Discharging a CRT?

[Heinz]

I'm starting to get info'ed up about doing a monitor chassis board swap with my Dual Sync MS9 Nanao for a Tri Sync Wei-Ya so I can enjoy some 31khz goodness.
I will have to discharge the monitor before I atempt this yes?
How do I do that?

 

[Mulletron]

Get a rubber glove (Optional, but safe)

Get a LONG Flat Head ScrewDriver (Metal w/plastic or rubber handle)

About 14/16/18 Gauge wire, about, 2 feet or more long.

Balls. (For the first time.)

----------------------

What you're going to be attempting to do is discharge the Anode Cap thats on the back of the tube, from the Flyback.

BE CAREFUL! This can hold upwards to 10,000 VOLTS! VERY VERY DANGEROUS!

With the Rubber Glove and Ground, Expect Absolute Safety.

You're going to strip and wrap the wire around the metal shaft of the long screwdriver. You are going to take the other end of the wire, and Strip it to A big chunk of metal it can discharge the electricity into... IE, the Monitor Frame.

Next, Put on your optional Rubber Glove on the hand you're going to hold the screwdriver with, and you're going to slide the screwdriver (With the wire thats already attacted securely to the frame) under the anode cap (Suctiony thingy on the back of the monitor (Technical name: Tube) and you May or May not hear a large (SNAP/CRACK!).

For the first few times, STAND ASIDE WHILE SLIDING IT IN. If you weren't properly discharging it, I've seen it throw the screwdriver through 2 sheets of drywall in my buddy's room. I'm just glad he wasn't hurt, or wasn't directly behind it.

Remove the ScrewDriver and do this a few times to make sure that it is fully discharged...(Secure the ground wire, and Wire on the driver, try a few more times) Then Pry under it and remove the Anode Cap. (Just press towards it and then pry out, very simple.)

VIOLA!

Some monitors discharge themselves, but ALWAYS MAKE THE ASSUMPTION YOURS DOESNT.

Some monitors lose their charge after X amount of days. ALWAYS ASSUME YOURS DOESNT.

When it comes to this kind of voltage, Safety is a MUST.

SAFETY SAFETY SAFETY!

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As for compatibility with Chasis/Neckboards/Tubes. I dunno, lol.

Hope this helps.

 

[Heinz]

Thank you!
This process sounds easy enough, now I've just got to source a rubber glove.

So all I need to do is connect some thick wire to the monitor frame, wrap the end of that wire to a nice big screwdriver with a plastic handle and then slide the screwdriver underneath the anode cap a few times.

 

[channelmaniac]

Just pick yourself up a long bladed screwdriver and then a set of wire jumpers that have alligator clips on each end. You can get those wire jumpers at Radio Shack.

Oh, and Color CRTs can hold upwards of 25 to 30 thousand volts - not 10K. 10K is in the range of black and white CRTs.

Are you trying to swap just the boards and not the tube too? If that's the case you better make sure the CRT is compatible with the other board set AND that the Yoke (big coil on the neck of the CRT) is compatible too. If not, things will not work and you may let the magic smoke out.

If you have to replace the Yoke assembly then be aware that you will have to converge all the color guns. This is not a trivial task and takes much patience.

Raymond

 

[Stellarola]

I thought you wouild need a specific monitor tube. I dont think you can just switch out the chassis on a dual sync compatible tube and have 31khz hi-res. I'm pretty sure.

 

[Heinz]

No, people have done this before.
It works with the Nanao MS9's with the Toshiba tube.
The monitor chassis controls the frequency, the tube displays the picture.

BTW, about those alligator clips, would the cables used to transfer power from one car battery to another be sufficient?

If you want more information look at this thread I made at KillerCabs forums.
http://www.killercabs.com/forum/viewtopic.php?t=4237

 

[chrisr]

Don't forget to discharge the tube AGAIN before you put the cap back on. As crazy as it sounds, these tubes can build a charge just sitting there, with no connection. I zapped myself once pretty good putting the cap back on before discharging again.

ChrisR

 

[Mulletron]

BTW, about those alligator clips, would the cables used to transfer power from one car battery to another be sufficient?

Uhhh... Those will do the job, but those are HUGE. Unless you have the wiener compact travel set... yeah, those will do. Normal Alligator clips are the ones you used to use for projects in your physics class in making circuits.

Tell us how it goes!

 

[Heinz]

Had a bit of a talk with some mates about this, would the monitor frame be the best thing to ground the electricity to? this kind of voltage wouldn't cause it to arc and zap something else right?

As soon as I get this chassis I'll discharge the tube.

 

[Mulletron]

Yeah, its absolutely Fine. Its the most readily available item to discharge it to. If you have anything else you can discharge it to, be my guest. But the frame is ALWAYS available, and I've never had any Arc Issues. Its discharging, not a live current, so the issue of Arc-ing isn't too high.

Good luck again bro, remember... its only scary the first time.

 

[norton9478]

Normal Alligator clips are the ones you used to use for projects in your physics class in making circuits.

That's what they were really for?

 

[Neo Ash]

Had a bit of a talk with some mates about this, would the monitor frame be the best thing to ground the electricity to? this kind of voltage wouldn't cause it to arc and zap something else right?

As soon as I get this chassis I'll discharge the tube.

I was told that the braided wire that runs around the tube is the ideal ground. That's what I used and everything came out okay.

 

[Heinz]

I was told that the braided wire that runs around the tube is the ideal ground. That's what I used and everything came out okay.

Really? I think I might use that instead, I'm really confused right now about the best way to ground it.
I'm being told here that the frame or that braided wire are fine to ground to but then some mates are telling me that I should ground it through the ground pin in the power sockets on the wall or wiring the screwdriver to a crowbar stuck in the ground?

I feel more conformtable grounding to the monitor frame/ braided wire than grounding to the ground pin on a power socket.
Then again they've never done anything like this before and have no idea about CRT's at all, you guys have done this before and have had no problems so it confuses me as to why they seem to think grounding to the monitor frame is stupid.

What actually happens to the electricity once it's in the frame?

 

[SpamYouToDeath]

I always took the monitor to the back yard and discharged it into the bottom of the lightning rod. I'm crazy like that.

 

[Neo Ash]

I feel more conformtable grounding to the monitor frame/ braided wire than grounding to the ground pin on a power socket.

Do not use a power socket. What you are trying to do does not coincide with the typical notions of grounding. You need to use the frame or braided wire.

 

[neo_frank]

Do not use a power socket. What you are trying to do does not coincide with the typical notions of grounding. You need to use the frame or braided wire.

Mind explaining this further?? I have fixed a lot of various arcade items, but the monitors needing caps are the one thing I have shyed away from. I have read a bunch of articles, but nothing actually detailing why you arent grounding into a traditional grouding source. Cause if the unit isnt plugged into the wall ground, then as far as I know the frame isnt actually "grounded" Correct?

We are probably over thinking some of this, but there can be a lot of power behind that suction cup

 

[Neo Ash]

Mind explaining this further?? I have fixed a lot of various arcade items, but the monitors needing caps are the one thing I have shyed away from. I have read a bunch of articles, but nothing actually detailing why you arent grounding into a traditional grouding source. Cause if the unit isnt plugged into the wall ground, then as far as I know the frame isnt actually "grounded" Correct?

We are probably over thinking some of this, but there can be a lot of power behind that suction cup

If you use a power socket you would be attempting to use an "earth ground". The braided wire that runs around the crt (a.k.a - aquadag strap ) is the ground for the tube that ties into the chassis. After you discharge the monitor you should discharge the crt a second time before you reconnect the anode cap. The crt can build up a charge just by sitting there.

Go here for more information.....
http://www.stickycarpet.com/pinx/md.html

ttooddddyy knows a great deal about monitor repair....he's the go-to-man for this sorta thing.

 

[channelmaniac]

I always have the cabinet plugged in with the power off... discharge the tube to the frame... wait 5 minutes... discharge it again... and then while the screwdriver is still clipped to the frame I'll take the anode cap off...

I've never been shocked by a monitor doing it like this...

You should discharge it again when you go to put the anode connection back on.

CRTs are like a big huge Leyden jar (capacitor) you don't fully discharge it the first time. The charge is reduced in one area of the CRT and as it redistributes on the inner surfaces the voltage at the anode connection will rise. That's why you need to discharge them again after about 5 minutes.

RJ

 

[Heinz]

Awesome, this sound pretty easy then, wouldn't have a chance without help from you guys.
Wont be for atleast a month before I'm on holidays, damn place that sells the chassis aren't open on weekends.

 

[Heinz]

I spent some time sorting out how i'd make this discharging tool.
Would this be sufficient?

 

[thegreathopper]

Discharge.

That would be perfect, I have discharged monitors lots of times and have never had as much as a spark. just clip on to the strap on the tube or the frame and wedge the screw driver under the rubber cap until you can feel the metal clip and the job is done.

It is nothing to worry about.

 

[Heinz]

Awesome.

 

[Mulletron]

Looks like you took that photo with a Sidekick. lol.

Tell us how it goes, Nice tool too!

 

[ttooddddyy]

double post edit

 

[ttooddddyy]

That would be perfect, I have discharged monitors lots of times and have never had as much as a spark.

Those monitors had built in EHT discharge circuitry (inside the flyback transformer)
It is still good practice to go through the discharge routine

Edit- that tool looks fine lachlan