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Science Forum Index » Electronics - Repair Forum » Red comes through on a black screen...
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 Posted: Thu Jun 12, 2008 2:17 pm |
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Guest
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I have red coming though when there shouldn't be anyone on the screen.
For instance, If I am at a no-input screen I can see some red on the
screen.
It is a 1994 Hitachi 50" rear projection TV. I am attempting to fix it
up to give it to a family who can't afford to replace their crappy 20"
tv, but they are giving me a place to stay over the summer.
any help would be great! |
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| Art... |
| Posted: Thu Jun 12, 2008 8:01 pm |
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<Johnhayden at (no spam) letu.edu> wrote in message
news:93941155-327a-4cea-bac0-438014afeac8 at (no spam) d77g2000hsb.googlegroups.com...
Quote: I have red coming though when there shouldn't be anyone on the screen.
For instance, If I am at a no-input screen I can see some red on the
screen.
It is a 1994 Hitachi 50" rear projection TV. I am attempting to fix it
up to give it to a family who can't afford to replace their crappy 20"
tv, but they are giving me a place to stay over the summer.
any help would be great!
Check the screen (G-2) settings for all three crts, you should be able to
obtain a fairly good white balance without retrace lines or other colours
showing thru onto a black (no signal) screen. Also, if you haven't cleaned
the face of the lens in a while it would be a good idea to open the back up
and have a go at that process also.
cheers! |
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| Sam Goldwasser... |
| Posted: Fri Jun 13, 2008 7:12 am |
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"Art" <plotsligt at (no spam) hotmail.com> writes:
Quote: Johnhayden at (no spam) letu.edu> wrote in message
news:93941155-327a-4cea-bac0-438014afeac8 at (no spam) d77g2000hsb.googlegroups.com...
I have red coming though when there shouldn't be anyone on the screen.
For instance, If I am at a no-input screen I can see some red on the
screen.
It is a 1994 Hitachi 50" rear projection TV. I am attempting to fix it
up to give it to a family who can't afford to replace their crappy 20"
tv, but they are giving me a place to stay over the summer.
any help would be great!
Check the screen (G-2) settings for all three crts, you should be able
to obtain a fairly good white balance without retrace lines or other
colours showing thru onto a black (no signal) screen. Also, if you
haven't cleaned the face of the lens in a while it would be a good
idea to open the back up and have a go at that process also.
cheers!
Here is a link he emailed me:
http://img123.imageshack.us/img123/3184/hitachi002su3.jpg
--- 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. |
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| whit3rd... |
| Posted: Thu Jun 19, 2008 7:03 am |
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Guest
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On Jun 12, 5:17 pm, Johnhay... at (no spam) letu.edu wrote:
Quote: I have red coming though when there shouldn't be anyone on the screen.
For instance, If I am at a no-input screen I can see some red on the
screen.
There are typically separate red/green/blue level and drive
adjustments in a TV set; get a good grayscale test pattern
(I assume you can hook up a DVD and load a test disk)
and adjust levels until the darkest band is without tint,
then adjust the drive controls until the white band is also
neutral (white) in color.
These adjustments are on/near the video amplifier board,
and always well labeled (like, with red/green/blue colored
knobs). The SCREEN control also may be beneficial,
it's likely to drift with time.
Projection TVs also will benefit from dusting of the optics. |
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