For another project I was lacking enough room to put a CRT monitor and a PC on relatively small shelf. So instead of getting another extra shelf I decided to put the monitor on the bottom side of the shelf. Yeah :)
I just need to manage to invert the image of the monitor, to make some use of this fancy setup.
Actually I found it's not a big deal.
Without going in too many details about how a CRT monitor works, it's enough to know that it consist on a cannon located on the back that 'fires' electrons to the screen in the front. When the electrons hit the screen it glows (phosphor) and the image can be form.
The important thing here are the coils. The cannon 'fires' in straight line to the center of the screen. To reach the entire surface the electron beam will be bent through magnetic deflection. Those magnetic fields are produced by the deflection coils.
This coils are located between the cannon and the screen. The intensity of the current flowing trough them determines the power of the magnetic field and how much will be the beam deflected. There are two pairs. One for vertical deflection and the other for horizontal.
The idea is incredible simple. Just invert the polarity of the coils. The beams will be then deflected in the opposite direction as intended, creating a mirror image. Great.
Let's find them.
WARNING: Inside the monitor there are big capacitors which work with really high voltage. Very important to take necessary protections and to unplug the monitor while it still on, to help the capacitors discharge themselves.
We are looking for a connector with two pair of cables. One for each coil. To make it even easier, the usually came in the same colors.
- Yellow/Brown
- Red/Blue
Just to be sure, we check with the multimeter. The coils are independent, so to find each coil you have to find the combination of cables who show some resistance in the multimeter.
Now lets make a test, and invert the polarity of the coil.
And test it.
Wonderful we inverted the vertical deflectors, and we are getting a vertically mirrored image.
To achieve the desired effect I will also switch the polarity of the horizontal deflectors and also make sure everything is well isolated.
Test again. Ta da! Exactly what I was needing.
Take a look at the final setup.
UPDATE: I found a nice video on the matter:
Author: Maximiliano Padulo
Category: hacks