PLAN B analog blog

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
> >
>