Vintage Synth Repair

Hello sythesists::

I'm wondering if anyone has ever worked on an arp quartet, I just got 
one which is producing no sound at all.  The only thing I can hear is 
the electrical contact in the buttons/ sliders sometimes, so I know 
something is coming out of the synth. I read that some of the 
capacitors and chips need to be replaced on the arps.  Any other 
ideas besides this?  Any good site links to show where/what I'm 
supposed to replace?
Please no big words, I'm just starting to learn electronics and was 
hoping this might be a decent project to get my feet wet!

This quartet also has a strange mod on it, looks like a centronics 
type scsi port (or similar) coming out of the back where someone 
apparently connected to another system.  The wires inside the Quartet 
go to each key - I'm assuming to send out triggers.  It's a very 
professional looking mod, so I can only assume the owner had taken 
care of it and knew what they were doing.  It also looks like it was 
done quite a while ago.  I only hope that if he disconnected/removed 
something to use this as a controller, that I can find it again

Thanks,
Ed