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[SOLVED] Using PC Monitor as FPV screen

#1
Edit: Option 2 "2(mildly easy) Use the same converter but rig a 3cell Lipo as the DC source instead of my car battery. " was used to solve this issue and is working well, Page 2 has the end result.


I bought my FPV gear and I'm currently studying for my HAM test to operate everything legally in the US. In the mean time I want to get my ground station set up since I will have all the parts long before my A/V Tx and Rx arrive from China.

I am going to use these 2 parts to make my ground station, I'm just not sure how I want to power it but I have these three options.

First, these are the parts I will be using:
Monitor: Acer 1716 s View attachment Acer_al1716.pdf <-- manual (I have more than one spare monitor but this one is the largest and has the best documentation)
RCA to VGA converter: http://www.ebay.com/itm/190596379150

The options to power these are ...
1(Easiest) Use a power inverter http://www.radioshack.com/product/index.jsp?productId=3812863 connected to my car and run the monitor and adapter off of my car battery.
2(mildly easy) Use the same converter but rig a 3cell Lipo as the DC source instead of my car battery.

I figure that going from DC to AC then back to DC will waste a lot of energy so I'd rather not do this. Which leads me to option 3.

3(Most efficient and most difficult) Bypass the AC to DC converter in the Monitor and run the display directly off of a 3cell Lipo, split the 12v power to a spare ESC and power the 5v adapter through the ESC's 3pin rx connector.

I know the monitor uses 12V DC because I took it apart and read the info on the AC converter board

Inverter1.jpg

The thing I need help with is figuring out where to connect my 3cell lipo to. The connection from the power board to the VGA controller board has 8 pins and I'm not sure what pins carry the power

InverterToVGABoard.jpg

I also am not sure how power gets to the display from the power board. There are 2 sets of 2 connectors (8 wires in all) from the power board to the display.

InverterToDisplay1.jpg
InverterToDisplay2.jpg

I am assuming that the display is using 12v and the LEDs are using 5v but I'm not sure what color wires go to what device. There are Red, Black, Green and White.

The good news: I found a manual with very detailed documentation including a wiring diagram! View attachment Acer_al1716.pdf
The bad news: I only understand half of the documentation!

Notes: Page 11 shows the connections of the modules within the device. Page 28 figure 7 is not accurate to my board model, there are no wires, but pins (see image included). Power board wiring diagram is on page 44.

So, my plea to the rest of the FT community who has been so friendly in the past, could you lend me a hand once more and help me figure out where to connect my 3cell lipo battery to power the display and vga control board without using the monitors AC converter board?

If this is successful (or an entertaining failure) I hope to produce an article on how to do this and will of course credit any who assist.
 
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BankNYank!

New member
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#2
First off I have to say, I hope your aren't too attached to this monitor. While doing this conversion shouldn't ruin anything there is always that chance. If your afraid of destroying your monitor then my suggestion is to use a dc/ac converter.

However, if your feeling adventurous then lets see what we can come up with! :D

I'm hoping you have a multimeter or at least a voltmeter handy!

My suggested approach on this thing is to inject your dc voltage into the circuit where the power supply drops the dc voltage to the operating voltage, which in this case looks to be 10 to 16 volts.

Without being able to pick the board up and flip it around in my hands I'm guessing your raw dc voltage is running through that 450 volt 100 microfarad capacitor. If that's the capacitor I think it is it is being used as a filter to smooth out any fluctuations in the dc voltage that is left over from the ac to dc conversion. My electronics is rusty but I think you should see dc 60 volts there. If I am correct then the voltage should end up at that transistor with the big heat sink attached to it's back. Check your voltage there, if I'm right you'll be getting your operating voltage coming out of that transistor which should be your 10 to 16 volts. If all of this holds true then the next thing I recommend doing is unplugging everything then connect your ac power and map out all your output wires and their voltages. After you have all the wires and their voltages figured out then unplug the ac power and remove that big 450v 100uf capacitor from the board. This should eliminate the circuit prior to getting your filtered 60 volts that way we aren't back feeding the circuit. Then, make sure everything is still unplugged including your ac power cord and with a 12 volt power supply inject 12 or so volts into the circuit just past that transistor where you found the operating voltage. As long as nothing smokes and your power supply doesn't over amp and freak out then check all your voltages on all your plugs and see if they are giving you similar voltages to what you wrote down when you mapped out the circuit with the dc voltage applied. If everything looks good then (in theory) you should be able to plug all the wires in and power your monitor!

Again, this is my best guess here. Without being able to actually hold that power supply in my hands and test it myself, I'm going on best guesses and assumptions here so I may end up being way off. If something doesn't look right don't do it!

I hope this helps to at least point you in the right direction.

I'm hoping others will chime in here with their advice and help out as well!



EDIT: I just noticed the other two transistors on the board. The two that are attached to the same heat sink. You'll need to test voltages there as well when you map out the voltages on all the plugs. Then after you inject the 12 volts from your power supply you'll need to check that they are getting the same voltage. If they aren't then they are being supplied from a different source and things may get slightly more complicated.
 
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#3
I have 5 "salvaged" monitors I can destroy so I'm willing to experiment.

I'll get the multimeter out (which I got for free from Harbor Freight) and see if I can map out a bit before moving forward.

I guess a question I should have asked earlier on was "Would it be bad to use a DC to AC converter connected to a power strip and powered by a 3cell lipo? (OP = option 2)

If I'm not loosing much with that approach then my life is made incredibly simple by soldering an XT60 connector to the DC to AC converter.

Like so...

Lipo > DC extension cable (xt60 soldered to lipo connector) > DC to AC inverter > Power strip (unregulated?) > Monitor and signal converter.
 

BankNYank!

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#4
I have 5 "salvaged" monitors I can destroy so I'm willing to experiment.

I'll get the multimeter out (which I got for free from Harbor Freight) and see if I can map out a bit before moving forward.

I guess a question I should have asked earlier on was "Would it be bad to use a DC to AC converter connected to a power strip and powered by a 3cell lipo? (OP = option 2)

If I'm not loosing much with that approach then my life is made incredibly simple by soldering an XT60 connector to the DC to AC converter.

Like so...

Lipo > DC extension cable (xt60 soldered to lipo connector) > DC to AC inverter > Power strip (unregulated?) > Monitor and signal converter.
It's not going to be very efficient and my guess is you'll get some pretty short run time's. But that will depend on current draw of the converter and how big a battery your using. My best answer is to test it and see. Your going to want to check the current draw of the converter first to make sure your not going to puff a battery. The fuse in it should give you a pretty good idea of where the current range is going to be. I'm thinking 70% of fuse rating should be max? I can't remember for sure but something like that. Regardless, for safety purposes, your going to want your battery to be able to handle at least what the fuse is rated at.
 

BankNYank!

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#6
Power divided by voltage equals current. So 150 watts divided by 12 volts equals 12.5 amps. That should be the max operating current. Given the 20A fuse I believe your battery should fair well. Think of it like a motor that normally draws 12.5 amps with the prop you have attached but maxes out at 20 amps if you really push. And in this case you probably won't be pushing it. Good way to test this theory would be to attach a watt meter in line between the battery and inverter and then power up your gear and see what the readings are.
 
#7
I didn't have a wattmeter so I just did a timed test with a voltage meter.

I couldn't find the car power extender so I just used a DC splitter and put an XT60 on it and plugged it all in, all the equipment was expendable so I figured ... just go for it. I brought all of the parts outside into the sand and tested.

Connected a voltage checker to the 3cell 2200mah 20-30C LiPo battery. Storage voltage of 11.25. CHECK
Connected the LiPo to the DC 4 way splitter and the red LED came on. CHECK
Connected the 150w power inverter to one of the ports in the 4 way DC splitter and the LEDs came on and the fan came to life. No noticeable draw on the battery was observed for at least a minute. CHECK
Connected the Monitor (in active use as my laptops second display) to the inverter. Voltage meter sunk by .2 sharply for 5 seconds and leveled out to 0.45 voltage dropped per 6 minutes of active use. CHECK!

So if I did my math right my 2200mah LiPo can operate my ground station for 20-30 minutes at safe voltages. Those are perfectly acceptable times to use the inverter rather than do all the wiring.
 
#8
Good thing you went with the inverter because bypassing the power supply in the monitor was not an option. According to page 11 of the manual linked above, this monitor uses CCFL (Cold Cathode Florescent Lamp) for the back light. This back light needs high voltage AC which requires an inverter to get from a DC source.

If you want to go with your original idea, the monitor you would have to use would be one with LED or OLED back light. These monitors do not need any AC internally so no inverter is needed.
 

BankNYank!

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#9
That's a pretty cool test and awesome results! If you can get 20-30mins that's looking promising! I'm glad to see it looks like this is going to work out for you the easy way! You should post a quick build thread in case anyone else is looking for a similar solution.


this monitor uses CCFL (Cold Cathode Florescent Lamp) for the back light.
I did not even think about the CCFL's. Good call on that! Like I said, my electronics is rusty!
 
#10
We'll Bitogre, I'm glad I took the easy route this time. I would have been soldering the parts back together on my monitor after a failure. This is exactly why I asked the community before seriously disassembling it. Not that I care a great deal about the monitor but I hate to be wasteful, ... how do you think I ended up with 5 monitors I don't even use! :)

Once I get the entire rig up and working I will do another time test during actual FPV flight so that I don't overpromise and under deliver on my claims when I write it up as an article or forum post.

That being said I think old PC monitors have incredible untapped potential for those new to FPV like me. Goggles and screens designed for FPV are expensive and (for me at least) one of the major financial hold-backs for getting into FPV.

Most people have a power inverter for their car (at least in the USA because we have so much road travel and we cant stay away from our electronics) and a power strip. I think most people also have a PC monitor and if they don't, can get one at a thrift store or garage sale for super cheap (I bought a 26in LCD for $1 once). The power problem has been solved with this thread and the input problem (monitors usually only having VGA or DVI input instead of BNC or RCA) is solved by a simple adapter you can get for less than $20.00 on eBay.

The monitor: free or cheap (arbitrarily assign a good thrift store price of $10)
The converter: $15- $20 on eBay
The inverter: $20 - $40
Power strip: Free or cheap ($6.00)
DC extender: free or cheap ($1.00 at a thrift store)

If you have much of this stuff (which you likely do) then the only thing you will likely need is a RCA to VGA converter. I was only missing the adapter so that really saved my budget. Next step, mount all the gear in my metal suit case
 

BankNYank!

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#11
I've been wanting to get into FPV for a while now but have always choked on the price for a decent pair of goggles. I've always wanted to do FPV with goggles. I've never cared much for the idea of using a monitor. However, like you I have most of this stuff laying around and the only thing I will need to buy is the rca to vga adapter. Video transmitters and receivers have gotten so cheap that, with this concept, you can actually get into fpv for like 75 bucks. I feel that is a very reasonable price!

Without even knowing it you may have talked me into this idea!
 
#12
I've been wanting to get into FPV for a while now but have always choked on the price for a decent pair of goggles. I've always wanted to do FPV with goggles. I've never cared much for the idea of using a monitor. However, like you I have most of this stuff laying around and the only thing I will need to buy is the rca to vga adapter. Video transmitters and receivers have gotten so cheap that, with this concept, you can actually get into fpv for like 75 bucks. I feel that is a very reasonable price!

Without even knowing it you may have talked me into this idea!
If you are going to pull the trigger on FPV gear, take a look at the collection I made for the FT giveaway. I bought all of the stuff listed in it except for the antennas (however I have bought from that seller before and was very happy). I'm currently waiting for it all to arrive in the mail.

http://www.ebay.com/cln/tacticalex/FPV-starting-Gear/102783887019

I actually spent less than $80 on all the equipment in the collection.
 

BankNYank!

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#13
I am going to start looking at fpv gear. Thanks for the link, I bookmarked it!

Let me know how the equipment does once you get it and your able to try it out.
 
#14
OK so I got the equipment all set up (with the exception of the receiver) for the ground station. It turns out you can run an N64 for 21 minutes before reaching the low voltage cut off for the inverter (which happens to be 10.4v). Since the safe cut off for a 3cell LiPo is 9.9v then I guess I can spare the 5 extra minutes I could have for a margin of safety.

Some notes:
No noticeable lag
As long as there was input of any kind going to the RCA to VGA converter the monitor didn't go to blue screen.
Not happy about the abrupt low voltage cut off from the inverter so I may hunt around for one with a lower cut off. I'd rather ruin a battery than loose video on a plane but I don't ever plan on doing any long range stuff.

 
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SnowRocker88

Amateur pilot and builder
#15
To find your 12v 5v leads can't you just plug the monitor into the wall (AC Converter circuit powered through wall outlet) and use a volt-meter to measure what output voltage each pin is giving? Then just delete (or bypass) the AC Converter as planned...? I would guess you could just leave the 5v circuit unpowered as it probably only runs the light and maybe USB ports (if it has any).
 

BankNYank!

New member
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#16
This is good stuff Tac Ex, thanks for getting back to us with your results!

This has inspired me to start out in FPV with a monitor rather than goggles. I park my truck right at the field where I fly so I can literally sit in the back of my truck and fly. Having this option, I won't need to use a 3s battery to power my gear but you have given me your great idea to use a computer monitor for my fpv monitor. Like you, and most others I'm sure, I have a couple extra old flat screen monitors laying around that could be used with your concept.

I'm still researching for my vtx/vrx and camera and waiting to hear your results on the ones you got. I'll probably come to a decision and place an order sometime this weekend.

Thanks again for your cool idea and for giving me the motivation to get some fpv gear in the air!
 
#17
This is good stuff Tac Ex, thanks for getting back to us with your results!

This has inspired me to start out in FPV with a monitor rather than goggles. I park my truck right at the field where I fly so I can literally sit in the back of my truck and fly. Having this option, I won't need to use a 3s battery to power my gear but you have given me your great idea to use a computer monitor for my fpv monitor. Like you, and most others I'm sure, I have a couple extra old flat screen monitors laying around that could be used with your concept.

I'm still researching for my vtx/vrx and camera and waiting to hear your results on the ones you got. I'll probably come to a decision and place an order sometime this weekend.

Thanks again for your cool idea and for giving me the motivation to get some fpv gear in the air!
Glad to assist, hopefully this cheap option will get many more people into FPV. I just finished a draft for an article on this and will publish when I get the final video of the review and how to. I'm supposed to get my remaining gear in this weekend or early next week so I'll have said video shortly after. I'll link the video here before then since the article will likely take a few weeks to be reviewed and published.
 
#18
Got my Tx and Rx today so I wired them up and tried it out. Here is the video of everything powered on. Everything looks good but I will most likely buy some better antennas next.