PLAN B analog blog

Ok i finally had the chance to try this modifcation out, and it works
like a charm!

Thanks for the easy fix peter!


--- In PLAN_B_analog_blog@yahoogroups.com, "(i think you can figure
that out)" <peter@...> wrote:
>
> Hello to everyone.
> 
> This is an easy fix.  On each of the two ICs on the M9 (one a TLO74,
> One a TLO72), you will find two small blue capacitors flanking those
> components which are unmarked (meaning there is no C number - as in
> C1, C2, etc. - designator).
> 
> SO two per IC for a total of 4 caps.
> 
> On the M9 all four of those guys are by the edges of the PCB.  There
> are a few other small blue caps on the board, but those have
> designator numbers and are in the pf range, somewhere around 22pf (I'm
> at my g/f's place, not around my schematic reference or system, please
> pardon my 52 year old memory).  These shouldn't be changed. They
> merely kill potential oscillation in the feedback loops of the gain
> buffers (wouldn't ya know it, hardest thing in analog is to get a
> oscillator to do it's thing properly, yet it will happen all over the
> place were you don't want it so you have to through components to it
> to stop that from happening).
> 
> Until quite recently those four caps were .01 uf, marked "103" on the
> cap itself. They need to be removed and replaced with .1 mf, which is
> marked "104".
> 
> That's it. Not that bad, five minute job and will cut the crosstalk
> down a lot.  We've been shipping the m9 with this new part since this
> was discovered about a month or so ago and are now using .1's on all
> of our modules.
> 
> For a reference of how to read the value of small capacitors, see this:
> 
> http://www.electronics2000.co.uk/data/itemsaf/capconv.php
> 
> CAPS are marked with the Picofarad value.  A .01 microfarad is 10,000
> pf - their marking reads 103, which visually must be read as 10 plus
> 3, meaning three extra zero's after the initial 10 (10,000).  .01's
= 100,000pf or 10 plus 4 - four extra zeros after the 10.
> 
> 
> 
> 
> 
> 
> --- In PLAN_B_analog_blog@yahoogroups.com, "murphybrandon87"
> <murphybrandon87@> wrote:
> >
> > I would love that mod Peter. Pinky swear! ;)
> >
> > --- In PLAN_B_analog_blog@yahoogroups.com, "(i think you can figure
> that out)"
> > <peter@> wrote:
> > >
> > > Hi guys.
> > >
> > > I've found a change which significantly improves the amount of bleed
> > > across the A/B channels on the Model 9 Mixer.  I'll be happy to post
> > > it (it's a snap), but you guys gotta promise me it's not going
to end
> > > up on some blog somewhere that we release goods with known
defects or
> > > some such nonsense.  Trust me, it's happened.  It doesn't happen
when
> > > other manufacturers post these types of things...but it does
with us.
> > >
> > > I've obviously had it 'up to here' with Plan B blog bashing.
> > >
> > > So, before I do this...we gotta deal?
> > >
> > > - P
> > >
> >
>