Strip Down Guide for BenQ 28" VA Monitor GC2870H

[Maros]

looks very nice let us updated about progress :)

[yep_DD]

@madscientist initially for the test runs I will install two temperature sensors one in the top and one in the bottom to monitor the temperature. I have considered venting holes in the wooden backplate (bottom and top) or above the monitor in the aluminum frame and the same on the bottom but I would like to avoid that as I don’t know how much light would enter the casing.

[yep_DD]

@maros thank you, I really don’t know id it will all work out, I started this for fun as I was reading about the amazing magicmirror2 project and their community. Two days later I am taking apart a brand new monitor… and now I have been constantly working on it on my days off.

[yep_DD]

@madscientist So, experiment done. This is the result of 24h continues running. You can see the temperature has not quiet stabilized but the trend is well below anything critical. My guess would be that with a glass cover instead of the wooden frame I used to insulate the power dissipation should be even better.

[MadScientist]

@yep_dd Less than I thought. But also check the temperature of the Pi. In my case the Pi runs at 63°C at 27°C room temperature. With active cooling it’s at ~52°C.

[yep_DD]

@madscientist good idea, I will do that as soon as I have the actual glass. I have a passive heatsink installed already and in landscape mode the pi usage is less than 25-30% at the moment

[MadScientist]

@yep_dd Same here for passive heat sink and usage. I just placed an old 40mm/12V fan in front of the Pi which runs at 5V. It’s hard to hear in an absolute silent environment. I’ve noticed crashes during the hot period in summer, that’s why I use a fan now and it generall runs smoother. I think at some points the Pi got hot enough to throttle.

[yep_DD]

@madscientist that is true… good idea, I have one 5V 40mm fan as spare. Just one question, are you using your MM in portrait or landscape mode?

[MadScientist]

I use it in portrait mode.

[yep_DD]

@madscientist my experience is that in portrait the performance is almost unusable since everything is copied and rotated and I now decided to go landscape.

[yep_DD]

Hi guys,

just an update on the mirror. Finally the glas has arrived. I am very happy with the quality and the 50mm edge that has been painted black. There were a few stains on the backside which I had to clean manually.

Overall I am pretty satisfied with the results, but I have to change a few things:

What I am happy with:

• quality of glass (polished and round edges)
• Monitor appearance
• aluminimum frame and design (even though it needs to be changed, see below)
• sound quality
• The quality of the double-sided tape (seems like this is minor, but it is so strong I have no doubt it will hold the glass)

What needs to be changed:

• I changed the PIR Sensor to a radar sensor (RCWL-0516) which works flawlessly behind the glass
• The wooden white background reflects too much sunlight during daytime so I have to get a black one
• The Nielsen frame is 50mm too large. The reason behind that is that they measure the inner length but since I put the mirror on the outside it is 50mm longer. It does look okay, but I want the frame to be more inset. So if anyone wants a Nielsen frame for their project. I give mine away for free or a few € whatever you feel is appropriate it measures 95cmx75cm and can be shipped in small pieces and has the high quality double sided tape attached. I could have also gotten a bigger mirror, but obviously that is too expensive
• the cheap capacitive Sensors from amazon don’t work well behind the glas so I am now getting these MT0.1N-NR. The datasheet looks promising, of course 10x more expensive…

A few impressions:

The package came very well shipped:

I initially fixed the monitor with duct tape to see if I was happy with the position, you can nicely see the 50mm painted edges:

First test:

I think the quality of the monitor at night is amazing:

Even from a steeper angle the backlight is barely visible:

[MadScientist]

Are you sure the touch sensor works behind the mirror? It’s pretty expensive and it would be a pity if it doesn’t. Touch-anything generally doesn’t work behind the mirror because of the metallic coating.

What mirror are you using and where did you get it from? I am still looking for a better alternative for mine. Not very happy with the transmission of only 8%.

[yep_DD]

@madscientist that is what I am afraid of as well, the metal coating sure does not help… but worst case I will put them on the aluminum frame below from the outside and a nice cover on top

I got the mirror from here: Glas-star.de

[yep_DD]

@madscientist you were right, it does not work well behind the mirror. I will keep the sensor anyway as the way it is designed it is easier to affix to my aluminum frame. I am now thinking of getting small black plexiglas casing to attach to the bottom part to control the mirror and make it look nice… let’s see.

So this could be the plan:

• Plexiglas with Cutout letters
  

• behind that translucent plexiglas

• glue together

• LED Strip on top of translucent glas to illuminate the cutout letters

• enjoy?

[yep_DD]

I am just going to follow up on that, I found a different solution. I am using a HUE Dimmer Switch that is controlled via FHEM and it controls a python script running on MagicMirror to play my podcast and change the volume:

(I found that script somewhere on github and modified it a bit)

#!/usr/bin/python3 -u

host_name = '10.0.1.49' 
host_port = 8000

import RPi.GPIO as GPIO
import os
import subprocess
import signal
from subprocess import call
from time import sleep
from http.server import BaseHTTPRequestHandler, HTTPServer




class MyServer(BaseHTTPRequestHandler):

    def do_HEAD(self):
        self.send_response(200)
        self.send_header('Content-type', 'text/html')
        self.end_headers()

    def do_GET(self):
        global proc
        html = '''
           <html>
           <body style="width:960px; margin: 20px auto;">
           <h1>Magic Mirror Control</h1>
           <p>Current GPU temperature is {}</p>
           <p>Podcast: <a href="/play">Play</a> <a href="/stop">Stop</a></p>
           <p>Volume: <a href="/down">down</a> <a href="/up">up</a></p>
           <p>System: <a href="/shutdown">Shutdown</a> <a href="/restart">Restart</a></p>
           <div id="podcast-status"></div>
           <script>
               document.getElementById("podcast-status").innerHTML="{}";
           </script>
           </body>
           </html>
        '''
        temp = os.popen("/opt/vc/bin/vcgencmd measure_temp").read()
        self.do_HEAD()
        status = ''
        if self.path=='/':
            status='nothing'
        elif self.path=='/play':
            proc = subprocess.Popen(["omxplayer", "-o", "alsa:hw:ALSA", "--no-osd", "/tmp/video.mp4"], preexec_fn=os.setsid)
            status='Playing Podcast'
        elif self.path=='/stop':
            status='Stopping Podcast'
            os.killpg(os.getpgid(proc.pid), signal.SIGTERM)
        elif self.path=='/shutdown':
            status='Shutdown'
            subprocess.Popen(["sudo", "shutdown", "-h", "now"], preexec_fn=os.setsid)
        elif self.path=='/restart':
            status='Restart'
            subprocess.Popen(["sudo", "reboot"], preexec_fn=os.setsid)
        elif self.path=='/down':
            status='Volume down'
            subprocess.Popen(["amixer", "set", "Master", "12%-"], preexec_fn=os.setsid)
        elif self.path=='/up':
            status='Volume up'
            subprocess.Popen(["amixer", "set", "Master", "12%+"], preexec_fn=os.setsid)
        self.wfile.write(html.format(temp[5:], status).encode("utf-8"))


if __name__ == '__main__':
    http_server = HTTPServer((host_name, host_port), MyServer)
    print("Server Starts - %s:%s" % (host_name, host_port))

    try:
        http_server.serve_forever()
    except KeyboardInterrupt:
        http_server.server_close()

[Adrien]

Hello,

Would it be possible to use a relay to power/unpower the screen ? On the sheet you show pin 3/4 power the backlight correct?

Thanks

[MadScientist]

@adrien check out this forum thread. cruunnerr explains different methods on how to turn on/off your screen. He helped me setting up my system which uses a relay and PIR-sensor to power on/off my LCD. I think that’s what you’re looking for.

[Adrien]

Well i’m not sure, i don’t use the magic mirror OS but home made application. I use a pir sensor, i would like to have instant poweron/poweroff without any OSD message on screen. So My question was if i cut the pin 3 or 4 on the backlight connector will it work ? To be clear when the PIR detect someone the relay connect the PIN (3 or 4) after few seconds relay disconnect the PIN (3 or 4)

[MadScientist]

@adrien That should still be possible with the script method described in 5.1. Instead of the power lines for the controller board of the LCD you use the cables that lead to your backlight.

I don’t know what LCD you have. Some have an extra inverter or LED driver board. You can take the cables from there. Some have a 40 pin LVDS cable (instead of 30 pin), so you have to check the datasheet which wires are for the backlight. I’d take the VCC wire for the backlight, snip it and connect both lose ends to the relay. That should work.

Keep in mind that with this method the LCD is always on, only the backlight is off.

[Adrien]

Thanks for your help. I use the same model :BenQGC2870H. I would like to combine a solution where i have a minimum power consumption and fast without osd message boot.