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Which circuits warms up the tv?

M

Meat Plow

Jan 1, 1970
0
On Tue, 07 Nov 2006 04:00:50 -0800, z Has Frothed:

[snip]
The idea of this ng is for hobbists to try to fix, seems to me you are
forgetting the reason for this ng. I am not going to do anything stupid,
all I want to do is spray a bit of freezer spray to locate this problem, I
am not even going to touch any connection, so what can go wrong? I will
not take it to a repair shop, if I can't fix it I will simply buy a new
one.

Experienced techs will always tell the hobbyist to stay clear of
potential exposure to lethal voltages. I couldn't tell you in good faith
to go poking around inside equipment with known hazardous voltages present.

Would you answer this? When your TV finally gets a picture, does it
appear all of a sudden with normal brightness and contrast? Or does it
gradually appear?
 
Z

z

Jan 1, 1970
0
Meat said:
On Tue, 07 Nov 2006 04:00:50 -0800, z Has Frothed:

[snip]
The idea of this ng is for hobbists to try to fix, seems to me you are
forgetting the reason for this ng. I am not going to do anything stupid,
all I want to do is spray a bit of freezer spray to locate this problem, I
am not even going to touch any connection, so what can go wrong? I will
not take it to a repair shop, if I can't fix it I will simply buy a new
one.

Experienced techs will always tell the hobbyist to stay clear of
potential exposure to lethal voltages. I couldn't tell you in good faith
to go poking around inside equipment with known hazardous voltages present.

Would you answer this? When your TV finally gets a picture, does it
appear all of a sudden with normal brightness and contrast? Or does it
gradually appear?

It appears normally, and the picture quality is as if I purchased it
new yesterday.
 
Z

z

Jan 1, 1970
0
ian said:
One possible cause is high value start up resistors in the PSU going very
high, this can mean the PSU doesn't start immediately but can be got going
by a random mains spike.

Here is another clue, sometimes it will startup when I press the
tv button (which switches between the normal aerial channels
and the sky digibix scrat connection, seems like your spike
theory is gaining ground...
 
M

Meat Plow

Jan 1, 1970
0
Meat said:
On Tue, 07 Nov 2006 04:00:50 -0800, z Has Frothed:

[snip]
Based on what you have just said, I would have to venture the opinion
that you do not have sufficient experience to be working on dangerous
items such as a TV set with a switch mode power supply, and any
further encouragement that we might give you to carry on trying to
get to the bottom of your problem, is likely to result in injury. In
view of the fact that you get sound immediately, it is unlikely that
the problem is one of the psu being slow to start. Please just take
it to a reputable repair shop.

Arfa

The idea of this ng is for hobbists to try to fix, seems to me you are
forgetting the reason for this ng. I am not going to do anything
stupid, all I want to do is spray a bit of freezer spray to locate
this problem, I am not even going to touch any connection, so what can
go wrong? I will not take it to a repair shop, if I can't fix it I
will simply buy a new one.

Experienced techs will always tell the hobbyist to stay clear of
potential exposure to lethal voltages. I couldn't tell you in good faith
to go poking around inside equipment with known hazardous voltages
present.

Would you answer this? When your TV finally gets a picture, does it
appear all of a sudden with normal brightness and contrast? Or does it
gradually appear?

It appears normally, and the picture quality is as if I purchased it new
yesterday.

Ok so the CRT is probably ok. Have you noticed that the back of the CRT is
glowing orange (filaments) while there is no picture and if so, does it
glow with the same intensity as when the picture appears? If so the
filament source can be ruled out. Also have you listened closely to the
set when the picture appears? Is there a crackle of high voltage? Does a
relay click? Degauss hum for half a second? There are so many things that
an experienced tech can diagnose just using their ears, eyes, and nose.
I can usually tell if a set has HV just by looking and listening to it
with the back off among other things like listening for deflection scans,
flyback noises, smps noises, whines, whistles, hums etc... etc... etc...
Certainly a can of freeze mist would be the very last thing I would reach
for.

Not many if any are going to teach you how to diagnose a tv in person let
alone by posting messages in a news group. The assumption is made that you
have a reasonable amount of experience in fixing what you're trying to fix
and that you have exhausted any other avenues you have available locally
before asking questions in a news group that is propogated globally.
 
I

ian field

Jan 1, 1970
0
z said:
Yes, it glows after 15 seconds, this seems fine, btw which is the
heater circuit, is it the one on the neck of the tube?

If you need to ask a question like that, you probably shouldn't be messing
with the potentially dangerous voltages around a CRT!

The heater is supplied by two of the pins in the connector on the end of the
tube neck, and in a TV usually gets its power from an extra winding on the
line O/P transformer.
 
I

ian field

Jan 1, 1970
0
z said:
Meat said:
On Tue, 07 Nov 2006 04:00:50 -0800, z Has Frothed:

[snip]
Based on what you have just said, I would have to venture the opinion
that you do not have sufficient experience to be working on dangerous
items such as a TV set with a switch mode power supply, and any
further
encouragement that we might give you to carry on trying to get to the
bottom of your problem, is likely to result in injury. In view of the
fact that you get sound immediately, it is unlikely that the problem
is
one of the psu being slow to start. Please just take it to a reputable
repair shop.

Arfa

The idea of this ng is for hobbists to try to fix, seems to me you are
forgetting the reason for this ng. I am not going to do anything
stupid,
all I want to do is spray a bit of freezer spray to locate this
problem, I
am not even going to touch any connection, so what can go wrong? I will
not take it to a repair shop, if I can't fix it I will simply buy a new
one.

Experienced techs will always tell the hobbyist to stay clear of
potential exposure to lethal voltages. I couldn't tell you in good faith
to go poking around inside equipment with known hazardous voltages
present.

Would you answer this? When your TV finally gets a picture, does it
appear all of a sudden with normal brightness and contrast? Or does it
gradually appear?

It appears normally, and the picture quality is as if I purchased it
new yesterday.

Sounds like maybe the auto-greyscale balancing circuit could be playing up,
alternatively some sets blank the picture if the A1 preset isn't set exactly
just so!
 
Z

z

Jan 1, 1970
0
Meat said:
Meat said:
On Tue, 07 Nov 2006 04:00:50 -0800, z Has Frothed:

[snip]

Based on what you have just said, I would have to venture the opinion
that you do not have sufficient experience to be working on dangerous
items such as a TV set with a switch mode power supply, and any
further encouragement that we might give you to carry on trying to
get to the bottom of your problem, is likely to result in injury. In
view of the fact that you get sound immediately, it is unlikely that
the problem is one of the psu being slow to start. Please just take
it to a reputable repair shop.

Arfa

The idea of this ng is for hobbists to try to fix, seems to me you are
forgetting the reason for this ng. I am not going to do anything
stupid, all I want to do is spray a bit of freezer spray to locate
this problem, I am not even going to touch any connection, so what can
go wrong? I will not take it to a repair shop, if I can't fix it I
will simply buy a new one.

Experienced techs will always tell the hobbyist to stay clear of
potential exposure to lethal voltages. I couldn't tell you in good faith
to go poking around inside equipment with known hazardous voltages
present.

Would you answer this? When your TV finally gets a picture, does it
appear all of a sudden with normal brightness and contrast? Or does it
gradually appear?

It appears normally, and the picture quality is as if I purchased it new
yesterday.

Ok so the CRT is probably ok. Have you noticed that the back of the CRT is
glowing orange (filaments) while there is no picture and if so, does it
glow with the same intensity as when the picture appears? If so the
filament source can be ruled out.

Have you read my previous answers? I said that the crt is glowing from
the very start.

Also have you listened closely to the
set when the picture appears? Is there a crackle of high voltage? Does a
relay click? Degauss hum for half a second? There are so many things that
an experienced tech can diagnose just using their ears, eyes, and nose.
I can usually tell if a set has HV just by looking and listening to it
with the back off among other things like listening for deflection scans,
flyback noises, smps noises, whines, whistles, hums etc... etc... etc...
Certainly a can of freeze mist would be the very last thing I would reach
for.

Not many if any are going to teach you how to diagnose a tv in person let
alone by posting messages in a news group. The assumption is made that you
have a reasonable amount of experience in fixing what you're trying to fix
and that you have exhausted any other avenues you have available locally
before asking questions in a news group that is propogated globally.

Well, I am not a professional, but I gather from the faq of this ng
that it is very hobbyist friendly. Having said that, the advise meeted
out is probably also on a hobbyist level, so is to be taken with
a pich of salt...
 
I

ian field

Jan 1, 1970
0
Here is another clue, sometimes it will startup when I press the
tv button (which switches between the normal aerial channels
and the sky digibix scrat connection, seems like your spike
theory is gaining ground...

Its been established in the flow of posts so far that your PSU is almost
certainly starting normally and the line O/P is very probably doing so as
well, it seems increasingly likely that the auto-greyscale circuit is
detecting an excessively worn CRT and shutting down the cathode drives. On
some sets an incorrectly set first anode can also confuse the g/s circuit.
 
M

Meat Plow

Jan 1, 1970
0
Meat said:
Meat Plow wrote:
On Tue, 07 Nov 2006 04:00:50 -0800, z Has Frothed:

[snip]

Based on what you have just said, I would have to venture the
opinion that you do not have sufficient experience to be working
on dangerous items such as a TV set with a switch mode power
supply, and any further encouragement that we might give you to
carry on trying to get to the bottom of your problem, is likely to
result in injury. In view of the fact that you get sound
immediately, it is unlikely that the problem is one of the psu
being slow to start. Please just take it to a reputable repair
shop.

Arfa

The idea of this ng is for hobbists to try to fix, seems to me you
are forgetting the reason for this ng. I am not going to do
anything stupid, all I want to do is spray a bit of freezer spray
to locate this problem, I am not even going to touch any
connection, so what can go wrong? I will not take it to a repair
shop, if I can't fix it I will simply buy a new one.

Experienced techs will always tell the hobbyist to stay clear of
potential exposure to lethal voltages. I couldn't tell you in good
faith to go poking around inside equipment with known hazardous
voltages present.

Would you answer this? When your TV finally gets a picture, does it
appear all of a sudden with normal brightness and contrast? Or does
it gradually appear?

It appears normally, and the picture quality is as if I purchased it
new yesterday.

Ok so the CRT is probably ok. Have you noticed that the back of the CRT
is glowing orange (filaments) while there is no picture and if so, does
it glow with the same intensity as when the picture appears? If so the
filament source can be ruled out.

Have you read my previous answers? I said that the crt is glowing from the
very start.

Also have you listened closely to the set when the picture appears? Is
there a crackle of high voltage? Does a relay click? Degauss hum for
half a second? There are so many things that an experienced tech can
diagnose just using their ears, eyes, and nose. I can usually tell if a
set has HV just by looking and listening to it with the back off among
other things like listening for deflection scans, flyback noises, smps
noises, whines, whistles, hums etc... etc... etc... Certainly a can of
freeze mist would be the very last thing I would reach for.

Not many if any are going to teach you how to diagnose a tv in person
let alone by posting messages in a news group. The assumption is made
that you have a reasonable amount of experience in fixing what you're
trying to fix and that you have exhausted any other avenues you have
available locally before asking questions in a news group that is
propogated globally.

Well, I am not a professional, but I gather from the faq of this ng that
it is very hobbyist friendly. Having said that, the advise meeted out is
probably also on a hobbyist level, so is to be taken with a pich of
salt...

I didn't say it wasn't hobby friendly. Hell I started out as a hobbyist
and I was just giving you an opinion based upon my 30+ years of on the
bench experience (retired now) that some things are best left to qualified
service personel. I have seen many hobbyists turn simple repairs into
expensive ones and even worst situations where the device wasn't
repairable.

Good luck
 
Z

z

Jan 1, 1970
0
ian said:
Its been established in the flow of posts so far that your PSU is almost
certainly starting normally and the line O/P is very probably doing so as
well, it seems increasingly likely that the auto-greyscale circuit is
detecting an excessively worn CRT and shutting down the cathode drives. On
some sets an incorrectly set first anode can also confuse the g/s circuit.

Why would it be doing that? What possible consumer benefit could be
obtained by greyscale shut down as you describe? Are you seriously
saying that the people at Panasonic will deliberately install a circuit
that
shuts down the tv. I have never heard of such a thing, they could be
sued for that. Are you really sure about that???
 
I

ian field

Jan 1, 1970
0
z said:
Why would it be doing that? What possible consumer benefit could be
obtained by greyscale shut down as you describe? Are you seriously
saying that the people at Panasonic will deliberately install a circuit
that
shuts down the tv. I have never heard of such a thing, they could be
sued for that. Are you really sure about that???

Most modern CRT displays have a multitude of safety shutdown circuits, this
can be very frustrating for the service engineer as often the unit will shut
down in response to relatively minor faults, making it impossible to observe
any symptoms that might betray the nature of the fault.

On the rare occasions that the service manual can be obtained at reasonable
cost (if at all!) these sometimes give guidance on which safety trips can be
overridden for servicing purposes, otherwise it can be a minefield - if you
short the wrong safety trip the unit can fail catastrophically at switch
on!!
 
M

Michael A. Terrell

Jan 1, 1970
0
z said:
The idea of this ng is for hobbists to try to fix, seems to
me you are forgetting the reason for this ng. I am not
going to do anything stupid, all I want to do is spray a bit
of freezer spray to locate this problem, I am not even going
to touch any connection, so what can go wrong? I will not
take it to a repair shop, if I can't fix it I will simply buy a new
one.


No, the newsgroup is for electronic techs to exchange information.
The group will help a beginner, but it is considered criminal to give
advice, without the proper warnings. A TV can kill you, if you don't
know what you are doing


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
M

Meat Plow

Jan 1, 1970
0
Why would it be doing that? What possible consumer benefit could be
obtained by greyscale shut down as you describe? Are you seriously saying
that the people at Panasonic will deliberately install a circuit that
shuts down the tv. I have never heard of such a thing, they could be sued
for that. Are you really sure about that???

This is starting to smack of a troll.
 
M

Michael A. Terrell

Jan 1, 1970
0
z said:
Why would it be doing that? What possible consumer benefit could be
obtained by greyscale shut down as you describe? Are you seriously
saying that the people at Panasonic will deliberately install a circuit
that shuts down the tv. I have never heard of such a thing, they could
be sued for that. Are you really sure about that???


What are you going to sue them for? Trying to comply with
international safety standards? You really are ignorant of how the
electronics industry works, after the lawyers got their hands into it.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
J

James Sweet

Jan 1, 1970
0
Why would it be doing that? What possible consumer benefit could be
obtained by greyscale shut down as you describe? Are you seriously
saying that the people at Panasonic will deliberately install a circuit
that
shuts down the tv. I have never heard of such a thing, they could be
sued for that. Are you really sure about that???


Why could they be sued for incorporating a circuit that shuts down when
a fault is detected? Sounds like good common sense to me, the service
literature generally explains how to narrow down which shutdown is
occurring so the problem can be diagnosed.
 
Z

z

Jan 1, 1970
0
z said:
Why would it be doing that? What possible consumer benefit could be
obtained by greyscale shut down as you describe? Are you seriously
saying that the people at Panasonic will deliberately install a circuit
that
shuts down the tv. I have never heard of such a thing, they could be
sued for that. Are you really sure about that???

oh, I see all the "experts" are joining in...
so if as the original replyer suggested the
grayscale circuit detected a bad crt than
the common sense thing to do would be
to make the tv stop working now rather
than give the poor customer a few more
month of pleasure. Sure, I believe you...
 
I

ian field

Jan 1, 1970
0
z said:
Meat said:
This is starting to smack of a troll.

go away!
you already asserted that you will not help
why r u still here?
You were given sound advice by several different people, its not their fault
its not what you wanted to hear and taking that attitude won't change that!
 
M

Meat Plow

Jan 1, 1970
0
go away!
you already asserted that you will not help why r u still here?

I wished you good luck and when you started talking about a company
getting sued over placing automatic measures in their equipment not only
to protect said equipment from catastrophic failure but to also protect
the consumer from hazardous emissions I mention you are starting to sound
like a troll. I think it is you that needs to go away if you can't listen
to the good advice of many of the techs here who donate their spare time
trying to help those that will listen without a fucked up attitude like
yours.

-PLONK-
 
H

Homer J Simpson

Jan 1, 1970
0
The idea of this ng is for hobbists to try to fix

No, it isn't. The idea is for those with experience to help those with a
little less.

Would you go to alt.brain.surgery if you had a headache?
 
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