Discharging old style Video CRT?

[John Crane]

I have an old Televideo dumb terminal that has shaky video brightness. It's
not dirty controls; but looks to be a bad/marginal capacitor. That
capacitor sits next to what I believe was called a "flyback unit" - it has
a rubber "hat" on it with a thick wire coming out of it. I also recall that
those things held a pretty nasty charge even when the video unit was powered
down.

Does anyone know the proper procedure to discharge it, so I won't get fried
when I replace the capacitor?

-J

 

[Dave Platt]

I have an old Televideo dumb terminal that has shaky video brightness. It's
not dirty controls; but looks to be a bad/marginal capacitor. That
capacitor sits next to what I believe was called a "flyback unit" - it has
a rubber "hat" on it with a thick wire coming out of it. I also recall that
those things held a pretty nasty charge even when the video unit was powered
down.

Does anyone know the proper procedure to discharge it, so I won't get fried
when I replace the capacitor?

I'd suggest reviewing the information at

http://www.repairfaq.org/sam/crtfaq.htm

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

On Mar 23, 8:51 am, "John Crane" <jc email> wrote:

I have an old Televideo dumb terminal that has shaky video brightness.  It's
not dirty controls; but looks to be a bad/marginal capacitor.  That
capacitor sits next to what I believe was called  a "flyback unit" - it has
a rubber "hat" on it with a thick wire coming out of it.  I also recall that
those things held a pretty nasty charge even when the video unit was powered
down.

Does anyone know the proper procedure to discharge it, so I won't get fried
when I replace the capacitor?

-J

First of all you have to determine where the Hotwire and the ground
wire is. The Hotwire is usually a red or black wire, and the ground is
usually green. You can discharge the capacitor by simply shorting both
leads together with a jumper. If it's already fried then it's probably
discharged. As far as the flyback transformer, It will usually
discharge itself after a while but just in case, if you have a long
shafted screwdriver, try shorting the positive side of the flyback to
the chassis of the set (metal casing of the set is probably ground.)
Make sure that your screwdriver has an insulated handle capable of
managing the discharge voltage(anywhere from 10 to 50kilovolts). If
you are still unsure or have any doubt or fear of trying this it would
be to your benefit and safety to either talk to a reputable tv
repairman or take it in for repair. Please don't take any chances if
you are unsure.

Mr. Rick

 

[Michael Kennedy]

"Dave Platt" <dplatt@radagast.org> wrote in message
news:16uk96-dt5.ln1@radagast.org...

I have an old Televideo dumb terminal that has shaky video brightness.
It's
not dirty controls; but looks to be a bad/marginal capacitor. That
capacitor sits next to what I believe was called a "flyback unit" - it
has
a rubber "hat" on it with a thick wire coming out of it. I also recall
that
those things held a pretty nasty charge even when the video unit was
powered
down.

Does anyone know the proper procedure to discharge it, so I won't get
fried
when I replace the capacitor?

I'd suggest reviewing the information at

http://www.repairfaq.org/sam/crtfaq.htm

--

I second this advice.. There is a ton of info there, maybe even something
helpful to your repair aside from discharging the CRT.

Mike