1 bit of ASM advice needed...

[Magnus Danielson]

>>>>> "S" == Stopp,Gene  <gene.stopp at telematics.com> writes:

 S> I'll have to check what type of solder I use - I'm sure it's Kester of
 S> some kind, and I think that it's the "water clean-up" type. It's
 S> whatever we used at my old company on the production lines. I'll have to
 S> get back to you on this one (I'm at work, solder's at home). But the
 S> problem is real - no cleaning, no work, clean, it works.

 S> The problems are erratic, but seem to affect VCO's the most (like they
 S> don't have the right range and don't have the proper scale factor). The
 S> multimode VCF in the ASM-1 gets all kinds of multi-volt offsets and
 S> locks up at the supply voltage when the frequency CV is too negative or
 S> positive. Like I said, only a throrough cleaning makes things work
 S> right.

Well, if you use a water clean-up defluxer, what happends when you
have high humidity? A water resolvent defluxer is most probably polar
and add some humidity and you got a pretty good conductor. It's like
adding water to salt...

For myself I use a Multicore 62/36/2 (Pb/Sn/Ag) with Ersin 362 and
then I use a highly cancerogenic Electrolube FLU 400 cleaning agent.
Now, isopropanol based stuff isn't good for your health, but then it
does the job and you just have to ensure to be in a drafty place - I
usually go outdoors when I clean my cards. I did the treatment rigth
after soldering and ensured that I had very little residue on it.
It worked perfect and I could trace no trouble to such leakage.
Also, as a bonus it looks better and I felt very nice about the work,
this helps bringing the spirit up and fixing all the small errors
rigth away and brings a good memory with it - this is also important.

Next to the negative input at the CA 3140 is a offset pin sitting very
closely to -15V with only 500 ohm down to it. This migth be good to
know if there is a odd frequency stick in the VCO which doesn't
correlate with the current in the Q1/Q2 10k resistor...

The CA3140 has an input impedance of about 1 Tohm so some caution
should be taken for low input currents... but I am not sure that the
VCO get that low current for it to be significant...

Cheers,
Magnus