Mytek Digital Private-Q Multichannel System (ver. 1.0 / Jan 2014) - Manual (Page 9)

Mytek PQ Multichannel System – User's Manual
Grounding
As most professional systems the Private Q uses +4dBm balanced
shielded lines and the grounding is configured on the "STAR"
principle. This means that all grounds and shields meet in one central
point inside the distribution rack and nowhere else to avoid ground
loops. For instance:
1. All the cables connecting the PQ mixers have the individual shields
connected on both connectors so it doesn't matter which end goes
where.
All shields of all the cables are grounded at the rack side.
Inside each PQ mixer the shields are disconnected from the ground
and the mixer sees the ground reference only through the main drain
wire (called on the schematics GND).
Each PQ mixer chassis is grounded through this drain wire.
2. The second Centronics on each mixer still feeds the shields through
so when few units are daisy-chained all of the individual cable
shields are still grounded at the rack side.
3. Rack chassis is always connected to the central ground point inside
the rack.
The power plug should be lifted if the input ground is connected to
the system ground.
4. In a floating system the shields of the rack's input cable are
connected on both sides (Centronics and pin 1 of all XLRs). The main
drain wire is connected to the central ground point and has an
"alligator" clip on the other side. This clip should be connected by the
user to the studio's ground.
5. In a permanently installed system the shields of the input cable
(except the control wire #15) MUST NOT be connected. The drain
wire however MUST be connected to the main studio's ground point.
It usually has to be extended using an insulated thick wire.
6. Properly installed system should be absolutely quiet.
7. PQ mixer output XLRs come from the factory with pin 1
disconnected. You may connect it if necessary by opening the mixer
and soldering the pin to the designated point on the printed circuit
board.
8. If you hear loud hum in one channel of a PQ mixer it is usually not
related to grounding but one of the channel wires (either hot or cold)
is not making contact.
Try resetting the DL, if it does not help check the cable.
User Manual ver. 1.0 / Jun 2013 www.mytekdigital.com Page: 9 / 14