Fairlight-CMI

Hello, 

There is a SIII service manual PDF  from the old Non-maskable web site, it can 
be found here:

http://cmi.fairlightus.com/

Best regards, Martin




________________________________
From: Joe Sleator <joe.sleator@gmail.com>
To: Fairlight-CMI@yahoogroups.com
Sent: Fri, 4 March, 2011 15:29:23
Subject: Re: [Fairlight-CMI] Series III Keyboard

  
Hi, Arron,

If you've got the right ROMS in the keyboard, you can pull the power lead off, 
then hold down * and D on the keypad, and connect the power again, to run some 
keyboard diagnostics, which will display through the keypad display. Make sure 
the keyboard is assembled enough to operate safely in this case, but it's not 
necessary to take it apart at all to run these diags. If PIA 2 has failed, 
there's your answer. Probably it hasn't. The PIAs are 6821s and you can get them 
from pinball machine supply places.

Once you get looking at the keyboard underside, you'll see two buss bars, with 
the keys holding nickel-silver wire springs which contact the two buss bars at 
various times. Firstly, make sure the ones on the "bad" keys look the same as 
the ones on the "good" keys, i.e. none of the contact springs have fallen loose 
or become disconnected. You can fix the ones that are bad by reconnecting them 
with tweezers. The keys hold the springs out between the two buss bars, and when 
the key flies down, the spring breaks loose from one and flies across to the 
other. The time interval is obviously proportional to the key-strike velocity, 
and that's how it works. It's very reliable and simple.

Before you start, it's a good idea to count up to where it starts mis-behaving. 
If the mis-behaviour or dead-key effect starts at the boundary of one of th 
CMI11 boards, that'd be a dead giveaway that one or more of the decoders (4051 
multiplexors) have failed. If you're just getting sporadic non-functional 
behaviour, that's more indicative of loose switch springs. You can easily buy 
4051 chips cheaply and replace any ones that are obviously bad. In fact you 
might just piggy-back the chips onto the suspect ones (right way round of 
course) briefly with the legs bent in to apply tension, to verify that they're 
the right answer. 4051's are fairly cheap and plentiful, so it's a low-risk 
activity.

Personally I've seen connections and springs fall off and get filthy way more 
that I've ever seen 4051s blow up from normal use.

The only other good test I can think of is to verify that the ribbon cable and 
end connections are healthy. They should be as that internal ribbon won't move 
much during normal operation.

Also, the voltages are fairly high by modern standards, +, - 5V and silver-oxide 
is conductive, so they should work unless they're very dirty. I'd inspect them 
before cleaning them to see if the springs have fallen loose with use or 
transportation.


IIRC, the relevant circuit schematics are in the IIx service manual (that part 
works  the same as the series III). I dunno if the III service manual has been 
digitized, but it wouldn't be a bad idea.

Good luck!

Joe

On Thu, Mar 3, 2011 at 9:14 AM, arroncx <aclague@synapse-consulting.com> wrote:

  
>So, as I mentioned earlier, Im almost there in full operation :)
>
>One thing that needs fixing is that there are a couple of areas of the music 
>keyboard which dont work : all of the bottom half trigger notes, then about half 
>an octave worth of notes do nothing, then the next few work, and then its dead 
>to the top.
>
>Anyone with any experiance ? Ive never taken the music keyboard apart before.
>
>Cheers,
>
>Arron
>
>