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Old April 15th, 2008, 02:42 AM   #1
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Flipping an old CRT

Does anybody know how I can do this??
I'm using a 35mm adapter and want to watch my images upright on set.
I tried turning the monitor upside down but then the colors are going weird. It all becomes green.

I've read it's just a matter of switching two cables, but which ones???


Thx,

Piet
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Old April 15th, 2008, 08:03 AM   #2
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Quote:
Originally Posted by Piet Deyaert View Post
I tried turning the monitor upside down but then the colors are going weird. It all becomes green.

I've read it's just a matter of switching two cables, but which ones???
I'm no expert, but neither of these make sense to me at all.
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Old April 15th, 2008, 11:24 AM   #3
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** DO At Your Own Risk!**

Having been a TV repairman for 25 years, yes there is a way to do it, but you have to dig into the tv. So I take no responsibility for telling you this procedure if you kill yourself!

1. UNPLUG and open up the TV

2. On the neck of the picture tube (The long thin tapered end) there is what is called a yoke. It looks like a large coil of wire around some dark metal looking pieces. There are 4 wires that some off of it and go to the circuit board. 2 are for vertical (up and down) and 2 for horizontal (left and right).

3. Here is where you have to experiment, you'll need to cut of the pairs of wires, strip off the insulation and swap them. In other words if the 2 wires were white and red you need to cut them and reconnect them so white is now connected to the red wire and via versa. Then make sure the bare wires are covered with electrical tape and hook the tv back up and turn it on. The picture should be either upside down or reversed left to right. If the wrong axis was changed put those wires back the way they were and do the same thing to the other pair.

The weird coloring you saw was caused by moving the tv while it was turned. When you turn it back on a built in device should take care of that.

Good luck and don't fry yourself!!

Jeff
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Old April 16th, 2008, 04:49 AM   #4
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Just to emphasise what Jeff said about safety:

Please be very, very careful when tinkering inside a CRT monitor. CRTs use extremely high voltages when switched on. I'm not trying to put you off, I'm just saying: please be careful!
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Old April 16th, 2008, 04:54 AM   #5
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I'd also like to add that I believe they can also store enough voltage even while unplugged... enough to make you never forget :-\
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Old April 16th, 2008, 07:08 AM   #6
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I'd also strongly suggest against tampering with the TV, proper High Voltage inside... Better use a (cheap) LCD.

The effect you're seeing on the CRT is the influence of the earth's magnetic field on the electron beams (which from the TV's perspective you've reversed!).

LCD's have no beams of electrons, so won't suffer this. Plus they're easier to carry as well.

George/
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Old April 16th, 2008, 12:42 PM   #7
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As an ex-tv repairman, the capacitors inside can store high power for hours after it is unplugged. don't touch anything inside other than the wires he mentioned. also, the end of the tube is extremely fragile, there is a little nipple of glass that usually protrudes through the middle of the connector on the back of the tube that is very easy to break off. if it gets broken the vacuum in the crt is allowed to escape :)
(you can easily ruin a picture tube this way, I know)
as long as you are careful, you should be fine. do not attempt this while there is no one around to help on the off chance of getting an electrical shock.
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Old April 16th, 2008, 03:43 PM   #8
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The high voltage from CRT TVs is is produced by the flyback transformer and it is stored, even after shut off, in the large capacitors nearby. This voltage on modern color TVs is in the 75,000 volt range, but it is very low amperage. If you look at the tube itself and find the wire that goes into the side of the tube, which is about 3/16's in diameter most of the time and has a rubber cover or boot around it where it connects to the side of the tube, you can visually trace it back to the flyback transformer. Avoid touching either of these and that includes your tools.

As I previously mentioned, the voltage is high, but the amperage is very low. If you do get zapped and I have many many times, the biggest danger is that your muscles will immediately react, jerk back, like touching a hot stove except that you have no control of the action. If you were to have your hand deep into the chassis, then get hit, your arm will pull back hard and if there are any sharp objects you will get cut right up. About the only other danger is if you have a bad heart. They sometimes don't like big shocks. If the TV is unplugged, you will get just one shock generally and that is it. You are just discharging the capacitors and that is generally only once and then they are empty.

The wires you are looking for on on the yoke or skinny end of the picture tube. The part you may try to modify are the wires that lead to the big bundle of copper looking wires that are actually electro magnets. Current fed to these direct the beam of electrons that eventually paints the picture of the inside front of the picture tube.

If you are careful, you should have no problem. But, an electronics shop could also do it for you and probably very reasonably. When I worked on TVs they were about 25,000 to 50,000 volts, now I think they are more like 70,000. Just think of a good static shock from walking across a carpet in winter and magnify it by about 100 or so. :)

Have fun, but be cautious.

Mike
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Old April 17th, 2008, 02:55 PM   #9
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Alright,

I did found the 4 cables to the Tube. And changed the blue wire with the yellow one.
(it actually become quit fun, we were all curious about what would happen)
But when I connected the camera nothing happenend. So we did connect the wires back like it was originally. But then a smell of something burning came free.

Connected the wrong wires??
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Old April 17th, 2008, 03:02 PM   #10
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There should be two sets, one each going to one of the electro magnets/coils. Make sure you switch the pairs, not just random. For example, if you have red and green going to one coil and blue and black going to the other, just reverse the red and green with each other, not the red with the black and blue.

Have fun and be careful!

Mike
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Old April 17th, 2008, 03:11 PM   #11
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On second thought, I don't know if these circuits are a/c or d/c. Therefore you may need to switch the wires from one coil to the other in total. Just don't mix them between. I hope you are not really attached to that TV! :)

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Old April 17th, 2008, 04:18 PM   #12
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A more simple solution is to wait.

I had a color TV stored on its side in the attic for a couple of years. When I put it back into service, the color of the image was distorted including the greenish tint. If I turned it back on its side, the image was fine.

It took about a week to readjust.

It's because of the alignment of the set w.r.t the earth's magnetic field.
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Old April 17th, 2008, 05:11 PM   #13
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I haven't got the monitor back to work. I actually took two cables from the same side, and switched them. There is also one cable which is thicker then the other. What kind of cable is this?
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Old April 18th, 2008, 04:01 AM   #14
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Hi Piet,

If at all possible, please could you show us some photos of the inside of your CRT showing the wires you cut? It might help us to get your screen working again.
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