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Message |
SomeBody
Guest
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 Posted:
Mon Dec 05, 2005 9:35 am Post subject:
Monochrome monitor questions? |
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I'm repairing a few monochrome monitors, these are 9" in size.
The problem I'm having is the screen has vert. lines spaced about every
1/2 in, they are about 1/2" in width. I believe it would be called
ghosting?
The pc board consist of some discreet components and two IC chips.
TDA1175 (vert) and TDA1180 (Hor). Both chips have been replaced as well as
the tube.
Any ideas what the problem could be, an area to look at?
I have a copy of a schematic, but don't now how to post it here for
viewing.
Thanks.
Jeff
--
A7N8X-Deluxe, AMD XP2500+ (Un-locked)
2x256mb Crucial PC3200 DDR ram
Palit-Daytona Ti4200/64M AGP
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James Sweet
Guest
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| Posted:
Mon Dec 05, 2005 9:35 am Post subject:
Re: Monochrome monitor questions? |
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SomeBody wrote:
| Quote: | I'm repairing a few monochrome monitors, these are 9" in size.
The problem I'm having is the screen has vert. lines spaced about every
1/2 in, they are about 1/2" in width. I believe it would be called
ghosting?
The pc board consist of some discreet components and two IC chips.
TDA1175 (vert) and TDA1180 (Hor). Both chips have been replaced as well as
the tube.
Any ideas what the problem could be, an area to look at?
I have a copy of a schematic, but don't now how to post it here for
viewing.
Thanks.
Jeff
|
If it's got vertical lines that's jailbars, you need to replace the
capacitor that filters the B+ to the video amp, on color monitors it's
normally on the neck board, on mono monitors it can be there or on the
main board. |
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Arfa Daily
Guest
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| Posted:
Mon Dec 05, 2005 5:35 pm Post subject:
Re: Monochrome monitor questions? |
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"James Sweet" <jamessweet@hotmail.com> wrote in message
news:cmSkf.4544$H84.2879@trnddc04...
| Quote: | SomeBody wrote:
I'm repairing a few monochrome monitors, these are 9" in size.
The problem I'm having is the screen has vert. lines spaced about every
1/2 in, they are about 1/2" in width. I believe it would be called
ghosting?
The pc board consist of some discreet components and two IC chips.
TDA1175 (vert) and TDA1180 (Hor). Both chips have been replaced as well
as
the tube.
Any ideas what the problem could be, an area to look at?
I have a copy of a schematic, but don't now how to post it here for
viewing.
Thanks.
Jeff
If it's got vertical lines that's jailbars, you need to replace the
capacitor that filters the B+ to the video amp, on color monitors it's
normally on the neck board, on mono monitors it can be there or on the
main board.
|
It can also be striations due to velocity modulation of the H-scan. It's
common to have a line linearity coil in series with the H-deflection yoke
windings on monochrome monitors. There is usually a damping resistor across
this coil, to stop it ringing immediately after the flyback ( retrace )
period. This resistor commonly goes open circuit, allowing the coil to ring,
producing the velocity modulation of the beam as a result of the decaying
sine wave that then gets impressed on the rising sawtooth.
Arfa
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JANA
Guest
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| Posted:
Tue Dec 06, 2005 1:36 am Post subject:
Re: Monochrome monitor questions? |
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Use an ESR meter and do an ESR test on all the caps, especially in the scan
and power supply circuits. It is possible that on an older monitor, you will
find many caps that are out of specs.
--
JANA
_____
"SomeBody" <SomeOne@Someplace.org> wrote in message
news:pan.2005.12.05.04.25.34.63363@Someplace.org...
I'm repairing a few monochrome monitors, these are 9" in size.
The problem I'm having is the screen has vert. lines spaced about every
1/2 in, they are about 1/2" in width. I believe it would be called
ghosting?
The pc board consist of some discreet components and two IC chips.
TDA1175 (vert) and TDA1180 (Hor). Both chips have been replaced as well as
the tube.
Any ideas what the problem could be, an area to look at?
I have a copy of a schematic, but don't now how to post it here for
viewing.
Thanks.
Jeff
--
A7N8X-Deluxe, AMD XP2500+ (Un-locked)
2x256mb Crucial PC3200 DDR ram
Palit-Daytona Ti4200/64M AGP |
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SomeBody
Guest
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| Posted:
Sat Dec 10, 2005 9:35 am Post subject:
Re: Monochrome monitor questions? |
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On Mon, 05 Dec 2005 04:25:34 +0000, SomeBody wrote:
| Quote: | I'm repairing a few monochrome monitors, these are 9" in size.
The problem I'm having is the screen has vert. lines spaced about every
1/2 in, they are about 1/2" in width. I believe it would be called
ghosting?
The pc board consist of some discreet components and two IC chips.
TDA1175 (vert) and TDA1180 (Hor). Both chips have been replaced as well as
the tube.
Any ideas what the problem could be, an area to look at?
I have a copy of a schematic, but don't now how to post it here for
viewing.
Thanks.
Jeff
|
An -UPDATE- on the jailbar problem.
It turned out to be some newer type FBT we installed on an older
board, since the old style FBT were not available. We pulled a few old
style flybacks from scrap boards and installed them on the boards in
question. The problems on this sample lot all disappeared.
Thanks.
--
A7N8X-Deluxe, AMD XP2500+ (Un-locked)
2x256mb Crucial PC3200 DDR ram
Palit-Daytona Ti4200/64M AGP |
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