"Neilish" wrote in message
...

i service a lot of casio keyboards and the most common thing to go wrong
with them is bad headphone sockets - this often causes one or both
channels to cut out due to the internal switches in the socket - try
swapping over the headphone socket from the good board

Thanks, I'll investigate that. I'm pretty sure the signal does not "pass
through" the headphone jack, because as far as I can remember the line outs
continue to work with headphones connected... but I'll double check!