Cabletron Systems manual Using the MPS14, Combining MPS14 Power units, Earthing

Earthing

Finally, some consideration should be given to the earthing arrangement of the system, at the centre of which is the console and the MPS14. The console chassis is earthed, to the mains earth, via the power supply. When rack-mounting the MPS14 care should be taken to avoid any possible “ground loops” in the system which may introduce audible hum or buzz to otherwise clean audio signals. Ground loops occur where signal processing equipment patched to the console, has its signal earth connected to the equipment chassis. A ground loop is formed if the chassis of the signal processing equipment and the MPS14 chassis are in electrical contact through the fixing rails they share in the rack. The MPS14 has audio 0V and mains earth connected internally. If a ground loop is formed operation of the “ground lift” switch on the rear panel of the MPS14 may reduce any unwanted hum or buzz.

Using the MPS14

The MPS14 will operate from an ac mains supply voltage from 100V to 240V. Before switching on the power supply, check that the ac mains fuse is of the correct type and rating. This is marked on the rear panel of the power unit. The power supply is provided with an IEC type mains connector and a moulded mains plug. Check that this is suitable for connection to the wall socket outlet.

Always switch the power supply off before connecting or disconnecting the console power cables, removing or installing console modules and any servicing work. In the event of an electrical storm, or large mains voltage fluctuations, immediately switch off the power supply and disconnect from the mains supply.

During normal operation some heat is generated. This is expelled via the front panel ventilation holes.

Combining MPS14 Power units

Each MPS14 power unit has a built in combiner allowing the direct connection of other MPS14 power units for backup. Connect the two power units together using the MPS14 “linking” cable (A&H Part No: 002-584) by plugging into the DC output sockets of each power unit.

To console

COMBINING MPS14 POWER UNITS

MPS14

“linking” cable

BACKUP

MPS14

Note; the “linking” cable can be connected to either of the two MPS14 DC output connectors on both units.

MPS14 User Guide 7