Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Old March 13th 07, 08:09 PM posted to sci.electronics.repair
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Default Strange LCD monitor symptom. MASCOT V chip?

I have a Sharp LL-T15A4-S LCD monitor.
Here's the symptom:
The screen is 12" wide.
Draw a vertical line 2" from the left side.
To the left of the line, the picture is perfect.
To the right of the line, every other horizontal
line is missing. Alternate horizontal lines
are perfect on the right of the line.

I can't think of a panel defect that could cause this.
Gotta be some addressing problem in the control chip.

I've been looking for information on the
CK1659 MASCOT V chip and the CS8528N chip in between
the MASCOT V and the panel.

I tried setting up a white screen, triggering on the
vertical sync and recording a few horizontal lines.
Instead of a clean signal, I see a LOT of noise and
maybe some places there's no signal, but it doesn't
correlate to the missing lines on the screen.
Shouldn't I expect clean digital signals to the panel?

Any info on how the MASCOT V works or FREE schematics of
this particular monitor? I did find a schematic of another
monitor with the MASCOT V chip and the signal names
suggest something about even and odd. But only part
of the odd horizontal lines have a problem.

I have lots of time and a desire to learn about this,
but I'm not willing to spend money on it.

Ideas?
Thanks, mike


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Return address is VALID!
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http://nm7u.tripod.com/homepage/sale.html

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Old March 14th 07, 08:13 AM posted to sci.electronics.repair
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First recorded activity by DIYBanter: Jul 2006
Posts: 221
Default Strange LCD monitor symptom. MASCOT V chip?

On Tue, 13 Mar 2007 20:09:20 GMT, mike wrote:

I have a Sharp LL-T15A4-S LCD monitor.
Here's the symptom:
The screen is 12" wide.
Draw a vertical line 2" from the left side.
To the left of the line, the picture is perfect.
To the right of the line, every other horizontal
line is missing. Alternate horizontal lines
are perfect on the right of the line.

I can't think of a panel defect that could cause this.
Gotta be some addressing problem in the control chip.

I've been looking for information on the
CK1659 MASCOT V chip and the CS8528N chip in between
the MASCOT V and the panel.

I tried setting up a white screen, triggering on the
vertical sync and recording a few horizontal lines.
Instead of a clean signal, I see a LOT of noise and
maybe some places there's no signal, but it doesn't
correlate to the missing lines on the screen.
Shouldn't I expect clean digital signals to the panel?

Any info on how the MASCOT V works or FREE schematics of
this particular monitor? I did find a schematic of another
monitor with the MASCOT V chip and the signal names
suggest something about even and odd. But only part
of the odd horizontal lines have a problem.

I have lots of time and a desire to learn about this,
but I'm not willing to spend money on it.

Ideas?
Thanks, mike


Have you checked for the basic problems? Despite all the complex
electronics in an LCD monitor, 9 times out of 10 these weird problems
are caused bt something simple like a bad cap, or bad soldering.
Andy Cuffe


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Old March 14th 07, 12:54 PM posted to sci.electronics.repair
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First recorded activity by DIYBanter: Dec 2006
Posts: 635
Default Strange LCD monitor symptom. MASCOT V chip?

Andy Cuffe wrote:
On Tue, 13 Mar 2007 20:09:20 GMT, mike wrote:

I have a Sharp LL-T15A4-S LCD monitor.
Here's the symptom:
The screen is 12" wide.
Draw a vertical line 2" from the left side.
To the left of the line, the picture is perfect.
To the right of the line, every other horizontal
line is missing. Alternate horizontal lines
are perfect on the right of the line.

I can't think of a panel defect that could cause this.
Gotta be some addressing problem in the control chip.

I've been looking for information on the
CK1659 MASCOT V chip and the CS8528N chip in between
the MASCOT V and the panel.

I tried setting up a white screen, triggering on the
vertical sync and recording a few horizontal lines.
Instead of a clean signal, I see a LOT of noise and
maybe some places there's no signal, but it doesn't
correlate to the missing lines on the screen.
Shouldn't I expect clean digital signals to the panel?

Any info on how the MASCOT V works or FREE schematics of
this particular monitor? I did find a schematic of another
monitor with the MASCOT V chip and the signal names
suggest something about even and odd. But only part
of the odd horizontal lines have a problem.

I have lots of time and a desire to learn about this,
but I'm not willing to spend money on it.

Ideas?
Thanks, mike


Have you checked for the basic problems? Despite all the complex
electronics in an LCD monitor, 9 times out of 10 these weird problems
are caused bt something simple like a bad cap, or bad soldering.
Andy Cuffe


Thanks for the input. Yes, I have checked the obvious stuff.
Re-read my descripton and give me a clue as to how the heck this
can be happening??????
mike

--
Return address is VALID!
Bunch-O-Stuff Forsale He
http://nm7u.tripod.com/homepage/sale.html


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