Roland Boss GT-10, Service Notes

22

Mar. 2008

GT-10

14. RETURN

Testing of the RETURN Circuitry and the RETURN 
Jack Switch

fig.14return2.eps

1.

Using the two cables with 1/4-inch phone plugs, connect the 

OUTPUT L

and 

R

 jacks to channel 1 and channel 2 of the oscilloscope and to the left-

channel and right-channel monitor speakers.

2.

Verify that the output waveform display on the oscilloscope is what is 
shown in the figure below.

fig.14return.eps

Upper: left channel, lower: right channel

3.

Verify that the peak value is from 

0.75

 to 

0.90 V for the left channel and 

from 0.60

 to 

0.70 V

 for the right channel.

4.

Verify that signals are output from the monitor speakers and no noise or 
other abnormal sound is heard.

5.

Insert a dummy jack (open plug) into the 

RETURN

 jack and verify that 

the sound and waveform disappear.

6.

Press [

] to advance to the next test.

15. INPUT NOISE

Testing of Residual Noise and Shock at the 
Respective Outputs

fig.15inputnoise2.eps

1.

Insert a 47-k ohm plug into the INPUT jack.

2.

Connect the left channel of the 

PHONES

 jack and the noise meter using a 

cable with a 1/4-inch stereo phone plug (with 33-ohm load resistor), and 
verify that the noise level is 

-96 dBu

 or less (

DIN audio

).

3.

Connect the right channel of the 

PHONES

 jack and the noise meter using 

a cable with a 1/4-inch stereo phone plug (with 33-ohm load resistor), 
and verify that the noise level is 

-96 dBu

 or less (

DIN audio

).

4.

Connect the 

OUTPUT L

 jack and the noise meter using a cable with a 1/4-

inch stereo phone plug, and verify that the noise level is 

-89 dBu

 or less 

(

DIN audio

).

5.

Connect the 

OUTPUT R

 jack and the noise meter using a cable with a 1/

4-inch stereo phone plug, and verify that the noise level is 

-89 dBu

 or less 

(

DIN audio

).

6.

Using the two cables with 1/4-inch phone plugs, connect the 

OUTPUT L

and 

R

 jacks to the left- and right-channel monitor speakers.

7.

Press the [WRITE] button and verify that the 

Check INPUT Noise

message displayed changes to 

Check SHOCK Noise

.

8.

Verify that the noise sound played by the monitor speakers is free of any 
problem.

9.

Subject the unit to vibration and verify that no abnormal sound is heard 
from the speaker.

10.

Press [

] to advance to the next test.

16. LOOP NOISE

Testing of the SEND/RETURN Connection and 
RETURN Shock

fig.16loopnoise2.eps

1.

Insert a 47-k ohm plug into the 

INPUT

 jack.

2.

Make sure that nothing is inserted into the 

RETURN

 jack.

3.

Connect the 

OUTPUT L

 jack and the noise meter using a cable with a 1/4-

inch phone plug, and verify that the noise level is 

-88 dBu

 or less (

DIN 

audio

).

4.

Connect the 

OUTPUT R

 jack and the noise meter using a cable with a 1/

4-inch phone plug, and verify that the noise level is 

-88 dBu

 or less (

DIN 

audio

).

5.

Using the two cables with 1/4-inch phone plugs, connect the 

OUTPUT L

and 

R

 jacks to the left- and right-channel monitor speakers.

6.

Press the [WRITE] button and verify that the 

Check LOOP Noise

message displayed changes to 

Check SHOCK Noise

.

7.

Verify that the noise sound played by the monitor speakers is free of any 
problem.

8.

Subject the unit to vibration and verify that no abnormal sound is heard 
from the speakers.

9.

Press [

] to advance to the next test.

17. FACT RESET

Factory Reset

* Unless instructed otherwise, do not execute a Test Mode Factory Reset. Pressing 

[EXIT] performs no Factory Reset.

Executing the Factory Reset in the Test Mode (

17. FACT RESET

) initializes the 

threshold value for pedal calibration (to a value of 

6

). When you have executed 

17. FACT RESET

, go to 

7. INT EXP PEDAL

 and make the setting for pedal 

calibration.

Short Check

Testing of AMP CTRL Insulation

1.

Switch off the power.

2.

Touch the tester to the ground for the 

AMP CTRL

 jack and to the chassis 

ground (a screw section on the chassis) and verify that no conduction 
occurs.