Centris 610 Clock Mod

Date: Sun, 6 Jun 1993 01:13:15 -0700 (PDT) From: Guy Kuo <guykuo@u.washington.edu> Subject: centris-clock-mod-11 Text File for Tech folder which describes how to accelerate a Centris 610 to Centris 650 speeds and beyond by changing the clock oscillator. This procedure is similar to that for the Quadra 700. --------------------------------------------------- Centris 610 Clock Mod Version 1.1 by Guy Kuo This information is only for those who are technically adept. The process requires soldering leads to surface mount components. This is not a good first soldering project and should be done only with electrostatic discharge safe equipment and the usual ESD workmats, etc. You will void your warranty. If you ruin your motherboard, your friends will laugh at you. Now that you have been properly warned, the procedure: 1) Apply ESD equipment and open the Mac. The power should be disconnected and the machine properly grounded. Disconnect and remove the hard drive to gain access to the clock oscillator. The metal shield in front of the hard drive pops off. The hard drive then slides forward and out. 2) Look just in front of the CPU. You will see a small 4 pin plastic IC which is marked 10 MHz. That is the original clock. You may either desolder it and replace with a new clock of a higher speed or install a socket. I prefer to place a socket. 3) Assuming you wish to add a socket, obtain a 14 pin IC socket. Remove all pins except numbers 1, 3, 5, 7, 8, 10, 12 and 14. If you use a machined pin socket simply push the unwanted pins out with a needle nose plier. 4) Cut the socket leads off the corner pins (#1, 7, 8 & 14) The remaining four central leads will later attach to the original oscillator. 5) Use some hook up wire on the underside of the socket to connect pin 5 to pin 7. 6) Connect pin 8 to pin 10. 7) Connect pin 12 to pin 14 8) Mount the socket such that pins of the socket match the oscillator pins as below. This means the socket's four pins ride on top of the original oscillator's leads. Simple lap joint soldering holds the socket in place. Socket Oscillator 3 1 5 2 10 3 12 4 9) Install a wire jumper between socket holes 3 and 5. This grounds the output enable pin 1 of the existing oscillator disabling it. 10) Install a full size TTL oscillator into your 14 pin socket. Pin 1 of the new oscillator goes into pin 1 of the socket. 11) Add a heatsink and (optionally?) a cooling fan to the CPU. I routinely add a cooling fan on top of my heatsinks for this type of modification. A 40 mm low profile 12 volt fan will do nicely. 12) Turn on the machine and it should "Bong" as usual. If not, IMMEDIATELY turn power off and recheck your connections. If you do not understand how this procedu…