Zeppelin Design Labs QUAK, Troubleshooting Manual

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C.  Is the relay properly switching the signal path? 

I.  With the bypass LED OFF, check for continuity between the tip of the input jack and the 

tip of the output jack. 

• 

Check for good solder joints on the input and output jacks.

• 

Check for good solder connections on all the relay associated components...D1, D2, 
Q4, Q5, R31, R32, and RL1. Also make sure D1, D2, Q4, and Q5 are installed in the 
correct orientation.

II.  With the bypass LED ON, check for continuity between the tip of the input jack and R1, 

and also continuity between the center lug of the VOLUME pot to the tip of the output jack. 
If you don’t have continuity between either of these connections, there is a problem with 
the relay circuit.

• 

Are you able to hear the relay “click” when the bypass foot switch is pressed? If not, check 
for good solder joints and correct orientation on the relay associated components... D1, 
D2, Q4, Q5, R31, R32, and RL1.

• 

Make sure the microcontroller is seated firmly in it’s socket.

D.  Is the relay silencing circuit working correctly? 

I.  Check for 5V on R28 (see PCB voltage graphic)

II.  Are the components of this circuit soldered and installed correctly?  Check R27, R28, R29, 

Q3, C18, C17, R33. Make sure that Q3 and C18 are not reversed, and the pads of C17 
and C18 are not bridged.