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AT-Case: wiring for Turbo-display AT-325 A/B, help needed

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First post, by ildonaldo

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Hello,
I am building a 486 machine at the moment and I'd like to add a speed display to the case.
The case has currently only a Turbo Button and a Turbo-LED but I have been able to lay hands on a AT-325 A/B speed display that will fit in the front dashboard.

... and now I want to properly wire this to the Display and the board (QDI MP4-P4U885P3 PCB V2.0).

Can you please help me with the correct wiring for that?

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(board manual see: http://www.elhvb.com/mobokive/archive/Qdi%20- … ls/p4u885g2.pdf)

Thank you in advance
ildonaldo

Building my own PCs since 1991 - for my retro builds it's "no CF-disks, no Floppy emulators, no modern cases etc.", only the real and authentic stuff whenever possible.

Reply 1 of 4, by PARKE

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The turbo button needs 2x2 sets of wires. This example below needs two extra wires on pins 3 & 4.

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2 wires go to the motherboard and 2 wires go to the display and connect to either 3 & 4 LOW or 5 & 4 HIGH.
5volt power for the display has to come from a power supply (molex) plug.
The turbo led on the frontpanel is fed by the motherboard.

The original buttons had 2x3 wires (for versatility between different board layouts) but only 2x2 are actually needed.
http://www.suntekpc.com/htm-2/power-switch-pu … urbo-3p3c-2.htm

Reply 2 of 4, by ildonaldo

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I now ripped the pc apart and found the second wire to the mainboard, but it is a 3-wire connector.
Any hint, which wires to connect to the mainboard (either black+red or black+white)?
(otherwise it is a try an error case)

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Building my own PCs since 1991 - for my retro builds it's "no CF-disks, no Floppy emulators, no modern cases etc.", only the real and authentic stuff whenever possible.

Reply 3 of 4, by PARKE

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Ok, you have the right button, I could not see that in the first photo. The black one in the middle is always connected. Whether you need white or orange depends on the motherboard. Two possibilities: the motherboard is default in turbo mode or default in non-turbo mode. You need to connect the button so that it works as intended when pressed in -or- pressed out. If you do not have enough space on your motherboard to switch the 3-wire Dupont plug 180 degrees in synchronicity with the plug on the display you have to remove the wire that you do not need (either white or orange) and cut the plug to size (neater is then to replace the 3-wire plug with a 2-wire and a 1-wire plug)

Reply 4 of 4, by ildonaldo

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OK, I will check with a continuity tester.

Building my own PCs since 1991 - for my retro builds it's "no CF-disks, no Floppy emulators, no modern cases etc.", only the real and authentic stuff whenever possible.

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