Newbie questions.

[tom story]

I'm just learning some basic electronics to try and repair my Oberheim DX
drum machine. I've replaced the CPU, nothing appears damaged physically,
but the machine is just sort of frozen. The sounds trigger once when it's
turned on, but after it's on nothing works and the screen just shows some
garbage.

What next? 	I've checked for continuity in the ribbon cables, reseated
all the ICs and checked for any breaks in the boards but nothing obvious so
far. I've been told it could the Crystal Oscialltor but I don't know what
frequency it is to get a replacement. Any ideas?

Sorry, but if anyone could recommend some good basic books it would be much
appreciated. The two I got from Rat Shack are a little TOO basic, going
into covalent bonds etc...yuck!

Thanks!
Tom