Fairlight-CMI

The buyer of my CMI SERIES III is having a couple issues that I was hoping to get some help with.

First, he is unable to play the instrument with the music keyboard.  The keyboard is getting power, as the numeric keypad lights up and functions (the LED didplay works, and the buttons function as they should), but when he plays the keyboard, there is no sound and no indication that the CPU is registering the keys.  He is able to play the Fairlight using a different midi controller keyboard.  

Second, he cannot get audio out of the mono output or the headphones.  When he uses the preview command to audition instruments, he can hear the preview through the headphones but not the mono output.  But he can't hear audio from the mono output or headphones when he plays instruments from a midi keyboard.  

Any ideas on how to troubleshoot these issues?  Thanks.

For the music keyboard problem, I would start by looking at the CMI-332 board.  The SIII music keyboard actually sends MIDI which winds up at one of the PC900 optoisolators on that board.  I once received a Series III with *all* of those optos blown.  If they are socketed, you can try swapping one of the other 3 PC900s (one for each MIDI in) to see if that gets it working again.  The schematic for the CMI-332 is in the service manual.

It could also be a problem in the keyboard itself.  The schematic for the keyboard is also in the service manual.  I would start with a scope or logic probe and verify that you see activity on pin 6 of U16 (the transmit line for the serial port IC for MIDI).  If that looks good then take a look at pins 3 & 4 of the inverter at C3,4 and then pins 9 & 8 of the NAND gate at D1,2.

It could also be a problem with the cable that connects the keyboard to the CMI.  Use a meter to verify continuity for each of the pins.  See the service manual for what signals are on each pin.

Hope that helps!
Joe

--- In Fairlight-CMI@yahoogroups.com, "KyleR" <kar_chicago@...> wrote:

>
> The buyer of my CMI SERIES III is having a couple issues that I was hoping to get some help with.
> 
> First, he is unable to play the instrument with the music keyboard.  The keyboard is getting power, as the numeric keypad lights up and functions (the LED didplay works, and the buttons function as they should), but when he plays the keyboard, there is no sound and no indication that the CPU is registering the keys.  He is able to play the Fairlight using a different midi controller keyboard.  
> 
> Second, he cannot get audio out of the mono output or the headphones.  When he uses the preview command to audition instruments, he can hear the preview through the headphones but not the mono output.  But he can't hear audio from the mono output or headphones when he plays instruments from a midi keyboard.  
> 
> Any ideas on how to troubleshoot these issues?  Thanks.
>