Re: Cable building attempt

[Mitchell Spector <mitch2gs@hotmail.com>]

"Michael J. Mahon" <mjmahon@aol.com> wrote:

>Mitchell Spector wrote:
>>>>>>I've had a Sony CPD-1302 monitor sitting on my floor about three weeks 
>>>>>>now and unable to use it (or even test it) since its missing the video cable.
>>>>>>I'd like to connect it up to my Apple IIGS.
>>>>>>
>>>>>>What I need is a 9-pin (DE-9 male) to 15-pin (Mac and IIgs) cable, or
>>>>>>alternatively a DE-9 to VGA.
>>>>>>
>>>>
[much talk about cutting and splicing cables together, snipped]
>
>>     I matched them up to the Sony CPD-1302 pinouts, minus the Green and 
>> Blue ground signal (they're supposed to go to pin-1, but that is also where
>> the Red signal is which is a problem). I'm pretty sure the G, B grounds are
>> necessary because all I could see is an inversed faint/ghosted image with 
>> no color. Pin-2 needs to be separate from pin-1 for this to work, but they're
>> wired together on the pre-molded end.
>
>Yes, that 1-2 connection is a fundamental problem.
>
>It's good to connect the shield grounds together, just to improve the
>high frequency grounding, but not having it wouldn't cause the symptom
>you describe.
>
>Something else may be wrong.  How are you determining the pin numbers of
>the connectors and corresponding them to pinout diagrams?  It's easy
>to get "front view" and "back view" interchanged and get wierdness.

    I visually traced the wires back to the pins (they appear to be arranged
in sequential order on a PC serial connector with flat ribbon cable) though
the actual problem was more likely loose wiring. Just lightly touching the
cable would make distortions on screen and whinning from the monitor. 
I just gave up on that (splicing wires).

    Yesterday, as luck would have it, I found a male-to-male DE-9 video 
cable with a VGA adapter attached at the thrift shop! Unfortunately it
turned out to be wired for a NEC monitor (at best, I got an image that
was all red. It also caused the Mac-to-VGA adapter to start smoking!).
The good news is the cable hoods have screw-on caps and color 
coded wiring, so figuring out the pinout and what was wrong was a 
snap.

    To make a long story short, I pushed out the female pin receptacles
on the NEC adapter and rewired it so it matches the signals coming from 
the Sony with DE-9 (pass-tru) cable and attached another Mac adapter. 
Now I see a picture with the _correct_ color, but the picture is jumping
around/somewhat scrolling vertically. On the other hand, it works 100%
connecting up the monitor to a VGA source, such as my Second Sight
or my Mac G3: stable image and correct color. It also has no problem
on the Mac if I use the very same Mac-to-VGA adapter.

>>    Hmm, what if I purchase a Sony multiscan DE-9 to VGA cable (I think a
>> few places still sell them) and attach a Mac-to-VGA adapter on the end?
>> I'm assuming that would work. Even if I had the homemade cable wired
>> correctly, it really needs to be soldered and not spliced and taped--the
>> connection wasn't exactly solid.
>
>That should work--assuming that the Sony finds the sync where it can use
>it.

    Well, I now essentially have the proper VGA cable. I just need to figure
out why it's jumping around. Interestingly, before I rewired the cable and
everything was red, the picture was perfectly stable.

    I suppose I should either disconnect the composite-sync or vertical-sync
wire, one of the two are probably causing the picture instability. Originally
neither signal was connected in the cable (the now fried Mac adapter did 
somehow get an image, it must have rerouted the composite sync; the
other adapter didn't even get an image at all before). At least I know the
monitor is working now, and I'm very close to having it work on the IIGS. :)
I'm leaning towards pulling out the v-sync pin.

Mitchell Spector