Australian Monitor SA60/SA120/IC30 Distortion when using Line sources.
SA60 Modification Instructions.

A number of customers have noticed that they get distortion when plugging a CD or Tape player directly into the inputs of the SA60. The problem is not as bad on Channel 6.

The problem is due to the unit having 6 Mic/Line inputs. Channel 6 is generally OK due to the fact it has a different gain (see User's Guide).

The inputs are generally sensitive enough for most microphone types but tend to be slightly too sensitive for some high level line sources.

A simple modification solves the problem :

To reduce gain on any channel (to accept CD/Tape machines directly) it is necessary to change the respective channel's input gain select resistors. There are two resistors for each channel (one for each phono socket). However, the channels are not laid out logically on the input board. Please refer to the photograph below of the board for the correct location of the resistors for each channel.



As standard, all inputs are stated as mic/line. If the device you wish to use has a very large output signal it will be necessary to change the value of the respective resistors for that channel (2 off) from 47k Ohms to 220K Ohms. Note that Channel 6 (see picture above) already has 220k resistors fitted.

Method:

1. Remove the mains plug.
2. Undo cover screws and lift the top cover.
3. Locate the input socket board (see picture)
4. Remove the screws securing the board to the rear panel
5. Change the appropriate resistors (from 47k to 220k)

Note: It is not necessary to remove any wires or remove the board completely from the amplifier. Replace the board and cover and you're done!

SA120.

The SA120, although more complex inside than the SA60, has a very similar input board. You can perform the same modification to this unit to get the same result.

IC30.

If you are experiencing a similar problem with the IC30 mixer amplifier, you can rectify it with a similar fix by adding a resistor in series with the wire that connects each socket to the main input/volume control board. You will need 3 150k resistors.

Method:

1. Remove the mains plug.
2. Undo cover screws and lift the top cover.
3. Locate the Aux Input phono sockets (there are 3 of them)
4. Remove the white wire from each socket centre pin termination
5. Add one end of a 150k ohm resistor to each socket centre pin termination
6. For each respective socket, solder the white wire on to the other end of the resistor
7. Replace the top cover

This will effectively reduce input gain and should stop the distortion.

For further information, please contact the Fuzion Technical Department.
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