SI-125 Power Amplifier Manual 6205 Kestrel Road; Mississauga, Ontario; Canada; L5T 2A1 November 2016, Rev 0.5 Phone: (905) 564-0801 Fax: (905) 564-0806 www.telecor.com E:\T2-108\T2-M108-ABC\T2-M108-B.doc/AD CAUTION These servicing instructions are for use by qualified service personnel only. To reduce the risk of electric shock, do not perform any servicing other than that contained in the operating instructions unless you are qualified to do so. The Telecor SI-125 Power Amplifier delivers 125 watts of audio power intended to drive industry standard speakers for sound reinforcement and paging systems. The amplifier will accept either a balanced or single-ended input source. A sensitivity Input Level switch is provided to select either the 1 V (0 db) or 100 mv (-20 db) input level. Output terminals are provided for 4 Ω, 8 Ω, 25 V and 70 V speaker lines. The amplifier contains current limiting circuitry on the output to protect it 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 Module provides the amplifier with additional inputs for a low impedance microphone and two balanced line level inputs. The SI-125 Power Amplifier conforms to UL 60065 ETL listed mark with listing number 3059290. The following symbols are on the amplifier and in this manual: SI-125 Power Amplifier Manual 1
Unit Description The various amplifier parts are: Figure 1: SI-125 Front View A. VU METER: The 30 db digital VU meter shows 0 db when the amplifier is operating at its rated output. Exceeding the rated output will cause the output to be clipped, which will be indicated by the illumination of the CLIP light. B. HIGH TEMPERATURE Light: If the internal temperature of the amplifier exceeds its normal operating limit, the High Temperature light will illuminate and the output level will begin to be reduced. The amplifier will continue to operate at a reduced output level until the temperature returns to an acceptable level. If the High Temperature light illuminates, see 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 Control: The gain of the amplifier can be adjusted using this potentiometer. The potentiometer is concealed behind a snap-on cover. The cover can be snapped off when the level needs to be adjusted but should be replaced to prevent unintended tampering. The amplifier gain is set by both this control and the sensitivity Input Level switch on the back of the amplifier. E. POWER Switch: Turns the amplifier on and off. The switch will illuminate when the amplifier is turned on. Figure 2: SI-125 Rear View SI-125 Power Amplifier Manual 2
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 Ω and 4 Ω 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 kω. 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. SI-125 Power Amplifier Manual 3
Clipping Output Clipping is the point where the peak output signal is limited to avoid damage to the amplifier from excessive output current (current overload). Once output clipping is detected, any increases in input level will not cause increases in output level (this is shown by the output plateau in Figure 4). To avoid distortion, the output signal is dynamically attenuated to give the maximum attainable output voltage without distortion, although technically the peak output level is clipped at this point. The Current Overload light will turn on when the current limiting circuitry is engaged. Figure 4: Effect of Clipping Input Attenuation will occur when the signal is limited due to excessively high signal level at the input. The clipping LED will turn 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 Amplifier. If any part of the amplifier has been damaged, please contact the shipping company as soon as possible. DO NOT ATTEMPT TO INSTALL EQUIPMENT THAT WAS RECEIVED DAMAGED. The amplifier mounts into a standard 19" Telecor equipment rack with 10-32 screws. The SI-125 requires 5 ¼" of vertical rack space. When mounting the amplifier into a rack with other equipment, be sure to allow for adequate ventilation. To accomplish this, ensure that a blank panel of 1 ¾" height (or greater) is installed between the amplifier and any other equipment (e.g. additional amplifiers, power supplies, etc.) in the rack. SI-125 Power Amplifier Manual 4
Do Not mount the amplifier such that: there is inadequate ventilation. the vents on the top, bottom or side of the amplifier are covered or blocked. it is susceptible to vibration. it is in an area of high ambient temperature. it is adjacent to other heat-radiating equipment. it is exposed to direct sunlight. it is exposed to moisture. The amplifier should be plugged into a standard three-prong 120 V, 60 Hz grounded outlet. Turn the Power Switch off when connecting or disconnecting the AC receptacle. 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. Input Connections: The screw terminals on the right side of the back of the amplifier are for signal input. The input terminals are suitable for both balanced and single-ended inputs. A ground terminal is provided for grounding the shield of the cable if required. An example of typical input wiring is shown 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 singleended), the GND terminal should not be connected to the (common) terminal. 3. Do not enclose input and output connectors in the same cable. Where possible and practical, and when the wire length exceeds 6 feet, the input and output wiring, in addition to being separate cables, should be physically separated. Set the Input Level switch to match the level of your input. If you are connecting the input of the amplifier to an unknown level signal, set the Input Level switch to 1 V and the GAIN Control to 0, then apply the signal and increase the gain. If an unacceptable level is not reached with the gain at maximum: turn the GAIN Control to 0, set the Input Level switch to 100 mv, and then increase the gain. 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. SI-125 Power Amplifier Manual 5
Output Connections: The left terminal strip is the signal output of the amplifier. Terminals are provided for 70 V and 25 V speaker lines, as well as 8 Ω and 4 Ω loads. Connect the speaker load to the appropriate terminals depending on the load impedance. Class 2 wiring may be used. The output of the amplifier is floating with respect to ground and should remain that way. Do not connect the COM and GND terminals together. The GND terminal is provided for use with shielded cable only. To reduce the incidence of output audio being induced into other conductors, use twisted pair wiring and keep the input and output wiring separated. To avoid overloading the amplifier, ensure that the total speaker load impedance is no less than the values in the table below: Output Terminals Maximum Load / Minimum Impedance 70 V 39 Ω 25 V 5 Ω 8 Ω 8 Ω 4 Ω 4 Ω Line Impedance Measurements: Measure the amplifier s load impedance using an audio signal impedance meter (1 khz) with the amplifier output disconnected. Also measure the impedance of each side of the load to earth ground, which should be an open circuit. If it is not (i.e. there is a fault to ground), isolate the fault and correct it. Do not operate the amplifier on a ground-faulted output line. Note: In school applications, 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, disconnect the amplifier output from the line, connect the impedance meter across the line, make sure the system is in an ALL CALL mode, and then measure the line s impedance and check for line ground faults. Operation Before turning the amplifier on, ensure that: o the speakers have an adequate power rating. o the proper output terminals have been used. o the gain of the amplifier is appropriate for the input signal supplied. If you are unsure about the Input Level and gain settings, turn the GAIN Control to minimum before turning the amplifier on. Once the amplifier is mounted and wired, turn the unit on. The Power Switch will illuminate. Watch the VU Meter on the front of the Power Amplifier. With no signal connected, ensure that none of the LEDs are illuminated. If any LEDs illuminate, refer to the Troubleshooting section With the signal applied, adjust the GAIN Control until an appropriate output level is obtained. If the Current Overload or Clip lights illuminate, see the Troubleshooting section To reduce the low frequency amplification, set the Low Cut switch to the CUT position. SI-125 Power Amplifier Manual 6
Optional Modules Additional functionality can be added to the SI-125 Power Amplifier with the factory installation of one of the following optional modules. Note: These modules must be ordered at the same time as the SI-125 Amplifier as they cannot be installed in the field at a later time. These modules are installed on the rear of the amplifier by the Telecor factory and therefore cannot be ordered independently without an amplifier. The PA-AM Power Amplifier Attenuator Modules provides the amplifier with the ability to support a 25 V input signal which is attenuated by -25, -45, or -70 db. Refer to the PA-AM Power Amplifier Attenuator Module Manual for more information. The PA-MM Power Amplifier Monitor Module will monitor the operational status of the amplifier. As long as the amplifier is operating normally, a relay will be activated. Refer to the PA-MM Power Amplifier Monitor Module Manual for more information. The PA-PM Power Amplifier Paging Module adds three additional input options to the amplifier: one low impedance microphone and two balanced line level inputs. The three inputs have adjustable level and remote mute controls. The three inputs can also be assigned to one of three available priority levels. Refer to the PA-PM Power Amplifier Paging Module Installation Guide for more information. Troubleshooting Problem VU Meter registers a signal when no signal should be present. The Current Overload light illuminates or flashes. The Clip light illuminates or flashes. The High Temperature light illuminates. Fuse blows. Description 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. This indicates that the amplifier is being overloaded. Check the total speaker load on the amplifier. Also check for shorts in the output wiring and for shorts to ground. If the amplifier is being overloaded, reducing the load or the gain should solve the problem. The input level to the amplifier is too great. Correct either by turning down the GAIN Control or by reducing the Input Level at the source of the amplifier s audio signal. This indicates an excessively high temperature on the heat sinks. When this occurs, the output level is reduced until the temperature returns to normal. Overheating of the heat sinks is usually caused by insufficient ventilation or operating the amplifier in an overload state for an extended period of time. Check the loading and ventilation of the amplifier. This indicates excessive current draw by the amplifier. To replace the fuse, turn the amplifier Power Switch OFF and unplug the amplifier from the AC receptacle. Unscrew the fuse knob and replace the fuse with the same type, voltage and current rating as indicated on the amplifier and below: SI-125 amplifier uses a 3AG 250V 3.5A fuse. If the new fuse also blows, unplug the amplifier and contact Telecor Technical Support. SI-125 Power Amplifier Manual 7
Specifications Characteristics: Input Level Input Impedance Output Frequency Response Total Harmonic Distortion Output Regulation (with Transformer) Signal to Noise Ratio (Band Pass 20 to 20000 Hz) Connectors Controls Indicators Protection Temperature Range Power Consumption Weight Dimensions (without amplifier handles) Finish Optional Modules SI-125 Power Amplifier 1 V or 100 mv (switchable) 10 kω (balanced) 125 watts RMS into balanced 4 Ω, 8 Ω, 25 V or 70 V line 50 to 15000 Hz (± 2 db) 0.05% @ 1 khz rated output < 1 db, no load to full load Input Level switch in 0 dbv (1 V) position: > 94 db Screw-Barrier Terminals on input and output. Mas-Con connectors are used with optional modules Power Switch (Illuminated), GAIN Control, Low Cut Switch, Input Level Switch (1 V / 100 mv) Clip, High Temperature, VU Meter and Current Overload Foldback current limiting, Over-temperature protection, Primary circuit fused at 3.5 A -10 C to +35 C (14 F to 95 F) AC 120 V, 60 Hz, 270 W 11.8 kg (26 lbs.) 5 ¼" H x 19 W x 12 ⅛" D Black Powder Coating PA-AM Power Amplifier Attenuator Module PA-MM Power Amplifier Monitor Module PA-PM Power Amplifier Paging Module Specifications are subject to change without notice. SI-125 Power Amplifier Manual 8
LIMITED WARRANTY POLICY Telecor Inc. warrants all products bearing the Telecor name to be free from defects in material and workmanship under normal use and service for a period of one year from date of delivery. Telecor will repair or replace (at our option), free of charge, any unit that is found to be defective and returned to us under warranty. Telecor warrants all other products made by others, and distributed by us, to be covered by the manufacturers' warranty period. This warranty shall not apply to any Telecor products that have been subject to misuse, neglect, accident, modification, water, fire, lightning, paint, or used in violation of instructions furnished, repaired or altered outside of the factory. This warranty does not cover batteries, bulbs, fuses or damage caused by batteries used in connection with the product. Telecor reserves the right to make the final decision on whether there is a defect in materials or workmanship, and whether or not the product returned is within the warranty period. This warranty covers bench repairs only. Telecor will not be responsible for any costs incurred involving on-site service calls. Repair or replacement by others, fire, transportation, 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 return authorization has been obtained. U. S. customers are required to ship any returns or repairs to: Telecor Inc. 2434 Jerauld Avenue * U. S. customers must not Niagara Falls, New York return products to Canada USA, 14305 Canadian and all International customers are required to ship any returns or repairs to: Telecor Inc. 6205 Kestrel Road Mississauga, Ontario Canada, L5T 2A1 For details on Telecor s Return Policy, see our Published Merchandise Return Policy. E:\T2-108\T2-M108-ABC\T2-M108-B.doc/AD Copyright 2016 by Telecor Incorporated. All rights reserved. No part of this publication may be reproduced in any form, or by any means, without the prior written permission of Telecor Incorporated. Telecor Inc. makes no representation of warranties with respect to this manual. Furthermore, Telecor reserves the right to make changes in the specifications of the products described in this manual at any time without notice, and without obligation of Telecor to notify any persons of such revisions or changes. www.telecor.com SI-125 Power Amplifier Manual 9