MOTM

Hi guys,

I am in need of some advice about de-soldering tools and 
techniques.  I have a couple of MOTM-300's, one of which has been 
rendered silent by a power supply connection goof (please don't ask, 
I hate to relive it!) 8 months ago.  I was going to send it to Paul 
for repair, but he suggested if I wanted to be adventerous, to buy a 
set if IC's and replace them one by one - process of eliniation 
style troubleshooting!  

So I've finally gotten around to it (work has been getting the way), 
and have found my desoldering tool, which is a no-name iron with a 
suction bulb at the end of a short tube.  The bulb can draw a pretty 
good amount of air, but the tip of the iron that it is attached to 
seems kind of crappy.  I've removed the TL074, but have had to do 
some clean up, and don't want to risk damaging anything here.

So what is the recommended desoldering hardware, and what is the 
best way to actually do this?

Thanks in advance!

Phil

Paul's recommendations for construction tools at the back of the pdf
catalogue http://www.synthtech.com/motmcat5.pdf are all good ones.  

A 'Solder Sucker'-This is a vacuum de-soldering tool. You'll be doing an
awful lot of soldering, but no matter how careful you may
be, eventually you will need to unsolder something. There are high-end
pedal-controlled electric de-soldering stations available, but
all you really need is something like the Soldapullt model AS196, about $21.
You 'cock' it, then press a button to release a springloaded
plunger that sucks molten solder right up. It has Teflon tips; it will last
a good 5 years if you clean it. Smaller versions are
available, but they just don't have the vacuum of this big boy.

John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com
The Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com

> -----Original Message-----
> From: motm@yahoogroups.com [mailto:motm@yahoogroups.com] On Behalf Of Phil
> 
> I am in need of some advice about de-soldering tools and
> techniques.  I have a couple of MOTM-300's, one of which has been
> rendered silent by a power supply connection goof (please don't ask,
> I hate to relive it!) 8 months ago.  I was going to send it to Paul
> for repair, but he suggested if I wanted to be adventerous, to buy a
> set if IC's and replace them one by one - process of eliniation
> style troubleshooting!
> 
> So I've finally gotten around to it (work has been getting the way),
> and have found my desoldering tool, which is a no-name iron with a
> suction bulb at the end of a short tube.  The bulb can draw a pretty
> good amount of air, but the tip of the iron that it is attached to
> seems kind of crappy.  I've removed the TL074, but have had to do
> some clean up, and don't want to risk damaging anything here.
> 
> So what is the recommended desoldering hardware, and what is the
> best way to actually do this?
>

Besides buying a desoldering pump like John suggested (I have one of the
smaller ones with an aluminum body--cost about $15 I think), another thing
I've found helpful is to use a pair of small wire cutters to cut all of the
legs of the IC near the IC itself. If you think the IC is dead there's no
need to salvage it, and after you cut the legs you can unsolder and remove
them one at a time rather than having to get all 14 or 16 free at once. My
method of attach is to first cut all of the legs, then remove them one at a
time by grabbing them from the top side with a pair of needle-nosed pliers
while melting the solder on the bottom side (obviously you need to hold the
PCB vertically in a clamp while doing this), then go back with a solder
sucker to remove any remaining solder. 

The good news is that MOTM PCBs are very high quality so you're unlikely to
damage them while doing this, if you're reasonably careful with the whole
operation.

--Adam

Thanks for the suggestions guys.  I will get my hands on the AS196, 
and in the meantime, try Adam's "snip the legs" technique.  Since I 
have a fair amount of 1013's and OP275's in my parts box, I feel a 
little more comfortable about snipping them off.  Since I only have 
a few CA3080's and LM319's, I'll use the vacumn method for them.  
That way, if those parts check out on the breadboard, I can 
potentially re-use them.

Thanks!

Phil

--- In motm@yahoogroups.com, "Adam Schabtach" <adam@s...> wrote:
>
> Besides buying a desoldering pump like John suggested (I have one 
of the
> smaller ones with an aluminum body--cost about $15 I think), 
another thing
> I've found helpful is to use a pair of small wire cutters to cut 
all of the
> legs of the IC near the IC itself. If you think the IC is dead 
there's no
> need to salvage it, and after you cut the legs you can unsolder 
and remove
> them one at a time rather than having to get all 14 or 16 free at 
once. My
> method of attach is to first cut all of the legs, then remove them 
one at a
> time by grabbing them from the top side with a pair of needle-
nosed pliers
> while melting the solder on the bottom side (obviously you need to 
hold the
> PCB vertically in a clamp while doing this), then go back with a 
solder
> sucker to remove any remaining solder. 
> 
> The good news is that MOTM PCBs are very high quality so you're 
unlikely to
> damage them while doing this, if you're reasonably careful with 
the whole

> operation.
> 
> --Adam
>

I always cut the legs and use a solder sucker to remove the individual 
pins.  Then I find that going over the pads with copper braid wick 
really cleans them up nice.  Then I use a bit of acetone to clean the 
top and bottom prior to soldering in the new chips.

Dave

--- In motm@yahoogroups.com, "Phil Peery" <ppeery@o...> wrote:

>
> Thanks for the suggestions guys.  I will get my hands on the AS196, 
> and in the meantime, try Adam's "snip the legs" technique.  Since I 
> have a fair amount of 1013's and OP275's in my parts box, I feel a 
> little more comfortable about snipping them off.  Since I only have 
> a few CA3080's and LM319's, I'll use the vacumn method for them.  
> That way, if those parts check out on the breadboard, I can 
> potentially re-use them.
> 
> Thanks!
> 
> Phil
> 
> --- In motm@yahoogroups.com, "Adam Schabtach" <adam@s...> wrote:
> >
> > Besides buying a desoldering pump like John suggested (I have one 
> of the
> > smaller ones with an aluminum body--cost about $15 I think), 
> another thing
> > I've found helpful is to use a pair of small wire cutters to cut 
> all of the
> > legs of the IC near the IC itself. If you think the IC is dead 
> there's no
> > need to salvage it, and after you cut the legs you can unsolder 
> and remove
> > them one at a time rather than having to get all 14 or 16 free at 
> once. My
> > method of attach is to first cut all of the legs, then remove them 
> one at a
> > time by grabbing them from the top side with a pair of needle-
> nosed pliers
> > while melting the solder on the bottom side (obviously you need to 
> hold the
> > PCB vertically in a clamp while doing this), then go back with a 
> solder
> > sucker to remove any remaining solder. 
> > 
> > The good news is that MOTM PCBs are very high quality so you're 
> unlikely to
> > damage them while doing this, if you're reasonably careful with 
> the whole
> > operation.
> > 
> > --Adam
> >
>