Re: 1084S-D2 Monitor

[Drew <GoggleDrew@gmail.com>]

On 15 Oct, 09:35, "Michael J. Mahon" <mjma...@aol.com> wrote:
> Drew wrote:
> > On 14 Oct, 23:26, "Michael J. Mahon" <mjma...@aol.com> wrote:
> >> Drew wrote:
> >>> On Oct 14, 10:06 pm, Alex Freed <alex_n...@mirrow.com> wrote:
> >>>> Drew wrote:
> >>>>> Well i connected the GS via the composite in and it only came up in
> >>>>> BW, so connected my xbox 360 and to be honest at first glance it look
> >>>>> ok, but then again it seemed a distinct lack of red in any of the
> >>>>> images
> >>>> If it is "black and WHITE" then red channel must be operational or it
> >>>> would be black and blue-green.
> >>>> There are generally  two separate controls for each color: black level
> >>>> and gain. Just like brightness and contrast per color. Chances are
> >>>> adjusting these controls should do the trick.
> >>>> And get color bars on the screen before attempting to adjust. If there
> >>>> is no other source, I guess "color test" from DOS 3.3 master should do.
> >>>> -Alex.
> >>> Cheers for the advice guys, was just using the control panel program
> >>> to check the colours and had another GS on with my Apple RGB monitor.
> >>> Only found one set of controls, labelled bias...would that be gain?
> >> "Bias" is equivalent to "brightness", "gain" would be equivalent to
> >> "contrast".
>
> >>  From your description, it sounds like the red channel gain needs to be
> >> turned up, or if it's up and insufficient, then a component in the red
> >> channel video amplifier is the likely cause.  Often the high-level part
> >> of the video amplifiers is on a PC board at the CRT socket (back of the
> >> neck).
>
> >> Low gain is often caused by imperfect contacts, loose connections,
> >> or open bypass capacitors in the (red, in this case) video amplifier
> >> circuit.
>
> >> -michael
>
> >> AppleCrate II: An Apple II "blade server"!
> >> Home page:  http://members.aol.com/MJMahon/
>
> >> "The wastebasket is our most important design
> >> tool--and it's seriously underused."
> >> ** Posted fromhttp://www.teranews.com**-Hide quoted text -
>
> >> - Show quoted text -
>
> > Hi,
>
> > If I turned the brightness down the red would pretty much disappear to
> > a dark blue/black. I will take the back off again tonight and have a
> > look for gain adjustment. Though its nice to have some red :-). Its
> > quite usable the way it is, but if i can make it better that would be
> > good.
>
> Although the maintenance manual no doubt has very specific instructions
> on how to adjust the color bias controls, a baseline adjustment can be
> made very similarly to the way you should adjust monochrome brightness.
>
> Display a black raster from the computer and slowly advance the bias
> control until the color it controls just becomes visible, then back
> it off slightly.
>
> This procedure sets the bias as high as possible without interfering
> with the color purity of lowlight areas.
>
> Similarly, when a white raster is displayed, the red gain control
> should be adjusted to produce a white (not red and not cyan) screen.
>
> This procedure sets the red gain to produce the same effect as the
> green and blue channels, causing a pure white.
>
> -michael
>
> AppleCrate II: An Apple II "blade server"!
> Home page:  http://members.aol.com/MJMahon/
>
> "The wastebasket is our most important design
> tool--and it's seriously underused."
> ** Posted fromhttp://www.teranews.com**

Hi,

Well i took the monitor apart last night and had a look for gain
controls, and couldn't see anything obvious. The bias controls were
clearly marked and all three colours were right next to each other.
There are a few other what seems be components that look like that can
be adjusted but nothing marked as gain or had a colour reference next
to them (and not in a bank of 3). At the moment the monitor is more
than usable and if i hadn't known that it had been adjusted i doubt
anyone would know. Its just the if i can get it better with simply
adjusting it that would be good :-). Will do a search for some
schematics to see if that shows anything relating to gain etc. If i
come across someone in the future in the UK that fixes these monitors
then might get him/her to have a look at it...anyway thanks everyone
for their help as now have a working monitor :-)

Drew