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TROUBLESHOOTING GUIDE
Well, we sincerely hope you get to skip this portion of the manual, but this is
here to help in the event of an emergency. Remember the detrimental effects
an incorrectly installed component may have on your circuit. Keep this in mind
as you troubleshoot your circuit for possible assembly errors.
PROBLEM: Nothing at all on the output of the mixer.
SOLUTION: Check your power supply voltages to make sure you have at
least 8 volts over all. Verify also that you have at least 4 volts between R15
and R17. If that is not it, check U1 for proper installation. Thereafter its a
matter of testing your source signal and that your destination is connected
properly.
PROBLEM: Left or right channel is out.
SOLUTION: This is a classic trouble shooting problem. Now is a great time to
have a little fun and teach yourself some trouble shooting skills. Make sure a
signal is present on both left and right inputs, then trace through the circuit
using an oscilloscope or DMM set on AC to find where the signal stops. You
will need to use the schematic and the board layout to assist in finding the
signal path.
PROBLEM: The microphone input screeches when I turn up the control and
no microphone is plugged in.
SOLUTION: Hmmm, the way this project worked out, by using a very high
input impedance on the microphone as well as high gain, the mic amplifier
tends to pick up on all sorts of circuit noise. Just make sure either to leave the
control turned all the way down when not in use, or just leave a microphone
plugged in.
PROBLEM: When running the output of this into the FM-10A or FM-25, I
seem to be driving the transmitters into distortion when MAIN is turned up full.
SOLUTION: Because the MX-5 has some gain, you will either need to keep
the MAIN adjustment from going all the way to full, or you can open the FM-
10A or FM-25, and adjust the controls for level on their inputs.
MX-5 Page 15
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