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TVs and speakers

  • Thread starter Sean O'Leathlobhair
  • Start date
S

Sean O'Leathlobhair

Jan 1, 1970
0
I have come to this group since it seems to contain the most posts on
this topic. Nonetheless, despite searching, I have not quite found
the answer to my question.

I have an 11 year old Sony TV. For most of its life it has had a pair
of HiFi speakers two feet to either side. These used to be Mission
707s but a couple of years ago they were replaced with bigger ones:
Tanoy R7s.

A few years ago (still the old speakers), the TV suffered some severe
discolouration. This was similar to the effect described by others in
this group: big green and purple patches. I guessed that it was
related to the speaker magnets so I moved them away and waited. This
did not seem to help and I considered bringing it into a shop to be
checked. Luckily, I could not do this for several days and during
these days the set corrected itself. The speakers had to go back to
their original place but the problem did not immediately reoccur.

In fact it was a long time (maybe more than a year) before the problem
reoccurred but eventually it did. Now the problem is occurring more
often (every few weeks) but also clears more quickly (hours).

Previous threads on this subject say that the internal degaussing does
not occur if the power is cycled with the remote control and suggest
disconnecting the mains. How about using the power button on the set,
is that enough? I don't normally disconnect the mains since unless I
crawl behind the furniture to the multiway extension cable, I have to
disconnect the extension cable and lose power to the video as well.
Losing video power is annoying since it is too old to set its own
clock. But if disconnecting from the mains were more effective than
using the power button on the set, I would rearrange the cabling to
make it easier.

Now the question. Is this a sign that my TV is aging and will die
soon? Or are the speakers to blame? Except in unusual circumstances,
they do not move. The TV malfunctions are not linked to any equipment
movements, they appear random but are becoming more frequent.

I am considering replacing the TV but if the speakers are to blame
then I may be in danger of ruining it as well. Are modern sets more
resistant to magnetic fields? Are some models better than others? I
cannot significantly rearrange the furniture so the TV will have to
live with these speakers 2 feet away.

Seán O'Leathlóbhair
 
J

Jerry G.

Jan 1, 1970
0
The TV's degaussing will work each time the set is turned off for more than
30 to 40 minutes. The degaussing coil should work each time the set's power
is re-cycled. It does not matter if it is done with the remote, or the main
power button on the set. The remote is controlling the same circuits as the
power button. There is no difference in this set.

If the speakers are closer than about 4 feet, they will re-magnetize the
CRT mask all the time. Normally this is not going to do permanent damage to
the CRT. It is only an annoyance.

If you place the speakers far from the set and the degaussing is not
working, it is possible you also have a fault in the degaussing circuit. The
degauss thermo-resistor failing is usually the main cause of this circuit to
not work. Other failures may be caused by cold solder connections, and or
the degaussing coil itself may be defective (very rare).

If the mask in the CRT is damaged from some type of disturbance, then the
colour errors will not be able to be corrected. Usually the mask can go
defective if the set was rough handled during transport, or if the set was
dropped or knocked over. It is rare, but if one of the support wires in the
CRT break or become out of position by themselves, there will be colour
errors showing that cannot be corrected.


--

Jerry G.
=====


I have come to this group since it seems to contain the most posts on
this topic. Nonetheless, despite searching, I have not quite found
the answer to my question.

I have an 11 year old Sony TV. For most of its life it has had a pair
of HiFi speakers two feet to either side. These used to be Mission
707s but a couple of years ago they were replaced with bigger ones:
Tanoy R7s.

A few years ago (still the old speakers), the TV suffered some severe
discolouration. This was similar to the effect described by others in
this group: big green and purple patches. I guessed that it was
related to the speaker magnets so I moved them away and waited. This
did not seem to help and I considered bringing it into a shop to be
checked. Luckily, I could not do this for several days and during
these days the set corrected itself. The speakers had to go back to
their original place but the problem did not immediately reoccur.

In fact it was a long time (maybe more than a year) before the problem
reoccurred but eventually it did. Now the problem is occurring more
often (every few weeks) but also clears more quickly (hours).

Previous threads on this subject say that the internal degaussing does
not occur if the power is cycled with the remote control and suggest
disconnecting the mains. How about using the power button on the set,
is that enough? I don't normally disconnect the mains since unless I
crawl behind the furniture to the multiway extension cable, I have to
disconnect the extension cable and lose power to the video as well.
Losing video power is annoying since it is too old to set its own
clock. But if disconnecting from the mains were more effective than
using the power button on the set, I would rearrange the cabling to
make it easier.

Now the question. Is this a sign that my TV is aging and will die
soon? Or are the speakers to blame? Except in unusual circumstances,
they do not move. The TV malfunctions are not linked to any equipment
movements, they appear random but are becoming more frequent.

I am considering replacing the TV but if the speakers are to blame
then I may be in danger of ruining it as well. Are modern sets more
resistant to magnetic fields? Are some models better than others? I
cannot significantly rearrange the furniture so the TV will have to
live with these speakers 2 feet away.

Seán O'Leathlóbhair
 
M

Mike Berger

Jan 1, 1970
0
The effects of magnetic fields may be subtle and the color
distortion may appear very gradually. Your degaussing coil
should activate any time you turn the TV on, whether you use
the remote or not, if it has been inactive long enough for the
thermistor to cool down (20-30 minutes on most TV's). In
other words, if you power cycle it 5 times in a row, it will
only degauss the first time. Let it sit for 30 minutes and
it should degauss again when you turn it on.

Newer TV's aren't any better shielded, and yes, you can expect
the problem to occur with a new TV. Many newer speakers are
better shielded, however, so they can be placed near the TV
in a home theater setup. You might want to consider getting new
shielded speakers along with the new TV.
 
S

Sean O'Leathlobhair

Jan 1, 1970
0
That was not the answer that I was hoping for but thanks.

I would be happy to replace the TV since it is very old and it would
be nice to get a widescreen model. I am not keen to replace the
speakers since they are quite new, sound nice, and cost more than the
TV. Except for the possibility of being the cause of this problem, I
am entirely happy with them.

I had failed to guess that the home theatre problem was solved by
shielding the speakers rather than the TV. I had hoped that it was
the TV that was better shielded so that it could placed close to the
speakers.

I now have a tricky decision to make. For stylistic reasons, my wife
would not accept the speakers moving further from the TV. Anyway, due
to the size and shape of the room, moving them further apart would
spoil the stereo effect since we sit only about 6 feet back from the
TV.

Suppose that the positioning must remain, is it best to leave the
speakers in place when a problem occurs and attempt to degauss?
Rather than move them away until the problem clears and then bring
them back. My theory is that the TV should adjust with the expected
fields present.

You say that the problem would be likely to occur with a new TV. But
would I be harming the new TV? If not, I could buy the new TV before
the move that I just described.

Longer term I may solve the problem in a different way. We may move
the TV to another room. I had planned to move the HiFi with it.
Maybe I will leave the HiFi where it is, dump the TV, and buy a small
home theatre system for the other room.

Just to confirm, is this the best possible degaussing strategy?

1. Turn the set on and run it for a few minutes (is the time
important?).

2. Turn it off (anyhow) and wait 30 - 60 minutes. (I guess that if
the run was short then this period could be short as well).

3. Repeat the above until the problem clears.

Seán O'Leathlóbhair
 
A

Art

Jan 1, 1970
0
Many SONY Teles have a symptom that develops after a while where components
in the degauss control and activation circuitry fail and need to be
addressed. Inclusive are the thermistor and relay, if implemented in your
set. Other possibility is if the set has been subjected to physical shock,
aka being dropped or bounced, causing sustained damage to the internal
components of the crt. May want to have a tech check it out for you for a
securely definitive answer.
 
S

Sean O'Leathlobhair

Jan 1, 1970
0
Thanks.

I don't know whether the degaussing works correctly when the speakers
are removed. It is quite a while since I moved the speakers away and
I do not recall details such as how long I waited between power
cycles.

It would seem that the mask is OK since the problem is not permanent.
It would also seem that the degaussing is working since the problem
does correct itself.

The odd thing is that the problem is becoming more frequent. Do you
know why that may be and whether there is a practical solution other
than replacing the TV? Although the problem does not take long to
correct, it is a nuisance since when it fails, my son takes over our
bedroom which contains the only other TV.

I used to do amateur TV repair but the last time I did, valves were
still in common use. I still have a soldering iron, a multimetre and
a fairly good theoretical knowledge of electronics but no experience
of working on a modern electronic appliance. So only simple repairs
(e.g. resoldering a poor connection) are feasible.

If you see my response to Mike, you will see that I am considering
replacing the set and later separating the TV and HiFi. If the
speakers are not likely to cause permanent damage then I may buy the
new TV in advance of the separation.

Seán O'Leathlóbhair
 
S

Sean O'Leathlobhair

Jan 1, 1970
0
I am fairly sure that the set has not had any serious shock but is 11 years
old so age is a candidate. The remote control has been well abused and it
look like someone has been eating it. I guess that it was my son when he
was younger. However, I don't think that abuse of the remote control is the
cause of the problem.

The trouble with getting it checked is that the minimum charge is a
substantial proportion of the value of an old TV. A friend took his oldish
but nice widescreen TV in for repair. The fault seemed to be an
intermittent power supply fault and worth fixing. The shop tried and failed
several times to fix it. The last I heard, he was discussing the cost of
the non-repair.

I could easily afford a new set but I don't like waste so if I can easily
extend the life of this one, I will. Also, I don't know what to do with the
old set. It is hard to even give them away. Charity (thrift) shops around
here won't accept mains powered items and even the poorest of my friends
already owns a better TV.
 
J

Jeff Strieble

Jan 1, 1970
0
The effects of magnetic fields may be subtle and the color
distortion may appear very gradually. Your degaussing coil
should activate any time you turn the TV on, whether you use
the remote or not, if it has been inactive long enough for the
thermistor to cool down (20-30 minutes on most TV's). In
other words, if you power cycle it 5 times in a row, it will
only degauss the first time. Let it sit for 30 minutes and
it should degauss again when you turn it on.

Newer TV's aren't any better shielded, and yes, you can expect
the problem to occur with a new TV. Many newer speakers are
better shielded, however, so they can be placed near the TV
in a home theater setup. You might want to consider getting new
shielded speakers along with the new TV.


I have one speaker of my stereo installation within a few inches of
my TV (RCA CTC185 - 1999 model). The speakers don't bother the TV
picture at all. I have an Aiwa shelf system with three-way speakers,
which are magnetically shielded so the speaker magnets cannot affect
the TV in any way.

I live in a small apartment and, like yourself, I cannot rearrange
my furniture (much, anyhow) either. Fortunately, as I said, even with
my stereo speakers close to the TV, there is no color distortion.

You will not ruin your TV with new stereo speakers. As others have
said here, the problem could well be the auto-degaussing circuit in
the television itself; if it is not operating, you will have color
distortion from your speakers being so close to the set, as they are
magnetizing the shadow mask. This, of course, always wrecks the
purity. Note as well that if you try to degauss the CRT more than once
every half-hour, the degaussing coils may actually work in reverse,
that is, remagnetizing the shadow mask. (The instruction manual for my
computer monitor cautions against this as well.)
 
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