What is this adjustment?

[Michael A. Covington]

While adjusting the focus in a 17-inch monitor, I found a small
potentiometer near the flyback and twiddled it. Immediately the horizontal
sweep ceased (the image collapsed to a vertical line) and I powered down
(not wanting to see what would fry!). I put it back in its original
position and the monitor works fine.

Query: What adjustment is this, and what is the correct way to adjust it?

Thanks!

 

[Patch]

"Michael A. Covington" <Michael@CovingtonInnovations.com> wrote in message
news:--KcnfKmc6_NEoOiXTWJkA@speedfactory.net...

While adjusting the focus in a 17-inch monitor, I found a small
potentiometer near the flyback and twiddled it. Immediately the
horizontal
sweep ceased (the image collapsed to a vertical line) and I powered down
(not wanting to see what would fry!). I put it back in its original
position and the monitor works fine.

Query: What adjustment is this, and what is the correct way to adjust it?

Thanks!

You're lucky you got it back. Sounds like the pot has a bad spot on it &
when you turned it the thing crapped out. What you are doing is called REA

by repair tech. (random experimental adjustments) It's hard to say what
control this is, it might be the width control. In times like this it's best
to remember "If it ain't broke, don't fix it"

 

[Michael A. Covington]

"Patch" <bob_acord@hotmail.com> wrote in message
news:6%wTa.61037$R92.30098@news2.central.cox.net...

"Michael A. Covington" <Michael@CovingtonInnovations.com> wrote in message
news:--KcnfKmc6_NEoOiXTWJkA@speedfactory.net...
While adjusting the focus in a 17-inch monitor, I found a small
potentiometer near the flyback and twiddled it. Immediately the
horizontal
sweep ceased (the image collapsed to a vertical line) and I powered down
(not wanting to see what would fry!). I put it back in its original
position and the monitor works fine.

You're lucky you got it back. Sounds like the pot has a bad spot on it &
when you turned it the thing crapped out.

That is very plausible, since its action was not like a continuum at all.
Also, the twiddle that made it malfunction was *very* small (like 1 degree
of rotation).

 

[Sofie]

Patch....
Yes.... the REA .....
.....most skilled technicians have a lot of experience with this...... but
as experience has taught most of us, one must be very careful. ..... and
if one makes more than one or two of these REAs then it can be big trouble
because there is now NOT just one REA to deal with to get the equipment
working again.... it is kind of like a combination lock....
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


"Patch" <bob_acord@hotmail.com> wrote in message
news:6%wTa.61037$R92.30098@news2.central.cox.net...

"Michael A. Covington" <Michael@CovingtonInnovations.com> wrote in message
news:--KcnfKmc6_NEoOiXTWJkA@speedfactory.net...
While adjusting the focus in a 17-inch monitor, I found a small
potentiometer near the flyback and twiddled it. Immediately the
horizontal
sweep ceased (the image collapsed to a vertical line) and I powered down
(not wanting to see what would fry!). I put it back in its original
position and the monitor works fine.

Query: What adjustment is this, and what is the correct way to adjust
it?

Thanks!

You're lucky you got it back. Sounds like the pot has a bad spot on it &
when you turned it the thing crapped out. What you are doing is called REA
by repair tech. (random experimental adjustments) It's hard to say what
control this is, it might be the width control. In times like this it's
best
to remember "If it ain't broke, don't fix it"

 

[Sofie]

Dave D:
That was my thought too...... I guess that great minds think alike......
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

snipperoo:

"Dave D" <someone@somewhere.com> wrote in message
That doesn't sound like an adjustment, it sounds like the service mode
switch, which can resemble a pot. Its function is to collapse the frame
for
setting beam cutoff / screen control.
Dave

 

[Chris]

potentiometer near the flyback and twiddled it. Immediately the
horizontal
sweep ceased (the image collapsed to a vertical line) and I powered

That doesn't sound like an adjustment, it sounds like the service mode
switch, which can resemble a pot. Its function is to collapse the frame
for
setting beam cutoff / screen control.

Dave

Better reread the piece I've clipped out before your response. A service
switch won't mess with sweep. The control was probably something to do with
width or HV.

 

[Sofie]

Chris......
you are correct as long as the OP really meant "horizontal sweep ceased"
and ".....collapsed to a vertical line".......
It has been my experience that many of my non-technical customers and many
non tech types who post questions on this newsgroup tend to get things
juxtaposed. How many times have we seen posts saying that all they have is
a "vertical line" on their television screen and the problem eventually
turns out to be faulty "vertical deflection" which causes a horizontal line
on the screen.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -



"Chris" <chrism@NSitproducts.com> wrote in message
news:LxDTa.165$T4.103@newsread2.news.atl.earthlink.net...

potentiometer near the flyback and twiddled it. Immediately the
horizontal
sweep ceased (the image collapsed to a vertical line) and I
powered



That doesn't sound like an adjustment, it sounds like the service mode
switch, which can resemble a pot. Its function is to collapse the frame
for
setting beam cutoff / screen control.

Dave



Better reread the piece I've clipped out before your response. A service
switch won't mess with sweep. The control was probably something to do
with
width or HV.

 

[Michael A. Covington]

"Sofie" <sofie@olypen.com> wrote in message
news:vhtju117dopfa9@corp.supernews.com...

Patch....
Yes.... the REA .....
....most skilled technicians have a lot of experience with this...... but
as experience has taught most of us, one must be very careful. .....
and
if one makes more than one or two of these REAs then it can be big trouble
because there is now NOT just one REA to deal with to get the equipment
working again.... it is kind of like a combination lock....
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Understood. I should add that this was an old monitor that I picked up for
$5. And I'm well aware of the combination lock effect, which is why I
wanted to isolate each adjustment from the others.

 

[Dave D]

"Michael A. Covington" <Michael@CovingtonInnovations.com> wrote in message
news:AkydnWrbsLYkNIOiXTWJkw@speedfactory.net...

"Patch" <bob_acord@hotmail.com> wrote in message
news:6%wTa.61037$R92.30098@news2.central.cox.net...

"Michael A. Covington" <Michael@CovingtonInnovations.com> wrote in
message
news:--KcnfKmc6_NEoOiXTWJkA@speedfactory.net...
While adjusting the focus in a 17-inch monitor, I found a small
potentiometer near the flyback and twiddled it. Immediately the
horizontal
sweep ceased (the image collapsed to a vertical line) and I powered
down
(not wanting to see what would fry!). I put it back in its original
position and the monitor works fine.

You're lucky you got it back. Sounds like the pot has a bad spot on it
&
when you turned it the thing crapped out.

That is very plausible, since its action was not like a continuum at all.
Also, the twiddle that made it malfunction was *very* small (like 1 degree
of rotation).

That doesn't sound like an adjustment, it sounds like the service mode
switch, which can resemble a pot. Its function is to collapse the frame for
setting beam cutoff / screen control.

Dave

 

[bigmike]

"Chris" <chrism@NSitproducts.com> wrote in message
news:LxDTa.165$T4.103@newsread2.news.atl.earthlink.net...

potentiometer near the flyback and twiddled it. Immediately the
horizontal
sweep ceased (the image collapsed to a vertical line) and I
powered



That doesn't sound like an adjustment, it sounds like the service mode
switch, which can resemble a pot. Its function is to collapse the frame
for
setting beam cutoff / screen control.

Dave



Better reread the piece I've clipped out before your response. A service
switch won't mess with sweep. The control was probably something to do
with
width or HV.

Actually it does in some monitors and TVs. It collapses the vertical sweep

to a thin line for setting up the screen and drive controls, as Dave said.
This type of service switch goes back to the early days of color tv.

 

[Chris]

You mean vertical deflection. No vertical deflection is a horizontal line
(left to right). No horizontal sweep or deflection is a vertical line (top
to bottom). I have never heard of adjusting CRT bias by killing horizontal
sweep or deflection, only vertical (unless the CRT is mounted sideways). In
most cases, a vertical line (no horizontal deflection) can seriously burn
the tube and/or mess with HV since horizontal deflection is usually derived
from the sweep circuits. Few units have seperate dedicated horizontal
deflection circuits seperate from the HV and these units are usually the
larger tubes (>15").

"bigmike" <bigmike@cornhusker.net> wrote in message
news:3f1f0eb7$0$39684$9a6e19ea@news.newshosting.com...

"Chris" <chrism@NSitproducts.com> wrote in message
news:LxDTa.165$T4.103@newsread2.news.atl.earthlink.net...

potentiometer near the flyback and twiddled it. Immediately the
horizontal
sweep ceased (the image collapsed to a vertical line) and I
powered



That doesn't sound like an adjustment, it sounds like the service mode
switch, which can resemble a pot. Its function is to collapse the
frame
for
setting beam cutoff / screen control.

Dave



Better reread the piece I've clipped out before your response. A service
switch won't mess with sweep. The control was probably something to do
with
width or HV.

Actually it does in some monitors and TVs. It collapses the vertical sweep
to a thin line for setting up the screen and drive controls, as Dave said.
This type of service switch goes back to the early days of color tv.

 

[Sofie]

Michael A. Covington:
Please do not be offended..... you would not believe how many folks....
even halfway technical types get this mixed up.... it is always worth
asking the question again for clarity.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -



"Michael A. Covington" <Michael@CovingtonInnovations.com> wrote in message
news:NJWcnVZipKkgioKiU-KYvg@speedfactory.net...

"Sofie" <sofie@olypen.com> wrote in message
news:vhu4373t1hgkd7@corp.supernews.com...
Chris......
you are correct as long as the OP really meant "horizontal sweep
ceased"
and ".....collapsed to a vertical line".......

That is exactly what I meant, and as soon as it happened I cut the power.

It has been my experience that many of my non-technical customers and
many
non tech types who post questions on this newsgroup tend to get things
juxtaposed. How many times have we seen posts saying that all they
have
is
a "vertical line" on their television screen and the problem eventually
turns out to be faulty "vertical deflection" which causes a horizontal
line
on the screen.

Thanks, but I've known horizontal from vertical since age 6 and have known
a
good bit of basic TV repair since about age 9 ... which was before color
TV!

 

[bigmike]

"Chris" <chrism@NSitproducts.com> wrote in message
news:m4TTa.262$i4.105@newsread1.news.atl.earthlink.net...

You mean vertical deflection. No vertical deflection is a horizontal line
(left to right). No horizontal sweep or deflection is a vertical line (top
to bottom). I have never heard of adjusting CRT bias by killing horizontal
sweep or deflection, only vertical (unless the CRT is mounted sideways).
In
most cases, a vertical line (no horizontal deflection) can seriously burn
the tube and/or mess with HV since horizontal deflection is usually
derived
from the sweep circuits. Few units have seperate dedicated horizontal
deflection circuits seperate from the HV and these units are usually the
larger tubes (>15").

Many people that post their problems here, without technical skill, confuse
horizontal and vertical. I use to run a lot of service calls where the only
problem was the customer messed with the service switch, or bumped it while
moving the set, and would call me and tell me he had a vertical line across
his set. Of course there is not a switch to kill the horizontal sweep,
unless you want to kill the set in the process We're on the same track,
it's just that the customer is not always on there with us.

"bigmike" <bigmike@cornhusker.net> wrote in message
news:3f1f0eb7$0$39684$9a6e19ea@news.newshosting.com...

"Chris" <chrism@NSitproducts.com> wrote in message
news:LxDTa.165$T4.103@newsread2.news.atl.earthlink.net...

potentiometer near the flyback and twiddled it. Immediately
the
horizontal
sweep ceased (the image collapsed to a vertical line) and I
powered



That doesn't sound like an adjustment, it sounds like the service
mode
switch, which can resemble a pot. Its function is to collapse the
frame
for
setting beam cutoff / screen control.

Dave



Better reread the piece I've clipped out before your response. A
service
switch won't mess with sweep. The control was probably something to do
with
width or HV.

Actually it does in some monitors and TVs. It collapses the vertical
sweep
to a thin line for setting up the screen and drive controls, as Dave
said.
This type of service switch goes back to the early days of color tv.