Initial Testing
It would be prudent to test the power supply first before applying power to either the SREIO or
SRE330 main boards. So remove any interconnections between the RPSU board and the other two
boards. Apply power and switch on.
Measure the voltage between pin 1 and pin 2 of PS1. You should have a voltage somewhere
b15V and +15.5V. Pin 2 and pin 3 of PS1 are both connected to 0V, the SRE330's
common reference point. Now measure between pin 4 and pin 3. You should have a negative
voltage between -15V and -15.5V. No part should be getting hot.
To be sure things are fine with the RPSU, leave the device on and measure the voltages again after
ten minutes. They should be roughly the same as they were before. Again no part should be getting
hot.
Switch off and wait about a minute. Connect the SREIO board. Switch on and after less than a
second, you should hear a click from the relay as the coil inside it is energised. Switch the unit off
and after a few seconds you should hear another click as the relay turns off. It should be noted that
once the SRE330 main board is connected the relay turn off time will be much shorter, but the turn
on time is the same.
Now it is time to connect the main board. As you turn it on for the first time you should notice all
four LEDs on the signal meter light up briefly and then go out in turn, the red first and the green
last. If any remain lit then you have a problem. The power on LED should light up and stay on for
as long as the unit is switched on.
Check that the power supply is still producing b/-15V and +/-15.5V.
Leave the unit on and check that no device is getting hot. A few ICs will get warm but none should
be too hot to touch. Check the power devices on the power supply. These should be getting warm
after a few minutes but neither should be getting hot. If they are, you may need to look at your
heatsinking arrangements.
The unit should pass and affect audio even without calibration. However, an uncalibrated SRE330
may produce some unwanted audio artefacts, so the first thing to do is to check that the dry signal
pathway is working correctly.
Connect a 5V peak sawtooth or triangle wave at around 220Hz to the left input socket. The signal
meter will light up as you turn up the input level. The red LED should be lit when the input level is
around half way.
Set the balance pot to dry and the input level so that the second yellow LED on the signal meter just
lights up. Monitor the audio output from the left hand output. Turn up the output level and you
should hear your audio input. Check the right hand output and this too should have the same audio
signal.
Now remove the input from the left hand input socket and use the right hand input instead. The
audio output should only be heard from the right hand output and now not the left hand output
socket. This is because only inserting a jack plug into the left input also sends that signal to the right
input automatically.
You should now calibrate your unit and the instructions for doing this are in the User Manual.