Path: news.uiowa.edu!news.physics.uiowa.edu!math.ohio-state.edu!howland.erols.net!news.sprintlink.net!news-peer.sprintlink.net!newsfeed.internetmci.com!in2.uu.net!news.mc.net!usenet From: "anomaly3@mc.net" Newsgroups: comp.sys.apple2 Subject: Apple //e Manual Fault Dict. Date: Wed, 18 Sep 1996 21:21:06 -0500 Organization: McHenryCom Lines: 87 Message-ID: <3240AE12.3937@mc.net> Reply-To: anomaly3@mc.net NNTP-Posting-Host: d3043.mc.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 2.01 (Macintosh; I; 68K) Apple //e Manual Fault Dictionary: How to use this chart: Switch on your Apple //e with no disk in any drives. Get out your logic probe, and test the pins on each chip and note their reading. Then check your list with the list below and compare them. Any inconsistencies could signal a faulty chip and should be tested and/or replaced. PIN # 1 2 3 4 CHIP 1234567890123456789012345678901234567890 ---------------------------------------------------- LS125 PPPLPPLHPHPPLH PLA PPPPPPHPHLLPPPPPPPPH FF HHLPHPPLPPHPPPHH Buffer LPPPPPPPPLPPPPPPPPLH LS245 LPPPPPPPPLPPPPPPPPPH LS374 PPPPPPPPPLPPPPPPPPPH LS244 LPPPPPPLPLPPPPLPLPLH Vid ROM PPPPPLPPLPPH MMU LPPPPPPPPPPPPPHHHPHPPLPPHPPPPPPPPPPPPPPP Processor LHPHOHPHPPPPPPPPPPPLLLLPPPPPPPPPPPOOPHPH ShRegistr PPPPPPPLHPPPPPPH IOU LLPPPHLLPLLHHPHOPPPPPPPPPPPHPPLLPPPPHPPP LS10 PPPHHPLHLHHHPH Dec/Demux PPPPPPHLHHHHHHPH All RAMs HPPPPPPHPPPPPPPL CD ROM HPPPPPPPPPPPPLPPPPPLPPPPPHHL S202 LHLPPLLPPPHPLH EF ROM HPPPPPPPPPPPPLPPPPPLPHPPPHHH LS154 PHHHHHHHHHHLHHHHHPPPPPPH Keybd ROM LLLHLLHHPPPLPPPPHLLPHLHH -------- -- LS251 OLLHPOHLPPPHHHHH RC741 PLLPPPHO NE558 HOHHHHOHHOHLHHOH Decoder PPPLLLLHLLLHHHLLLLLLLLLLLLLHHHLPPPPPPPPP --------- P = Pulse H = High L = Low O = No Light Pins 1-8 & 22 & 23 on the Keyboard ROM as well as pins 6-14 on the Decoder are readings made after "space bar" pressed. + These readings are taken under normal stand-by conditions. That's all there is to it! Please do not ask what the chips themselves do - refer to the Apple //e Technical Reference Manual, in the Hardware Implementation section. - Tony :-) ** This list was obtained from p.232 of "Troubleshooting and Repairing Personal Computers 2nd Edition" by Art Margolis published by Windcrest/McGraw Hill. ISBN 0-8306-2187-3. ** <<<<< DISCLAIMER: This post is for reference only - I will not be held responsible for any damages or personal injury as the result of the use, misuse, or otherwise of the information contained herein. The above procedures should only be performed by a qualified technician, or Apple authorized representative. >>>>>