Crown Micro-Tech MT-1000 Informations techniques télécharger pdf (Page 19)

Page 19

Micro-Tech 600/1200/2400 Power Amplifiers

4 Operation

4.1 Precautions

Although your amplifier is protected from internal and

external faults, you should still take the following pre-

cautions for optimum perfromance and safety:

1. Improper wiring for the Stereo, Bridge-Mono and

Parallel-Mono modes can result in serious operat-

ing difficulties (see Section 3.3).

2. WARNING: Do not change the position of the

stereo/mono switch unless the amplifier is first

turned off.

3. CAUTION: In Parallel-Mono mode, a jumper is

used between the red (+) channel 1 and 2 red

output binding posts. Remove this jumper for

Bridge-Mono and Stereo modes, or high distor-

tion and excessive heating will occur. Also,

check the stereo/mono switch for proper setting.

4. Turn off the amplifier and unplug it from the AC

mains before removing the back panel cover plate

or before removing and cleaning the dust filter.

5. Use care when making connections, selecting sig-

nal sources and controlling the output level. The

load you save may be your own!

6. Do not short the ground lead of an output cable to

the input signal ground. This will form a ground loop

and may cause oscillations.

7. Operate the amplifier from AC mains of not more

than 10% above or below the selected line voltage

and only at the specified line frequency.

8. Never connect the output to a power supply out-

put, battery or power main. Such connections

may result in electrical shock.

9. Tampering with the circuitry by unqualified person-

nel or making unauthorized circuit changes may be

hazardous and invalidates all agency listings.

Remember: Crown is not liable for damage that results

from overdriving other system components.

4.2 Indicators

The amber enable indicator is provided to show that

the amplifier has been turned on (or enabled), and its

low-voltage power supply and forced-air cooling sys-

tem are working. It does not indicate the status of the

high-voltage power supplies. For example, the enable

indicator will remain lit during unusual conditions that

would cause the amplifier’s protection systems to tem-

porarily remove power from a high-voltage power sup-

ply (see Section 4.3).

The amber

ODEP

indicators confirm the normal op-

eration of Crown’s patented Output Device Emulation

Protection circuitry. During normal operation, they glow

brightly to show the presence of reserve thermody-

namic energy. They dim proportionally as the energy

reserve decreases. In the rare event that there is no

reserve, the indicators turn off and

ODEP

proportion-

ally limits the drive level of the output stages so the

amplifier can continue safe operation even when con-

ditions are severe. (For a more detailed description of

ODEP

, see Section 4.3.1.)

The

ODEP

indicators also turn off if the amplifier loses

AC power, the power switch is turned off, or the low-

voltage power supply fuse blows. The

ODEP

indicator

for the affected channel will turn off if a high-voltage

power supply fuse or breaker blows, or if the channel

activates transformer thermal protection. Conditions

that activate “drive protection” do not affect the

ODEP

indicators (see Section 4.3.3).

4.3 Protection Systems

Micro-Tech

amplifiers have extensive protection sys-

tems including

ODEP

, ultrasonic/RF protection, drive

protection, and power supply fuses or breakers.

4.3.1

ODEP

Crown invented

ODEP

to solve two long-standing prob-

lems in amplifier design: to prevent amplifier shutdown

during demanding operation, and to increase the effi-

ciency of the output circuitry.

To do this, Crown established a rigorous program to

measure the

safe operating area

(SOA) of each output

transistor before installing it in an amplifier. Next, Crown

designed intelligent circuitry to simulate the instanta-

neous operating conditions of those output transistors.

Its name describes what it does: Output Device Emu-

lation Protection or

ODEP

. In addition to simulating out-

put transistor operating conditions, it compares their

operation to their known SOA. If

ODEP

sees that more

ODEP

CH1 CH2

POWER

OFF

Fig. 4.1 Indicators

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 38 39

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