From: baron@insane.sanders.lockheed.com (Robert P. Baron)
Subject: Re: 25 MHz Mac IIsi - Another Success
Keywords: 25MHz, MACIIsi
Organization: Information Systems Division, Lockheed Sanders
Date: Wed, 11 Nov 92 13:08:13 GMT

In article <tal691.721448646@huxley> tal691@huxley.anu.edu.au (Tonio Loewald) writes:

>baron@insane.sanders.lockheed.com (Robert P. Baron) writes:

>>I finally got my crystal oscillator from Fry's and replaced the 40 MHz one 
>>with the 50 MHz one last night. My si is working fine and much faster than 
>>before. I really noticed improvement when playing Quicktime movies, they 
>>play back a lot smoother than before. I was concerned about doing this 
>>upgrade since I bought my si when they first came out (2/40 configuration), 
>>but the upgrade went well. I did put a heat sink on the 68030, not because I 
>>saw any problems but because its cheap enough and good design practice 
>>as running the processor at a faster clock rate will expend more heat. 

>Could someone re-post the details on this upgrade? (Or e-mail them to
>me?) It seems pretty simple - replace the 40MHz oscillator with a
>50MHz oscillator (after saying the magic words "it's out of warranty
>anyway") and stick a heat sink to the back of the '030. What is
>Apple's comment on this? Do they claim that IIsi's aren't designed for
>it and may not be able to take the "pressure", etc?

   1) Remove the cover
   2) Remove any boards in the PDS slot
   3) Remove the hard drive, floppy drive, fan and power supply
      (this is pretty simple, unplug the cables and the components
       snap out of the case)
   4) I installed a ground strap on myself at this point to protect
      the logic board from any ESD problems (it might explain why 
      some people's Mac fail to work afterwards. I live in the Northeast
      and this time of year static electricity starts to become a real
      problem)
   5) Pull the logic board forward (make sure all the connections in the 
      back are off or unplugged) and then up to remove it.
   6) Unsolder the 40.0000 MHz oscillator.
   7) Install an IC socket (I ordered my 50 MHz oscillator from Fry's
      and bought the IC socket from them - total cost $10.14) by soldering
      it where the oscillator was.
   8) Install the old oscillator in the socket. Put you Mac back together
      and test it.
   9) Once you've determined the Mac survived the procedure, shutdown the
      Mac and swap the oscillators.
   10) Install a heat sink on the 68030. I got mine at Radio Shack. About
       $3.00 for both the heat sink and thermal compound to mount it.
   11) Test your Mac again.  If all goes well install any boards you had
       in the PDS slot and retest. (I have a VideoSpigot in my si with
      a 20 MHz FPU. Both the Spigot and FPU work fine at 25MHz.)


>It your machine DOESN'T work afterwards, can you restore the old
>oscillator and expect it to work again? (Assuming that it fails
>because of some marginal problem and not because you stuck your
>soldering iron through one of the ASICs by accident.)
  If you put in an IC socket for the cost of $0.22 then this is real easy.

>Tonio


>-- 
>Tonio Loewald            | Ph  06 290 1594 | 13 Sabine Cl. Garran
>tal691@huxley.anu.edu.au | Fax 06 290 1595 | ACT 2605   AUSTRALIA
>"You can lie/You can cry/For all the good it'll do you, you can
>die/But when it's done/And the police come/And they lay you down