fix magnet distortion on TV/CRT screen ?

[robb]

i know not really electronic repair but i could find no other
suitable group.

I have two big color spots/circles (3" diameter) on the TV/CRT
with a big bright stripe between the two spots put there by a
3/4" x 3/4" cylinder (? hematite ? it is strong ?) type magnet,
the cylinder version of these

http://www.kjmagnetics.com/proddetail.asp?prod=MT%2DM

is there a best way to repair ? how ?

helpful replies appreciated.
robb

 

[Rich Webb]

On Fri, 14 Aug 2009 15:32:55 -0400, "robb" <some@where.on.net> wrote:

i know not really electronic repair but i could find no other
suitable group.

I have two big color spots/circles (3" diameter) on the TV/CRT
with a big bright stripe between the two spots put there by a
3/4" x 3/4" cylinder (? hematite ? it is strong ?) type magnet,
the cylinder version of these

http://www.kjmagnetics.com/proddetail.asp?prod=MT%2DM

is there a best way to repair ? how ?

You might recover the display just with a few on/off cycles. Many (most?
all?) modern CRTs include a degauss cycle on power-up.

Sam Goldwasser's Repair FAQ is probably the best summary of the manual
method if the set doesn't cure itself:

<http://www.repairfaq.org/samnew/tvfaq/tvdegacrt.htm>

Bookmark the parent page. Lots of good dope.

helpful replies appreciated.

Always an optimist, eh? ;-)

--
Rich Webb Norfolk, VA

 

[Dave Platt]

i know not really electronic repair but i could find no other
suitable group.

I have two big color spots/circles (3" diameter) on the TV/CRT
with a big bright stripe between the two spots put there by a
3/4" x 3/4" cylinder (? hematite ? it is strong ?) type magnet,
the cylinder version of these

http://www.kjmagnetics.com/proddetail.asp?prod=MT%2DM

is there a best way to repair ? how ?

Google for "CRT degaussing".

If you're lucky, proper application of a degaussing coil will remove
the residual magnetization which has been left in the CRT's shadow
mask/lines by the small magnets, and will restore proper color on the
screen.

If you are *un*lucky, the little magnets are so strong that they
actually attracted and bent the shadow mask/wires when they were held
up to the front of the CRT. If this has happened, degaussing probably
won't eliminate the discoloration - I don't know of a remedy other
than replacing the CRT itself.


--
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!

 

[William Sommerwerck]

If you are *un*lucky, the little magnets are so strong that they
actually attracted and bent the shadow mask/wires when they
were held up to the front of the CRT. If this has happened,
degaussing probably won't eliminate the discoloration -- I don't
know of a remedy other than replacing the CRT itself.

There is a solution, which was discussed not long ago in this group.

My Sony WEGA had this problem, caused when I (deliberately) turned off a
bulk tape eraser near the CRT. The splotch lasted for years, but disappeared
"spontaneously" when the set was moved to my bedroom in March.

The solution is simple -- "bang" the set gently.

 

[AZ Nomad]

On Fri, 14 Aug 2009 15:46:07 -0700, William Sommerwerck <grizzledgeezer@comcast.net> wrote:

If you are *un*lucky, the little magnets are so strong that they
actually attracted and bent the shadow mask/wires when they
were held up to the front of the CRT. If this has happened,
degaussing probably won't eliminate the discoloration -- I don't
know of a remedy other than replacing the CRT itself.

There is a solution, which was discussed not long ago in this group.

My Sony WEGA had this problem, caused when I (deliberately) turned off a
bulk tape eraser near the CRT. The splotch lasted for years, but disappeared
"spontaneously" when the set was moved to my bedroom in March.

Silly sod. All you had to do to reverse it was place the bulk tape
eraser >10' away from the tv, turn it on, approach the tv to the
distance you had it before, wave it around then BACK AWAY TO 10' while
waving it around before turning it off.

 

[William Sommerwerck]

"AZ Nomad" <aznomad.3@PremoveOBthisOX.COM> wrote in message

news:slrnh8brfr.rfv.aznomad.3@ip70-176-155-130.ph.ph.cox.net...
On Fri, 14 Aug 2009 15:46:07 -0700, William Sommerwerck
grizzledgeezer@comcast.net> wrote:

If you are *un*lucky, the little magnets are so strong that they
actually attracted and bent the shadow mask/wires when they
were held up to the front of the CRT. If this has happened,
degaussing probably won't eliminate the discoloration -- I don't
know of a remedy other than replacing the CRT itself.

There is a solution, which was discussed not long ago in this group.
My Sony WEGA had this problem, caused when I (deliberately) turned
off a bulk tape eraser near the CRT. The splotch lasted for years, but
disappeared "spontaneously" when the set was moved to my bedroom
in March.

Silly sod. All you had to do to reverse it was place the bulk tape
eraser >10' away from the TV, turn it on, approach the TV to the
distance you had it before, wave it around then BACK AWAY TO 10'
while waving it around before turning it off.

You obviously didn't see the discussion. I've been servicing electronic
equipment for 50 years, and know how to use a degausser.

This was not a case of magnetization, but a case of tangled Trinitron grille
wires. All the demagnetizing will not fix the problem. A mechanical jarring
is needed.

One person told us of the man on the Trinitron production line who banged
the CRTs with a rubber mallet as they passed.

 

[none]

If the problem is magnetic and not physical, you can (as was mentioned)
use a bulk tape eraser as a makeshift degaussing coil. If you can't find
one of those, you can use other electromagnetic devices that are powered
by alternating current (AC, not DC). I've used 200 watt soldering
pistols to good effect, engraving tools to less-but-still-workable
effect, and a cheap aquarium air pump once that almost worked a little bit.

Activate the electromagnetic device, bring it close to the discolored
spot, and hope it starts looking rather psychedelic - that means it's
working... Then gradually draw the device away from the CRT until it no
longer has any visible effect, and then turn the device off.

This process should demagnetize the part of the CRT that was affected by
the magnet.

You might have to do it several times, especially with low-power
electromagnetic devices... like aquarium pumps.

Don't turn the device off while it is near enough to affect the CRT. The
result will be colorful, but you will have to do it all over again.

The discoloration may fade in time, as most CRT based TV's have a weak
degaussing coil built in, (as was mentioned earlier) which activates for
a few seconds each time the power is turned on.

Have fun with it...

Karl

 

[AZ Nomad]

On Fri, 14 Aug 2009 16:25:26 -0700, William Sommerwerck <grizzledgeezer@comcast.net> wrote:

"AZ Nomad" <aznomad.3@PremoveOBthisOX.COM> wrote in message
news:slrnh8brfr.rfv.aznomad.3@ip70-176-155-130.ph.ph.cox.net...
On Fri, 14 Aug 2009 15:46:07 -0700, William Sommerwerck
grizzledgeezer@comcast.net> wrote:

If you are *un*lucky, the little magnets are so strong that they
actually attracted and bent the shadow mask/wires when they
were held up to the front of the CRT. If this has happened,
degaussing probably won't eliminate the discoloration -- I don't
know of a remedy other than replacing the CRT itself.

There is a solution, which was discussed not long ago in this group.
My Sony WEGA had this problem, caused when I (deliberately) turned
off a bulk tape eraser near the CRT. The splotch lasted for years, but
disappeared "spontaneously" when the set was moved to my bedroom
in March.

Silly sod. All you had to do to reverse it was place the bulk tape
eraser >10' away from the TV, turn it on, approach the TV to the
distance you had it before, wave it around then BACK AWAY TO 10'
while waving it around before turning it off.

You obviously didn't see the discussion. I've been servicing electronic
equipment for 50 years, and know how to use a degausser.

This was not a case of magnetization, but a case of tangled Trinitron grille
wires. All the demagnetizing will not fix the problem. A mechanical jarring
is needed.

One person told us of the man on the Trinitron production line who banged
the CRTs with a rubber mallet as they passed.

ooops

 

[PeterD]

On Fri, 14 Aug 2009 16:25:26 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

"AZ Nomad" <aznomad.3@PremoveOBthisOX.COM> wrote in message
news:slrnh8brfr.rfv.aznomad.3@ip70-176-155-130.ph.ph.cox.net...
On Fri, 14 Aug 2009 15:46:07 -0700, William Sommerwerck
grizzledgeezer@comcast.net> wrote:

If you are *un*lucky, the little magnets are so strong that they
actually attracted and bent the shadow mask/wires when they
were held up to the front of the CRT. If this has happened,
degaussing probably won't eliminate the discoloration -- I don't
know of a remedy other than replacing the CRT itself.

There is a solution, which was discussed not long ago in this group.
My Sony WEGA had this problem, caused when I (deliberately) turned
off a bulk tape eraser near the CRT. The splotch lasted for years, but
disappeared "spontaneously" when the set was moved to my bedroom
in March.

Silly sod. All you had to do to reverse it was place the bulk tape
eraser >10' away from the TV, turn it on, approach the TV to the
distance you had it before, wave it around then BACK AWAY TO 10'
while waving it around before turning it off.

You obviously didn't see the discussion. I've been servicing electronic
equipment for 50 years, and know how to use a degausser.

This was not a case of magnetization, but a case of tangled Trinitron grille
wires. All the demagnetizing will not fix the problem. A mechanical jarring
is needed.

One person told us of the man on the Trinitron production line who banged
the CRTs with a rubber mallet as they passed.

yes, try to use the rubber mallet. It should work if the wires are not
too messed up.

 

[Meat Plow]

On Fri, 14 Aug 2009 15:32:55 -0400, "robb" <some@where.on.net>wrote:

i know not really electronic repair but i could find no other
suitable group.

I have two big color spots/circles (3" diameter) on the TV/CRT
with a big bright stripe between the two spots put there by a
3/4" x 3/4" cylinder (? hematite ? it is strong ?) type magnet,
the cylinder version of these

http://www.kjmagnetics.com/proddetail.asp?prod=MT%2DM

is there a best way to repair ? how ?

helpful replies appreciated.
robb

If you've not managed to mess the mask aperture up an external
degaussing should work. Google it.

All sets have some kind of self degaussing built in. Over time and
on/off cycles the set should fix itself.

 

[robb]

"Rich Webb" <bbew.ar@mapson.nozirev.ten> wrote in message
news:q4fb85173qs464foefg4begutbtv0aa7k9@4ax.com...

On Fri, 14 Aug 2009 15:32:55 -0400, "robb" <some@where.on.net
wrote:

I have two big color spots/circles (3" diameter) on the
TV/CRT
with a big bright stripe between the two spots put there by a
3/4" x 3/4" cylinder (? hematite ? it is strong ?) type
magnet,
the cylinder version of these

is there a best way to repair ? how ?

You might recover the display just with a few on/off cycles.
Many (most?
all?) modern CRTs include a degauss cycle on power-up.

Sam Goldwasser's Repair FAQ is probably the best summary of the
manual
method if the set doesn't cure itself:

http://www.repairfaq.org/samnew/tvfaq/tvdegacrt.htm

Bookmark the parent page. Lots of good dope.

helpful replies appreciated.

Always an optimist, eh? ;-)

Yes. thanks Rich, for the info and help.

The color spots improved with the 20 minutes off/on but the
bright flaring bar between the dots did not.

I started with weaker magnets. I tried moving them in front of
the bar in/out every which way with only minor changes. I put
the original offending magnet in a fist and waved it about the
same way. While brushing fist by the screen
diagonally/chaotically across the bar seemed to have the most
desired result.

The spots are gone and slight remnant of the bar.

Thanks again,
robb

 

[robb]

"Dave Platt" <dplatt@radagast.org> wrote in message
news:q90hl6-vcs.ln1@radagast.org...

i know not really electronic repair but i could find no other
suitable group.

I have two big color spots/circles (3" diameter) on the
TV/CRT
with a big bright stripe between the two spots put there by a
3/4" x 3/4" cylinder (? hematite ? it is strong ?) type
magnet,
the cylinder version of these

http://www.kjmagnetics.com/proddetail.asp?prod=MT%2DM

is there a best way to repair ? how ?

Google for "CRT degaussing".

If you're lucky, proper application of a degaussing coil will
remove
the residual magnetization which has been left in the CRT's
shadow
mask/lines by the small magnets, and will restore proper color
on the
screen.

If you are *un*lucky, the little magnets are so strong that
they
actually attracted and bent the shadow mask/wires when they
were held
up to the front of the CRT. If this has happened, degaussing
probably
won't eliminate the discoloration - I don't know of a remedy
other
than replacing the CRT itself.


--
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!

Thanks Dave,

That seems to be what possibly happened. The degausing part
seemed to help some of the problem but the rest was remedied (?
perhaps luckily ?) by waving the original magnet diagonally
across the screen and problem area.

Thanks again.
robb

 

[robb]

"robb" <some@where.on.net> wrote in message
news:F4ednfwGxeeCJhjXnZ2dnUVZ_qOdnZ2d@earthlink.com...

I have two big color spots/circles (3" diameter) on the
TV/CRT
with a big bright stripe between the two spots put there by a
3/4" x 3/4" cylinder type magnet,
is there a best way to repair ? how ?

thanks to all that sent helpful replies.
robb

 

[JB]

This was not a case of magnetization, but a case of tangled Trinitron
grille
wires. All the demagnetizing will not fix the problem. A mechanical
jarring
is needed.

One person told us of the man on the Trinitron production line who banged
the CRTs with a rubber mallet as they passed.

ooops

The only sure fix is a CRT replacement. This can be done most easily by
going
around town checking around dumpsters, curbsides, thrift stores and yard
sales
for perfectly good CRT type TVs discarded in favor of large HDTVs.