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From: wtm@neoucom.UUCP
Newsgroups: comp.sys.att
Subject: Re: 6300 Clock & PC-DOS 3.1
Message-ID: <383@neoucom.UUCP>
Date: Mon, 9-Feb-87 19:09:54 EST
Article-I.D.: neoucom.383
Posted: Mon Feb  9 19:09:54 1987
Date-Received: Tue, 10-Feb-87 18:37:17 EST
References: <254@rocksanne.UUCP> <967@ur-tut.UUCP> <1969@mmintl.UUCP> <381@neoucom.UUCP>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 29
Summary: correction to my previous article


I incorrectly stated that there is a trimmer cap on the the 6300
motherbard for adjusting the clock accuracy.  You can add your own
trimmer, but you shouldn`t do it unless you know what you are
doing.  Since the resonant frequecy tends to be less than desired,
you can add a small capacitory in series with the crystal to raise
its resonant frequency.  A 3-10 pF capacitor would be a good
choice.  Radio Shack sells 6-50 pF capacitors 2 for $1.59, part
number 272-1340 that might give you an acceptible adjustment range.

The clock chip is located at position D-9 on the motherboad, it is
numbered MM5328, if memory serves me right (too lazy to take the
cover off right now).  The crystal is at approximately C-10.  It is
the wee little cylinder with two wires coming out one end that is
taped to the motherboard.  Some crystals are metal, and some are
coated with white plastic.  They may be numbered "32768".  You can
unsolder one of the leads of the capcitor (IT IS VERY DELICATE!)
and install the capacitor in series.  A screw driver and a high
accuracy frequecny counter are required for adjustment.  Unless you
have access to an electonic shop, you might as well settle for the
chronically slow time of day clock.  Secure the capacitor to the
motherboard with a drop of silicone rubber "bathtub" compound to
keep it from breaking loose.

PLEASE don't fiddle with the machine unless you know what you are
doing and are willing to take the responsibility for anything that
you happen to goof up.  Watch out for shorting out the NiCd battery
that powers the clock if you decide to monkey around.  You can
disable the battery by removing the jumper at approximately D-10.