Towering My AMiGA 3000

Last update: 19. November 2002

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Step by step Tower Project



Useful Computer tools



[tools]


Enderes (TM) double ended screwdriver, made in USA, great for computer work. So good I've got 2!




[tower1]


The case, stripped of it's wintel motherboard and ready for the drill and file!
[CybSCSI]


The bottom of the 5.25" drive bay needs to be cut away to fit the 3000 motherboard and SCSI unit, 2 bays are lost :-(


The 3.5" drive bays moved from under the 5.25" bays to the top rear of the case.
[tower3]


The original 3000 PSU has been used. The wires to the motherboard had to be lengthened. The Power switch needs to be replaced with one off a dead PC PSU (still to be done) and rehousing A3000 PSU in a dead PC PSU case (still to be done).


[tower3]


Rear plate of the tower cut out to fit ZORRO cards and 3000 rear ports.


[tower3]


A3000 original case modified for tower.


[tower2]


Plugs extended for keyboard, mouse and joystick ports.

Once in the tower the keyboard, mouse and joystick ports end up inside the case, pointing up.
To get the ports to the back of the case I brought the needed plugs (4x 9 pin D, 2x male, 2x female, 2x PC keyboard plugs, 1x male, 1x female) from Dick Smith store (Radio Shack for US visitors) and pulled apart an old floppy cable for the wire.

Be VERY careful and check with multimeter! PIN 7 on the mouse and joystick ports are + 5 Volts DC


[tower3]


ZORRO cards assembled on ZORRO daughterboard


[tower3]


Assembled with drives in place


[tower4]


Power and harddrive wired to Tower LEDs


[tower5]


Wired up




Using a Powersupply from a AT or ATX IBM compatible machine



AT powersupply.txt

The ATX and AT PSUs do not have a TICK signal so if you need to run a genlock set the jumper for TICK on the motherboard (Jumper J350) to VSYNC.

DIY tick.txt

TickIt.lha

Information regarding finding parts to modify a AT PSU

To keep your original A3k PSU inact you can buy the PSU mobo connector and connector pins:

The manufacturer and part numbers for the A3K PSU mobo connector and connector pins are:

CONNECTOR: 15Pos MINI UNIVERSAL MATE-N-LOCK CONN. PLUG HOUSING (UL94V-O) MANUFACTURER: TYCO (FORMERLY 'AMP') TYCO PART #: 172171-1

PLUG HOUSING (UL94V-O)

PINS FOR THE ABOVE CONNECTOR: MINI UNIVERSAL MATE-N-LOK SOCKET CONTACT LOOSE PIECE MANUFACTURER: TYCO (FORMERLY 'AMP') TYCO PART #: 170366-1

SOCKET CONTACT LOOSE PIECE

The pins are small, but most multiple pin crimpers will crimp them.

The hard-to-get wire colours can be found, in the correct gauge (18 AWG), at most automotive supply stores.

A AMiGA 3000 user reported this problem to me when he had a AT type Powersupply modified for his AMiGA 3000.

Subject: Mysterious Mouse Glitch

We've got our ol' A3k bus mouse back! Cracked the problem yesterday - and it's all been due to two crossed wires! I can hardly believe it... ;-)

I could never figure it out. I'd had a brand new AT PSU (complete with remote switch) modified for the A3000 according to the instructions at:

AT powersupply.txt

The job was done by competent technicians at a local electronics repair shop, who followed the instructions to the letter. It's possible that following those instructions so strictly actually led to the problem.

And the problem was:

Even though the AT PSU modification resulted in all wires present (including the tick wire 'coz I also had the tick circuit from AmiNet's 'TickIt.lha' built), with correct voltages at the mobo connector, and all ground wires present and working correctly, and even though the machine powered up just fine, the A3000's bus mouse (standard AMiGA mouse connected to mouse port) cursor refused to budge. It was paralysed! The mouse buttons still worked though - just no cursor movement.

I mentioned the problem in the Amiga hardware newsgroup on several occasions but nobody had an answer. Most replies told me to replace the wee pico fuse near the mouse port, or to connect the green user wire - or to forget about it and just use a serial mouse via AmiNet's 'Sermouse' driver (which I did for a long time).

But the pico fuse was fine, and the +5v user wire was connected and working, and a serial mouse is OK but I like my ol' bus mouse!

So, I revisited all this... and eventually... discovered why my ol' bus mouse wasn't running around looking for cheese...

The cause of the glitch:

The AT PSU has an orange 'power good' (PG) +5v wire. When that wire is attached to the A3k's purple +5 VID wire, you get a +5v voltage at the mobo connector alright - BUT IT FREEZES THE A3k's BUS MOUSE CURSOR! No +5v current gets to pin 7 at the mouse port. I don't know why this happens, but it happens!

Solution:

Simply attach the AT PSU's orange PG wire to one of the A3k's yellow +5v wires; and attach one of the AT PSU's red +5v wires to the A3k's purple +5v VID wire.

Epilogue:

Yup - on my modification, that orange PG wire was married to the purple +5v VID wire. It was probably done for two reasons:

1: The PG wire carries the required +5v current. 2: The instructions mentioned above do say in part:

"The +5VID [Purple Wire] is separated from the rest of the +5V lines. I suspect it goes to the Video slot. +5VID only connects to the logic +5V in the power supply through a diode/capacitor/resistor circuit. I imagine this is to keep the high frequencies from the logic from getting into the video circuitry."

Perhaps due to the above paragraph, the techie who did the modification thought the AT PSU's orange PG wire should run to the A3k's purple +5v VID wire as the PG wire is separate from the 'main bunch' of wires on the AT PSU's circuit board. But the first sentence of that paragraph is actually referring to the A3k motherboard - not the A3k PSU! In fact, I'm not sure about the rest of the paragraph either - it could be referring to mobo or PSU. Anyone not familiar with the A3000 motherboard - no matter how competent a technician - could be forgiven for taking such instruction literally.

So, this whole problem may be down to simple misinterpretation. In other words, somebody got their wires crossed! ;-)

NB: Take note of the above anyone contemplating modifying an AT PC PSU for an Amiga 3000. 'Tis only a small thing - but it could easily happen to you! ;-)

As for me... well, desperation being that other mother of invention, I've learned how to modify AT PSU's for the A3k. (Got two of 'em now.) Dab hand at soldering wires now too - and taking apart PSUs. If only I'd known about all this a year ago... ;-)

Cheers, Tony McKee



AMiGA A3000 Home Made (Custom) Towers


A3000 in ATX case.


A3000 in a groovy ATX case!


Idle's A3000 ATX still not finished!


Towered your AMiGA 3000? Thinking of towering your AMiGA 3000? Got some pictures of your Towered AMiGA 3000? Struck any problems like the Reluctant Mouse? E-Mail me and I will link to your site or post your info, pictures or problems here.


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