Violectric HPA V281 User Manual page 8

hum or jitter caused by different ground/earth potentials.
Of coarse full electrical protection is granted as the case is always
connected to ground/earth potential !
See page 32 "Technical Appendix" for details.
Unfortunately there is no general recommendation how to solve hum
and jitter problems - or even minimize them. The best way to succeed is
to check different options !! In case of balanced cables, it should always
been verified if the shield of the cable is connected to the shell of the
XLR connector. The shell is ALWAYS connected to earth potential when
the connector is inserted !!
Concerning ANALOG inputs and outputs, the relationship between
ground and earth may be modified. Electrical safety is always ensured,
since the earth conductor is permanently connected to the enclosure !!
XLR GROUD-LIFT Jumper ( accessible from the inside.
Mind the SECURITY INSTRUCTIONS !! ):
G(ROUND): Ex-works all jumpers are set to "G" (ground) position.
Pin 1 is connected to the internal ground reference.
High frequency interference is deflected to the case via a
100 nF capacitor.
L(IFT): The interconnection between Pin 1 and ground is open.
High frequency interference is deflected to the case via a
100 nF capacitor. This jumper position is specifically
useful if the unit is equipped with transformers !!
C(ASE): Pin 1 is connected to the case, the 100 nF capacitor is
bridged. This jumper position may be varied together with
the General GROUND-LIFT jumper.
Please note that with jumpers not in the ex-works position
for which the user is responsible only !
EMC emission might occur,
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