright. / other.. The board you've purchased has a pinout list on it? If not connect the 5v / gnd and play with the others until you see the monitor running.
(lost for lost..)

[mokie]

Re: How to use an universal power supply?

Now I have this (look at the photo):

3 wires coming from de psu and 4 wires (red and orange are the same) coming from the display board.

I'm trying all posible combination among them without any result.
Only when I link the blue with any other(so I think this is the on/off?) the ccfl turn on for a moment and sound something but it turns off inmediatly.

The voltages when the monitor is OFF are:

Yellow(PSU): 2v
Blue(PSU): 0v
Green(PSU): 33v AC (weird?)

Grey(main board): 0v
orange/red((main board):0v
brown(main board): 0v
black(main board): 0v


The voltages when the monitor is ON are:
Yellow(PSU): 2v
Blue(PSU): 0v
Green(PSU): 33v AC (weird?)

Grey(main board): 4.25v
orange/red((main board):0v
brown(main board): 3.3v
black(main board): 3.44v


Thanks, I'm going crazy with this.

[Davi.p]

Re: How to use an universal power supply?

2vdc and 33vac from psu is something very uncommon, is there or not a list of pinout on board??
From this site:http://www.edaboard.com/thread214069.html#
you can see that boards for your monitor are: 48.L9502.A01 and 48.L9501.A00
the first is the one you have to search for -in future- now there's a -0-
It's interesting to know why you have thrown away your old board, ie what was the sympthom?

[mokie]

Re: How to use an universal power supply?

No, I haven't got any pinout.
I have thrown away my old board because I broke part of the pcb that was imposible to repair.

[mokie]

Re: How to use an universal power supply?

looking for the model number of this power board, I have found this http://www.shopjimmy.com/pk10v000500...t-inverter.htm