Computer Monitor Conversion AC to DC

[Oshi]

Re: Computer Monitor Conversion AC to DC

While you do this, one of the pins you check would be the adjust pin, which should have something between 1.5-2v and 5v... 5v would be the highest brightness possible. Since it's unlikely you had the monitor on highest brightness, you should see on the pin something less than 5v.


LM317T for this purpose.

I could only get 3.3 volts from pin 1. I used another meter to make sure.

[mariushm]

Re: Computer Monitor Conversion AC to DC

That 3.3v is sent from the display board TO the power supply, towards the inverter.

As it is right now, my guess is the two pins at the top are the ADJUST and ON/OFF pins. The monitor may have the brightness set to maximum or the processor only adjusts the brightness after it "boots up" so initially you see 3.3v on that pin.

Either way, that automatic inverter will survive for a short time if you somehow mix up the on/off pin and the adjust pins, it will just run the lamps at maximum brightness. And if you adjust the brightness at something very low and the wires are inverted, the inverter may turn off (then you know they're mixed up)

Attach two wires to those two pins, tie them to on/off and adjust on your inverter... get that 14v pin and connect it with a wire to input voltage on your inverter, ground to ground, and attach the lamps to the new inverter and see what happens.

[Oshi]

Re: Computer Monitor Conversion AC to DC

That 3.3v is sent from the display board TO the power supply, towards the inverter.

As it is right now, my guess is the two pins at the top are the ADJUST and ON/OFF pins. The monitor may have the brightness set to maximum or the processor only adjusts the brightness after it "boots up" so initially you see 3.3v on that pin.

Either way, that automatic inverter will survive for a short time if you somehow mix up the on/off pin and the adjust pins, it will just run the lamps at maximum brightness. And if you adjust the brightness at something very low and the wires are inverted, the inverter may turn off (then you know they're mixed up)

Attach two wires to those two pins, tie them to on/off and adjust on your inverter... get that 14v pin and connect it with a wire to input voltage on your inverter, ground to ground, and attach the lamps to the new inverter and see what happens.

If I got this correct I attached 2 wires to the pins #1 & #2 on the top row of the smaller PCB board/display board . Also the 14volt and the ground to the top row. All four were connected to the new inverter output 4 pin plug.

When you say attached the lamps I gather it's the screens plugs?

Also where does the external +12 volt supply input go to the new inverter and which is the earth or -12volt?

And do I need to supply and external 5 volt supply?

[mariushm]

Re: Computer Monitor Conversion AC to DC

You have four wires coming from the small inverter board. Turn it on its back and you have there the text saying which wire does what.

Mine looks like this:



But the colors might be different on your inverter.


One wire will be on/off , one will be adjust ... those two wires you tie to the first two pins on the small display board.

One wire will be Vin which accepts anything above 10v, so that goes to your 12v or 14v

The GND wires goes to ground.

As you can see on my inverter, the colors don't make sense - normally black signifies ground, red signifies 5v, yellow 12v... on my inverter are exactly opposite.

Yes, if you remove the power supply board from the back, you need to create the 12v and 5v voltages for the display board through some other method. Easiest way would be to get a 12v laptop/monitor dc adapter and then use a 7805 or something compatible to get 5v.

You can feed the inverter with around 12v with no problems and you should connect 12v to the pin on the display board that acccepted 12-14v previously.
As the power supply is no longer used, not connected to the display board, you will need to create those 5v for the display board, and this is where the circuit with 7805 comes in play on the previous page.

You can use however LM317 or whatever you have, fixed version for 5v or with adjustment resistors - you said you did an adjustable supply with something like this before so it should be easy for you.

[Oshi]

Re: Computer Monitor Conversion AC to DC

You have four wires coming from the small inverter board. Turn it on its back and you have there the text saying which wire does what.

Mine looks like this:



But the colors might be different on your inverter.


One wire will be on/off , one will be adjust ... those two wires you tie to the first two pins on the small display board.

One wire will be Vin which accepts anything above 10v, so that goes to your 12v or 14v

The GND wires goes to ground.

As you can see on my inverter, the colors don't make sense - normally black signifies ground, red signifies 5v, yellow 12v... on my inverter are exactly opposite.

Yes, if you remove the power supply board from the back, you need to create the 12v and 5v voltages for the display board through some other method. Easiest way would be to get a 12v laptop/monitor dc adapter and then use a 7805 or something compatible to get 5v.

You can feed the inverter with around 12v with no problems and you should connect 12v to the pin on the display board that acccepted 12-14v previously.
As the power supply is no longer used, not connected to the display board, you will need to create those 5v for the display board, and this is where the circuit with 7805 comes in play on the previous page.

You can use however LM317 or whatever you have, fixed version for 5v or with adjustment resistors - you said you did an adjustable supply with something like this before so it should be easy for you.

On the one I have, black is power in and red is earth. The two yellows come from adjust and on/off on the inverter.
Lucky you mentioned that as I had tied the red and black to the display board, red as power in and black earth. Red has always been positive 12 volts and black negative earth in my experience.



I will be picking up two of 7805's and two lots of caps from my city today.

When the 12 volts and 5 volts are attached they basically piggyback the 4pin plug that is supplied and also tied off to the display board from the inverter?

[mariushm]

Re: Computer Monitor Conversion AC to DC

On computer power supplies, orange is 3.3v, red is usually 5v, yellow is 12v .. ground is always black.

There's usually one exception, where the connector has just two wires... then black is almost always ground, the other color is voltage... ex 2 wire fans have black ground, red is 12v

You don't need 2 x 7805, you can connect both 5v pins in that connector to one 7805. A single 7805 should be quite capable of delivering enough power to that display board.

The inverter needs ground, 12v

The display board needs ground, 12v , 5 v

So both the display board and the inverter will share 12v and 5v.

Inverter needs to receive on/off signal and adjust from the display board, so there's the two wires between inverter and display board for that.

Here's a really poorly drawn schematic... I barely passed the technical design exam at university that's how bad i suck at drawing but should still be easy to understand



In theory both of those capacitors are optional, but it's really safer to have them around.

[Oshi]

Re: Computer Monitor Conversion AC to DC

On computer power supplies, orange is 3.3v, red is usually 5v, yellow is 12v .. ground is always black.

There's usually one exception, where the connector has just two wires... then black is almost always ground, the other color is voltage... ex 2 wire fans have black ground, red is 12v

You don't need 2 x 7805, you can connect both 5v pins in that connector to one 7805. A single 7805 should be quite capable of delivering enough power to that display board.

The inverter needs ground, 12v

The display board needs ground, 12v , 5 v

So both the display board and the inverter will share 12v and 5v.

Inverter needs to receive on/off signal and adjust from the display board, so there's the two wires between inverter and display board for that.

Here's a really poorly drawn schematic... I barely passed the technical design exam at university that's how bad i suck at drawing but should still be easy to understand



In theory both of those capacitors are optional, but it's really safer to have them around.

I'm back again after being away. Thanks for the drawing it's fine and I'm sure I will make sense of it as soon as I get a moment to revise all the info.
I did put together the 5volt power supply after my first attempt failed.
My soldering was atrocious and one of the joints failed making me think at first I had cooked the IC.
I really need a proper soldering iron that works.
I ended up using an old spring circuit board that's used for kit projects and the components were still working. I ended up getting an amazing 5.01volts.

[Oshi]

Re: Computer Monitor Conversion AC to DC

That 3.3v is sent from the display board TO the power supply, towards the inverter.

As it is right now, my guess is the two pins at the top are the ADJUST and ON/OFF pins. The monitor may have the brightness set to maximum or the processor only adjusts the brightness after it "boots up" so initially you see 3.3v on that pin.

Either way, that automatic inverter will survive for a short time if you somehow mix up the on/off pin and the adjust pins, it will just run the lamps at maximum brightness. And if you adjust the brightness at something very low and the wires are inverted, the inverter may turn off (then you know they're mixed up)

Attach two wires to those two pins, tie them to on/off and adjust on your inverter... get that 14v pin and connect it with a wire to input voltage on your inverter, ground to ground, and attach the lamps to the new inverter and see what happens.

I've all but wired up the Inverter, Displayboard, the 12volt supply
with only the 5 volt positive supply to put in place.
In your drawing the 5v at the display board goes into which pin?

"My guess is the two pins at the top are the ADJUST and ON/OFF pins."

So would it therefore mean the 5 volts goes to pin 5 or 6 ?


My Display top row is..1= 0volts, 2=5volts, 3=grd, 4= 14volts,

bottom row... 5= -0.12volts, 6= 5 volts, 7=grd, 8= 14 volts