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SI-125 Power Amplifier Manual 

 

F.

 

FUSE

: Protects the amplifier if the maximum current draw is exceeded. If the fuse blows, 

see the Troubleshooting section. 

G.

 

AC Power Cord:

 Connects the amplifier to a standard 120 V, 60 Hz grounded outlet. 

H.

 

OUTPUT TERMINALS:

 Terminals are provided for 70 V and 25 V speaker lines, as 

well as 8 

 and 4 

 loads. Class 2 wiring may be used. 

 

Ensure that the amplifier is OFF

before making, removing or handling any 

input or output connections. The output cover must be in place when the
amplifier is operating. 

I.

 

ACCESSORY MODULE SLOT (for optional accessories):

 Several accessory 

modules are available, which may be installed into the amplifier. If no accessory module 
is installed, a blank cover plate covers the slot. 

 

Please note that the 

accessory modules are not user installable

. They must be 

factory installed and ordered with the amplifier. Do not remove any modules or
the cover plate. 

J.

 

INPUT LEVEL Switch:

 The Input Level switch selects the range of the input level. This 

switch works in conjunction with the GAIN Control on the front of the amplifier. The 
Input Level switch should be set to match the level of the input in either the 1 V or 100 
mV (-20 dB) range. 

K.

 

LOW CUT Switch:

 The Low Cut switch will reduce the low-end frequency response of 

the amplifier as shown in Figure 3. 

 

Figure 3: Relative Level (dB) vs. Frequency (Hz) 

L.

 

INPUT TERMINALS:

 The input terminals are electronically balanced with an input 

impedance of 10 k

. The input signal level should be in either the 1 V or 100 mV range 

with the Input Level switch set to the appropriate position. The GND terminal is 
provided, if required, for grounding the cable shield. 

Summary of Contents for SI-125

Page 1: ... from overloading The amplifier also has circuitry to protect it from overheating The SI 125 Power Amplifier can have optional modules installed for additional functionality The PA AM Power Amplifier Attenuator Module allows the amplifier to support a 25 V input signal The PA MM Power Amplifier Monitor Module activates a relay under normal amplifier operation The PA PM Power Amplifier Paging Modul...

Page 2: ...ee the Troubleshooting section C CURRENT OVERLOAD Light If the current output of the amplifier exceeds its maximum power output the Current Overload light will illuminate and the output level will begin to be reduced The amplifier will continue to operate with the current limiting circuit reducing the output power If the Current Overload light illuminates see the Troubleshooting section D GAIN Con...

Page 3: ...overs the slot Please note that the accessory modules are not user installable They must be factory installed and ordered with the amplifier Do not remove any modules or the cover plate J INPUT LEVEL Switch The Input Level switch selects the range of the input level This switch works in conjunction with the GAIN Control on the front of the amplifier The Input Level switch should be set to match th...

Page 4: ...urn on either when there is excessive signal level on the input or when there is hard clipping present on the output The CLIP light will not turn on when the output level is clipped due to current overload Installation Before installing an SI 125 Power Amplifier carefully inspect the device for any damage that may have occurred during shipping The shipping package should contain only the Power Amp...

Page 5: ...own in Figure 5 Figure 5 Input Connections To reduce the incidence of ground loop hum oscillation or interference from other audio sources 1 Use a shielded cable for input wiring The shield must be grounded at one end of the cable only not both 2 Regardless of what type of input signal is supplied to the amplifier balanced or single ended the GND terminal should not be connected to the common term...

Page 6: ...pplications there is often a privacy switch in the room When this switch is activated it grounds one side of the room speaker line through a transformer Make sure that all these privacy switches are not in the Privacy position when measuring line impedance to ground These switches do not adversely affect the operation of the amplifier When measuring load impedance on a Telecor installation disconn...

Page 7: ...registers a signal when no signal should be present The amplifier may be oscillating possibly at a very high frequency This may be caused by running input and output wires close together grounding the input or incorrect grounding of the shield The Current Overload light illuminates or flashes This indicates that the amplifier is being overloaded Check the total speaker load on the amplifier Also c...

Page 8: ...ls on input and output Mas Con connectors are used with optional modules Controls Power Switch Illuminated GAIN Control Low Cut Switch Input Level Switch 1 V 100 mV Indicators Clip High Temperature VU Meter and Current Overload Protection Foldback current limiting Over temperature protection Primary circuit fused at 3 5 A Temperature Range 10 C to 35 C 14 F to 95 F Power Consumption AC 120 V 60 Hz...

Page 9: ...ansportation labor charges indemnity etc are not covered by this warranty and no responsibility for same will be assumed by us Our liability does not extend to consequential damage AUTHORIZED REPAIR STATION All participating Distributors and Dealers are authorized to accept Telecor products for return to us for repair or replacement or customers may return goods to us directly providing that retur...

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