Roland AC-90 Service Notes page 16

Jul. 2007
12. [Foot SW 2] jack switch
• Detaching the plug from [Foot SW 1] on the AC-90 makes the [ANTI-
FEEDBACK] and [MUTE] LEDs go dark.
• Inserting a plug into [Foot SW 2] on the AC-90 makes the following LEDs
light up.
GUITAR channel [CHORUS] LED
MIC/LINE channel [CHORUS] LED
[ANTI-FEEDBACK] LED
[MUTE] LED
13. [Foot SW 2] [TIP] switch
Depressing the [TIP] (white) foot switch makes the [ANTI-FEEDBACK]
LED go dark.
14. [Foot SW 2] [RING] switch
Depressing the [RING] (red) foot switch makes the [MUTE] LED go dark.
15. [PHONES] jack switch
• Detaching the plug from [Foot SW 2] on the AC-90 makes the GUITAR
channel and MIC/LINE channel [CHORUS] LEDs go dark.
• Inserting headphones into [PHONES] makes the following LEDs light
up.
GUITAR channel [CHORUS] LED
MIC/LINE channel [CHORUS] LED
[ANTI-FEEDBACK] LED
[MUTE] LED
• Detaching the headphones plug inserted into [PHONES] makes the
following LEDs go dark.
GUITAR channel [CHORUS] LED
MIC/LINE channel [CHORUS] LED
[ANTI-FEEDBACK] LED
[MUTE] LED
* If an error is made in the inspection-test sequence, or of a test is failed, execution
cannot advance to the next test.
• When all switch testing are completed, the following LEDs flash.
GUITAR channel [CHORUS] LED
MIC/LINE channel [CHORUS] LED
[ANTI-FEEDBACK] LED
[MUTE] LED
• Insert a PCS-31 plug into [Foot SW 1] on the AC-90 and depress the [TIP]
(white) foot switch to make execution advance to the next inspection test.
4. Volume Control Test
When the volume-control test is begun, the following LEDs go dark.
GUITAR channel [CHORUS] LED
MIC/LINE channel [CHORUS] LED
[ANTI-FEEDBACK] LED
[MUTE] LED
• Operating the volume knob makes self-oscillation by the DSP start, and
audio is output from the speakers.
• Until the inspection test for a single volume control ends, the volume
level changes according to the position of the control knob.
• In testing the volume controls, verify the change from minimum to center
and from center to maximum, and be sure to go on to testing of the next
volume knob while leaving the first one at maximum.
16
• Perform testing of the volume controls in this sequence: [MASTER] =>
[CHORUS] => GUITAR channel [TREBLE] => GUITAR channel
[MIDDLE] => GUITAR channel [BASS] => GUITAR channel [VOLUME]
=> MIC/LINE channel [VOLUME] => MIC/LINE channel [BASS] =>
MIC/LINE channel [MIDDLE] => MIC/LINE channel [TREBLE] =>
[REVERB/DELAY] => [FREQUENCY].
fig.VR-test.eps
• When the "minimum" setting of the volume control is detected, the
[ANTI-FEEDBACK] and [MUTE] LEDs go dark.
• When the "center" setting of the volume control is detected, the [ANTI-
FEEDBACK] LED lights up.
• When the "maximum" setting of the volume control is detected, the
[ANTI-FEEDBACK] and [MUTE] LEDs light up.
* If a failed test occurs before inspection of the volume controls finishes, execution
cannot advance to testing of the next volume control.
• When the tests for all volume controls have been passed, the following
LEDs flash.
GUITAR channel [CHORUS] LED
MIC/LINE channel [CHORUS] LED
[ANTI-FEEDBACK] LED
[MUTE] LED
• Switch off the power.
5. Phantom Voltage Test
• Switch on the power.
• Adjust the [MASTER] volume knob to minimum.
• The settings of the other switches and volume controls are unspecified
(not relevant).
• Using the tester, check the DC voltage between each MIC/LINE channel
[INPUT] XLR terminal.
• Set the measurement range on the tester to 50 V or higher.
• Bring [COM] (black) on the tester into contact with the [1: GND]
terminal.
1. [PHANTOM] OFF Voltage
• Set the [PHANTOM] switch to OFF.
• Bring the tester's [+] probe (red) into contact with the [2: HOT] connector
and verify that the voltage is near 0 V.
• Bring the tester's [+] probe (red) into contact with the [3: COLD]
connector and verify that the voltage is near 0 V.
2. [PHANTOM] ON Voltage
• Set the [PHANTOM] switch to ON.
• Bring the tester's [+] probe (red) into contact with the [2: HOT] connector
and verify that a voltage of 44 to 49 V is output.
• Bring the tester's [+] probe (red) into contact with the [3: COLD]
connector and verify that a voltage of 44 to 49 V is output.
AC-90