I didn't answer because the title didn't indicate it was anything of
interest to me (digest 61 is all I saw!) Anyway sounds like we are talking
about a capacitor in line with a signal jack? If so electrolytics are often
used in this appication; polarity is irrelevant since the voltage is usually
real low. They are used to high pass signal and filter off DC levels in
particular that might exist. When a circuit failure happens sometimes, then
a large offset voltage like +_15V might be seen ACROSS the capacitor. In
that case, you have a 50/50 chance. If you happen to know whether say an op
amp is more likely to fail going to positive rail than negative, then of
course allign the polarity of the capacitor to take that possibility into
account! Otherwise, just pick a direction and stick it in there UNLESS it's
a case where there is an actual intentional DC level (like where you are
isolating an op amp that runs off a single 9V supply say...such that the
output averages 4.5V in that example...). In that case you must put the +
side towardst he + voltage or it will ruin the cap.. -Bob
----- Original Message -----
From: Rory McDonald <rmcdonald@...>
To: <oldsynths@yahoogroups.com>
Sent: Saturday, August 02, 2003 4:07 PM
Subject: RE: [oldsynths] Digest Number 61(should have been MG-1 input filter
mod)
> Shayne. If I follow you the cap is in line with the wire going to the
jack?
> If that is so you dont have to worry about polarity- a ceramic will do it.
> Rory
>
> -----Original Message-----
> From: Shayne Cafferata [mailto:scafferata@...]
> Sent: Saturday, August 02, 2003 11:35 AM
> To: oldsynths@yahoogroups.com
> Subject: Re: [oldsynths] Digest Number 61(should have been MG-1 input
> filter mod)
>
>
> thanks, rory. i very much appreciate your replies.
> i'm afraid i wasn't specific enough in my description of the mod. the
> negative pole of the capacitor i am connecting to is already on the main
> circuitboard. between that capacitor and the positive center of the input
> jack, there is to be installed a length of wire and a .47mf cap. and
that's
> all
> there is to it, except for scraping away the trace coming off the center
of
> the input jack in order to disconnect it from the output. the mg-1 has
> stereo
> rca inputs which are routed directly to the outputs. the apparent intent
was
> to enable a connection to a home stereo for jam-along funtimes. so the
input
> filter mod routes the input signal through the filter instead of sending
it
> straight to the ouput. being a korg x911 enthusiast, i'm excited to put
the
> mg-1 to similar use. maybe i'm being a little overcautious, but i just
> scored this sweet thing. i love the sounds and don't want to do any
damage.
>
> shayne
>
>
> > Well I am definitely no expert on this, but no one else has answered you
> > besides me so:
> > If your instructions say "come off the negative pole of a capacitor"
then
> I
> > would assume an Electrolytic since ceramics dont have neg/positive
leads.
> > Pick a electrolytic that has a voltage rating above that of the voltages
> at
> > the circuit.
> > So if +15v is going thru the circuit at that point, perhaps a 25v rating
> on
> > the cap.
> > SOMEBODY STOP ME IF I AM WRONG ON THIS!
> > Rory
> > Oldsynths Moderator
> >
> > -----Original Message-----
> > From: Shayne Cafferata [mailto:scafferata@...]
> > Sent: Friday, August 01, 2003 12:01 PM
> > To: oldsynths@yahoogroups.com
> > Subject: Re: [oldsynths] Digest Number 60
> >
> > > Message: 2
> > > Date: Thu, 31 Jul 2003 10:23:30 -0700
> > > From: Rory McDonald <rmcdonald@...>
> > > Subject: RE: MG-1 input filter mod
> > >
> > > Well an electrolytic would be polarity sensitive...
> > >
> > > -----Original Message-----
> > > From: Shayne Cafferata [mailto:scafferata@...]
> > > Sent: Thursday, July 31, 2003 9:54 AM
> > > To: oldsynths@yahoogroups.com
> > > Subject: [oldsynths] MG-1 input filter mod
> > >
> > > i'm wondering, for those familiar with the input filter mod on the
> > realistic
> > > mg-1, does it make a difference what type
> > > of capacitor is used? a .47mf has been recommended over the originally
> > > suggested .1mf , but does it matter if it's an
> > > electrolytic or ceramic?
> > > i have both.
> > >
> > > thanks,
> > > shayne
> >
> > the instructions i have are pretty straightforward. basically, you come
> off
> > the negative pole of a capacitor on the board to the positive center of
an
> > input jack, with a .47 mf cap inline. the type of cap was not specified
> and
> > i am too much a novice to know if it matters, but cautious enough to ask
> > before plugging in the soldering iron. the electrolytic, being polarity
> > sensitive, does this mean the flow of electrons is directional? as in,
> > flowing only one way? i'm thinking that the type of cap probably doesn't
> > matter, except if i use the electrolytic it would need to be properly
> > oriented(which would be - coming from the input - negative to
positive?).
> i
> > know i'm in the presence of masters here, so please bear with these, uh,
> > questions from the back row, so to speak...
>
>
>
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