Monitor goes out of focus after warming up

C

ch

Guest
Hi,
My 17" monitor seems to have a strange out-of-focus problem. When I
first turn it on, it's okay. The focus was ok, but after abt 15-20mins
of usage, the screen will go out of focus, and the background will
kind of brighthen up a little. I opened the cover and adjust the focus
knob at the flyback, and it seems to be able to get the screen back to
focus. But when i turn the monitor off and turn it on again the next
morning, the screen again will be out of focus. I need to adjust the
focus knob again to get it focused, but then after 15-20mins usage, it
will go out of focus.

Apparently, some components (perhaps the flyback) deteriote after the
monitor warms up. Anyone has any idea how can I solve the problem?
Really appreciate some advice and tips. Thank you.

Regards,
ch
 
"ch" <choon_ng@hotmail.com> wrote in message
news:2251fb06.0311030133.4e3e0f2e@posting.google.com...
Hi,
My 17" monitor seems to have a strange out-of-focus problem. When I
first turn it on, it's okay. The focus was ok, but after abt 15-20mins
of usage, the screen will go out of focus, and the background will
kind of brighthen up a little. I opened the cover and adjust the focus
knob at the flyback, and it seems to be able to get the screen back to
focus. But when i turn the monitor off and turn it on again the next
morning, the screen again will be out of focus. I need to adjust the
focus knob again to get it focused, but then after 15-20mins usage, it
will go out of focus.

Apparently, some components (perhaps the flyback) deteriote after the
monitor warms up. Anyone has any idea how can I solve the problem?
Really appreciate some advice and tips. Thank you.

Regards,
ch
AFAIK this usually happens with age and is the result of electrolytic
Click to expand...
capacitor degeneration. Which in a practical situation means you replace all
the electrolytic caps you can see !!
More info to be found on Sams site.

--
Regards ............... Rheilly Phoull
 
Sounds like bad FBT

On 3 Nov 2003 01:33:54 -0800, choon_ng@hotmail.com (ch) wrote:

Hi,
My 17" monitor seems to have a strange out-of-focus problem. When I
first turn it on, it's okay. The focus was ok, but after abt 15-20mins
of usage, the screen will go out of focus, and the background will
kind of brighthen up a little. I opened the cover and adjust the focus
knob at the flyback, and it seems to be able to get the screen back to
focus. But when i turn the monitor off and turn it on again the next
morning, the screen again will be out of focus. I need to adjust the
focus knob again to get it focused, but then after 15-20mins usage, it
will go out of focus.

Apparently, some components (perhaps the flyback) deteriote after the
monitor warms up. Anyone has any idea how can I solve the problem?
Really appreciate some advice and tips. Thank you.

Regards,
ch
Click to expand...
 
It is very common in these monitors that components in the power supply,
scan generators, and HV section go thermo sensitive. The electrolytic caps
are most common to do this type of fault. In your monitor, going by your
description, I would assume it to be the flyback assy, since the focus
supply is derived from there.

Considering the age of the monitor, I would strongly suggest to replace it,
rather than spend money on parts and time to service it. The CRT monitors
are very low in cost these days. This will not last more than about another
year or two. They will soon be phased out for newer and more expensive
display technology.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"ch" <choon_ng@hotmail.com> wrote in message
news:2251fb06.0311030133.4e3e0f2e@posting.google.com...
Hi,
My 17" monitor seems to have a strange out-of-focus problem. When I
first turn it on, it's okay. The focus was ok, but after abt 15-20mins
of usage, the screen will go out of focus, and the background will
kind of brighthen up a little. I opened the cover and adjust the focus
knob at the flyback, and it seems to be able to get the screen back to
focus. But when i turn the monitor off and turn it on again the next
morning, the screen again will be out of focus. I need to adjust the
focus knob again to get it focused, but then after 15-20mins usage, it
will go out of focus.

Apparently, some components (perhaps the flyback) deteriote after the
monitor warms up. Anyone has any idea how can I solve the problem?
Really appreciate some advice and tips. Thank you.

Regards,
ch
 
You didnt specify a Brand or a model?

I have an older Mitsubishi Monitor that was doing the same thing. I was told
it was likely the FBT. When I took out the old FBT, I saw that someone had
turned the Focus Pot too far and broke open the housing around it.


"ch" <choon_ng@hotmail.com> wrote in message
news:2251fb06.0311030133.4e3e0f2e@posting.google.com...
Hi,
My 17" monitor seems to have a strange out-of-focus problem. When I
first turn it on, it's okay. The focus was ok, but after abt 15-20mins
of usage, the screen will go out of focus, and the background will
kind of brighthen up a little. I opened the cover and adjust the focus
knob at the flyback, and it seems to be able to get the screen back to
focus. But when i turn the monitor off and turn it on again the next
morning, the screen again will be out of focus. I need to adjust the
focus knob again to get it focused, but then after 15-20mins usage, it
will go out of focus.

Apparently, some components (perhaps the flyback) deteriote after the
monitor warms up. Anyone has any idea how can I solve the problem?
Really appreciate some advice and tips. Thank you.

Regards,
ch
Click to expand...
 
"techforce" <toomuchspam@messedup.com> wrote in message news:<Muwpb.2183$Y26.1696909@news2.news.adelphia.net>...
You didnt specify a Brand or a model?

I have an older Mitsubishi Monitor that was doing the same thing. I was told
it was likely the FBT. When I took out the old FBT, I saw that someone had
turned the Focus Pot too far and broke open the housing around it.
Click to expand...
DOH!

Gives a new meaning to the phrase "snap on pot assembly" .... used on
some more expensive units so if just the pot(s) fail the entire
flyback need not be dumped. :)

-A

"ch" <choon_ng@hotmail.com> wrote in message
news:2251fb06.0311030133.4e3e0f2e@posting.google.com...
Hi,
My 17" monitor seems to have a strange out-of-focus problem. When I
first turn it on, it's okay. The focus was ok, but after abt 15-20mins
of usage, the screen will go out of focus, and the background will
kind of brighthen up a little. I opened the cover and adjust the focus
knob at the flyback, and it seems to be able to get the screen back to
focus. But when i turn the monitor off and turn it on again the next
morning, the screen again will be out of focus. I need to adjust the
focus knob again to get it focused, but then after 15-20mins usage, it
will go out of focus.

Apparently, some components (perhaps the flyback) deteriote after the
monitor warms up. Anyone has any idea how can I solve the problem?
Really appreciate some advice and tips. Thank you.

Regards,
ch
Click to expand...
 
Yea.

I was wanting to send this to a FBT Place for Duplication, but since its
such an old model, the demand is low for these right now.
I dont know if its something I could fix With contact Spray on the exposed
control, or if in Fact there is a problem inside the FBT causing this....

The Focus Control has to be about 95% Fully CW in order for it to be within
acceptable focus on power up. Or maybe even the CRT is degraded?
Its a 1988 Mitsubishi HA3905ADK. One of the Earliest SVGA 20 Inch Monitors
that Accepts EGA, TTL or Analog Inputs.


"Andre" <testing_h@yahoo.com> wrote in message
news:2c2cf14c.0311040637.67630598@posting.google.com...
"techforce" <toomuchspam@messedup.com> wrote in message
news:<Muwpb.2183$Y26.1696909@news2.news.adelphia.net>...
You didnt specify a Brand or a model?

I have an older Mitsubishi Monitor that was doing the same thing. I was
told
it was likely the FBT. When I took out the old FBT, I saw that someone
had
turned the Focus Pot too far and broke open the housing around it.

DOH!

Gives a new meaning to the phrase "snap on pot assembly" .... used on
some more expensive units so if just the pot(s) fail the entire
flyback need not be dumped. :)

-A



"ch" <choon_ng@hotmail.com> wrote in message
news:2251fb06.0311030133.4e3e0f2e@posting.google.com...
Hi,
My 17" monitor seems to have a strange out-of-focus problem. When I
first turn it on, it's okay. The focus was ok, but after abt 15-20mins
of usage, the screen will go out of focus, and the background will
kind of brighthen up a little. I opened the cover and adjust the focus
knob at the flyback, and it seems to be able to get the screen back to
focus. But when i turn the monitor off and turn it on again the next
morning, the screen again will be out of focus. I need to adjust the
focus knob again to get it focused, but then after 15-20mins usage, it
will go out of focus.

Apparently, some components (perhaps the flyback) deteriote after the
monitor warms up. Anyone has any idea how can I solve the problem?
Really appreciate some advice and tips. Thank you.

Regards,
ch
Click to expand...
 
I had 3 Acer 7276ie monitors with such a problem. The solder on the
CRT socket board, specifically the focus spark gap ground, was bad and
would get worse with heat. This would affect the voltage enought to
show up on the screen, especially changing from bright to dark images.
Good luck.
choon_ng@hotmail.com (ch) wrote in message news:<2251fb06.0311030133.4e3e0f2e@posting.google.com>...
Hi,
My 17" monitor seems to have a strange out-of-focus problem. When I
first turn it on, it's okay. The focus was ok, but after abt 15-20mins
of usage, the screen will go out of focus, and the background will
kind of brighthen up a little. I opened the cover and adjust the focus
knob at the flyback, and it seems to be able to get the screen back to
focus. But when i turn the monitor off and turn it on again the next
morning, the screen again will be out of focus. I need to adjust the
focus knob again to get it focused, but then after 15-20mins usage, it
will go out of focus.

Apparently, some components (perhaps the flyback) deteriote after the
monitor warms up. Anyone has any idea how can I solve the problem?
Really appreciate some advice and tips. Thank you.

Regards,
ch
Click to expand...
 
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