Bose 1401 I Series User Manual

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TECHNICAL INFORMATION
Trouble Shooting Guide
Symptom Check
Draws current:
Check D55, series II; Check D2, series I
No left or right output: Check electrolytic caps at the input to U51 or at the output
of U52 for series I and U53 for series II. Replace all caps
with a silver colored can.
Spatial not working:
Check C88, C87 series II, C65, C85 series I
Drivers running hot: Check the bias diodes D11, 12, 21, 22, 31, 32, 41 and 42.
No output one channel only or unit
cycles on and off:
1: Check output and drivers; Replace both outputs, both
drivers and both bias diodes, if one is found defective.
Check the 27Ω resistors connected to bias diodes.
2: Check Q54 and Q55 for series II.
Unit will not turn on: 1: Outputs should not be grounded. Isolate test
equipment from ground.
2: Check Q62, Q63, U52 for series II. Check Q51, Q54,
U50 for series I.
3: Check D51, R120, Q53. Make sure the remote turn on
violet wire is connected to power, series II.
No output or cycles on and off after
installing new outputs and drivers:
Check for cracked screw insulators and make sure that the
insulator between transistors and heat sink is good.
No low frequencies: Check U53

Bose 1401 I Series Specifications

General

Brand	Bose
Model	1401 I Series
Category	Car Stereo System
Language	English