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Author Topic: an electrifying experience  (Read 1211 times)

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Rocky

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an electrifying experience
« on: March 19, 2004, 11:24:58 am »
I did a cap job on my WG4900 monitor. I discharged the tube with my handy jumpercables and screwdriver setup. I got a nice snap. I waited 15 minutes and did it again. no snap this time, ready to take the chassis off.

Well..... I finish the work and am reassembling the thing. All I have left to do is put the suction cup on the tube and attach the little clip. As I'm compressing the clip with a screwdriver, my index finger moves from the plastic handle to the metal shaft and zowie   :o

That picture tube still had a  charge in it!  Fortunately, the jolt only felt like 110V house current, but it got my attention.

Just a word to those working on monitors. Leave the power off for a while and discharge it several times (over time) before working on it.

The good news is the monitor is very bright and crisp!


Rocky

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Re:an electrifying experience
« Reply #1 on: March 19, 2004, 03:18:18 pm »
As has been noted many times here.. Discharging doesn't only apply to taking the anode wire off, but ALSO to putting it back on.

The longer the tube sits without being grounded (anode cap and ground wire attached through a properly functioning chassis), the more of a charge it will build up naturally. It will gain more the dryer it is as well.  Remember the tube is nothing more than a massive capacitor.

Always short the anode connection (inside the hole) to the aquadag on the outside of the tube PRIOR to reattaching the anode cap.

Also, be sure you discharge the large capacitor on the circuit board chassis, especially if you had a fuse burn out prior to removing it. That filter capacitor holds quite a nasty charge as well.