User manual CROWN POWER-TECH 2

[. . . ] POWER-TECH TM Models: Power-Tech 1, 2 & 3 ® Some models may be exported under the name Amcron. © 2000 by Crown International, Inc. , P. O. Power-Tech amplifiers are produced by the Professional Audio Unit of Crown International, ® Inc. Trademark Notice: Power-TechTM is a trademark and Amcron, ® Crown, IOC ® and ODEP ® are registered trademarks of Crown International, Inc. Other trademarks are the property of their respective owners. 125351-4 02/00 YEAR 3 THREE YEAR FULL WARRANTY 3 YEAR WORLDWIDE SUMMARY OF WARRANTY The Crown Audio Division of Crown International, Inc. , 1718 West Mishawaka Road, Elkhart, Indiana 46517-4095 U. S. A. [. . . ] By design, Power-Tech amplifiers have a controlled slew rate to limit the highest frequencies that they reproduce. Limiting occurs well above 20 kHz, so there is no audible affect on performance. This approach protects the amplifier from radio frequencies and can even protect some sensitive loads (including some tweeters). 3. 3. 3 Drive Protection The drive protection system temporarily removes output drive to protect the amplifier and its loads. First, if dangerous subsonic frequencies or direct current (DC) is detected in the amplifier's output, the unit will activate its DC/low-frequency protection circuitry which puts the amplifier in drive protection mode. The unit resumes normal operation as soon as the amplifier no longer detects dangerous output. Although it is extremely unlikely that you will ever activate the amplifier's DC/low-frequency protection system, improper source materials like subsonic square waves or input overloads that excessively clip the input signal can activate this system. 3. 2 Indicators When lit, the amber enable indicator shows that the amplifier has been turned on. It is driven only by the lowvoltage power supply and does not indicate the status of the high-voltage supplies. The signal/IOC indicators flash green in sync with the audio input signal, and flash yellow if the input waveform differs from the output by more than 0. 05%. IOC reports any distortion over 0. 05% introduced by the amplifier including harmonic distortion, intermodulation distortion and clipping distortion. Reference Manual Page 9 Power-Tech Series Power Amplifiers The amplifier's fault protection system will put the amplifier in drive protection mode in rare situations where heavy common-mode current is detected in the output. The unit should never output heavy commonmode current unless its circuitry is damaged. 3. 3. 4 Transformer Thermal Protection All Power-Tech amplifiers have transformer thermal protection. This protection circuitry is activated in unusual situations where the unit's transformer temperature rises to unsafe levels. Under these abnormal conditions, the unit removes power to the highvoltage transformer. The fan will continue to run in all units except those with 220/240 VAC transformers. The amplifier will return to normal after it cools to a safe temperature. It is very unlikely that your Power-Tech amplifier will ever activate transformer thermal protection as long as it is operated within rated conditions. Your amplifier is designed to keep working under conditions where other amplifiers would fail. But even when you exceed the limits of a Power-Tech amplifier, it still protects itself-- and your investment--from damage. 3. 3. 5 Fuses and Circuit Breakers Your amplifier's low-voltage power supply is protected by an internal fuse, and its high-voltage power supplies are protected by a circuit breaker. The circuit breaker is built into the power switch for all Power-Tech 1, Power-Tech 2 and 220/240 VAC Power-Tech 3 amplifiers. The circuit breaker is located on the back panel of 100/120 VAC Power-Tech 3 amplifiers. [. . . ] 5. 2 MT-BB Reference Manual Page 17 Power-Tech Series Power Amplifiers 6 Service This unit has very sophisticated circuitry which should only be serviced by a fully trained technician. This is one reason why each unit bears the following label: CAUTION: To prevent electric shock, do not remove covers. When sending a Crown product to the factory for service, be sure to fill out the service information form that follows and enclose it inside your unit's shipping pack. Do not send the service information form separately. 6. 1 Worldwide Service Service may be obtained from an authorized service center. [. . . ]