2006-02-04 by Roy J. Tellason
On Saturday 04 February 2006 01:40 am, P........ wrote:
> --- In vintagesynthrepair@yahoogroups.com, "Roy J. Tellason"
>
> <rtellason@...> wrote:
> > On Saturday 04 February 2006 12:14 am, P........ wrote:
> > > Well hello, everyone! I have recently purchased a Arp Omni 1, but from
> > > the first moment on I kept having trouble with one note stuck at E in
> > > the first octave. Let me explain the symtomes: when switched to
> > > bass(synth) I'm able to play the notes from C1 to E1 then every other
> > > key I press after that makes the same sound. When switched to full
> > > strings/brass no matter which or how many keys I press or how I set
> > > the attack/sustain envelopes I always keep hearing E1 playing along
> > > with a long sustain. Did anybody else encounter this problem and how
> > > can I get that fixed? Help, please??
> >
> > You're getting one note that just wants to bleed through the whole
> > time? I've hit that one before, a few times...
> >
> > ARP screwed up on the choice of one particular component in there, the
> > 22uF/25V Tantalum caps they use to sustain a note. That particular
> > circuit has, with extreme settings of the sustain slider, up to 30V
> > across those caps at times. I guess it speaks well for the quality of the
> > parts that more of them don't blow up, tantalum caps have a way of doing
> > that, rather spectacularly at times.
> >
> > You'll need to find out which cap it is (there are rows of them)
> > that pertains to the particular note that's bleeding through -- easy
> > enough, it'll be the one note that plays cleanly without any _other_ note
> > coming through. Clip out that capacitor and the bleedthrough will be gone,
> > except of course that the note now won't sustain until you put a new cap
> > in there. Get a 35V unit to replace it with, and you should be okay.
>
> Thanks alot! Well I took the synth apart and.. this might sound silly
> but I'm really not that technically gifted although I do have some
> soldering skills and as you propably found out through my not so good
> grammar I don't originate from this country so I'm wondering if when
> you talk about caps do you mean the blue capacitors which I see
> together with rows of resistors at the bottom part of the lower
> voicing section
Yeah, they're the blue ones...
> and should I do the same thing in the upper voicing section too? And would
> that also fix the problem with the bass section? I also could need some
> schematics and info to see which cap refers to which key so that I don't cut
> the wrong one.
I have seen one or two units where more than one of these was the problem, but
usually it's just one. Dunno if I'd try to do anything at all here without a
schematic, but they're out there on the 'net, I would make it a point to go
for that first!
If you aren't sure which note is the problem, look for one that comes through
clean by itself, and then count keys from one end of the keyboard, count
caps from one end of the setup there, that should get you to the right
one...
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin