Mellotronists

Hi all-
   My M400 tone control is non-operational, thought I
would dig into the problem.  Tested it, wiper appears
to be open.  Reads 32K for the full value between the
other terminals.  Is this a correct value, and is this
pot linear or log(audio) taper?  I don't have
schematics yet.  This machine has 2 cards in the
preamp box, pots have plastic shafts.  May as well get
the volume pot value, too, if it is not too much
trouble.

   Thanks
 
  -Bruce Daily
   M400 #1221

PS- The control knobs on Mark Wallis' WEM Audiomaster
mixer look quite familiar...





       
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In a message dated 25/05/2007 19:47:05 GMT Standard Time,  pocotron@... 
writes:

My M400 tone control is non-operational, thought  I
would dig into the problem.  Tested it, wiper appears
to be  open.  Reads 32K for the full value between the
other terminals.   Is this a correct value, and is this
pot linear or log(audio)  taper?


Dear All,
 
I believe it is a 25K log pot.
 
Norm

Bruce Daily wrote:

> Hi all-
>    My M400 tone control is non-operational, thought I
> would dig into the problem.  Tested it, wiper appears
> to be open.  Reads 32K for the full value between the
> other terminals.  Is this a correct value, and is this
> pot linear or log(audio) taper?

  --------------------------------------------------------------------------------

Hi Bruce,  Tone Control is 25K log-taper ,volume is 10K log-taper.
Dave Kean had a note in his svc. manual to use a 10K log-taper
for better range in tone control.  Tried this in a few cases, slight improvement.

BTW, it's becoming increasingly difficult here in the USA to find audio-taper pots
with 2-inch long shafts (brass,alum,plastic,etc).

  --------------------------------------------------------------------------------

>  I don't have
> schematics yet.  This machine has 2 cards in the
> preamp box, pots have plastic shafts.  May as well get
> the volume pot value, too, if it is not too much
> trouble.
>
>    Thanks , -Bruce Daily  ,    M400 #1221
>
> PS- The control knobs on Mark Wallis' WEM Audiomaster
> mixer look quite familiar...

  --------------------------------------------------------------------------------

Those cards are the venerable WME289 and WME290 line amp and preamp
boards,resp.    Control knobs on WEM and M400's are the same, mfgd.
by Bulgin, England.

Cheers, -- Jerry Korb at the Mellotron Ranch

In a message dated 5/25/2007 4:05:25 P.M. Eastern Daylight Time,  
jkorb@... writes:

BTW, it's becoming increasingly difficult here in the USA to find  
audio-taper pots 
with 2-inch long shafts  (brass,alum,with 2-inch wi


 
How many do you want? I have tons. They are very high quality with  2"  steel 
shafts.
 
$15.00 each plus shipping.



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