"Michael Black" wrote in message
...

"Colin Swift" ) writes:
Hi,

I've been given a wavefront travel case Theremin to repair.... seems
the
power supply is dead, it has a 3 pin DIN connector alas I am not 100%
sure
as to what the voltages should be on these pins? Is there anyone out
there
who knows? I tried e-mailing the company however haven't received a
reply.

So far the voltages measured on the pins on the din connector are -12, 0
and -0.71V - I guess the latter pin should be +12v. The power supply
that
came with the unit is an adapted computer psu with output voltages of
+/-12v
and +5v - but only 3 outputs are used. Looking at the resistor to the
'on'
LED (220 ohms) I am now 90% sure that there should be +12V and not +5V
on
this line. I just want to be 100% sure if possible.

The inline LED resistor is 220 ohm, LED's dropping voltage is about 1.2 V.
With 5 V that is about 17 mA, for 12 V that would be about 50 mA and
that amount of current would kill most LED's rather sooner than later.
Bottom line... that 'on line' should be + 5 Volts.