On Wed, 30 Jan 2008 00:53:03 -0600, Ignoramus1782
wrote:

I just finished a mini project. I fixed a "broken" Miller XMT 300
CC/CV welding machine, which had the switch for the display
broken. That switch was switching the display between showing voltage
or current on a mini LED screen.

The broken switch had to be desoldered and a new one had to be
soldered in.

The issue that I ran into was desoldering. I have a "Pace SMD 2000
desoldering station" from my younger military surplus days. This
station has a tool that is like a soldering iron, but has a axial hole
in the tip and an adapter for a vacuum, and the built in vacuum. When
I push on a pedal, the vacuum starts sucking through the tip. So I
would melt the solder with the hot tip, push the pedal and...

My problem was that it barely sucked. Not enough to vacuum in the solder
from the circuit board.

As a stopgap measure, I used my 1/3 HP vacuum pump by connecting it to
the desoldering tool and turning on at the proper moment.

In the end, it all worked, the old switch was removed, a new one
installed, and the welder has a working selector of V vs. A display.

All this leads me to the conclusion that something is wrong with the
vacuum pump on this station. Would you say that it should provide very
strong suction?

Any experience here?


The name (SMD2000) suggests that it is intended mostly for use with
surfacemount devices. Very little solder is used per connection with
these tiny devices and soldering irons (as by Pace) are quite small.
A better choice for larger connections, like switches in a welder,
would be a heavier iron (Weller?) and a manual soldersucker as
"Soldapullt".
http://www.hmcelectronics.com/cgi-bi...uct/2920-0019/

Avoid the cheapos from Radio Shack, the Edsyn Soldapullt is far
superior. It's simply a trigger-released spring-loaded plunger. The
tip is teflon, self-clears when the tool is cocked. They can suck a
rather surprising amount of solder per shot. They're way too big and
clunky for surfacemount work, but they are great for thru-hole and for
soldered terminals.

Mine is at least 20 years old, still works perfectly.