QSC ISA 280 Technical & Service Manual Download

Page: 9 / 142

Technical Service Manual

ISA Series Power Amplifiers

1. Introduction

1.2 Service bulletins

Contact QSC Technical Services to make sure you have the most up-to-date service bulletins for ISA Series amplifiers. Service bulletins
may be distributed in hard copy, via fax, and electronically (Adobe Acrobat PDF) via CD-ROMs, FTP from the QSC web site
(www.qscaudio.com), and e-mail.

One service bulletin has been issued for the ISA Series at the time this manual was printed:

ISA0001

, “ISA Turn-on Hangup” (ISA450,

ISA500T, ISA750 and ISA800T)

1.1 Restriction of Hazardous Substances Directive (RoHS)

Beginning in June 2006 (serial number date code 0606xxxxx), all ISA Series amplifiers are manufactured to conform to the European
Union’s RoHS Directive, which reduces the amount of hazardous substances allowed in products for sale within its member nations. In
electronic equipment such as audio power amplifiers, this applies primarily to certain toxic heavy metals, such as lead, which may be
present in electronic components, solder, and other parts.

RoHS-compliant materials

When servicing RoHS-compliant amplifiers, it is important for the service technician to use only RoHS-compliant components and solder
(lead-free). All replacement parts provided by QSC for RoHS-compliant products are certified as RoHS compliant.

RoHS-compliant tools

Soldering irons and desoldering apparatus used on RoHS-compliant products must also not be contaminated by hazardous substances,
such as lead. Therefore, you cannot use the same soldering and desoldering tools for RoHS-compliant products and solder as you do for
non-compliant products and solder. You must either use separate soldering irons, desoldering tools and braid, etc., or at the very least
designate separate tips and braids and use only the appropriate ones. If you contaminate a tip or braid, even inadvertently, by using it on
a non-compliant product or solder, you can no longer use it with RoHS-compliant products or solder.

1.3 The well-equipped service bench

To properly service ISA amplifiers, a technician needs the right tools. The technician’s service bench should have the following equipment:
• Digital multimeter with RMS AC voltage and current
• Digital clamp-on ammeter
• Dual-trace oscilloscope
• Audio distortion analyzer
• Non-inductive load resistors, configurable as 8 ohms (min. 500 watts capacity), as 4 ohms (min. 750 watts capacity), and 2 ohms (min.

1200 watts capacity)

• Variable AC voltage source, such as a Variac or Powerstat variable transformer, with a rated current capacity of up to 25A (for 120V

models) or 12A (for 230V models)

• Low-distortion audio sine wave generator
• Philips and flat screwdrivers
• Soldering iron with a fine tip (25–60W recommended)
• Rosin-core solder (RoHS-compliant solder, or 60/40 or 63/37 for non-RoHS product only)
• Long-nose pliers
• Diagonal cutters
• Wire strippers
Automated test equipment, such as an Audio Precision workstation, is very useful for servicing ISA amplifiers. Contact QSC Technical
Services to obtain applicable AP test files.