JX8P PS problem?

[Mikko Helin]

Hi,

I once repaired a dead JX8P: the diode bridge (rectifier) was broken.
Don't know if it's the same reason. You can get schematics
from your local Roland representavites.

-Mikko

-----------------

Sorry, but here's another really basic question regarding my JX8P-

The power supply board has connectors labeled +5, +7, +15, and -15v.
Checking it without disconnecting the cables to the other boards, +5
reads about 4.9v, but +7 reads about 10v, +15 reads about .566v, and -15
reads about .5v.  This has got to be a problem.  Once the cables are
disconnected, the +5 stays the same, but the +7 goes up to about 11.9v
and both the + and -15v supplies read 2 or 3 mV.

Bear in mind that I'm an absolute beginner.  This is bad, right?  Any
suggestions on where to begin?

I know that one of the op amps on the board needed replacing.  I removed
it and checked the voltages at the positive and negative input.  Pin 4
(the positive input) is reading between .65 and .76v, it's not stable.
Pin 11 (the negative input) is reading .496v.  Shouldn't one of these be
a negative voltage?  If anyone has a service manual handy it's IC53, a
TL064.

I'm waiting on a service manual for this, but if anyone can advise me
here it would be incredibly helpful.

Thanks,


Tim