Degaussing wand

"JERD"

But any repair shop would have one - so why not take the darn thing to one ?

...... Phil

Not sure where you're located, but WES (Wagner Electronic Services) in Ashfield, NSW has them.

On Thu, 04 Oct 2007 04:04:57 GMT, "JERD" put finger to keyboard and composed:

The trade price for a degaussing wand is around $80.

If your job is a one-off thing, then I'd try disconnecting the monitor's degaussing coil and hooking it up to 240V via a series 100W incandescent lamp, or two such lamps in parallel.

You could also try some of these tricks:

- Franc Zabkar

At some point you have to switch that jig off, if that happens at any point other than zero crossing it leaves a magnetic polarisation on the shadowmask, what I use is a degauss coil from a scrap monitor and a variac, the variac should be carefully turned up until the coil held close to the screen produces strong visible distortion and moved around to disperse the magnetisation, then either slowly withdraw the coil away from the screen or slowly turn down the variac, after that the picture should be OK.

On Thu, 04 Oct 2007 21:49:27 GMT, "ian field" put finger to keyboard and composed:

You're right. Sorry.

I suspect the OP is asking about a one-off job, in which case a variac may be too expensive.

What about wiring an on/off switch across the PTC and adding a lamp load between the PCB's degaussing coil connector and the coil itself?

- Franc Zabkar

A good alternative is to find a suitable power resistor to put in series with a salvaged coil, the important thing is that the magnetic field is reduced slowly as can be done by moving the coil away.

If the rogue magnetisation isn't too severe, possibly a simpler tactic would be temporarily wire a second posistor in parallel with the one on the PCB, its likely that the mains fuse will also have to be temporarily upgraded. There is one significant risk to avoid, the common 3-pin posistors usually have 2 PTC elements - the one in series with the degauss coil and a second directly across the mains to heat the first above it's knee temperature. Some manufacturers (especially Philips) occasionally use PTC/NTC parts, the usual PTC in series with the coil plus a NTC in series with the mains feed to the rectifier, any salvaged posistor should be checked for both PTC (unless the original itself is PTC/NTC). It might take several goes and the posistors take about 6 minutes to cool down each time.

You will have to leave the monitor off for some time between attempts (say 10 minutes.) If the monitor is one that you can disconnect the mains, then reconnect it and monitor will turn on without needing the power button pressed, you could buy one of those cheap mechanical appliance timers from bunnings for under $10, set it to turn on for 15 min then off for 15 min repeatedly and leave it run the monitor overnight)

In my experience, especially with severe distortion (that sounds like what you have there) a degaussing wand is the way to go, however with the end of CRT technology in sight, it will be something you have no use for in the future.

Here are a couple of sources that might end up cheaper than the WES one mentioned elsewhere. A degaussing wand will do the job much better/faster than the inbuilt coil every time in my experience.

Even better - here is one for $25 ! (+$5 postage) I dont think you will do better than that anywhere.