BASS
2
1
FOOTSWITCH
3
M E
G
5 0K
SPEED
INTENSITY
1
7
6
5
4
3
2
8 9
1
7
6
5
4
3
2
8 9
V1
V2
1
7
6
5
4
3
2
8 9
1
7
6
5
4
3
2
8 9
V3
V4
1
0
0
K
.022
µF
630V
Step 6:
Remove unnecessary circuit board
components.
1) Remove the cathode bias components connected to
V1 pin 3.
2) Remove the bass channel tone-stack components.
3) Remove the plate resistor and capacitor connected
to V1 pin 1.
4) Remove the plate resistors connected to V1 pin 6
and their connection to the 400V power supply wire.
5) Remove the cathode bias components connected to
V1 pin 8.
6) Remove the 220K feedback resistor connected to
V2 pin 6.
7) Remove the wire connecting V3 pin 6 to 470K
resistor.
(1)
(1)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(3)
(4)
(4)
(4)
(5)
(5)
(6)
BASS
2
1
FOOTSWITCH
3
M E
G
5 0K
SPEED
INTENSITY
1
7
6
5
4
3
2
8 9
1
7
6
5
4
3
2
8 9
V1
V2
1
7
6
5
4
3
2
8 9
1
7
6
5
4
3
2
8 9
V3
V4
1
0
0
K
.022
µF
630V
Step 7:
Add new circuit board
components.
1) Connect new cathode bias components (22µF
cap and 2.7K resistor) to V1 pin 3.
2) Connect new cathode bias components (22µF
cap and 100K resistor) to V1 pin 8.
3) Connect a new plate resistor (220K) to V1 pin 1.
4) Connect a new plate resistor (8.2M) to V1 pin 6.
5) Add the two .01µF feedback capacitors as
shown.
2
.7
K
2
2
µ
F
5
0
V
+
2
2
µ
F
5
0
V
100K
+
2
2
0
K
8
.2
M
.0
1
µ
F
6
3
0
V
.0
1
µ
F
6
3
0
V
(7)
400V Power
Supply Line
4
7
0
K
Positive
2
2
µ
F
5
0
V
Negative
Connect these
polarized capacitors
with the positive
lead connected to
the tube as shown.
Each instruction line number here corresponds to the
numbers on the drawing where missing components are
outlined.
21