User manual MARTIN AUDIO SCREEN5B SCHEMATICS

[. . . ] Always operate the amplifier with the chassis ground wire connected to the electrical safety earth. Do not parallel or series connect an amplifier output with any other amplifier output. Do not connect the amplifier output to any other voltage source, such as battery, mains source or power supply, regardless of whether the amplifier is turned on or off. Do not run the output of any amplifier back into another channel's input. [. . . ] Do not use shielded wire, such as microphone or guitar cable. Remember that the speaker cable robs the power of the amplifiers in two ways: It increases the load impedance and introduces resistive power losses. 5. 8 Impedance matching (MLS switch) The MLS switch is located on the rear panel with an LED showing the switch depressed and in the 2 ohms position. The MLS ( Minimum load select ) switch offers an impedance matching, so you can drive the SCREEN5B in 2 ohms without increased heat losses. Table 2 shows the possible combinations: SCREEN5B MLS switch Speaker Impedance 8 ohms Stereo 4 ohms Stereo 2 ohms Stereo 8 ohms Bridged mono 4 ohms Bridged mono MLS Position 4 ohms 2 ohms 430W 220W 840W 430W 1540W* 870W 1680W 870W 3000W* 1740W Power rating at 1kHz and 1% THD * Not recomended selection, thermal protection may occur at high continous power. Table 2. The way to find the best MLSTM position for your application is by experimentation. The amplifier is very well protected (even down to 0. 3 ohms), but where speed is of the essence, stick to the fixed positions. 11 Martin Audio ­ SCREEN5B Power Amplifier CONTENTS < 6 > ENGLISH PRINT GUIDES OPERATION MODES 6. 1 Stereo operation For stereo (dual channel) operation, leave the Link and Phase reverse switches in the un-depressed position. In this mode, both channels operate independently of each other, with their level attenuators controlling their respective levels. Never connect either output terminal to ground or in parallel. The recommended minimum nominal impedance for stereo or tandem operation, is 2 ohms per channel. 6. 2 Tandem mono For tandem (dual channel-single input) operation, depress the Link switch. This is significant for signals below 100Hz (sub bass etc. ). 13 Martin Audio ­ SCREEN5B Power Amplifier CONTENTS < 7 > ENGLISH PRINT GUIDES OPERATION 7. 1 Operation precautions · Make sure that the power switch is off before making any input or output connections or operating the switches on rear panel. · Make sure that the AC mains is correct and the same as that printed on the rear panel of the amplifier. See pages 6-8 about operating voltage and power consumption. · Make sure that the switches on the rear panel for operation modes, clip limiters and the MLSTM switches are in the correct position. See pages 12-13 about operation modes, page 15 about clip limiters and page 11 for the MLS switches. · It is always a good idea to turn down the gain controls during power up as this prevents speaker damage, especially if there is a high level signal at the input. 7. 2 Powering up - Soft start When you power up the amplifier it takes a couple of seconds to self check. This is known as the "soft start" or "slow start" sequence. The fans then blow at high speed before going into "idle" and the two bottom green LED's illuminate to show the amplifier is operational. 7. 3 Input attenuators The two input level attenuators on the front panel adjust the signal level for their respective amplifier channel in all modes. They are calibrated in dB to assist setting up active loudspeaker systems. [. . . ] If you are using your amplifier for heavy-duty use i. e. concert touring or industrial music, it is recommended that you have your amplifier serviced every 3 years, purely as a preventative measure. Troubleshooting These are typical things to check if you think your amplifier is faulty: Fault: No output. If the -40dB LED is functioning there is nothing wrong with the amplifier and the likely cause is an unsecured Speakon. [. . . ]