Audio Authority 1500 Service Bulletin

2048 Mercer Road, Lexington, KY 40511-1071 • 800-322-8346 or 859-233-4599 • www.audioauthority.com
1/13/2017 SB-003
Service Bulletin
Subject:
Grounding suggestions for Series 1500 Intercom Counter Stations.

Summary:

Counter Stations in Series 1500 and Series 1580 Intercom systems may be subject to noise or erratic
behavior created by ground loops. In certain instances, a Counter Station may exhibit erratic behavior
such as intermittent lane deselection or a phantom call due to an insufficient grounding path. If you
experience these unusual problems call our technical support department for guidance
and troubleshooting.

Models Affected:

1500A and 1580.

Description:

Ground loops can occur when the ground connection in a facility's electrical system is duplicated by other
electrical connections that have different impedance or resistance. This difference causes voltage to flow
between various pieces of equipment, which create an audible hum or may cause erratic behavior.
Establishing one path to ground for every intercom system component can reduce or eliminate
this problem.

Instructions:

Remove one rubber foot from the rear side of each Counter Station in the system. Attach a ground wire
with a ring terminal to the screw (see Figure 1), and re-attach the foot. Terminate the ground wire from
each Counter Station to the point of ground where the hub is connected (see Figure 3). For added
protection connect all 1500 (or 1580) Counter Stations to the same outlet or power strip being used by the
hub as shown in Figure 2. Equipment in the lane, such as the Model 1520, which uses a different source
of power, may also benefit from grounding (see Figure 4).

Materials Required:

16AWG stranded wire, insulated crimp-on ring terminals for #8 screws.
Attaching ground wire to Counter Station.
Figure 1.
Counter Stations and Hub sharing power.
Figure 2.