spraggs@mprvaxa.UUCP (John Spraggs) (11/12/86)
In article <1140@cit-vax.Caltech.Edu> lyles@tybalt.caltech.edu.UUCP (Lyle N. Scheer) writes: > > The monitor you are talking about has to be a Digital RGB. With Digital, >the colors will not work correctly(Digital RGB just cannot handle all those >shades). On the other hand, an Analog RGB will work correctly. Being an >Amiga owner with a Digital RGB/composite/tv, I know all about this(say, does >anyone know how to rewire digital to analog???). Therefore, if your Amdek is >Analog, you will have no problems. > A digital monitor has an input stage such as a TTL gate which acts as a slicer to convert incoming voltages to saturated logic levels. Since it has gain, there is only a very small input range of voltages which correspond to the region between the saturated output values. The circuit is not intended to be operated in this region. The following stages are analog and should not need to be modified if you replace the input stage. One reason for using a digital input might be the classic TV 'hot chassis' which would require opto-couplers or equivalent to isolate your computer from 120 VAC. This would require particular care in designing the mod, or else! Since you have to replace the digital stage as opposed to connecting a little adapter in the cable, it is not really practical for most of us. You need a wide bandwidth, fixed gain amplifier with 75 ohm input that matches the impedances and voltages needed by the circuit at the point you are going to cut into. An OEM RGB monitor I bought a few years ago had a plug in its wiring harness that gave the necessary access. Don't forget you will need to do this 3 times for the video and then somewhat differently for the composite sync. Does the //gs put the sync on one of the video lines? Your monitor will probably want to see it on a separate port. I don't know how many monitors have hot chassis, if any. But before I considered anything else I would check that out. John Spraggs {}!ubc-vision!mprvaxa!spraggs
hyman@ICS.UCI.EDU (Glenn Hyman) (11/21/86)
Bill try calling apple computer in Newport Beach at 714-752-0303
they have techs there who can help I worked for a computer store
in Santa ana for 1yr and was there when they came out with the llGS
we never did try any of the other rgb monitors but we were told they
would work. good luck............
Glenn