Audio Failsafe Model AFS-1 – Instruction Book – This documentation is valid for Audio Failsafe hardware version 2.
Table of Contents Section 1 — Warranty/Product Registration Paragraph Title 1.1 1.2 1.3 Warranty Suitability For Use Product Registration Page Number 1.1 1.1 1.1 Section 2 — Safety Information Paragraph Title 2.1 Safety Information Page Number 2.1 Section 3 — Specifications Paragraph Title 3.1 3.2 3.3 General Audio Input Relay Output Page Number 3.1 3.1 3.1 Section 4 — Equipment Description Paragraph Title 4.1 4.2 Functional Description Physical Description Page Number 4.1 4.
Section 6 — Circuit Description Paragraph Title 6.1 6.2 Audio Section Power Supply Page Number 6.1 6.1 Section 7 — Illustrations and Diagrams Paragraph Title Page Number 7.1 7.2 7.3 List of Illustrations and Diagrams AFS-1 Schematic Diagram AFS-1 Component Locations 7.1 7.2 7.3 Section 8 — Parts List Paragraph Title 8.1 AFS-1 Audio Failsafe Parts List Version 2.00 Page Number Table of Contents 8.
Section 1 — Warranty/Product Registration 1.1 Warranty Sine Systems, Inc. agrees to repair or replace the AFS-1 Audio Failsafe at no cost, if the unit fails in normal use, during the first year of original ownership. This Warranty does not include damage caused by improper installation or use nor does it include damage caused by any other external means. 1.
Section 2 — Safety Information 2.1 The AFS-1 Audio Failsafe should be installed only by qualified technical personnel. Incorrect or inappropriate installation could result in a hazardous condition. Service of the AFS-1 Audio Failsafe should be performed only by qualified technical personnel. Even though the AFS-1 is powered by 12 volts AC from a "wall plug" transformer, failure of this transformer could cause dangerous and potentially lethal voltages to become present.
Section 3 — Specifications 3.1 General Output Relay Operation Output relay contact closes within one second after audio becomes present and remains closed as long as audio is present. Output relay contact opens at the end of an adjustable delay period after audio becomes absent. Delay Range 7 seconds to approximately 4.5 minutes. (factory adjusted to approximately 4.5 minutes) Indicators 1. Audio Present (Green LED) 2. Relay Closed (Green LED) 3.
Section 4 — Equipment Description 4.1 Functional Description The AFS-1 is designed to monitor one or two audio signals and provide a relay contact closure as long as at least one of the audio signals is present. When neither audio signal is present for an adjustable delay period (7 seconds to 4.5 minutes), the relay contact opens and remains open until one or both of the audio signals return.
Section 5 — Installation Installation of the AFS-1 Audio Failsafe should be performed only by a qualified technician. Installation is not difficult; however, an attempted installation by a person who is not technically qualified could result in danger to operating or maintenance personnel, or damage to the unit. 5.1 Unpacking When the AFS-1 is unpacked, it should be inspected for obvious signs of mechanical damage or loose parts. Loose parts should be tightened before installation.
Although the relay contacts are rated at 120 volts AC, it is not recommended that 120 volts AC be connected to the AFS-1. The screwterminal connectors have several exposed points that could produce a dangerous or even lethal shock if they were contacted. Low voltage AC or DC is much safer and eliminates the potential for a shock hazard. The "G" terminal next to the "RELAY" terminals is a connection to the internal circuit ground but it is not connected to the case. 5.
5.9 Modifying Operating Parameters The AFS-1 operating parameters can easily be modified to suit special applications. The period of time required after the loss of audio before the relay contact opens is set at the factory to approximately 4.5 minutes. This can be adjusted with the 22 turn potentiometer located on the AFS-1 main board. The adjustment range is approximately 7 seconds to 4.5 minutes. Version 2.00 Installation page 5.
Section 6 — Circuit Description 6.1 Audio Section The first two sections of U1 are balanced audio input stages of the "A" and "B" audio inputs. Overall, these have a gain of 0.33 (loss). The next stage combines the two channels and has a gain of 10. Capacitors C1 through C12 provide high frequency roll-off and RFI immunity. A rectifier, short term integrator (about 1 second), and comparator follow. When audio is present, the "AUDIO" LED is turned on by this comparator.
