G4 Cube logic board in Color Classic video issues -- Welcome to the Colo(u)r Classic Forum

[ Show ]

Support VoyForums

[ Shrink ]

VoyForums Announcement: Programming and providing support for this service has been a labor of love since 1997. We are one of the few services online who values our users' privacy, and have never sold your information. We have even fought hard to defend your privacy in legal cases; however, we've done it with almost no financial support -- paying out of pocket to continue providing the service. Due to the issues imposed on us by advertisers, we also stopped hosting most ads on the forums many years ago. We hope you appreciate our efforts.

Show your support by donating any amount. (Note: We are still technically a for-profit company, so your contribution is not tax-deductible.) PayPal Acct: Feedback:

Donate to VoyForums (PayPal):

[ Login ] [ Main index ] [ Post a new message ] [ Search | Check update time | Archives: 1, 2, 3, 4, 5, [6], 7, 8 ]

[ Next Thread | Previous Thread | Next Message | Previous Message ]

Date Posted: 14:03:33 09/08/01 Sat
Author: Garth Beagle
Subject: G4 Cube logic board in Color Classic video issues

I was responding to another post in this group about a project I was working on about a year ago but finished in a different manner. I was trying to put a G4 Cube logic board/innards into a Color Classic and use the internal video on the CC. I had a lot of problems (see below) with the video signal quality and finally gave up using the built-in video and just made it with a POS 10" VGA monitor which works pretty well. I thought I'd just post this "cry for help" I sent out to a bunch of people last year in case it might help anyone or in case anyone has any ideas on what the problem was..
Thanks
-----------------------------------------------------------
(Original problem):
I'm hoping that perhaps someone can help me or point me to someone who's done something like this - I've been working on a project where I'm going to be sticking a G4 Cube logic board (with it's AGP video card, etc.) into a Color Classic to make a "Color Clasic G4". I have already modified the Color Classic's screen resolution sucessfully to 640x480 and it works nicely with an original Color Classic logic board.

To hook the video from the Color Classic's screen to the Cube's VGA port I created a special Analog Board loom connector where I simply took the following lines off the Analog Board connector and made a cable that connected from it to a standard Mac 2 row DB15 male video connector using the following pinouts (Using pinout info from http://member.nifty.ne.jp/frogeye/connector.html#Analogwiring):

Mac DB15 connector Analog Board Connector
1 (GND Red) 14
2 (Red) 15
3 (Composite Sync) 9
4 (Monitor Sense 0) 25
5 (Green) 13
6 (GND Green) 12
7 (Monitor Sense 1) 24
8 (NONE) (NONE)
9 (Blue) 11
10 (Monitor Sense 2) 20
11 (Sync GND) 8
12 (Vertical Sync) (NONE)
13 (GND Blue) 10
14 (Horizontal Sync GND) (NONE)
15 (Horizontal Sync) (NONE)

So, basically I'm taking a 40 pin flat cable, hooking it into the Color Classic's Analog Board connector and connecting a Mac 2 row DB15 video connector on the other end per the above pinout. It works, and I get video on the Color Classic's screen from the Cube's video source, but here's the problem: it's almost as if the brightness is set way too high - I can see things on the screen, but everything is majorly washed out. I can't adjust it out with any of the adjustments on the analog board (either the ones on the back or the Contrast/Focus knobs on the side). Other than that, the colors are correct (hard to see since it's too bright though) and even the screen size, shape looks good (no major bowing, distortion). Basically it looks as if some signal I'm sending to the display is way too high and there isn't a way to compensate for it (that I'm aware of...)

Here's what I'm pretty sure of right now:
1) I know the analog board/screen works ok since I've hooked in an original Color Classic loom board, logic board, etc. and it looks great.
2) It's not the CRT as I've a few Color Classics here to work with and a couple CRTs both show the same issue.
3) I've made two of the special loom-to-MacDB15 cables and both have the same issue.
4) I've tried different video sources than from the Cube (ie: a B&W G3, a PowerBook, etc.)
5) I tried putting 75OHM resistors on all/some of the signal lines from the video source.

Knowing this, I'm thinking either there's something wrong with the connector I'm making (pinout is wrong, etc.) or there's something else off the analog board I need to be connecting to to control the screen (like perhaps the brightness and contrast controls??)

I was hoping someone might have some suggestions or could point me to someone whos done a similar modification like this (like people putting the iMac logic boards in the Color Classics) that might help.

Thanks a lot for your time!
-Garth
oddsoft@pacbell.net

[ Next Thread | Previous Thread | Next Message | Previous Message ]

Replies:

Re: G4 Cube logic board in Color Classic video issues -- Alexey Danilchenko, 23:53:12 09/10/01 Mon
- Re: G4 Cube logic board in Color Classic video issues - correction -- Alexey Danilchenko, 23:59:03 09/10/01 Mon
- Re: G4 Cube logic board in Color Classic video issues -- Derek Sweeney, 02:17:07 09/11/01 Tue