Foreword
The Afterburner is more compatible than most people might think,
but it's still not 100%. Albeit we hardly need to use 040-incompatible
programs, we all have a favourite game or demo that we're missing. It might
even be an ST-program, like Super Sprint, that work with the 030 and
not the 040...
That's why it would be nice to have a possibility to switch back
to the 030-processor,especially since the 030 still is there!
Switches have been available for some time now, but when you have
to physically remove the AB-card, it's not very handy.
After some exploration, I finally came up with a way to avoid this,
and that's what this web-page is all about!
I would like to thank my good friend Jo Even Skarstein for
letting me use some of his internet-account for this page!
Yours truly
Disclaimer:
I do not take any responsability for what you do with your computer.
If you choose to follow these instructions, you do it at your own risk.
I don't earn any money on this, and I don't intend to. All I can say is
that it worked fine with mine and it might not do with yours!
There might also be errors in this text!
Ingredients
- A two pole relay. (ELFA: 37-072-62, page 246)
- A switch of some kind (I used the Turbo-switch on my tower)
- Different coloured wires (Just to make things easier...)
- One red wire
- Four black wires
- One orange wire
- One light green wire
- One dark green wire
- One light blue wire
- One dark blue wire
- two approx. 10kOhms resistors
- Sharp Knife or scalpel
- Soldering Iron with a fine tip (15W is best)
- Solder
- A pair of pliers
- Preferably a multimeter
- Glue or double-sided adhesive tape
The resistors must be rated higher than the resistance in the
respective systems! The reason is that the signal always travels the
easiest rout, the one with the smallest resistance. We want the signal
to travel through the computer, and not through the resistor. But when the
particular CPU is turned off, the signal goes straight to ground as it should.
Figure 1 - CPU On
The systems resistance, R1, is less than 10kOhm while R2 is 10kOhm, so the signal
chooses to go via the system.
Figure 2 - CPU Off
The systems resistance, R1, is infinite while R2 is 10kOhm, so the signal will go
through the resistor instead.
Installation
At this point, I guess it's no need to explain how to unscrew your own
computer, and besides there are so many different casings that it would just be
impossible to cover all possibilities.
Hopefully you've got yourself a relay that fits between the motherboard
and the Afterburner-card, as some relays are a bit too big...
I believe that the best place to put the relay
is directly to the left to the U62-chip. This is where you'll get the
shortest cables without too much fuzz.
Use some glue or tape to fix the relay in place. It's up to you to
find out if it best to do it before or after you have soldered all the wires.
Relay Pinout
Figure 3 - Relay seen from below
Note that the pin configuration differs from relay to relay. The pinout
shown here is the pinout of the relay I used, and not the pinout of the relay from
ELFA.
You have to figure out for yourself how the pin configuration is on your
relay, but the one shown here is a good example...
Note! Scandinavian users might consider getting the ELFA-catalog. It
contains very detailed information about relays, and they also have a good
range of different relays. I recomend it!
Red Wire
After soldering the red wire to the correct pin on the relay, you must solder the
opposite end to one of the following places:
- Right pin of inductor L177
(Bottom left of the motherboard)
- Pin 20 on U62, U63, U67 or U68
- Or any other +5V source
Black Wire
Solder one of the black wires to the relay as shown in fig. 3, and solder the other
end of the wire to the switch. Then take one of the other black wires and solder it to the
other pole of the switch. The other end of the second wire must be soldered to ground.
It's easiest to use the outer grounding rail, but it should be easy to find other places as
the PCB is full of grounding points.
Purple Wire
This is the same purple wire as the one on the AB-cable. Remove it from pin 4 on
the U68 and solder it to the relay as shown on the figure 3.
Important pins on the 030
Figure 4 - Lower left corner of the 030.
Orange Wire
Solder the orange wire to the relay (fig. 3) and to one of
the following places:
- Pad 16 at the 030 (as shown in fig. 4)
- Pin 4 on U68 (Recommended)
Light Green Wire
Solder the green wire to the relay (fig. 3) and solder the other end to pin 16
on the 030. (Fig. 4)
Be careful! It's far from impossible to repair a broken chip-leg, but it's very annoying!
I know because I've broken two allready!
Dark Green Wire
Take one of the 10kOhm resistors and solder it to the outer grounding rail.
Solder one of the remaining black wires to the other end of the resistor.
Then you must solder both the black wire and the dark green wire to the relay (fig. 3).
Take the remaining end of the dark green wire and solder it to pin 17 on the 030 (fig. 4).
Light Blue Wire
Solder the light blue wire to the relay and to one of the following places:
- Pad 17 near the 030 (fig. 4)
- The hole just to the left of pad 17. (fig. 4)
- Pin 3 on J16 - The biggest expansion slot.
Dark Blue Wire
This is the hardest part, at least emotionally. Locate
the upper-leftmost Mach-chip on the Afterburner. It's the one marked
X in the leftmost figure. Find pin 11 on the chip by counting
counter clockwise from the little dot marking pin 1. There's a track from that pin
to pin 3 on the expansion slot(seen as solderpoints). Cut this track.
Take the remaining black wire and solder it to the last resistor. Solder the other end of the
resistor to a nearby grounding point (outer rail or wherever)
Solder both the dark blue wire and the black wire to the relay (fig. 3). The remaining end
of the dark blue wire should then be soldered to to pin 11 on the mach chip.
Note that it might be smart to use some kind of a plug and socket
for this. It'll make it easier if you have to remove the Afterburner
later on...
Operation
It's advisable to switch off your computer before switching, but
if you do it without turning off, you might press reset a couple of times.
That's all...
Problems
If you have problems, try reseting the computer a couple of times. You
should try both modes too.
Don't worry if things don't work the first time! You can still go back to
how it was before...
Check that:
- you have the jumper on pins 20 & 22 on J20...
- the other processor's 'pin 17' (blue or dark green wire) is
properly grounded so it don't pick up any unwanted noice. Use a
multimeter to measure the voltage between the outer grounding rail
and either pin 16 on the 030 or pin 11 on the mach chip. (Depending
on which processor you're trying to use) You have to do this while
running the machine, so be careful!
- the track is properly cutted
- you have the correct relay pinout.
- the relay really works.
- none of the wires are misplaced or switched.
- you using a switch with only two poles. If not, check
that the relay gets grounded in one of the switch positions. If not,
move one of the black wires to another pole on the switch and do
another test.
- your relay work in the same manner as mine. With a different
relay you might need to ground the black wire, and use a three pole
switch connected to the red wire so that the red wire is either
connected to +5V (Mode 1) or ground(Mode 2)... This is due to the
nature of the electro-mechanical relays I used.
- the resistors is rated high enough.
Typical problems are:
- White screen with no logo
- Possible cause: Disturbance from the other processor.
(Check points 1,2,3,4,5 and 9)
- Black screen
- Possible cause: Disturbance from the other processor.
(Check points 1,2,3,4,5 and 9)
Problem(s) that migth arise:
- Getting the same processor in both mode 1 and mode 2
- Possible cause: Faulty relay, fitting or switch.
(Check points 3,4,5,6,7,8 and 9)