Analogue systems

I have an RS40 whose clock drifts quite a bit (I've also noticed that it's sample and held output drifts upwards too). I suspect it's the same clock circuit as the RS200 (same min and max frequency, output levels). I haven't quite had the time to investigate properly, but I did swap out the TL072  in the clock circuit with no improvement. There are two 1u (or is it 2u2?) film caps on there which I believe are the timing caps, so those were my next port of call. I should really trace out the circuit so I can fault find it properly. My RS40 is probably two years old, maybe they had a batch of some particular part which is prone to failure. Actually now I think of it, I believe the S&H circuit uses the same type of cap for storing the sampled voltage so if they had a bad batch maybe there is a connection between the two faults... I did speak to Bob about it, he'd said he'd never heard of this particular problem before but it seems likely that we have the same issue. When I get to the bottom of it I'll let you know.

Regards,

Daniel.

To: analogue_systems@yahoogroups.com
From: coenen.olivier@skynet.be
Date: Sat, 15 Oct 2011 14:42:02 +0000
Subject: [analogue_systems] RS-200 CV & Clock drift


















 



  


    
      
      
      Hello,



I've noticed on several occasions that the clock of my RS-200 is far from rock steady...

Small but obvious speed variations appear from time to time, and it has been doing this since I bought it new more than a year ago...independent of whatever modules are plugged in the same RS-15 case (current consumption cannot be an issue with so few modules in the case and all other modules do function properly).



Also, during the past week, the CV outputs A, B and C produced some seriously drifting CVs...

This problem seems now to have disappeared or to be attenuated in a way it is barely noticeable, for whatever reason... I don't know why or how it appeared in the first place ?!



Last year, during the very hot summer days, the sequencer stopped running after some time...no way to get it running again but after the modular was shut down for while...

Perhaps some heat dissipation problem...I e-mailed Bob about it and at the moment I decided to send it out for revision, it started working properly again... just like it "felt" I was going to send it out and it was afraid to undergo an "operation" :-)



Anyone experiencing similar problems or is my module a monday morning assembly ?

Definitely a ghost in the machine...



Thanks





    
     

    
    






   		 	   		  

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