Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

z wrote:
Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

Tube cathodes heating up via the filament (heater).

"z" wrote in message
ps.com...
Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?


In the old days you only had to wait for the CRT heater (and longer ago - a
set full of tubes) nowadays you have to wait for the front panel micro to
boot up!!!

boardjunkie wrote:
z wrote:
Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

Tube cathodes heating up via the filament (heater).

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?

z wrote:
boardjunkie wrote:

z wrote:

Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

Tube cathodes heating up via the filament (heater).


O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?



What sort of TV is this? It could be that the CRT heater supply is low,
I've seen this caused by dried up electrolytic capacitors. If it's a
Sony TV, the CRT may be aging, causing the AKB circuit to blank the
picture. Unless you're experienced working with electronics there isn't
anything you can do aside from take it to a reputable tech and let them
have a look.

"z" wrote in message
ps.com...

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?

How do you define warming up?

And the degauss thermistors.

Homer J Simpson wrote:
"z" wrote in message
ps.com...

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?

How do you define warming up?

When I switch the tv on in the morning (after it cooled of all night)
it takes about 10 minutes until the picture comes on. (the voice
does not have this delay) and this delay has become worse in
the last years. It's not a Sony it's Panasonic tx-w28r3

"z" wrote in message
ps.com...

boardjunkie wrote:
z wrote:
Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

Tube cathodes heating up via the filament (heater).

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?


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.

Some designs use the charging current through a small high voltage
electrolytic to kick-start the PSU.

Another capacitor related problem is whichever electrolytic holds the PSU
error feedback voltage goes high ESR giving a false excess voltage error
voltage - this causes the PSU to idle at too low O/P to start the set - in
both capacitor related faults, the capacitor in question gradually warms up
causing the ESR to decrease, at some point the capacitor may then get close
enough to normal operation for the set to start.

"z" wrote in message
ps.com...

Homer J Simpson wrote:
"z" wrote in message
ps.com...

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?

How do you define warming up?

When I switch the tv on in the morning (after it cooled of all night)
it takes about 10 minutes until the picture comes on. (the voice
does not have this delay) and this delay has become worse in
the last years. It's not a Sony it's Panasonic tx-w28r3


Examine the CRT PCB and see if there's any small chokes in series with the
heater - if so replace with wire links and see if the CRT warms up any
quicker.

z wrote:

Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

In most sets today there is what you call an IK curcuit, what this does
is let the guns come up to snuff equally. It keeps the picture of till
they are of equal value so you don't get and of color picture.when the
CRT starts to go south or weaken it takes longer. sometime if you crank
up the g2 on the flyback ,just a slight tad, it will force the picture
to come on sooner. but is sounds as though your crt is getting weak

"z" wrote in message
ps.com...

When I switch the tv on in the morning (after it cooled of all night)
it takes about 10 minutes until the picture comes on.

Could be end of life for the tube, or a problem with the heater power
supply.

(the voice does not have this delay)

That eliminates many other possibilities.

ian field wrote:
"z" wrote in message
ps.com...

boardjunkie wrote:
z wrote:
Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

Tube cathodes heating up via the filament (heater).

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?


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.

Some designs use the charging current through a small high voltage
electrolytic to kick-start the PSU.

Another capacitor related problem is whichever electrolytic holds the PSU
error feedback voltage goes high ESR giving a false excess voltage error
voltage - this causes the PSU to idle at too low O/P to start the set - in
both capacitor related faults, the capacitor in question gradually warms up
causing the ESR to decrease, at some point the capacitor may then get close
enough to normal operation for the set to start.

O.k, this is useful, I will spray some freezer spray to see if I can
locate a faulty electrolytic or resistor. Which area of the chasis
should I look at? The power supply area is it near where the ht cable
which goes into the crt (the suction pad at the other end), there seems
to be one very big electrolitic there rated at 400volts and quite a few

smaller ones near it. The other circuits are for example the one on
the neck of the tube, and several circuits are inside metal boxes
(like the tuner).

z wrote:
ian field wrote:

"z" wrote in message
oups.com...

boardjunkie wrote:

z wrote:

Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

Tube cathodes heating up via the filament (heater).

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?


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.

Some designs use the charging current through a small high voltage
electrolytic to kick-start the PSU.

Another capacitor related problem is whichever electrolytic holds the PSU
error feedback voltage goes high ESR giving a false excess voltage error
voltage - this causes the PSU to idle at too low O/P to start the set - in
both capacitor related faults, the capacitor in question gradually warms up
causing the ESR to decrease, at some point the capacitor may then get close
enough to normal operation for the set to start.


O.k, this is useful, I will spray some freezer spray to see if I can
locate a faulty electrolytic or resistor. Which area of the chasis
should I look at? The power supply area is it near where the ht cable
which goes into the crt (the suction pad at the other end), there seems
to be one very big electrolitic there rated at 400volts and quite a few

smaller ones near it. The other circuits are for example the one on
the neck of the tube, and several circuits are inside metal boxes
(like the tuner).



Turn off the lights and watch the neck of the tube, does the heater glow
appear normal after 10-15 seconds or does it take a while? If the heater
is glowing and still no picture, you can eliminate the heater circuit as
a culprit.

"z" wrote in message
ups.com...

O.k, this is useful, I will spray some freezer spray to see if I can
locate a faulty electrolytic or resistor. Which area of the chasis
should I look at?

Fire up the set with the back off and watch the heater in the tube.

pebe writes:

boardjunkie Wrote:
z wrote:-
Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?-

Tube cathodes heating up via the filament (heater).
And the degauss thermistors.

Not likely.

Does the CRT heater come on immediately? You may be able to see it
at the very back of the tube through the ventilation holes.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

"z" wrote in message
ups.com...

ian field wrote:
"z" wrote in message
ps.com...

boardjunkie wrote:
z wrote:
Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

Tube cathodes heating up via the filament (heater).

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?


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.

Some designs use the charging current through a small high voltage
electrolytic to kick-start the PSU.

Another capacitor related problem is whichever electrolytic holds the PSU
error feedback voltage goes high ESR giving a false excess voltage error
voltage - this causes the PSU to idle at too low O/P to start the set -
in
both capacitor related faults, the capacitor in question gradually warms
up
causing the ESR to decrease, at some point the capacitor may then get
close
enough to normal operation for the set to start.

O.k, this is useful, I will spray some freezer spray to see if I can
locate a faulty electrolytic or resistor. Which area of the chasis
should I look at? The power supply area is it near where the ht cable
which goes into the crt (the suction pad at the other end), there seems
to be one very big electrolitic there rated at 400volts and quite a few

smaller ones near it. The other circuits are for example the one on
the neck of the tube, and several circuits are inside metal boxes
(like the tuner).


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

James Sweet wrote:
z wrote:
ian field wrote:

"z" wrote in message
oups.com...

boardjunkie wrote:

z wrote:

Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

Tube cathodes heating up via the filament (heater).

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?


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.

Some designs use the charging current through a small high voltage
electrolytic to kick-start the PSU.

Another capacitor related problem is whichever electrolytic holds the PSU
error feedback voltage goes high ESR giving a false excess voltage error
voltage - this causes the PSU to idle at too low O/P to start the set - in
both capacitor related faults, the capacitor in question gradually warms up
causing the ESR to decrease, at some point the capacitor may then get close
enough to normal operation for the set to start.


O.k, this is useful, I will spray some freezer spray to see if I can
locate a faulty electrolytic or resistor. Which area of the chasis
should I look at? The power supply area is it near where the ht cable
which goes into the crt (the suction pad at the other end), there seems
to be one very big electrolitic there rated at 400volts and quite a few

smaller ones near it. The other circuits are for example the one on
the neck of the tube, and several circuits are inside metal boxes
(like the tuner).



Turn off the lights and watch the neck of the tube, does the heater glow
appear normal after 10-15 seconds or does it take a while? If the heater
is glowing and still no picture, you can eliminate the heater circuit as
a culprit.

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?

Arfa Daily wrote:
"z" wrote in message
ups.com...

ian field wrote:
"z" wrote in message
ps.com...

boardjunkie wrote:
z wrote:
Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

Tube cathodes heating up via the filament (heater).

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?


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.

Some designs use the charging current through a small high voltage
electrolytic to kick-start the PSU.

Another capacitor related problem is whichever electrolytic holds the PSU
error feedback voltage goes high ESR giving a false excess voltage error
voltage - this causes the PSU to idle at too low O/P to start the set -
in
both capacitor related faults, the capacitor in question gradually warms
up
causing the ESR to decrease, at some point the capacitor may then get
close
enough to normal operation for the set to start.

O.k, this is useful, I will spray some freezer spray to see if I can
locate a faulty electrolytic or resistor. Which area of the chasis
should I look at? The power supply area is it near where the ht cable
which goes into the crt (the suction pad at the other end), there seems
to be one very big electrolitic there rated at 400volts and quite a few

smaller ones near it. The other circuits are for example the one on
the neck of the tube, and several circuits are inside metal boxes
(like the tuner).


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.

One more question:
I am considering subscription to the following database
http://www.euras.com/repair_tips_1/P..._Panasonic.htm
however mt model is tx-w28r3, would this be the same as the one
above?

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.




--
Pierre Salinger Memorial Hook, Line & Sinker, June 2004

COOSN-266-06-25794

ian field wrote:
"z" wrote in message
ps.com...

boardjunkie wrote:
z wrote:
Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

Tube cathodes heating up via the filament (heater).

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?


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...


Some designs use the charging current through a small high voltage
electrolytic to kick-start the PSU.

Another capacitor related problem is whichever electrolytic holds the PSU
error feedback voltage goes high ESR giving a false excess voltage error
voltage - this causes the PSU to idle at too low O/P to start the set - in
both capacitor related faults, the capacitor in question gradually warms up
causing the ESR to decrease, at some point the capacitor may then get close
enough to normal operation for the set to start.

"z" wrote in message
oups.com...

James Sweet wrote:
z wrote:
ian field wrote:

"z" wrote in message
oups.com...

boardjunkie wrote:

z wrote:

Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

Tube cathodes heating up via the filament (heater).

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?


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.

Some designs use the charging current through a small high voltage
electrolytic to kick-start the PSU.

Another capacitor related problem is whichever electrolytic holds the
PSU
error feedback voltage goes high ESR giving a false excess voltage
error
voltage - this causes the PSU to idle at too low O/P to start the set -
in
both capacitor related faults, the capacitor in question gradually
warms up
causing the ESR to decrease, at some point the capacitor may then get
close
enough to normal operation for the set to start.


O.k, this is useful, I will spray some freezer spray to see if I can
locate a faulty electrolytic or resistor. Which area of the chasis
should I look at? The power supply area is it near where the ht cable
which goes into the crt (the suction pad at the other end), there seems
to be one very big electrolitic there rated at 400volts and quite a few

smaller ones near it. The other circuits are for example the one on
the neck of the tube, and several circuits are inside metal boxes
(like the tuner).



Turn off the lights and watch the neck of the tube, does the heater glow
appear normal after 10-15 seconds or does it take a while? If the heater
is glowing and still no picture, you can eliminate the heater circuit as
a culprit.

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.

"z" wrote in message
ups.com...

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.




--
Pierre Salinger Memorial Hook, Line & Sinker, June 2004

COOSN-266-06-25794


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!

Meat Plow wrote:
On Tue, 07 Nov 2006 06:01:36 -0800, z Has Frothed:


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...







--
Pierre Salinger Memorial Hook, Line & Sinker, June 2004

COOSN-266-06-25794
--
Pierre Salinger Memorial Hook, Line & Sinker, June 2004

COOSN-266-06-25794

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...

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.

ian field wrote:

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...

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???

"z" wrote in message
oups.com...

ian field wrote:

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...

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???


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!!

z wrote:

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

z wrote:

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

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 wrote:
ian field wrote:

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...

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???

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...

Meat Plow wrote:
On Tue, 07 Nov 2006 08:29:37 -0800, z Has Frothed:


ian field wrote:

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...

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???

This is starting to smack of a troll.

go away!
you already asserted that you will not help
why r u still here?



--
Pierre Salinger Memorial Hook, Line & Sinker, June 2004

COOSN-266-06-25794

"z" wrote in message
ups.com...

Meat Plow wrote:
On Tue, 07 Nov 2006 08:29:37 -0800, z Has Frothed:


ian field wrote:

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...

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???

This is starting to smack of a troll.

go away!
you already asserted that you will not help
why r u still here?



--
Pierre Salinger Memorial Hook, Line & Sinker, June 2004

COOSN-266-06-25794


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!

"z" wrote in message
oups.com...

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?

"z" wrote in message
ups.com...

go away!
you already asserted that you will not help
why r u still here?

"If these were woodworking newsgroups, their questions would be the
equivalent of "What are the best kind of rocks to use to pound screws into
fine furniture?" When someone tells them to use large chunks of granite,
they are happy, but if you try to tell them about screwdrivers, they explode
into a rage."

"Michael A. Terrell" wrote in message
...
z wrote:

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


Thank you for backing me up Michael. It never ceases to amaze me how some
people appear on here, demonstrating a lack of knowledge that makes the risk
of injury to them probable rather than possible, and then take a ridiculous
level of offence when an experienced person tries to look after their
welfare, and politely points out the potential danger of what they are
doing. I sometimes wonder why we bother ... Keep well.

Arfa

Meat Plow wrote:

On Wed, 08 Nov 2006 02:58:04 +0000, Homer J Simpson Has Frothed:


"z" wrote in message
oups.com...

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?

LMAO!


A young man I worked with at Microdyne was hit with a severe headache
at work. He was in so much pain we called for an ambulance. He was
dead a little over an hour later from a brain aneurysm.


--
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