Thanks for your advice. I'll look into the cassette transistors after I figure out the character issue. I also came across a page by Dave Gostelow that shows some pictures of his keyboard dismantling which will also help when I get around to fixing the keyboard. http://webspace.webring.com/people/ed/davegostelow/PETrestore/PETrestore.html I had only a few spare moments this evening to probe around the Character ROM, so I though I'd post the results in the hopes that it may help someone help me ;-) Firstly, let me start by saying my logic probe is totally crap, and I've been meaning to get a good one. The ROM adaptor I previously spoke about made it quite difficult to actually get to the pins of the 6540 socket, so instead I probed the 2316 that was mounted to the top. Here are the results: http://web.me.com/lord_philip/other_computers/PET_2001_2316.html Seems that all the inputs are pulsing except 9 and 10 which are at 0V. All the outputs seem to be at 0V. I downloaded the 2316 datasheet and looking that the truth table: if CE = Low, WE = Hi and OE = Low, then the mode is READ, Output is ACTIVE, and power is ACTIVE. Unfortunately I don't actually know what all that means :-( Thanks again Philip On Nov 9, 2009, at 2:39 AM, William Levak wrote: > On Sun, 8 Nov 2009, Philip Lord wrote: > >> Hi William, >> Thanks for he reply. >> For my own education, I was wondering why you feel the the >> transistors are the issue? > > Experience! > >> I'm also wondering how exactly would you test for a short in a >> transistor??? Is that something that can be done in circuit with a >> multimeter?> > > Since it causes the computer to hang up, you want to check for any > changes other than putting power on the cassette motor line. I once > found one that had a short between two traces on the circuit board. > >> I'll take your advice on dismantling the keyboard and cleaning with >> alcohol. I'll need to be especially careful as this keyboard is >> actually a Japanese variant with Japanese characters also printed >> on the keys. > > Cleaning the keyboard contacts involves removing the keyboard from > the computer and removing the back of the keyboard. It does not > involve the front of the keyboard at all. > > email@example.com > SDF Public Access UNIX System - http://sdf.lonestar.org > > Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing listReceived on 2009-11-09 14:00:04
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