Iisi Clock Mod Poll

Date: Tue, 4 May 1993 03:49:58 -0700 (PDT) From: Guy Kuo <guykuo@u.washington.edu> Subject: IIsi-clock-mod-poll.txt Report on poll of users who have upgraded their IIsi clock oscillators for higher speed. Suggest placement in reports folder. ------------------------------ This poll was conducted to help users decide whether or not to alter their IIsi clock oscillator. I have attempted to gather as many case histories as possible to find some estimate of success and risk. The number of replies probably shows how rare this modification is but give the impression that success rates may be higher than the previous 80% estimate. 25 of 25 machines were able to run at 25 mhz when no add on boards were present. This is not a scientific survey but it is the best we have to work with. Thanks to all who contributed to this poll. Issues: Speed) 25 mhz to 27.5 mhz appears to be the norm for machines without add on cards. All reported machines were able to use 25 mhz as long as no add on cards were present. Several Apple cards were in use. No machine with the Nubus adapter was able to go faster than 25 mhz. One wasn't even able to achieve 25 mhz with the Nubus adapter in place At speeds >= 30 mhz, the startup sound may crackle and hi density floppy disk problems have been reported. Note: Unless specifically listed below, machines were not tested with a higher speed clock to failure. Hence, the 25 mhz operational machines may well work at higher speeds. Damage) One user reported pulling out the plating of one pad. This was repaired and the machine is operational. One other reported pulling the pin out of the original clock oscillator during desoldering. There is one second hand report of a user putting a gash in the motherboard with a slipped soldering iron. No reports of static discharge damage. No reports of high speed operation causing damage. Then again, I also don't have any reports from users of defective parachutes. Add on boards) Compatibility appears to be a problem with Apple Nubus Adapters. Several other add on boards have been used with success. See case histories Heat Sinks) Virtually all modified machines had a heat sink installed. These were often the TO-220 style power transistor type. Some used epoxy. Some used a dab of heat sink compound with a dab of cyanoacrylate glue. There was also use of a clamp with a bolt through the hole in the …