Differences between Alchemy and Gazelle regarding CC display

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Joined: Jun 8 2004
Posts: 3

I am working on a Takky, after successfully getting a Mystic to go. I been working on a 6420/180 Sonnet Crescendo G3/400 Power Color Classic and it works great (Sonnet Trio and ATI64 PCI's) running OS 9.22.

In trying to upgrade the 6420/180, I just bought a 6500/275 and installed in the CC. Everything works but the PCC screen remains black. The PPC external monitor works fine (ATI 64 PCI card) and the same black screen is produced with or without the PCI ATI card. This motherboard works perfectly when it is back in the tall 6500 case and again produces a black screen on the PCC. The PCC works normally when the 6420/180 board is back in place.

I've read everything I could find on the web, including the 12 pages of the previous installment of this color classic forum, and could not find any difference in the VGA sensing or wiring between Alchemy and Gazelle that would produce this effect.

Does anybody has seen this before and/or have any suggestions?

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tmtomh's picture
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Joined: Dec 20 2003
Posts: 568
Nothing definitive here...

... but I'm thinking of what's different about the two boards. The first thing that comes to mind is system bus speed. The 6400 is 40MHz and the 6500 is 50MHz. I don't know what effect that would have, but who knows?

BTW, may I ask why you're trying to do this logic board swap on your PCC? Since both boards have the same RAM limit and expansion capabilities, and since you're using a G3 card, the only difference I can see is the aforementioned system bus speed difference. But I can't imagine it would make that much difference, everything else being equal.

Matt

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Joined: Dec 20 2003
Posts: 180
ISTR having similar problems. . .

. . . but it was a long time ago!

IF the new board was last used at, say 1024 x 768, and it detects a VGA screen, it may try to drive the CC at that resolution.

If you have a proper 6500 chassis, or similar, boot the new board in that, and select 640 x 480 or whatever (I assume you've done a screen mod on your Takky).

If that fails, try removing any PRAM battery from the new board, or doing a CUDA reset, or anything to set the video properly.

One last option is that the new board doesn't need a 3.3v supply, but the old board did. Could there be some strange issue arising from that?

Stuart

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Stuart Bell,
Developer of the PowerCC site a long time ago.

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Joined: Jun 8 2004
Posts: 3
Need for speed!

The decision to move up was indeed to have the 20% increase in bus speed as despite the G3/L2, several process are still limited by it. Additionally I got it very cheap at eBay and it included several of the additional boards (all video input/output, zip drive & ethernet on Comm II) that I wanted.

After trying many times to get it going, I left powered on and about some 10 minutes it came to life. There is maybe something that needs to change during a significant change like that, maybe PRAM related that just requires time.

I guess the moral is that sometimes time is the answer.

Miguel Angelo

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Joined: Jun 8 2004
Posts: 3
Right on target!

I believe the resolution difference was the issue and after you wait long enough it catches on somehow.

Thank you for the prompt replies, this is a great forum!

Miguel Angelo