Sun (Sony?) GDM-5410 Excessive brightness
 

Hi,

I have a GDM-5410 monitor that can no longer adjust the brightness/contrast.
The display *works* -- but appears as if the brightness and contrast
controls
are pegged at maximum (even when I set them at their minimums).

I've tried RESET. And the "auto adjust" function to no avail.

I'd hate to add another 70 pounds of glass and heavy metals to our local
landfill if there's a relatively simple fix for this (like most big Sony's,
they
are a real mess inside!)

Any suggestions?

Thanks,
--don

[email address is bogus]

Sun (Sony?) GDM-5410 Excessive brightness
 

"Don" None@Given wrote in message
...
Hi,
I have a GDM-5410 monitor that can no longer adjust the
brightness/contrast.
The display *works* -- but appears as if the brightness and contrast
controls
are pegged at maximum (even when I set them at their minimums).
I've tried RESET. And the "auto adjust" function to no avail.
I'd hate to add another 70 pounds of glass and heavy metals to our local
landfill if there's a relatively simple fix for this (like most big
Sony's,
they
are a real mess inside!)
Any suggestions?

From what I've read this is a pretty common problem -- read more he

http://www.hutzelman.com/home/hardware/mods/monitor/

Hope that helps!

Sun (Sony?) GDM-5410 Excessive brightness
 

That's the exact site I used to fix one a couple of months ago.
That WILL fix you up, great unit to keep. The problem is in
getting the right resistance to give you a good level. Sky.

Sun (Sony?) GDM-5410 Excessive brightness
 

On Sun, 30 Oct 2005 22:13:20 -0330, "Skype_man"
wrote:

That's the exact site I used to fix one a couple of months ago.
That WILL fix you up, great unit to keep. The problem is in
getting the right resistance to give you a good level. Sky.


Does anyone know why this problem happens? CRTs don't normally
increase in brightness as they age.
Andy Cuffe

-- Use this address until 12/31/2005

-- Use this address after 12/31/2005

Sun (Sony?) GDM-5410 Excessive brightness
 

Andy Cuffe wrote:
On Sun, 30 Oct 2005 22:13:20 -0330, "Skype_man"
wrote:


That's the exact site I used to fix one a couple of months ago.
That WILL fix you up, great unit to keep. The problem is in
getting the right resistance to give you a good level. Sky.



Does anyone know why this problem happens? CRTs don't normally
increase in brightness as they age.
Andy Cuffe


Something must drift in the circuitry, my Sony G520 is on the verge of
being too bright, with the user brightness control turned all the way
down and I've seen others that were worse.

Sun (Sony?) GDM-5410 Excessive brightness
 

Hi,

"JM" wrote
"Don" None@Given wrote

I have a GDM-5410 monitor that can no longer adjust the
brightness/contrast.
The display *works* -- but appears as if the brightness and contrast
controls
are pegged at maximum (even when I set them at their minimums).

[snip]

From what I've read this is a pretty common problem -- read more he
http://www.hutzelman.com/home/hardware/mods/monitor/
Hope that helps!

Thanks for the pointer but the "fix" appears to be just a bandaid -- it
doesn't identify the actual *failure*... just patches things to limp along.

frown

A quick peek at the schematic seems to suggest the contrast regulator
may be wimping out (beta degradation?). I'll try to make some time
to pull the skin off it this weekend and see what things look like.
Maybe a $5 repair (instead of the 10c workaround). Worth the
extra money, IMO! :

Thanks!
--don

Sun (Sony?) GDM-5410 Excessive brightness
 

On Tue, 01 Nov 2005 04:37:08 GMT, James Sweet
wrote:




Something must drift in the circuitry, my Sony G520 is on the verge of
being too bright, with the user brightness control turned all the way
down and I've seen others that were worse.

If that's the case, it would be nice to find what's drifting and
replace it instead of making other modifications. The resistors in
the G2 circuit are not off value.
Andy Cuffe

-- Use this address until 12/31/2005

-- Use this address after 12/31/2005

Sun (Sony?) GDM-5410 Excessive brightness
 

It is not a matter of what is drifting on the Sony monitors.

The use I2C control for the G2 voltage. If either the video process ic
that also does the G2 fails (which it does) or the eeprom gets
corrupted or fails (which they do), there is no way to actually
troubleshoot and fix it without the Sony DAS alignment software for the
unit.

With the alignment software it is possible to find out what the G2
value is in the eeprom and see if it can be changed. If it can be
changed then you know the failure is in the CXA video ic.

The usual failure mode is the eeprom will fail completely. Totally
black picture due to no G2 voltage. Eeprom will become corrupt, either
full G2 voltage or no G2 voltage. Video ic will fail, OSD will be ok,
almost always full G2 voltage and over bright.

The design and high failure basically requires that you are a Sony
authorized servicer for these in order to see enough of them to warrant
the cost of all the different alignment jigs and software versions for
each monitor line.

Sun (Sony?) GDM-5410 Excessive brightness
 

Forgot to add one thing. The auto adjust looks at the AKB return from
the guns. We are all aware of how well Sony specs out the AKB circuit
to determine when the picture tube is beyond tolerance.

So if the tube is beyond what Sony considers acceptable specification,
the auto adjust will not work and you may wind up with all bright or
all dark picture. Basically not useable.

Sun (Sony?) GDM-5410 Excessive brightness
 

On 1 Nov 2005 13:50:29 -0800, "
wrote:

It is not a matter of what is drifting on the Sony monitors.

The use I2C control for the G2 voltage. If either the video process ic
that also does the G2 fails (which it does) or the eeprom gets
corrupted or fails (which they do), there is no way to actually
troubleshoot and fix it without the Sony DAS alignment software for the
unit.


The problem I'm talking about is a gradual increase in brightness over
a long period of time. Eventually, even at minimum brightness, black
is no longer black. Reducing the G2 voltage, either through DAS, or a
resistor change restores normal operation. I'm just wondering what is
actually drifting. Is the G2 going too high? Is something in the
video circuit drifting? Is the CRT changing in some way?

The auto adjust in a lot of the 21" monitors won't fix it for some
reason. They seem to have fixed this in the next generation of 21"
monitors which respond well to running auto adjust. The 19" ones can
always be fixed by running auto adjust. I've seen ones that were so
bright the background had retrace lines, but auto adjust brought
everything back to normal.
Andy Cuffe

-- Use this address until 12/31/2005

-- Use this address after 12/31/2005

Sun (Sony?) GDM-5410 Excessive brightness
 

That would be the picture tube causing the problem then.

The G2 is directly controlled by the AKB as well as the base value of
the eeprom.

I am assuming that in later versions they reduced the amount the AKB
affected the G2 voltage.

As always make sure the standard stuff is good, video output power
supply voltage that could be low due to a weak or high esr capacitor,
etc.