last update: 2007-12-27
This Page helps if you have troubles with your
2101 or expect a failure in the hardware...
If you have questions send me an Email.
- Reset GSP 2101:
a. Power the 2101 OFF.
b. Press and hold Function Key 1.
c. Power the 2101 ON.
d. After the Asterisk (*) appears in the upper
right corner, release Function Key 1.
e. Press Program UP key.
- Turn on power at Power- Switch and
quickly check power supplies.
+5VDC U93 Pin "o"
+12VDC U91 Pin "o"
-12VDC U92 Pin "o"
+5VDC U17 Pin "o"
+5VDC U14 Pin "o"
-5VDC U13 Pin "o"
approx. +42VDC* J4 Pin 3
+240 VDC +/- 10%* B+ on R253 Pin in direction to
+11VDC* on + side of C249
*use DMM to measure these voltages
- Check 10 (20) MHz and 24.576 MHz
- Select Program 1.
- Switch all Effects off.
- Select Compression.
- Turn on Compression.
- Select Compression Level 0.
- With no input signal, adjust P2
until pin 1 of U9 measures 0VDC +/- 30mV.
- Select Distortion.
- Turn on Distortion.
- Select Distortion "Heavy
- Select Gain then use the data
wheel to set at 0.6
- Adjust P3 until pin 1 of U62
measure 0mVDC +/-2mV
- Trim Digital/Analogue Converter For Lowest Noise
- Set unit to Mono- Mode (Utility-
- Connect Probe to Mono- Output.
- Make sure Compression and
Distortion are off. Set Master Volume to 0 dB.
- Turn Output Level up full and
adjust P1 for least noise.
- Turn Output Level back down.
- Set unit back to Stereo- Mode
- EQ Test
- Input a sweep signal @ 1Vpp.
- Select EQ ("Local EQ" at
- Put Probe on TP3 (EQ- Board) and
verify the cut and boost of each band.
(use the data wheel to cut and boost each band)
- Leave each band at 0dB (Flat).
Note: The last band 5.12 kHz will effect from 5.12
kHz on up.
- Press Utility Button and select #1
"Global EQ" and repeat steps 3 and 4.
- Put probe on one of the outputs of
J14 and check the Cabinet Simulator (SW34).
- Repeat step 6 for the other sides
- Verify the Cabinet Simulator (low
pass filter) to both sides of the headphone outs.
- Select Compression and turn on.
- With probe on TP3, verify ratio (select
Ratio then turn data wheel from 1.5:1 to INF:1).
- Verify Threshold (select Threshold
then turn data wheel from -30dB to -45dB).
- Verify Compression Output Level (select
Output Level then turn data wheel from -6 to 6).
- If compression do not sound right,
refer the charts at the end of these procedures
Click here to go to
the additional compressor check.
- Clean Tube
- Turn compressor off. Select
Distortion. Select "Clean Tube".
Adjust signal generator output until a 4Vpp
signal is measured at U36 pin 1. select gain
- Set gain 1 = 11.0. Adjust R188 (10k
trim pot) for a 15Vpp signal at U6 pin 1.
- Adjust gain 1 = 3.0. The signal at
U6 pin 1 should now be between 0.8 Vpp and 2 Vpp.
- Connect a guitar into either input
(J5 or J6).
- Select Distortion and turn on.
- Select distortion type, then turn
data wheel to "Saturated Tube".
- Check again: Turn data wheel while
listening to Gain 2. Verify the increase from 0.6
- Repeat same steps for Gain 1.
Leave at 11.00
- Check Distortion types and use the
data wheel to change through the distortions.
Verify the Type.
- If distortion or compression do
not sound right, refer the charts at the end of
Click here to go to
the additional distortion check.
- FX Loop
- Select Parameter "External FX
- Select "loop No Sum".
- Plug an open dummy plug into J9.
This should terminate one side of the signal (J12).
- Plug a ¼" cable into J8.
This should terminate the other side (J11).
- Connect the other end of the ¼"
cable into J10 and the signal should return to J11.
- Verify FX loop settings.
- Bypass: signal to both
Summed: signal increase.
No Sum: signal to one side
- MIDI Test
- Connect a PDS3500 or PMC10 MIDI
pedal set to Channel 1 to the MIDI in jack (J1)
of the 2101.
- Connect a MIDI addressable device
to the MIDI through jack (J3).
- Verify that program changes are
received on the 2101 when sent from these pedals,
and that the other device receives them as well.
- Connect the MIDI addressable
device to the MIDI out (J2) of the 2101.
- Select MIDI. Select "Front
Panel Program Change" (SW27 4 times) and
change to "yes".
Press "Next" to the Device screen and
press #1 (SW30). Using the data wheel, change
from "Disabled" to "CH1".
Press MIDI. Changing programs from the front
panel of the
2101 should now send program changes to the
- Sound Test
- Using the data wheel, scroll
through the programs and listen to them for any
- Using the Effects Library
switches, turn each effect on and off to verify
- Connect the XLR outputs and verify
both outputs (+ and -) of each jack. Also press
SW34 and listen for any pops or noise and it is
engaged or disengaged.
Information for Distortion Check
- Gain 2: Adjust the distortion type
to "Distored Tube".
Set Gain 1 = 2.0 and Gain 2 = 11.0. Adjust the
input signal until signal measured at R217
(the side away from V2) is 6Vpp. The signal at
the other side of R217 should be between
1.7Vpp and 2Vpp. Set gain 2 = 0.6. The signal at
R217 should now be between 100mVpp
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