Crumar Musical Instruments User Group.

> I don´t have a Bit One, but check Pin 4 of the TL072 against ground and
> even Pin7 against ground. Me thinks that the TL gets maybe ground onto
> Pin4 or Pin7, or some voltages are missing (Pin 4 should have a negative
> voltage, pin7 a positive, -maximum- at +/-18 Volts!) and that causes the
> overheat.

I'm not detecting any continuity between ground and pins 4 or 7 on any
of the TL072s.  I am also not detecting continuity between pins 4 and
7 on each IC.  Is that the right thing to look for?

Pin 4s: -11.5v
Pin 7s: -9.9v, 0, or +10.5 (only one 14 ICs)
Pin 8s: 11.14v

> Check for some chips called 7805/78L05 /
> 7812/78L12/7815/78L15/7905/7912/7915 and measure their outputs. Those
> componets have three pins and usually a heatsink installed. Left pin ist
> the VCC input, middle is usually ground, right pin is the output. A 7805
> should output a fixed voltage of 5 Volts, a 7905 a -negative- voltage of
> 5 volts, a 7812=12 Volts positive etc. Same goes to the other "78" and
> "79"-Chips. Even check their middle pin against case ground, maybe they
> get from somewhere voltage where they shouldn´t.

I cannot find 780x or 781x, but there is one 7912 on the PSU board,
and it measures:
Left 0
Middle -17v
Right -12v

All three pins have continuity with the case ground, but only when the
connecting cables for the other boards are connected to it.

Suggestions?

Thanks!