Monitor Discharging
This story is from a guy named Aaron Mahler. While reading USNET (rec.games.video.arcade.collecting) I saw this story and thought it would be good to share as this is something a lot of people will face. If you do not know what Monitor Discharging is, I suggest you look at Al's Bizzaro World and check out the information on installing a Cap Kit. (Under Cool Arcade on the main page) If you attempt to discharge a monitor and you have no clue what you are doing, you could wind up dead or just have a really bad day. Please use caution when working with hi-voltage.
Here is his story: Well, tonight I finally had to get my butt in gear and face up to the scariest part of game repair. I've never done a monitor repair before, so the dreaded discharge had arrived. The item in question was a Sanyo EZV in a Super Mario Brothers (Nintendo Vs. System) that was missing a band of video across the top.
The monitor originally came out of a Donkey Kong and I've had it sitting around for several months and didn't even know if it worked until last night. I knew that I'd seen a real monitor discharging tool (not to knock the screwdriver technique) somewhere around the office and decided to try to keep the electrocution odds as much in my favor as possible. While I was grabbing that, a colleague said "here, take this - we never use it" and handed me this mean looking probe from Fluke (still in the packaging). I never knew these existed. It's called an 80K-40 and allows you to measure up to 40,000 volts with your normal meter.
It steps down the voltage 1000:1 so you don't blow a wormhole in the fabric of space when you starting poking where you normally shouldn't. It looks like the discharging tool (long probe, handle, and an alligator clip for ground), but with the addition of two poles to plug in place of the probes on your meter. I found this profile if anybody is interested: http://www.fluke.com/scripts/mdb/accdesc.asp?AccNo=80K-40 I've been keeping the new games at my parents' house in their workshop (lots of room that I don't have at my house) and working on them in the evenings. I took a poll to see if I should blow myself dead before dinner or after.
Mom said there were only three pieces of chicken, so there would be more to go around if my demise came on an empty stomach. With my family's best interests in mind, I headed for the workshop. Dad used to keep bees, so I borrowed his arm-length rubber gloves, hooked the ground clip to the metal chassis and struck a very fine fencing-type pose as I went after the suction cup with the probe. The meter showed a few thousand volts (in tens due to the step-down) and then started counting down smoothly.
It hit zero after about 8 to 10 seconds and sat there. Pause. Poke. Slight reading... then zero.
Pause. Poke. Lesser reading... then zero. Pause.
Not much... then zero. It was that easy? Of course, there's not even a zap with this nifty resistance-filled probey thing. The next part involved figuring out how the hell to get the anode off the tube.
To make a long story short, not having seen what was underneath the suction cup before made it a slightly frustrating and nervous bout of prodding and fiddling. I finally used some pliers to apply enough pressure to the back of the cup to squeeze it right and get the thing off. Now that I've seen it, I understand why everybody's screwdriver instructions work... but with a pointy probe you can't push on it the right way. Anyway... I know now.
I removed the monitor and proceeded to wrestle with the wire-mired boards for a while until I could get them far enough off to do the repair. I located the suspect cap and was quickly rewarded with encouraging signs when the negative leg fell out during the desoldering process. The leg hole is all crusty and has powdery carbon stuff falling out of it now. I didn't expect it to look as bad as it was apparently acting. ;) I put in the new cap, replaced a broken volume pot (another issue), and put everything back together.
I did another couple discharges (got higher levels after the time it took to do the cap work) and the put the monitor back in the chassis. I was rewarded with gorgeous, fully working display: vivid, crisp, and no burn. I'm one happy, more monitor-confident dude now. ;) So, did I do things right or am I just lucky to be alive today? Any pointers or comments from the experienced members out that (that are probably already laughing at all my paranoid antics)? Thanks! - Aaron P.S.
For the other newbies that have been dreading this... I can finally say that it isn't so bad. ;)