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Doepfer

Index last updated: 2026-04-29 00:15 UTC

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Re: PWM with A-111

2006-12-30 by Tim Stinchcombe

Hi Markus,

> I didn't find any hint at the Doepfer page. Any other idea?

After checking some of the history on this problem, I realised I too 
had this problem when I first got my A-111 (over 4 years ago), and 
the solution then, by EMIS the UK distributor, was to replace the 
CEM3340 chip. In an old email I had written to Dieter at the time, I 
mentioned that specifically grounding the hard sync input did *not* 
cure the problem!

However, checking past messages, the last time this appeared seems to 
have been post #9193, about a year ago: one of the follow-up posts, 
#9203, contained the suggestion from Dieter about grounding the hard-
sync input, but checking my module against what he says doesn't make 
sense, as the switched contact on mine is *not* grounded (but I'm 
guessing on new modules they solder across the gap). Hence I suggest 
the following:

Insert a patch lead into the hard sync socket, and *deliberately 
ground the tip at the other end*.

If this cures it, have a look at the switched contacts on the hard 
sync socket - these are the two on the very end of the board. I 
suspect that they are bridged with solder: if they are, then probably 
a new socket is needed; if they are not, then bridging them with 
solder will have the effect of always grounding the hard sync line 
when no plug is inserted, which hopefully should then give a 
permanent solution.

If inserting and grounding the lead doesn't totally remove the 
problem, then I suspect you'll need a new chip as I did!

Tim

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