Страница 1: ...405 POWER AMPLIFIER Service Data The Acoustical Manufacturing Co Ltd Huntingdon Cambridgeshire PE29 6XU England Tel 44 0 1480 447700 Fax 44 0 1480 431767 www quad hifi co uk...
Страница 2: ...5 6 14 Circuit Diagram M12333 iss 3 Amplifier PCB M12368 iss 7 15 Circuit Diagram M12333 iss 4 Amplifier PCB M12368 iss 9 16 Circuit Diagram M12333 iss 5 Amplifier PCB M12368 iss 9 10 17 Amplifier Bo...
Страница 3: ...the loudspeakers at all times calling upon the high power section to provide most of the muscle The small amplifier is so arranged it carries an error signal that provided the larger power transistor...
Страница 4: ...405 fitted with a clamp circuit it may be necessary to bypass this circuit For 405s fitted with amplifier boards M12368 this may be done by removing t push on connectors carrying brown wires from ampl...
Страница 5: ...ct 20Hz and output level should fall by approximately 1 Select 10 and output level should fall by 7dB 1 5dB Increase frequency to 1 For 405s with amplifier boards type M12368 insert 1 8k voltage limit...
Страница 6: ...utput for 0 3V input R20 or R21 o c Waveform trace as in Fig 3 Tr8 o c Tr6 s c R36 o c R30 o c C10 s c Waveform trace as in Fig 4 L2 o c solder joints Approximately 4W output R16 o c 4 Second Harmonic...
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Страница 8: ...ged from 1k to 1k8 R27 changed from 8k2 to 15k R29 changed from 8k2 to 15k R35 changed from 0 08 to 0 091 R36 changed from 0 08 to 0 091 D1 changed from LR120C to LR150C op amp voltage increased from...
Страница 9: ...e clamp board over the output connectors and re solder It is advisable to tin the output connector tags before positioning clamp board This makes soldering easier Replace the capacitor and reconnect t...
Страница 10: ...6 Fit the new printed circuit clamp board to the output sockets and reconnect the output leads Brown Red to pin marked R Brown White to the pin marked L and both Green leads to the pin next to L 7 Re...
Страница 11: ...bottom plate 4 M4 screws 2 Note the connections then unsolder the external wiring to the a c supply transformer 3 Remove two retaining screws through t e large centre holes of each T section heat sink...
Страница 12: ...405 models after serial number 59001 output stage clamp cicuit is incorporated in main module boards and a shorting link used for the voltage limiter first 405 2 cicuit diagram was 12333 iss 7and the...
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