possible problem with Sony flat-face WEGA

  • Thread starter William Sommerwerck
  • Start date
W

William Sommerwerck

Guest
I'm posting this to see if anyone /knows/ the answer, or has a reasonable
suspicion. I do not want to initiate an interminable chain of speculation.

I own a 36" flat-face 400-series Sony WEGA IDTV and, yes, I have the service
manual. The set has gotten heavy use over the past decade; I often leave it
on when I go to bed. It wasn't cheap, and I'd like to get at least another
five years out of it. For a non-HD CRT set, it has an excellent picture,
especially with RGB signals from a DVD player.

When the set's turned on, the HV is apparently shut off, so that the CRT
heater has time to come to full temperature, to avoid stripping the cathode.
(This is speculation.) Though sound comes on almost immediately, it takes
about 10 seconds for the raster to appear.

Recently I've noticed "something new". For about two seconds after the
raster comes on, the black level is too light. You can see the image
"darkening" as the black level drops to its "correct" point. This occurs
only when the set is "cold"; cycling the power doesn't cause this.

I'm hoping someone will say "I've seen this. It's the ___________."
Troubleshooting this set won't be easy (if only because it's close to the
wall on a near-immovable stand). I don't want to tear into it until I'm
reasonably certain I can fix it on the first try.

Thanks in advance.

--
"We already know the answers -- we just haven't asked the right
questions." -- Edwin Land
 
On 1/30/2011 9:21 AM, William Sommerwerck wrote:
I own a 36" flat-face 400-series Sony WEGA IDTV and, yes, I have the service
manual.
Click to expand...
Is that the same set you kept trying to give away on
rec.antique.radio+phono?

Jeff
 
I own a 36" flat-face 400-series Sony WEGA IDTV
and, yes, I have the service manual.

Is that the same set you kept trying to give away
on rec.antique.radio+phono?
Click to expand...
Are you kidding? That was an NAD MR-20A with a failing focus system.

It is a classic set, and worth restoring -- if you can find the parts needed
(most likely a no-longer-available HOT system). If someone wants it, it's
theirs for the cost of shipping.
 
Wait until it's a problem that doesn't go away after 2 seconds.
Click to expand...
In other words, wait until an "intermittent" becomes permanent.

Definitely common sense -- but I'd rather make an end run around the
problem.
 
On Sun, 30 Jan 2011 07:21:36 -0800, William Sommerwerck wrote:

I'm posting this to see if anyone /knows/ the answer, or has a
reasonable suspicion. I do not want to initiate an interminable chain of
speculation.

I own a 36" flat-face 400-series Sony WEGA IDTV and, yes, I have the
service manual. The set has gotten heavy use over the past decade; I
often leave it on when I go to bed. It wasn't cheap, and I'd like to get
at least another five years out of it. For a non-HD CRT set, it has an
excellent picture, especially with RGB signals from a DVD player.

When the set's turned on, the HV is apparently shut off, so that the CRT
heater has time to come to full temperature, to avoid stripping the
cathode. (This is speculation.) Though sound comes on almost
immediately, it takes about 10 seconds for the raster to appear.

Recently I've noticed "something new". For about two seconds after the
raster comes on, the black level is too light. You can see the image
"darkening" as the black level drops to its "correct" point. This occurs
only when the set is "cold"; cycling the power doesn't cause this.

I'm hoping someone will say "I've seen this. It's the ___________."
Troubleshooting this set won't be easy (if only because it's close to
the wall on a near-immovable stand). I don't want to tear into it until
I'm reasonably certain I can fix it on the first try.

Thanks in advance.
Click to expand...
Wait until it is a problem that doesn't go away after 2 seconds.



--
Live Fast, Die Young and Leave a Pretty Corpse
 
On Sun, 30 Jan 2011 12:22:35 -0800, William Sommerwerck wrote:

Wait until it's a problem that doesn't go away after 2 seconds.

In other words, wait until an "intermittent" becomes permanent.

Definitely common sense -- but I'd rather make an end run around the
problem.
Click to expand...
Good luck.



--
Live Fast, Die Young and Leave a Pretty Corpse
 
On Sun, 30 Jan 2011 07:21:36 -0800, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

I'm posting this to see if anyone /knows/ the answer, or has a reasonable
suspicion. I do not want to initiate an interminable chain of speculation.

I own a 36" flat-face 400-series Sony WEGA IDTV and, yes, I have the service
manual. The set has gotten heavy use over the past decade; I often leave it
on when I go to bed. It wasn't cheap, and I'd like to get at least another
five years out of it. For a non-HD CRT set, it has an excellent picture,
especially with RGB signals from a DVD player.

When the set's turned on, the HV is apparently shut off, so that the CRT
heater has time to come to full temperature, to avoid stripping the cathode.
(This is speculation.) Though sound comes on almost immediately, it takes
about 10 seconds for the raster to appear.

Recently I've noticed "something new". For about two seconds after the
raster comes on, the black level is too light. You can see the image
"darkening" as the black level drops to its "correct" point. This occurs
only when the set is "cold"; cycling the power doesn't cause this.

I'm hoping someone will say "I've seen this. It's the ___________."
Troubleshooting this set won't be easy (if only because it's close to the
wall on a near-immovable stand). I don't want to tear into it until I'm
reasonably certain I can fix it on the first try.

Thanks in advance.
Click to expand...
William, the condition is usually caused by the crt cathode emission
becoming weaker. When the picture no longer comes on, adjusting the
screen control higher will allow the set to work for a few months to a
year more. Chuck
 
The condition is usually caused by the CRT's cathode
emission becoming weaker. When the picture no longer
comes on, adjusting the screen control higher will allow
the set to work for a few months to a year more.
Click to expand...
I kinda expected that. If you're correct, it looks like I won't get my
money's worth out of the set.

I wonder if anyone still makes CRT heater boosters. <grin> Remember those?
 
William Sommerwerck wrote:
The condition is usually caused by the CRT's cathode
emission becoming weaker. When the picture no longer
comes on, adjusting the screen control higher will allow
the set to work for a few months to a year more.

I kinda expected that. If you're correct, it looks like I won't get my
money's worth out of the set.

I wonder if anyone still makes CRT heater boosters. <grin> Remember those?
Click to expand...

If they use DC on the fliament check for a bad electrolyytic in it's
power supply. I used to add a filamnet transformer to series string TV
sets with a dropping diode to power an 84 volt string of filaments.
They barely lasted a year from new, without the modification.


--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.
 
If they use DC on the filament, check for a bad electrolyytic
in its power supply. I used to add a filament transformer to
series string TV sets with a dropping diode to power an 84
volt string of filaments. They barely lasted a year from new,
without the modification.
Click to expand...
Well, this set's over 10 years old. I'll pull out the service manual and
give it a look.
 
On Mon, 31 Jan 2011 11:41:03 -0800, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

The condition is usually caused by the CRT's cathode
emission becoming weaker. When the picture no longer
comes on, adjusting the screen control higher will allow
the set to work for a few months to a year more.

I kinda expected that. If you're correct, it looks like I won't get my
money's worth out of the set.

I wonder if anyone still makes CRT heater boosters. <grin> Remember those?

CRT brighteners are still available but I wouldn't go that route
Click to expand...
until the screen control adjustment is no longer effective.
 
On Jan 30, 7:21 am, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:
I'm posting this to see if anyone /knows/ the answer, or has a reasonable
suspicion. I do not want to initiate an interminable chain of speculation..

I own a 36" flat-face 400-series Sony WEGA IDTV and, yes, I have the service
manual. The set has gotten heavy use over the past decade; I often leave it
on when I go to bed. It wasn't cheap, and I'd like to get at least another
five years out of it. For a non-HD CRT set, it has an excellent picture,
especially with RGB signals from a DVD player.

When the set's turned on, the HV is apparently shut off, so that the CRT
heater has time to come to full temperature, to avoid stripping the cathode.
(This is speculation.) Though sound comes on almost immediately, it takes
about 10 seconds for the raster to appear.

Recently I've noticed "something new". For about two seconds after the
raster comes on, the black level is too light. You can see the image
"darkening" as the black level drops to its "correct" point. This occurs
only when the set is "cold"; cycling the power doesn't cause this.

I'm hoping someone will say "I've seen this. It's the ___________."
Troubleshooting this set won't be easy (if only because it's close to the
wall on a near-immovable stand). I don't want to tear into it until I'm
reasonably certain I can fix it on the first try.

Thanks in advance.

--
"We already know the answers -- we just haven't asked the right
questions." -- Edwin Land
Click to expand...
The industrial Sony's do a very similar thing as the CRT warms up. In
those you're waiting for the beam current feedback to get up to speed.
Since you have the service manual, is there anything in there about
setting G2 by monitoring a specific set of lines in the vertical
interval?

G˛
 
The industrial Sonys do a very similar thing as the CRT
warms up. In those you're waiting for the beam current
feedback to get up to speed. Since you have the service
manual, is there anything in there about setting G2 by
monitoring a specific set of lines in the vertical interval?
Click to expand...
I don't know; I haven't looked yet.

Is there any way to do that without reducing vertical scan?
 
On Tue, 01 Feb 2011 19:34:56 -0600, Chuck wrote:

On Mon, 31 Jan 2011 11:41:03 -0800, "William Sommerwerck"
grizzledgeezer@comcast.net> wrote:

The condition is usually caused by the CRT's cathode emission becoming
weaker. When the picture no longer comes on, adjusting the screen
control higher will allow the set to work for a few months to a year
more.

I kinda expected that. If you're correct, it looks like I won't get my
money's worth out of the set.

I wonder if anyone still makes CRT heater boosters. <grin> Remember
those?

CRT brighteners are still available but I wouldn't go that route
until the screen control adjustment is no longer effective.
Click to expand...
Once you need a filament booster it's time to get the good old Sencore
CR70 'Beam Builder' out of storage.

Or maybe just a bottle of Jim Beam?



--
Live Fast, Die Young and Leave a Pretty Corpse
 
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