2-3
2.3
Ground
It is normal practice to connect signal ground to power line ground for many reasons
including safety. In the SEU4 they are linked by a jumper on the input/output board
inside the unit.
On occasion, hum can be reduced by separating the two grounds. If this is necessary,
remove the front panel (2 screws on top and 5 along the bottom) and the top cover (2
screws each side), and move the jumper at the rear left of the unit (J510) to the “holder”
position. There is a 1 k ohm resistor across the link, so the signal ground is never totally
isolated from the chassis.
Note that the chassis is always connected to the ground pin of the power line cord; for
safety reasons, this ground MUST NEVER be disconnected
2.4
Audio Connections
The SEU4 has been designed to interface with professional audio equipment at commonly
found studio operating levels. Connections to and from the unit are made using standard
3-Pin XLR-type connectors. Both the input and output stages are electronically balanced with
pin 2 being positive and pin 3 being negative. For optimum immunity to radio-frequency
interference, cable shields should be connected to the shells of the XLR connectors, not to
pin1. For unbalanced operation, at the SEU4 end connect cables exactly as for balanced
circuits and unbalance the circuit only at the remote end.
2.5
Regulatory Notices
UL
Troubleshooting must be performed by trained technicians. Do not attempt to service the
unit unless you are qualified to do so.
WARNING:
Check that the units have been set to the correct supply voltage and that the
correct fuses have been installed. To reduce the risk of fire, replace the fuses only with
the same type and rating. Do not use a ground-lifting adaptor and never cut the ground
pin on the three-prong power plug.
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