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From: default on 3 Jun 2010 20:16
Do all TV's have built in degaussing coils these days?

I have a CRT style TV that's been in service for ~ 4 years and it has
been gradually losing "color purity" mostly on the bottom edges in a
circular pattern - center good.

I can null out the green or magenta it favors and correct the color by
holding a piece of non-magnetized iron in just the right place in
front of the screen, one corner at a time, so I'm fairly sure it is a
problem with a magnetized chassis or color mask.

I've never heard a 60 cycle buzz when the set fires up the way normal
degaussing circuits sound, but didn't think anything of it until the
purity started to go out. Could I have skated this long without a
problem with no built-in coil? And can they make them totally silent?

Plan A is to whip up a manual degaussing coil. I have 5,000 feet of
24 AWG and figure 3,000 feet on a 14" diameter coil will have a
reasonable impedance and use ~60 watts.

Plan B is to fix the set
--
From: Sjouke Burry on 3 Jun 2010 20:47
default wrote:
> Do all TV's have built in degaussing coils these days?
>
> I have a CRT style TV that's been in service for ~ 4 years and it has
> been gradually losing "color purity" mostly on the bottom edges in a
> circular pattern - center good.
>
> I can null out the green or magenta it favors and correct the color by
> holding a piece of non-magnetized iron in just the right place in
> front of the screen, one corner at a time, so I'm fairly sure it is a
> problem with a magnetized chassis or color mask.
>
> I've never heard a 60 cycle buzz when the set fires up the way normal
> degaussing circuits sound, but didn't think anything of it until the
> purity started to go out. Could I have skated this long without a
> problem with no built-in coil? And can they make them totally silent?
>
> Plan A is to whip up a manual degaussing coil. I have 5,000 feet of
> 24 AWG and figure 3,000 feet on a 14" diameter coil will have a
> reasonable impedance and use ~60 watts.
>
> Plan B is to fix the set
My tv, and my 7 crt's give a nice "boing" when swithed on,
so there must be something wrong with your tv.
There sould be a coil around the front of the tube, and a relay and ptc
resistor to let the current trough that coil fade away to zero.
That somewhat de-gauses your screen.
But only if it works.
Very big errors need an external paddle de-gauser.
From: Phil Allison on 3 Jun 2010 22:43

"default"
>
> Do all TV's have built in degaussing coils these days?


** All colour TVs and monitors that use CRTs have them.

It's essential.


> I have a CRT style TV that's been in service for ~ 4 years and it has
> been gradually losing "color purity" mostly on the bottom edges in a
> circular pattern - center good.
>
> I can null out the green or magenta it favors and correct the color by
> holding a piece of non-magnetized iron in just the right place in
> front of the screen, one corner at a time, so I'm fairly sure it is a
> problem with a magnetized chassis or color mask.
>
> I've never heard a 60 cycle buzz when the set fires up the way normal
> degaussing circuits sound, but didn't think anything of it until the
> purity started to go out. Could I have skated this long without a
> problem with no built-in coil? And can they make them totally silent?


** Most degaussing coils make a bit of noise when the screen is switched
on - but some may be very nearly silent.

Your problem is that the PTC thermistor circuit that drives the coil has
failed.

May be because of the PTC device itself, a blown fuse or a bad connection to
the coil.



..... Phil




From: John Larkin on 4 Jun 2010 15:22
On Thu, 03 Jun 2010 20:16:52 -0400, default <default(a)defaulter.net>
wrote:

>Do all TV's have built in degaussing coils these days?
>
>I have a CRT style TV that's been in service for ~ 4 years and it has
>been gradually losing "color purity" mostly on the bottom edges in a
>circular pattern - center good.
>
>I can null out the green or magenta it favors and correct the color by
>holding a piece of non-magnetized iron in just the right place in
>front of the screen, one corner at a time, so I'm fairly sure it is a
>problem with a magnetized chassis or color mask.
>
>I've never heard a 60 cycle buzz when the set fires up the way normal
>degaussing circuits sound, but didn't think anything of it until the
>purity started to go out. Could I have skated this long without a
>problem with no built-in coil? And can they make them totally silent?
>
>Plan A is to whip up a manual degaussing coil. I have 5,000 feet of
>24 AWG and figure 3,000 feet on a 14" diameter coil will have a
>reasonable impedance and use ~60 watts.
>
>Plan B is to fix the set

Do you have a soldering gun? They are good degaussers.

John

From: default on 4 Jun 2010 19:34
On Fri, 04 Jun 2010 12:22:17 -0700, John Larkin
<jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:

>On Thu, 03 Jun 2010 20:16:52 -0400, default <default(a)defaulter.net>
>wrote:
>
>>Do all TV's have built in degaussing coils these days?
>>
>>I have a CRT style TV that's been in service for ~ 4 years and it has
>>been gradually losing "color purity" mostly on the bottom edges in a
>>circular pattern - center good.
>>
>>I can null out the green or magenta it favors and correct the color by
>>holding a piece of non-magnetized iron in just the right place in
>>front of the screen, one corner at a time, so I'm fairly sure it is a
>>problem with a magnetized chassis or color mask.
>>
>>I've never heard a 60 cycle buzz when the set fires up the way normal
>>degaussing circuits sound, but didn't think anything of it until the
>>purity started to go out. Could I have skated this long without a
>>problem with no built-in coil? And can they make them totally silent?
>>
>>Plan A is to whip up a manual degaussing coil. I have 5,000 feet of
>>24 AWG and figure 3,000 feet on a 14" diameter coil will have a
>>reasonable impedance and use ~60 watts.
>>
>>Plan B is to fix the set
>
>Do you have a soldering gun? They are good degaussers.
>
>John

Thanks

I do, and tried that. Winding a coil and connecting it in place of
the tip may be a winner. The gun alone, with a regular soldering tip,
tried in all orientations, did help - the side bands are almost gone
and the center (where I didn't think there was a problem) looks
better.

But there are still two pesky areas on the bottom corners. If I
didn't know better, I'd be looking for a hidden magnet.


--
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