Gauss Master audio output modification :

When using the Gauss Master , sometimes it would be  desirable
to have  an audio output for a number of reasons.  These could include
wearing  headphones  for privacy , audio signal  recording / documentation
with a audio recorder ,  computer recording and analysis of  gauss master
 signals for the  ULF  hobbyist.  These recording  applications could be very
helpful for  EMF wave  detection,  the ULF hobbyist, ghost hunters , UFO hobbyist
or about anyone using the gauss master .

First  remove the battery compartment cover and lay it aside. Remove the 4 screws
holding the back on , lay them aside.  Look at the back of the gauss master and locate
the  rear of the front panel meter and it's two solder tabs.



Carefully unsolder the two meter tabs with a low wattage iron as to not damage the delicate
meter parts.  Carefully lift up the tabs as seen in the picture above ,  they are delicate and
care needs to be taken so they won't break off.

Now  lift up the whole circuit board assembly , taking care not to damage or pull the
two wires ( one red , one black ) that go to the front panel speaker. ( Your stock
Gauss Master will not have the jack shown at  the top of this board. This is the
external antenna mod mentioned elsewhere . A yellow coil will fill the open board
area seen here with a jack and two wires in it.  )




You will be installing a  3.5 mm  ( mini ) jack  into the " RIGHT " ( facing the meter )
top of the plastic case , the " left  " side is reserved for the "  external antenna mod  " .
( antenna mod seen above )

The picture below shows the  audio mod ( on the left seen from the back )
and the antenna mod with the red and black wires. ( on the right , seen
from the back )  Use your soldering iron or drill and make a hole in the top
plastic for the audio jack .  Mount the jack in place.



Solder the cap and wires to the audio jack and route them along side the meter  , down the left side of the case , when facing it from the rear .  Inline with the audio jack center ( hot ),
jack pin, solder  either  a 1 uf  or 10 uf tantalum standard Radio Shack  capacitor,  positive
side to the  hot , non ground pin of the 3.5mm jack.  .  This isolates  the gauss master
 audio output IC from other equipment that might be connected to it.
I  recommend the 10 uf tantalum capacitor to allow the lower frequency audio signals to pass
more efficiently. either will work OK , tho.

The image , below, shows the location of the audio pads on the gauss master circuit card.
Solder the ground wire from the  audio jack to the audio ground pad. the audio ground
pad , in this picture , is located directly over the top switch and has a blue wire soldered
to it.  Now  solder the cap / center ( hot ) pin of  the jack to the audio output  pad.
The audio output pad is seen below with a green wire soldered to it.




Set the card back in place and temporarily replace the battery . Check the jack  for
proper operation with a headphone.  Remove the battery, solder the meter pins back in
place ,  and reassemble the meter.  That completes the audio jack  modification.  

Installing a " muting " audio jack, one that kills the gauss master speaker  or installing
a mini spst toggle switch to kill the front speaker  are options that might be considered
if needed.  They are simple and  straight forward  changes and not covered here.