MOTM

Hopefully Paul will add Mouser part numbers to the BOMs someday. I've  
gotten some bad parts myself.


On Sep 16, 2008, at 7:59 PM, Dave wrote:

> As an update to others who may run in to the same problem I had with
> my MOTM 440 build I'll post the solution to my problem. I took my
> MOTM 440 to a tech friend of mine who literally spent hours trying to
> figure what went wrong as at first glance everything was done right.
> After comparing the schemes to the PCB he noticed that the BC550
> transistors were a different configuration (EBC) than what he is
> normally used to seeing (CBE) which I think is fine for most TO-92
> BC550 transistors but not good for the BC550 trans that I got from
> Futurelec which are (CBE). I had all the trans in backwards even
> though I put them in to match the silk screen (I of course didn't
> think to question the orientation of the trans). I'm not sure why my
> BC550s were opposite of Pauls but I did learn a lot about transistors
> as a result of this problem which has actually helped me trouble shoot
> other modules I have built :)
>
> I hope this helps others if they build this and can't figure out
> what went wrong :)
>
> Dave
>
> --- In motm@yahoogroups.com, "Paul Schreiber" <synth1@...> wrote:
> >
> > The caps were melted due to soldering, not of the circuit.
> >
> > I use the ones from Mouser.
> >
> > Paul S.
> >
> > ----- Original Message -----
> > From: "lexvortex" <lexvortex@...>
> > To: <motm@yahoogroups.com>
> > Sent: Tuesday, August 26, 2008 3:53 PM
> > Subject: [motm] MOTM 440 problem
> >
> >
> > > Hi everybody, I just finished building a MOTM 440 filter but am  
> having
> > > some problems with it. I bought some polystyrene caps from a  
> surplus
> > > place that didn't have any voltage rating on them like pauls  
> does on
> > > his polystyrene caps (I also have a MOTM 440 built by him, loved  
> it so
> > > much I needed another!). After powering it up and trying to use it
> > > there was no sound only what sounded like a quiet bleed through  
> of the
> > > oscillator hooked up to it which the none of the controls had any
> > > effect on. I took it back to the bench and started trouble  
> shooting
> > > and what I found was that some of the polystyrene caps were  
> melted, I
> > > assume because they had too low a voltage rating (they are smaller
> > > than Pauls).
> > >
> > > What I want to know is if this could have damaged any of the  
> ICs? I'm
> > > gonna see if I can find some more polystyrene caps with a higher
> > > voltage rating but I'd be surprised if the place has them :(
> > >
> > > Thanks a lot for any help :)
> > >
> > > Dave
> > >
> > >
> > > ------------------------------------
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> >
>