MAELSTROM BASS DRIVE
26
TROUBLESHOOTING INFORMATION
What happens if you finish building the kit and find that it doesn’t work right? Here are a few common
problems people have with this pedal and how to solve them.
The LED doesn’t light up.
First, does the pedal sound right? If you aren’t getting any sound, you probably have a power issue with
the whole circuit that is not specific to the LED, so you’ll want to look elsewhere for the problem.
If it does pass a signal, it’s probably just the LED itself. Is the flat side facing to the right (looking in the
enclosure from the back)? If it’s reversed, it won’t work and you’ll have to re-solder it the right way.
All other issues
For any other problems, the next step is to measure the voltages on each pin of the ICs
and transistors using a digital multimeter. To start, touch the black lead to a ground point
for the circuit. The easiest spot is inside a tapped screw hole in one of the corners of the
enclosure. This way the probe stays in place without needing to use alligator clips. The
circuit must be fully installed in the enclosure for this to work.
Then, touch the red probe to the first leg of IC1 and read the voltage. Note that IC pins
are labeled counter-clockwise from the upper-left, as shown in the diagram to the right.
These baseline voltages are taken using a
9.6V
supply. Your measured voltages won’t be
exactly the same due to variance in power supplies and component tolerances. However,
if you see anything more than +/-0.5V from the listed voltages, it’s a good indicator of an
issue and the voltages can help narrow it down.
1
8
2
7
3
6
4
5
PIN
VOLTAGE
1
4.63
2
4.64
3
4.20
4
0
5
4.64
6
4.64
7
4.64
8
9.32
PIN
VOLTAGE
1
4.64
2
4.64
3
4.20
4
0
5
4.64 (falling)
6
4.64
7
4.64
8
9.31
PIN
VOLTAGE
1
8.57
2
3.26
3
3.26
5
0
7
0
8
0
9
0
11
0
14
0
PIN
VOLTAGE
1
4.63
2
4.64
3
4.57
4
0
5
4.61
6
4.64
7
4.64
8
9.32
IC1
IC2
IC3
IC4
1
5
16
12
2
6
15
11
3
7
14
10
4
8
13
9
Note: The pins not listed for IC3 do not have any electrical
connection to the rest of the circuit and do not need to be
tested.
PIN
VOLTAGE
D
9.32
S
4.95
G
4.42
PIN
VOLTAGE
D
4.95
S
0.28
G
0
Q2
Q1
