Date: Wed, 17 Nov 1993 09:13:05 -0700 (MST)
From: Russ Pagenkopf <cs000rjp@selway.umt.edu>
Subject: submission
To: macgifts@mac.archive.umich.edu
This is a text file with good instructions on how to change the speed of your
mac by changing the clock speed of the timing crystal. Written by Marc
Schrier (schrier@garnet.berkeley.edu), and humbly submitted with permission by
Russ Pagenkopf (cs000rjp@selway.umt.edu). Enjoy!
----------
[Corrections to this document should be sent to cs000rjp@selway.umt.edu -NOT- Marc. Note though, his request at the bottom.]
-------------------
From: schrier@garnet.berkeley.edu (Marc Schrier)
Subject: Accelerating Mac's via crystal oscillators
Date: Sat, 6 Nov 93 22:42:20 GMT
Several people were interested in a summary on what I've learned about
crystal swapping/acceleration, so here goes.
This was initially done on PC's, and then later on Mac's. The first Mac's
were the IIsi's since their architecture was so similar to the IIci it
seemed reasonable to run them at IIci speeds. The basic idea is that there
is a bit of leeway built into these machines and the parts used, that you
can push them closer to their limits. Of course this will void the
warranty, but many people find the 20-40% speed increase worth it.
For the IIsi, 700, 900, and 950 the procedure is all the same. You have to
unsolder the TTL crystal oscillator from the motherboard on the Mac, and put
in a new one. Instead of putting one straight onto the board, it is nice to
use a socket so you can test your individual Mac, and see what the cutoff is.
I have done this to a few IIsi, and the highest frequency we could get to
work with out problems was 27.5MHz. Thus a speed increase from 20 to
27.5MHz. The actual crystal is 55MHz i.e. double the frequency. TTL 55MHz
crystal oscillators do exist, but are rare. The thing most people seem to
do is get a CMOS oscillator, and they work just fine. Digi-Key sells a
55MHz CMOS crystal oscillator in a 14 pin package, part #SE1509. At 58.9
and above, there are problems with the floppy drive; I'm not sure if it has
been tested between 55 and 58.9. Get a small heat sink to attach to the
68030 to cool it down. As some people have said, be careful when you put on
the heat sink. Typically you'll use some heat transfer grease, but the heat
sink can slide off if the mac is moved, and might short something out. The
best thing seems to be to use the heat transfer grease, but also put a
small drop of crazy glue through a hole in the heat sink onto the chip;
this should hold it in place.
For the Quadra 700, you can get 70MHz TTL crystals from Fry's. The 70MHz
may not work, and you may have to back down to 66.6666MHz, the next most common frequency is Digi-Key part #CTX137.
I have not done a 900 or 950, but the general idea is the same. It is
usually best to add a heat sink, and fan depending on the machine. Fry's
sells nice heat sink/fan combo's. I'm not sure what they cost, and I think
they are more than you need, but it should keep the processor cooler. I
happen to have a JAMECO catalog next to me, and they sell these as well.
Heatsink/fan for 80486 CPU, part #67660. These are 1.75"L X 1.88"W X
0.75"H. And then you need a Y cable from your hard drive power cable to
power the fan and your hard drive. I'm guessing these will fit fine, but I
have not tried one.
The neat thing about this comes into play with the new Mac's. In June '93
Guy Kuo reported the first crystal swap on a Centris 610 to the net. He
soldered a socket directly onto the surface mount crystal oscillator and
disabled the crystal on the board by shorting pins 1 and 2, and then put the
new crystal in the socket and connected all the pins except pin 1, leaving it
free. I wrote to him a few days later about using a surface mount test
clip, and asked his thoughts. He suspected I could not find a reasonable
test clip, but otherwise it would work. A few days later the 3M surface
mount test clip arrived, and the test clip worked perfectly. I was running
my Quadra 800 at 40MHz, with no problems, and 48MHz without the serial
ports. A few days later I got several crystals, and found the highest
frequency on my Quadra 800 to be 42MHz. I tried it at 42.768MHz, and the
serial ports did not work, so the cutoff for my 800 is at 42MHz. If you do
not need your serial ports, 48MHz worked fine for me, and at 50MHz my Mac
was not happy. And thus the removable test clip approach was born.
So with this second approach, you can use a new crystal on a 475, 605, 610,
650, 660AV, 800, and 840AV.
You do not have to do any soldering on the motherboard itself, just on the
part you clip onto the surface mount crystal oscillator. Thus the clip can
be removed at a later date. Even though there is no sign that you have
voided the warranty on the Mac, you have. As Apple states:
"This warranty does not apply if the product has been damaged by
accident, abuse, misuse, or misapplication; if the product has been
modified without the written permission of Apple; or if any Apple
serial number has been removed or defaced."
So you will need a 3M surface mount test clip. Make sure you get a surface
mount test clip, the regular IC test clips will not work. I used an 8-pin
one in my first clip, and later tried 12 and 14 pin clips. I'd say go with
a 14 or 16; a 16 will line up with the size of the surface mount chip the
nicest, but a 12 works fine. Digi-Key does not have the 12's, but they have
the 14 and 16's.
14 pin, part #923655-14-ND $7.31
16 pin, part #923655-16-ND $7.74
These are the part numbers for the ones with gold leads; you only need 4 of
the 14 or 16 leads, so if you plan to make several, buy some of the alloy
ones, and put the extra gold pins in there.
You will also need a 14 pin IC socket, there are plenty of types. The
machined pin ones are nice because you can pop out the pins that are not
needed to get them out of the way since you only need three pins in the
socket. You can do the same here with gold and tin, and use the extra gold
ones.
Gold pins, part # ED3314 $0.73
Tin pins, part #ED3114 $0.57
You will also need an oscillator, a little wire, soldering iron, and heat
sink depending on the machine.
For 610's I've used a heat sink. HS143-ND is the 0.600 inch one, and is
plenty ($5.16). The 650's and 800's already have a large heat sink, and do
not get too hot at 28MHz and 42MHz respectively. I had an extra fan with my
800, but removed it, and it has been fine. The heat sinks come with the clips
needed to attach them to the chip. Some people have been using the heat
sink/fan combo's. I have not, but they seem to work fine as well.
How to put it all together.
Stand the clip so it's jaws are facing down, and the rows of pins go from
left to right, and call the closer row A and the further row B. Number the
pins from left to right 1 through 7 (for the 14 pin clip). Next place the
IC socket with the pins down, and the notch to the left, and number the
pins as 1,2,3,4,5,6,7 in the row closest to you, going left to right. The
other row is numbered 8,9,10,11,12,13,14 as you go right to left (back
towards the notch). For the TTL crystal, place it with the dot to the left and
the pins down and use the same numbering system as the IC socket.
Now starting with the test clip, leave pins in positions A2, A6, B2, and
B6. Next solder a little jumper wire between pins A2 and A6. Now get the 14
pin IC socket, and remove all the pins but 7, 8, and 14. Solder a jumper
wire from pin 7 on the IC socket to the jumpered pins on the clip, either
A2 or A6. Also solder a jumper wire from pin 8 to pin B6, and pin 14 to pin
B2.
Now put the crystal in the socket with pin 1 in 1, 2 in 2, 3 in 3 and 4 in 4.
The surface mount crystal oscillator on the mother board will have a
frequency on it half that of your computer, so a C610 has a 10MHz, and a
Q800 has a 16.6666MHz xtal.
That is it, now you just clamp it on. You may want to clip the spring to
reduce the pressure, and clamp it onto the surface mount crystal oscillator
with the notches all facing the same way and pin 1 in 1, 2-2, 3-3, and 4-4.
And watch to make surce the little pins clamp onto the surface mount chip.
These clips hang on very, very well, I've never had mine move in the last 6
months, nor any of the other ones I've done. In the C610 and C650's it is
vertical, and in the Q800's it's horizontal, but it hangs on fine.
To test it out, the best thing to do is just use it a while. You can run
Speedometer to see the changes. I use Snooper with the dongles to check the
serial ports to find their limits; Snooper also tells you what frequency
you are running at in round numbers.
Your computer may work with a faster crystal, but you may have problems
with the serial ports or memory.
This is what I seem to be finding:
C610 max at 28MHz i.e. 14MHz xtal
C650 max at 28.63636MHz
C800 max at 42MHz
Jonathan Jacobs reported a C650 working fine with a 14.75MHz xtal Digi-Key
part #X127, and that the normal 3M IC test clips work fine; 8-pin clip,
Digi-Key part #923690-08-ND ($5.00).
The crystals I have found are:
12.0 $3.44 @ Digi-Key $3.75 @ Fry's
14.0 $2.99 @ Fry's
14.31818 $3.44 @ Digi-Key
16.0 $3.44 @ Digi-Key $4.46 @ Newark
18.0 Inductive
18.432 $3.44 @ Digi-Key $2.99 @ Fry's
19.6608 $3.44 @ Digi-Key $2.99 @ Fry's
20.0 $3.44 @ Digi-Key $4.46 @ Newark
21.0
21.384 $3.50 @ Electronics Etc.
22.0
22.0320
22.5
23.892
24.0 $3.44 @ Digi-Key $4.46 @ Newark
25.0 $3.44 @ Digi-Key $4.46 @ Newark
25.1750 $3.44 @ Digi-Key $2.99 @ Fry's
28.322 $3.44 @ Digi-Key $2.19 @ Fry's
40.0 $3.44 @ Digi-Key $4.46 @ Newark
50.0 $3.44 @ Digi-Key $4.46 @ Newark
55.0 (CMOS) $3.60 @ Digi-Key
55.0 $4.00 @ Electronics Etc.
58.90
66.6666 $4.70 @ Digi-Key $4.46 @ Newark
70.0 $6.49 @ Fry's
Address' for parts suppliers:
Fry's Electronics
340 Portage Ave
Palo Alto, CA
(415) 496-6000
Electronics Etc.
2738 10th
Berkeley CA
(510) 845-0169
Digi-Key
(800) 344-4539
Newark
15 Crow Canyon Court
San Ramon, CA 94583
(510) 743-0250
JAMECO Electronic Components
1355 Shoreway Road
Belmont, CA 94002-4100
(800) 831-4242
You can have crystals custom made, but it takes a while, and would be best
to do in large quantities The best thing is to shop around, I have not had
any of these custom made.
If you have gotten a C610, C650, or Q800 to go any faster **and** the
serial ports still work, please let me know.
Marc Schrier