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what makes the weird crackling sound when you turn off a TV or computer CRT monitor?

R

Ryan Meier

Jan 1, 1970
0
And, can you really get a bad electric shock if you open the case of a TV or computer monitor and
touch the wrong innard?
 
Ryan Meier:
Are you serious? What are you? ..... 6 years old?
The crackling noise is the high voltage....
......and yes you can get knocked on your ass from many points of the
circuitry inside the television.
electricitym
 
I

Inty

Jan 1, 1970
0
Ryan Meier said:
And, can you really get a bad electric shock if you open the case of a TV or computer monitor and
touch the wrong innard?

ROTFL !!!!!!!!!!!!!!!!!!!!!
This is a troll ?

I.
 
N

N Cook

Jan 1, 1970
0
Ryan Meier said:
And, can you really get a bad electric shock if you open the case of a TV or computer monitor and
touch the wrong innard?

I've always assumed its something to do with the deflection coils on the
neck of the CRT
when they have the current switched off. Then some sort of induced back-emf
and consequential mechanical disturbance in the windings.Sounds a bit like
HV sparking but I'm not sure it is.
 
J

Jumpster Jiver

Jan 1, 1970
0
Ryan said:
And, can you really get a bad electric shock if you open the case of a TV or computer monitor and
touch the wrong innard?

OK, Here's a real answer...
If there is no prblem with the TV, usually the crackling is static
electricity jumping around the dust on the back of the picture tube.
And yes if you touch the wrong part you can get seriously hurt (or
worse) - even if the TV is off and has been unplugged for weeks!
However if you read the FAQ and know how to safely discharge the high
voltage it is very safe to work on an unplugged TV.
Troubleshooting a TV while it is on is sometimes necessary and should be
reserved for more experienced servicers because of the dangers involved.
-Mike
 
A

Alan the Tech

Jan 1, 1970
0
OK, Here's a real answer...
If there is no prblem with the TV, usually the crackling is static
electricity jumping around the dust on the back of the picture tube.
And yes if you touch the wrong part you can get seriously hurt (or
worse) - even if the TV is off and has been unplugged for weeks!
However if you read the FAQ and know how to safely discharge the high
voltage it is very safe to work on an unplugged TV.
Troubleshooting a TV while it is on is sometimes necessary and should be
reserved for more experienced servicers because of the dangers involved.
-Mike
Your not kidding there, back in the 80's when I was still in tech
school I decided to fix my old tv ( I was a quite a bit dumber back
then) A power resistor controling the horizontal picture cracked.
The tv was an old one that still had tubes. I had the tv on and the
back off after replacing the resistor and when adjusting the
horizontal, I was on the side of the tv to see the picture while
reaching around the back to set the pot and not looking where my hand
was. I touch the anode of a 600 Vdc tube. The charge went from my
wrist thru the first two fingers on my right hand. My fingers were
numb for 2 days and I still carry the scar to this day. I was lucky.
It serves as a reminder to me to be dam sure you know what you are
doing before tinkering on something that could easlly kill you.
 
I

Inty

Jan 1, 1970
0
It serves as a reminder to me to be dam sure you know what you are
doing before tinkering on something that could easlly kill you.
I still remember when repairing an Hitachi set I discharged on my finger the
bigger electrolytic cap, in USA it's about 150-200VDC, in Italy we have
220VAC and 300-350VDC on this cap... about 100-120uF
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Fortunately I wasn't killed
!!!!!!!!!!!!!!!!!!!!!!!!!1

I.
 
N

NSM

Jan 1, 1970
0
I still remember when repairing an Hitachi set I discharged on my finger the
bigger electrolytic cap, in USA it's about 150-200VDC, in Italy we have
220VAC and 300-350VDC on this cap... about 100-120uF
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Fortunately I wasn't killed

I picked up a working tube amp by the chassis and the main electro.
Unfortunately for me the main electro was loose and not always grounded. 400
Volts DC can spoil your whole day.

N
 
A

Asimov

Jan 1, 1970
0
"NSM" bravely wrote to "All" (04 Jul 05 07:13:28)
--- on the heady topic of "Re: what makes the weird crackling sound when you
turn off a TV or comp"

NS> From: "NSM" <[email protected]>
NS> Xref: aeinews sci.electronics.repair:52378


I still remember when repairing an Hitachi set I discharged on my finger the
bigger electrolytic cap, in USA it's about 150-200VDC, in Italy we have
220VAC and 300-350VDC on this cap... about 100-120uF
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Fortunately I wasn't killed

NS> I picked up a working tube amp by the chassis and the main electro.
NS> Unfortunately for me the main electro was loose and not always
NS> grounded. 400 Volts DC can spoil your whole day.


Same thing the deflection plate drivers of an old tube o-scope. OUWCH!
Don't ask me how I know...

A*s*i*m*o*v

.... You mean 15" sparks are SUPPOSED to come out of this thing?!?
 
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