DISCLAIMER
----------

Don't attempt this if the descriptions are not clear.
You screw up your Falcon its your fault, not mine, not Mitja Rateiczak
and not even the governments.

This file was forwarded to me by Daniel Richter:
daniel@ollom.prima.ruhr.de


How to clock the Falcon DSP with 48 MHz.
----------------------------------------

*(c)1995 Mitja Rateiczak*
*translated into english by Maarten van den Berg*
Tools needed:

Small wire-cutter
Sharp knife
Desoldering-Pump
Low-Power (16W) soldering iron
"Hot-Glue-Gun" (=pistol with glue-cartridges)
Multimeter

Materials needed:

Solder 0,7 mm
Small wire like 0,08 mm^2 or similar
Quarzoscillator 48MHz
Heatsink, like one for a 24-p DIL IC
Heat-Conductive paste
Double-sided-adhesive tape

Miscellaneous:

At which end does the Soldering iron get hot ?
A steady hand.
About two hours time.

WARNING !
Because I do not know for 100% sure that the partnumbers are the same in
all revisions of the motherboard, this list applies only to Rev. D/C !

U38 is the DSP-Chip
U37 is the Quarz-oscillator 32MHz for the DSP- and DMA-Chip
U36 is the DMA-Chip

The Pins of a Quarzoscillators (as seen from the underside):

 +---------                       +---------------
 |*1     4*|                      |*1           7*|
 |         |                      |               |
 |*8     5*|                      |*14          8*|
  ---------                        ---------------

1 Not connected                   1  Not connected
4 0 V                             7  0 V
8 +5V                             14 +5V
5 Clockoutput                     8  Clockoutput


On the falcon REV D/C board the Layout is as follows:
(View from above!)

DMA   |                U37
      |           Not*     *+5V
      |     connected
------+
U36               0V *     *DMA     +--------+
                            clock   |        |   U38
                                    |  DSP   |
                  0V *     *DSP     |        |
                            Clock   +--------+

* =the soldering-points for the Oscillator

You have to remove the complete casing and all the metal shielding of the
Falcon because you need to have access to the underside of the motherboard!

First you carefully desolder/remove the Quarzoscillator U37.
In my case a smaller one was used by atari, which is square instead of
rectangular and has 4 pins instead of 6.
This square version is absolutely needed for this modification!

On the underside of the Motherboard there is a connection between the
soldering-points 'Clock DMA' and 'Clock DSP'. This connection must be cut
with the knife. DON'T cut too deep, the Falcon has a multilayer PCB,
so you can easily ruin the computer by cutting deeper than you wanted.

IMPORTANT: test with the mutimeter if the connection is really cut.

Next you solder a high-precision 14-pin IC socket in the 6 holes for U37.
Cut off the 8 other pins of the socket that are not needed beforehand.
Make sure none of these cut-off pins can touch the board afterwards.

So, that was the difficult part.

Now the original oscillator is put back at the exact place it came from.
(In the IC socket of course; clean the pins of the oscillator of any
residual solder first)

Now the new 48 MHz oscillator must be connected, the way to do that depends:

If you have a Falcon-tower:
Bend the pins '0 V' and 'clock-out' close to the oscillator-casing 90 degrees
outward, so that when those pins are inserted in the last two free holes of
the IC-socket the two remaining pins of the oscillator point to the audio
in-/outputs of the Falc.

If you have a Falcon in original case:
Put the oscillator upside-down on IC U45 using the special adhesive tape.
Then connect the 0V pin of the oscillator to the 0V pin of the socket.
Also connect the clock-out-pin of the oscillator to the DSP-clock-pin of
the socket in the same manner.

In both cases: Connect the +5V of the oscillator to the +5V of the falcon.
A good place for +5V is pin 50 of the memory-daughterboard, but the +5V
line can be found almost anywhere.

Check for any mistakes you might have made and remove all loose bits of
solder, also the ones atari themselves may have left :-(
(I once found a bit of solder of 2 mm by 6 mm size !)

When you have lightly applied some heatconductive paste on the heatsink,
place it on the DSP and fix it well with the hot glue.
Alternatively you may choose to use heat-conductive-GLUE instead, but it's
usually prohibitively expensive.

Now you can put everything back together again.

When you turn on the computer but nothing happens IMMEDIATELY TURN IT OFF and
check everything again.
If you get the Atari-logo but nothing happens after that, it is possible the DSP
does not get any clocksignal.

IMPORTANT:
This manual was made by me taking the greatest care, however, I take no
responsibility for any damages that may result of the use of this document.

(c)1995 Mitja Rateiczak                 eMail: mitja_rateiczak@bm.maus.de

IMPORTANT #2:

I translated this manual in a very short time into english. I am not english,
nor did I take the greatest care while translating, although I believe it
is an acceptable, albeit not _too_ accurate, translation.
In some places additions and/or omissions were made where it felt appropriate.
I accept NO responsibility whatsoever for any mistakes/omissions.
If you are in any doubt, refer to the original german document.

(c)(translation)1995 Maarten van den Berg        eMail: maberg@xs4all.nl

mgrove@owens.ridgecrest.ca.us

 *****************************************
/All my other computers run Atari Software\
******************************************
