Doepfer

Hi everyone!

I have got an A-155 sequencer where one of the pots on the bottom row does not work. At all. 

In order to try to pin down the error I have swapped the ICs from the top row to the bottom row (http://www.doepfer.de/A100_pictures/doepfer_a155.jpg, the two PCBs with the knobs), but the problem was still there. Is there anything else I can do? I have also tried to measure resistance what is happening when turning the pot, but I did not see anything that made the offending pot differ from working pots. 

Is the pot itself broken, or is there anything else I should try to pin down the problem?

Modular regards,

Janne

 		 	   		  

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Hello

Am 24.08.2012 15:04, schrieb Janne Gson Berg:
> Is the pot itself broken, or is there anything else I should try to pin down the problem?
You might try to measure the voltage between the centerpin of the 
potentiometer and ground.
Check, whether this voltage changes, if you turn the potentiometer.
Then track the copperline from the centerpin on the pcb whether this 
voltage is transported correctly to the socket of the CD4051 and also 
check whether it appears at the IC pin itself.

Florian
-- 
http://fa.utfs.org/

Hi

And one other thing comes to my mind: the switching contact of the 
socket below the potentiometer might make no contact.

Florian

try inputing/outputing a plug into the audio input jack of the exact same step (as the knob) of the bottom row.


 
Bakis 


________________________________

 From: Janne Gson Berg <tapirkillen@hotmail.com>
To: doepfer_a100@yahoogroups.com 
Sent: Friday, August 24, 2012 4:04 PM
Subject: [Doepfer_a100] Troubleshooting A-155
 

  

Hi everyone!

I have got an A-155 sequencer where one of the pots on the bottom row does not work. At all. 

In order to try to pin down the error I have swapped the ICs from the top row to the bottom row (http://www.doepfer.de/A100_pictures/doepfer_a155.jpg, the two PCBs with the knobs), but the problem was still there. Is there anything else I can do? I have also tried to measure resistance what is happening when turning the pot, but I did not see anything that made the offending pot differ from working pots. 

Is the pot itself broken, or is there anything else I should try to pin down the problem?

Modular regards,

Janne



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[Non-text portions of this message have been removed]