Re: What is with these silly monitors

[Rubywand <rubywand@swbell.net>]

spierings writes ...
> 
 ....

> >      It may be that the video level from your VCR is too high. You could
> > experiment with clips and, say, a 500 Ohm (or so) pot. Connect the pot across
> > the VCR composite Video Out cable's output. Send the center tap + signal ground
> > to a cable connected to your monitor. See if adjusting the pot gets you some
> > color.
> 
> You have sort of lost me. I'm not well versed on TV technology or manual
> electronics. I'm only a humble programmer.

     That alone makes you nearly unique.


> What is a pot and where do I get one?

     A "pot" is a potentiometer-- a variable resistor with a center tap (like a
volume control thing with a shaft you find in a transistor radio).


     However, I did some more experimentation. Our Amdek Color-1 is normally
connected to the II+. Several years ago we did a mod which switches in a color-killer
for display of Text portions of a display-- to get rid of the "rainbow" Text at the
bottom of hires game, etc. displays. (Works great.)

     Even though the test video was coming from the TV tuner, the computer was ON and
the color-killer lead was plugged in. Since the computer happened to be displaying a
Text screen, the color-killer was active and doing its best to squash color. Pulling
the color-killer fixed my color problem and the display shows a beautiful color TV
picture.


     It is true that an incorrect video level can mess up color. With the color kill
active, reducing level did improve color. (So did turning _down_ the Color control on
the monitor-- which is what led to checking things and rediscovering the color-killer
lead.) 

     The way my monitor behaved with the color-killer active sounds so much like
yours that I wonder if some color-kill switch on your monitor is not causing your
problem. If diddling such a switch on both monitors fails to produce good color,
you've got to suspect that you may be looking at a design flaw-- i.e. in time, the
color-killer switch or circuit blows and leaves you locked in to a no-color mode. (I
don't know if this is known problem or not for Apple IIe monitors.)

     Another control to check is Contrast. A high contrast setting will tend to wash
out color. (On some monitors, a high brightness setting will wash out color.)  Also,
be sure your video source does not have some Color ON/OFF switch set to OFF.



     Anyway, to experiment with reducing video level, a simpler connection than my
original suggestion should work. You just insert a pot in series with the signal.

     Here's a picture of the hookup to experiment with adjusting video output from a
VCR (or whatever) to a composite color monitor:


  _____________________________                  Pot (approx 1000 Ohms max) 
                               --(center)----------Z               ______________
  _____________________________._(shell )______    Z<--- (center)--
      cable to VCR composite                   |   Z
         video output                          |_________(shell)__._____________
                                                                      cable
                                                                    to monitor


     You can use a couple short 'hi-fi' cables or for-real video cables. One goes to
the VCR and the other goes to the monitor. Alligator clip leads are used for
connecting.  (You can get the alligator clip leads and, probably, the pot from Radio
Shack. The pot's max value is not critical; adjusting should easier if the max is
1000-5000 Ohms.)

     The center of the VCR cable plug goes to one outside tab and the center of the
plug on the monitor cable connects to the middle tab of the pot. The VCR cable plug
shell connects to the plug shell of the monitor cable.

     Once the connections are made, you can turn the shaft of the pot to control how
much of the VCR signal gets to the monitor.



Rubywand