Re: Bad monitor discharge instructions

The formula for Joules stored in the tube is:

J = 0.5C * V^2.

I don't remember what you determined C to be for the tube though. So, I'll
let you plug the numbers in for yourself. Remember to convert your
capacitance into Farads before using the equation.

Joel-

-----Original Message-----
From: John Robertson <jrr@flippers.com>
To: vectorlist@lists.cc.utexas.edu <vectorlist@lists.cc.utexas.edu>
Date: Monday, December 20, 1999 2:23 AM
Subject: Re: Bad monitor discharge instructions

>I guess what I was looking for was the number of Joules stored in the tube.
>So are we talking one Joule or how many?
>
>As for being discharged, well, the tube had been sitting under the bench
>for about one year with no chassis attached. Rather discharged I think, but
>I did short it out with a jumper for a minute to be real safe...meters
>handle 500VDC on there cap analyzing function-at least this meter does...
>
>John :-#)#
>
>At 12:42 AM 12/20/1999 -0600, you wrote:
>>Current is voltage divided by resistance. So 20 kV into a short is one
>>hell of a
>>lot of current for a very short time. Into 20 kohms you would initially
>>have 1 amp
>>decaying exponentially to zero. Assuming 2000 pF of capacitance and 20
>>kohms you
>>would have a time constant of 40 uS. So every 40 microseconds the voltage
and
>>current will decrease by about 67 %. It never actually gets to zero, but
>>for all
>>practical purposes it is assumed to be zero after 5 time constants (200
>>microseconds, in this example).
>>
>>Your reading was based on the response time of whatever meter you were
>>using. I
>>wouldn't be trying that with a digital meter if you will be needing to use
it
>>again, there is a very real danger of blowing out parts.
>>
>>John Robertson wrote:
>>
>> > For anyone that remembers the formula (or can find it) for the amount
of
>> > current stored in a capacitor, I measured a 13 inch picture tube on
>> > Saturday and came up with a value of 0.001 (102). This was between the

>> > anode cap and the chassis that it was mounted in. The tube was not
>> > connected to anything else.
>> >
>> > So @ 20KV what are we talking about? I left my Nomographs sitting on
the
>> > filing cabinet.. somewheres...
>> >
>> > John :-#)#
>> >
>> > At 11:26 PM 12/19/1999 -0500, you wrote:
>> > >I agree this is the best course. It will ruin the topic of my radio
>> show, but
>> > >hey, that's better than crispy newbies!
>> > >
>> > >-Al-
>> > >
>> > >saint wrote:
>> > >
>> > > > I emailed the owner of the web site with the bad monitor discharge
>> > > > instructions to tell him conventional wisdom was that he was in
>> error - if
>> > > > he wants to see them, I was thinking of forwarding the
>> > > > discussion from Vectorlist on his web page, with names/emails
removed.
>> > > > Before I did so, I wanted to make sure no one objected?
>> > > >
>> > > > --- saint
>> > > > Build Your Own Arcade Controls FAQ
>> > > > http://www.arcadecontrols.speedhost.com
>> > > >
>> > > > On Mon, 13 Dec 1999, saint wrote:
>> > > >
>> > > > > I was thining about it, but didn't want to get into a flame war,
>> > > > > particularly since I can't speak from any position of
>> > > > > personal-certainty-of-knowledge...
>> > > > >
>> > > > > --- saint
>> > > > > Build Your Own Arcade Controls FAQ
>> > > > > http://www.arcadecontrols.speedhost.com
>> > > > >
>> > > > >
>> > > > > On Mon, 13 Dec 1999, Christopher X. Candreva wrote:
>> > > > >
>> > > > > >
>> > > > > > One thing this show reminded me of -- did anyone ever contact
the
>> > > person
>> > > > > > with the alternate cap-kit instructions, and actually tell him
his
>> > > > > > method of tube discharging is -- suboptimal ?
>> > > > > >
>> > > > > > :-)
>> > > > > >
>> > > > > > -Chris
>> > > > > >
>> > > > > > ==========================================================
>> > > > > > Chris Candreva -- chris@westnet.com -- (914) 967-7816
>> > > > > > WestNet Internet Services of Westchester
>> > > > > > http://www.westnet.com/
>> > > > > >
>> > > > > >
>> > > > >
>> > > > >
>> > >
>> > >--
>> > >
=====================================================================
>> > >-= Al Warner batlzone@cyberenet.net
=-
>> > >-= Learn how to install a Cap Kit in your video game's monitor and
=-
>> > >-= see a whole lot more on my web page at:
=-
>> > >-= http://www.cyberenet.net/~batlzone
=-
>> > >
=====================================================================
>> >
>> > John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
>> > Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
>> > http://www.flippers.com
>> > "Old pinballers never die, they just flip out."
>>
>>--
>>Windows:
>>
>>32 bit graphical interface for a
>>16 bit patch for an
>>8 bit operating system written for a
>>4 bit processor by a
>>2 bit company that can't stand
>>1 bit of competition.
>
>
> John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
> Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
> http://www.flippers.com
> "Old pinballers never die, they just flip out."
>
>
Received on Mon Dec 20 14:49:28 1999