quadra clock modification long here is how i modified my quadra for higher speed previously i had been using a variable speed overdrive for accelerating my cpu but this modification is testing out as more stable at higher speeds your mileage may vary the top speed you achieve cannot be predicted before hand my personal q has tested fine up to mhz thus far i didn t have higher speed clock oscillators on hand to test higher speeds parts clock oscillators pin ttl variety you will need a selection of speeds beginning at mhz on up the cpu will run at the oscillator speed the original one is a mhz unit i recommend getting a mhz clock in case you damage the existing one i obtained my clock oscillators from digikey for less than each some of their part numbers are mhz ttl clock oscillator part x mhz ttl clock oscillator part x mhz ttl clock oscillator part ctx don t get the half size clock oscillators they won t fit there are also cmos clock oscillators i haven t tried one in a quadra they work fine in iisi s socket obtain a pin socket which is in the same form factor as a pin dip package alternatively use machined socket pins from an augat style socket just cut them out of the socket cooling fan a very small volt fan to keep the cpu cool is a must my vso came with a specially modified heatsink which had a fan built onto it it had a pass through connector which tapped into the hard drive power cable you should rig up something similar or risk frying your cpu procedure insert usual disclaimer and antistatic warnings here remove the top lid of the machine you will see the floppy disk and hard drive mounted in a plastic tower follow the usual anti static precautions and of course make sure the machine is off when you do this unplug all cables wall and monitor power supply cords from the back of the mac remove the power supply by pulling the plastic interlocking tab on the tower forward and simultaneously pulling the power supply straight up the tab is a piece of plastic from the left posterior aspect of the tower which extends downward to hook on to the power supply you may also feel a horseshoe shaped piece at the right portion of the power supply leave that alone the plastic tab from the tower is all you need release look at the rear of the tower assembly you will see the flat ribbon scsi connector to the hard drive a power cable and a flat ribbon cable leading to the floppy drive disconnect all these from the motherboard the hard drive power cable connector has a tab which must be squeezed to release it unplug the drive activity led from its clear plastic mount look down the posterior cylindrical section of the plastic tower a phillips head screw is at the base remove it taking care not to drop it into the case a bit of gummy glue on your screwdriver is helpful here remove the tower assembly by pulling medially the plastic tab on the right side of the tower this tab prevents the tower from sliding posteriorly slide the entire tower assembly cm posteriorly then lift the tower assembly straight up and out of the case remove the interrupt switch assembly it is a strangely shaped plastic device at the left front edge of the motherboard pull the middle rear plastic prong up and forward the entire device will release unplug the speaker cable squeeze the plastic tab on the speaker to free it then swing it backwards to free it from the case remove the motherboard form the case lift the front right corner of the motherboard about mm this allows it to clear the clear plastic power light guide slide the motherboard forward about cm the motherboard then comes directly out locate the mhz clock crystal it is a small metal box near the cpu chip note and remember its orientation the new clock oscillators must be aligned with pin in the same orientation very carefully desolder and remove the old clock oscillator some of the pins may be bent over simply desolder then unbend them be sure your desoldering iron is hot enough before heating the board i used a suction desoldering iron to accomplish this task this is not appropriate for a first soldering experience the motherboard is a multi layer design with very fine traces easily damaged without proper care install your socket or socket pins where the old oscillator once was put a mhz clock oscillator into the new socket you could use the old clock but it has solder on its pins this may come of inside the socket and cause corrosion problems later i suggest using a new mhz clock install your cooling fan system to complete the modification reinsert the motherboard and slide it into place snap in the interrupt switch assembly and speaker to lock the mother board firmly plug the speaker wire back into the motherboard reinstall the tower assembly by first placing the right wall of the tower against the right wall of the case with the tower assembly about cm posterior of its intended position lower the tower assembly into place while maintaining contact with the right wall of the case once fully down slide the tower assembly anteriorly until it clicks into place reconnect the motherboard ends of the cables dont t forget the floppy drive cable replace the phillips head screw drop the power supply straight down into place until it clicks in plug the hard drive activity light back into its clear plastic mount reattach your cables and power cords cross your fingers and turn on the mac it should make the usual power on chord if it doesn t something is amiss immediately turn of the power and recheck your handiwork if all is not well you have my sincere condolences hopefully all will work normally turn the machine back off and replace the mhz clock oscillator with a faster one reboot and be astounded you will need to fully test the machine for many hours before deciding a particular speed is truly usable with my vso a machine lock up might take hours of operation to occur in the brief time since modifying my clock oscillator hours i have not had a single problem good luck to all who attempt this modification there is a small but real risk but you could well reach quadra speeds or higher with less than in parts guy kuo guykuo u washington edu
