Computer Monitor Conversion AC to DC

[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

[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.

[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

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

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

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

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

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.

[Oshi]

Re: Computer Monitor Conversion AC to DC

I did the test this morning and could only find 3.3volts from pin #1.
No voltage could be seen from pin #5.
Would that voltage be correct?

It was a bit fiddly and the contacting points were difficult together with pulling the 240 volt plug in and out.
I'll try again this evening.
I need to go out and pull my car's back caliper apart now.

[mariushm]

Re: Computer Monitor Conversion AC to DC

That's OK, very good of you that you checked.

I got those from a service manual, but the pictures showed probably an older revision of the power supply using a connector having all those 8 pins in a single row.

14v is actually 12v, but the power supply is not regulated.. When the monitor isn't running or the lights are off, the power supply idles at 14v but as soon as something draws power from that, the voltage will go down towards 12v

So now your 12v and 5v pins are obvious, but it's not so obvious is which one is the on/off pin for the inverter and the adjust brightness pin.

Connect the two boards together, put the red probe on one of pins 1, 5 , 3, 7 and plug the monitor in the mains socket. You don't have to connect the lamps.

The display board should send the command to the inverter to turn on, which is done by sending 5v to the on/off pin.. so one of those pins that weren't 5v or 14v before should be around 5v, at least for a brief moment until the monitor goes back to stand by. If it remains ground or zero, remove the plug from the socket, move to another pin and plug it again.

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.

I have made a couple of DC to DC variable units using the IC LM317T which can be plugged into 12 volts to be turned down using a variable resistor to give 5 volts.

That's great, so you're already familiar with making up something like this. As you won't adjust the voltage, you would be able to change the variable resistor with a fixed one.

The output doesn't have to be exactly 5v, so don't be concerned if the resistor combination gives you 4.9-5.1v, that's close enough.

The beauty of that 7805 is that it's fixed, it doesn't need resistors for the feedback, so it's kind of "idiot proof". But it's not worse or better than a LM317T for this purpose.

[Oshi]

Re: Computer Monitor Conversion AC to DC

Anyway, you only have to care about 12v and 5v, these two are needed by the display board. The inverter only needs 12v or more.

So you only supply 12 volts to the inverter. I gather it's the 4/6 pin connector in the middle between the caps in the above photo? Colour of the wires are red, black and two yellow. I guess now is how to wire/solder what to where?

If you can use a small power supply (adapter) to provide both 12v and 5v directly, that's great, but it would really be better if you'd use a DC-DC converter to generate that 5v from 12v.

I have made a couple of DC to DC variable units using the IC LM317T which can be plugged into 12 volts to be turned down using a variable resistor to give 5 volts.

.

I checked the voltage of the pins and they were different from those you listed.
Looking at the back of the pins on the power board toward the connector of the disconnected display board.

left to right
top row... 1= -0volts, 2=5volts, 3=grd, 4= 14volts,
bottom row... 5= -0.12volts, 6= 5 volts, 7=grd, 8= 14 volts

[mariushm]

Re: Computer Monitor Conversion AC to DC

I was talking in general.

Yes, generally monitors need several voltages but use a power supply to generate one or two of them at high current, then use some very small converters to generate the smaller voltages on the display board.

In your particular case, on your monitor, the big power supply only generates 12v and 5v, and the display board has on it a small dc-dc converter which generates 3.3v (and maybe another one for 1.8v but I didn't check the service manual in great detail)

Anyway, you only have to care about 12v and 5v, these two are needed by the display board. The inverter only needs 12v or more.

If you can use a small power supply (adapter) to provide both 12v and 5v directly, that's great, but it would really be better if you'd use a DC-DC converter to generate that 5v from 12v.

This is because if you have long cables, you may not actually get 5v at the end of the wires, and also there may be noise, interference which can affect the quality of that 5v input

That small circuit I put a picture of above, makes sure the 5v it generates is very smooth, clear of noise, and as it's produced inside the monitor, very close to the connector, you will almost definitely have no problems.

The only concern is like i said, heat... but that's easily solved if you leave it screwed on one of those rectangular metal bars that are used on the old power supply board.

But feel free to test with 12v and 5v directly from something before, you won't do anything bad with it. If the monitor resets or acts out, consider doing like I said.

[Oshi]

Re: Computer Monitor Conversion AC to DC

[QUOTE=mariushm;283294]
The monitors usually run on 5v and 3.3v and sometimes 1.8v.
All at the same time or only one?

The lamps What are the lamps?
usually run from 12-16v which gets converted by the inverter to 600-1000v.
Sometimes, this power supply also sends 12v to the display board, in case the display board also has a small audio amplifier for speakers.


You can get rid of the big board if you have a way to give 12v to the inverter and the display board, and a separate 5v to the display board separately.
I can supply both 5 and 12 volts.

[Oshi]

Re: Computer Monitor Conversion AC to DC

Thank you mariushm for the detailed info. I will need to digest this tonight when I have a few moments.

Can you post good clear pictures of the power supply-inverter board, both sides?

Couldn't get both photos up together. Here's two close ups.
http://sphotos-g.ak.fbcdn.net/hphoto...86854495_n.jpg

http://sphotos-e.ak.fbcdn.net/hphoto...60320626_n.jpg

[budm]

Re: Computer Monitor Conversion AC to DC

Can you post good clear pictures of the power supply-inverter board, both sides?

[mariushm]

Re: Computer Monitor Conversion AC to DC

The power supply (the big uglier board with the mains plug) is connected to the smaller display board with that 8 pin connector.

It's possible they used that 8 pin connector simply because it was the most convenient or because it was more reliable or provided a better connection.

The monitors usually run on 5v and 3.3v and sometimes 1.8v.
The lamps usually run from 12-16v which gets converted by the inverter to 600-1000v.
Sometimes, this power supply also sends 12v to the display board, in case the display board also has a small audio amplifier for speakers.

So the big power supply's purpose is made out of two sides - the actual power supply which creates around 12v for the inverter and usually 12v and 5v for the display board.

You can get rid of the big board if you have a way to give 12v to the inverter and the display board, and a separate 5v to the display board separately.

In your exact case, after looking at the service manual for the monitor, that 8 pin connector is like this:

1. ON/OFF monitor
2. Adjust brightness
3. 12v
4. Ground
5. 5v
6. 5v
7. Ground
8. Ground

Usually, pin 1 is the top left pin in that 8 pin connector on the power supply and pin 5 is the bottom left pin, but you can be sure by testing with a multimeter.

Disconnect the two boards, remove the big power supply board from that metal case, put it on a few big sheets of paper or a cardboard sheet so that no part of it touches anything, carefully plug the cable into the connector then plug the cable into the wall socket.
Now get the multimeter, put it on DC, if it doesn't autorange put it on 20v or some value similar to that, put the black probe on the top right pin and the red probe on the 3rd pin from the top.
If you see 12v, then it means the 3pin is 12v, so the layout above is right.

So now you have all four pins for the inverter: on/off , adjust brightness, 12v, ground all at the top.
The first two pins on the bottom row are 5v for the display board. Easy.

Now, if you have an external 12v DC power supply, you can simply remove the power supply board completely.

You only need to generate that 5v for the display board. This can be done with a linear regulator. The classic 7805 will do, you can find it on eBay or shops under various names, but as long as it has 7805 in the name and can provide at least 1.5A it will do.



So as you can see it's very simple: 12v goes into the first pin, out comes 5v from the third pin. You just need those capacitors to made the output smoother.

You will however have to be careful because this chip will stay hot as long as it runs, so you can't just stick/tape it to the back of the screen. You should unscrew one of those metal plates (heatsinks) from the power supply board, screw this chip to it and then screw the metal plate to one of the old screw holes where the big power supply board was screwed to.

[Oshi]

Re: Computer Monitor Conversion AC to DC

I have that exact model of universal inverter.

As in the picture, it has four wires and they're labeled on the back side... power (Vin) , ground (GND), adjust brightness (ADJ) , and enable/disable (ON/OFF)

The Vin goes to where you have 10v or more on the power supply, GND goes to ground.

The two other wires, adjust and on/off are to be connected on the display board and there should be two wires from the old power supply going to the display board.

Either on the power supply or on the display board, there should be by the connectors text saying what each wire does (or pins in a connector do)

If you can't tell which is what, the adjust wire should have a voltage of around 2-4 volts, depending on what brightness you used before. The On/Off pin should have 5v coming from the display board when the backlights are supposed to be on, nothing when the monitor is supposed to be in standby.

I must admit of being a novice at this.
I used this link to help me get the monitor apart.
http://martybugs.net/electronics/Acer-AL1716-caps.cgi

I gather you are referring to the 2 PCB boards that can be un-hooked. Is
the larger one not used anymore as it is only the power supply and can be discarded? I noticed the inverter has the 4 plugs for the monitor. So the smaller PCB is connected to the inverter as you described to that 6-pin connector (circled in figure 11 below) as described in the link I used.
Do you need to solder it in some how? I noticed there are 8 pins. Four lots doubled up somehow? How do you connect to thees pins.
Also where do you put in the 12 volt supply?
Thank you and budm for any assistance.

[mariushm]

Re: Computer Monitor Conversion AC to DC

I have that exact model of universal inverter.

As in the picture, it has four wires and they're labeled on the back side... power (Vin) , ground (GND), adjust brightness (ADJ) , and enable/disable (ON/OFF)

The Vin goes to where you have 10v or more on the power supply, GND goes to ground.

The two other wires, adjust and on/off are to be connected on the display board and there should be two wires from the old power supply going to the display board.

Either on the power supply or on the display board, there should be by the connectors text saying what each wire does (or pins in a connector do)

If you can't tell which is what, the adjust wire should have a voltage of around 2-4 volts, depending on what brightness you used before. The On/Off pin should have 5v coming from the display board when the backlights are supposed to be on, nothing when the monitor is supposed to be in standby.

[Oshi]

Re: Computer Monitor Conversion AC to DC

If I were to do it, I will take out the power supply board and replace the backlights inverter with this board: http://www.ebay.com/itm/Universal-CC...item41606f799e

Then use a simple linear regulator to drop 12v to 5V for running the logic board.
The on/off control of the backlight can be done by using a switch and a pot for adjusting the brightness of the backlights.
Does you monitor look like one of these ACER?
http://s807.photobucket.com/albums/yy352/budm/ACER/

The inverter came yesterday. Is it straight forward to replace and recognise where it goes?

[Oshi]

Re: Computer Monitor Conversion AC to DC

Something fishy in the spec, it says 5V, 500mA USB powered, but the power consumption shows "Power Consumption: 4W-5W " How can you get that much brightness and power to run all the logic at 2.5W (Max power for one USB port), unless it uses one of those USB Y cable to use 2 USB ports to get enough power to run it. You may be able to get car adapter that convert 12V to 5V for it.

I checked their 7 inch and it is powered similarly. They sell a 10 inch and it's 12 volt powered?
Another company is flogging the same unit.
I was going to email them and ask some questions but there's only provision to do so by companies.

http://newaye.en.made-in-china.com/p...-CLi156B-.html