How a shipping-damaged motherboard and an unloved 386 joined to
create Damaged Goods, the World's Ugliest Quadra.
I hope that by relating this tale of giving new life to a dead
Mac I can inspire others to do the same. When these vintage Macs
are found, they've often been abused and neglected, but with some
care they can be brought back to health and function. Even if you
don't have money to spend on the repair, with time these great
oldies can often be revived.
Genesis
Every sordid love story has a humble beginning, and this is no
different. Another vintage Mac user and I had decided to trade some
extra equipment. Eventually, the postman had a present for me: two
working ST34501W 4.5 GB Cheetah hard drives and a Quadra 840AV motherboard in unknown
condition. Feeling excited, I tore into the package. Now I'd have
everything I needed to finish research for my articles on
Overclocking the Turbo 040 and
System 6 Performance (coming Real Soon Now™.)
I hadn't expected the 840AV to work, but I needed a real 40 MHz
68040 chip. My plan was to grab the 40 MHz part and then ashcan the
motherboard.
As the tape and cardboard gave way, I got a bad feeling. In
shipping, the hard drives had migrated to the topside of the
motherboard and there danced a fandango. The drives were a total
loss, and the board was a wreck with broken and bent pieces all
over the place.
I was very disappointed - but happy that at least the precious
40 MHz chip survived. I transplanted it into my Turbo 040 and
continued my research while the forlorn 840AV looked on from the
corner of my workbench. Sitting in such close proximity, I began to
wonder if it really did work or not, and that's the start of our
adventure.
The Rescue Begins!
Revivification first required a through looking-over to note all
obvious problems. I used pliers to repair the bent metal and
plastic, and with soldering gear affixed everything that had been
knocked loose. I even amazed myself by reattaching a tiny leg that
had been sheared clean off of a surface mount RAM chip!
I socketed the 33 MHz 68040 from my Turbo 040 and used thermal
tape to affix a giant copper-bottomed Pentium III heatsink.
Noting that the main power connector found in later PCI Power
Macs debuted in the 840AV, I connected the power supply from my
Power Mac 7500, a keyboard,
mouse, monitor, and speaker.
Pressing the power button yielded a startup "Bong" from the
speaker, and then nothing. No gray pattern, no flashing question
mark, just nothing.
To find out if it was just fried video or if the whole board was
bad, I fitted a small SCSI drive with a universal System 7.5.5. I
planned to listen to the hard disk to tell if it was doing
anything.
With everything connected . . . the screen came alive
and 7.5 started booting!
I tinkered with it a little more and then asked myself, "What am
I going to do with this thing?" I had no case to put it in nor a
power supply to run it - but I just couldn't junk a perfectly
working Quadra.
Looking first to eBay, I found the
going price of new power supplies too steep for my budget. I found
the pinout for the 840AV power supply connector on Accelerate Your Mac; with it I could
use any PC power supply, but I still didn't have one.
I remembered that my wife's parents upgraded from a 386 to a
Pentium PC several years ago and just stuck the old machine in a
closet. That would be my source! I asked for and was given a
Magitronic 386 SX/40 in an ugly AT-style case.
Get ready, little Quadra, you're going to be moving in here!
Transmogrification
The first step was to strip the chassis. Removing the 3.5" and
5.25" floppy drives as well as the 120 MB hard drive proved easy,
but the motherboard was a challenge. The plastic mounting offsets
that held it had gotten stiff and brittle with age and were
extremely difficult to unhook. After bandaging a small cut I
received in the process, I succeeded in emptying the metal 386
case.
Another problem: The bottom of the case had three ridges that
stuck upward and could short out my Quadra if I left them in place.
On this particular case they were held fast by pop-rivets, which
were drilled out with an electric drill. There was a smooth surface
on which to place the 840AV board.
The ISA slot cutouts in the case would have presented a problem
if they hadn't been stamped into a large assembly and screwed into
place. Removing a few screws allowed me to create a large hole in
the back right-hand side for the ports and NuBus cards to peek out
of. The ports still needed more room, and the metal case back gave
way to a Dremel with a fiberglass cutoff wheel.
With the case prepared, a way to hold the motherboard was
necessary to prevent short-circuit. The board was kept at a safe
height by applying copious amounts of 3/4" stick-on weather
stripping to the underside. Then its physical location was secured
using duct tape. (A more permanent fix using plastic wire-ties is
forthcoming.)
More than "Pure Imagination"
Using the case's built-in faculties to hold floppy drives, hard
drives, and CD-ROM drives was easy, leaving the power supply hookup
as the last major roadblock to having a functional computer. I had
the AT-style power supply from the 386, but I needed a connector.
To acquire one, I went down to my local computer wrecking yard and
asked for a dead ATX power supply.
The Quadra power connector is just like an ATX connector but
with an extra column of pins. It also has two "unused" pins that
get no connection when doing a PC power supply conversion.
Converting an ATX connector is as simple as cutting the last two
pins off and plugging them into the Mac one column over. Then leave
the two unused pins with nothing connected to them at all.
Perfect!
I cut the connectors off the ATX and AT power supplies. Using
the Mac and AT wiring diagrams, I wired the PC/AT power supply to
the modified ATX power connector, plugged it into the Quadra, and
fired it up.
It worked the first time.
Now only minor issues remained. The 386's speaker worked great
and plugged right in. The Opteron light was easy to figure out
using a multimeter. The Reset switch wires are soldered onto the
built-in Power button. The disk activity light wires will
eventually be soldered onto the permanent hard disk, and RCA jacks
will be back panel mounted and wired to the video-in and video-out
ports.
Damaged Goods is complete!
Putting It to Task
Every vintage Mac I own needs to have a purpose - otherwise it
ends up getting buried under dirty clothes in the closet. What
purpose has a Quadra 840AV?
I mulled this question for a few days until I realized that in
my spare time I used to enjoy playing video games. Having quit
Diablo II (after six years!), I was looking for a game to play, and
I remembered that I had never finished Marathon.
I've acquired a Gravis Mac GamePad and puzzled out a good keyset
for Marathon play. In the near-term, the 840AV's lease on life will
be helping me battle the Pfhor. In the future, I'll use the built
in video-out functionality to enable a portable retro gaming rig. I
can show off classic Mac games like Marathon, Super Maze Wars,
Bolo, and Harry the Handsome Executive. It can display on any TV -
no monitor required!
Holding down cmd-opt-T-V during startup forces the 840AV to use
video-out instead of the monitor port.
Powerful Software
Several pieces of freeware and shareware help to maximize the
capabilities of this formidable machine, but they've become all but
lost. James
Wang's Quadra AV Pitstop website still has these valuable
control panels and extensions.
- Sound Effects - Cutesy demo to show off the power of the
DSP by applying selected audio filters to everything the Mac puts
out - in realtime. Macintosh performance is unaffected. Very
interesting for Marathon, but I don't think I'll keep it.
- AV DSP Power - Adobe Photoshop plugin that uses the
Quadra DSP (digital signal processor) to accelerate Photoshop
filters. A neat toy, but I'd rather have a Power Mac or a Thunder IV GX. The price is unbeatable
though!
- sAVe the Disk - This system extension takes the place of
several (now lost?) Apple patches and also fixes some bugs Apple
never touched at all. Most notable is a bug-fix that speeds up
programs that play lots of sounds, such as games. Every time a new
sound channel is allocated, the "DSP Preferences" file is updated;
what this means is that every time you fire a shot in Marathon,
your hard disk is accessed - that's crazy! sAVe the Disk fixes this
problem and more!
- Fix-Gamma - An application that launches, patches a bug
that makes gamma-table changes look ugly, and quits. Great to drop
into your Startup Items folder.
- AV Digitizer Options - This QuickTime component adds
support for the Quadra's many advanced hardware capabilities.
Digitize color video in grayscale, use hardware chroma-key masking,
and even blend digitized TV with your applications while you work.
All these tricks are performed in real-time by the DSP, so the
Quadra never slows down.
Finis
As you can see, bringing this Quadra back from the brink of
disaster has taken a while! Now it has drive, purpose, and special
software to help it work its best. The effort has been rewarding
and fun; that's the joy of the vintage Mac hobby.
If you've got an AV Quadra or Centris and haven't tried watching
translucent video while you work, you owe it to yourself to
download the software and experience the marvel of these old
machines.
Next time you see an old Mac languishing under abuse, think of
Damaged Goods' rescue when all seemed lost. Don't hesitate to lift
that fine computer from destruction and restore it to use. You'll
be rewarded with a feeling of accomplishment, and the price is
lower than buying on eBay.
But excuse me for now - a hostile craft is nearing our ship.
"Somewhere in the Heavens, they are waiting...." 
