Vintage Synth Repair

>>thanks scott-lets just say that for safety's sake, i wanted to
replace both the transformer AND the voltage regulators-can you help
me read this schematic?(id rather just do it now while i've got the
unit disassembled). i cant figure out the secondary voltage of the
transformer, or the regulator values.<<

ah-hah. the synth uses +15V & -15V, so the transformer is likely to be
(as someone has already pointed out) something like 18-0-18. 
I would leave this alone unless it's obviously damaged somehow, or if
it's buzzing & you need to quieten the synth down acoustically. you
could replace it with a suitable toroidal. 
look on the case of the arp for guidance as to the number of VA the
transformer should be rated at, but bear in mind that it likely uses
more current on the + rail than on the -.

if you are unable to begin, or are worried about measuring the
secondary voltages of the trafo, find a tech who can. it doesn't need
to be a synth tech, just someone who understands electronics. 

the power supply is college-grade stuff, a simple series regulator
design, & could easily be replaced with off-the-peg 78xx/79xx devices
if the current load is not excessive. other designs using
pass-transistors could still use these devices as reference voltages.
again, this is not beyond the scope of any decent radio/tv/audio tech,
even if they've never seen a synth before. find one, & have him/her
measure the secondary voltages & the regulator outputs on & off load;
you may discover that there's a bad module in the arp causing these
problems. I wish I was nearer & able to help more.

duncan.