Build Your Own Arcade Controls Forum

Main => Monitor/Video Forum => Topic started by: captbaritone on October 30, 2007, 05:39:45 am

Title: Computer power supply distortoing color of CRT?
Post by: captbaritone on October 30, 2007, 05:39:45 am

I am building a cocktail cabinet with a huge old 22 inch CRT monitor. When the monitor is installed the color in the lower right hand corner of the screen gets slightly distorted (as if a magnet were being held near it). It just so happens that the computer power supply is mounted in this corner underneath (behind) the monitor. Is it possible that the power supply is causing this magnetic field? If so, how would I go about shielding the monitor from it?

Thanks!
-Captbaritone

Title: Re: Computer power supply distortoing color of CRT?
Post by: ChadTower on October 30, 2007, 11:52:39 am

Yes, it is very possible and common in cocktails.  You need to shield the power supply with something metal.  I've seen a lot of power supply transformers covered in metal coffee cans and the like to do that.  Just make damn sure you don't short anything with the improvised metal shielding.

Title: Re: Computer power supply distortoing color of CRT?
Post by: captbaritone on October 30, 2007, 01:33:42 pm

Does it need to completely encase the power supply? or could I simply insert a metal plate between the two?

Title: Re: Computer power supply distortoing color of CRT?
Post by: HaRuMaN on October 30, 2007, 01:35:22 pm

Quote from: captbaritone on October 30, 2007, 01:33:42 pm

Does it need to completely encase the power supply? or could I simply insert a metal plate between the two?

I would say encased... since magnetic field lines curve between N and S poles, a flat plate will probably not catch them all.

Title: Re: Computer power supply distortoing color of CRT?
Post by: bluevolume on October 30, 2007, 01:54:31 pm

Try this -- but be VERY careful not to touch anything on the monitor or any other live power source.

Get a piece of sheet metal from Home Depot or wherever, and cut it down just small enough so you can slide it in between the monitor and the power supply.  It doesn't need to be perfect, this is just a test.  See if it affects the monitor; move it around if you have to.  

If this does lessen/eliminate the distortion, then you've figured out the problem.  You can try the coffee can idea above, or you can build a shield out of sheet metal using a vice and some rivets (or spot welds if you are so equipped).  You may need to use a couple layers of metal depending on how strong the magnet is.