Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Desoldering question (Miller XMT welder repair)

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?

i
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Default Desoldering question (Miller XMT welder repair)


"Ignoramus1782" wrote

Two words.

Solder wick.




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Default Desoldering question (Miller XMT welder repair)

In article ,
Ignoramus1782 wrote:
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?


Obviously it should provide enough to remove molten solder from the joint.

Most desolder tools can get blocked. So check the pump with the tool
disconnected you should feel the vacuum with your finger. Also check the
output air stream from the pump. Many have an adjustable restrictor valve
to set the vacuum level.
If it's been used without the proper filters it's possible the pump is
dirty, blocked or damaged. They usually strip down easily. The one Pace
I've had apart had sort of carbon vanes which move in slots to make
contact with the body by centrifugal force. If those were stuck it
wouldn't work properly.

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Default Desoldering question (Miller XMT welder repair)


"Ignoramus1782" wrote in message
...
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?


My Weller 900 desoldering station, is of exactly the same construction, and
probably similar vintage. It has a vacuum gauge on the front, that reaches a
reading of "-0.6" - so I guess that's 0.4 atmospheres - when it is working
normally. But that's the trick to it. It works extremely well when it *is*
working well. It develops enough suck to be able to hear it 'slurp' up the
solder from a joint, and will readily remove solder from around IC pins in a
thru' plated hole board - an action that's notoriously difficult to achieve.

But when it's not working well, then man, it's a dog. It requires regular
maintenance of making sure that the hole in the nozzle is clear, using the
proper ream-out tool, every few sucked joints. About once a week, I clear
out the passage between the tip, and the solder collection chamber, again
using the proper reamer. Once a month, it will need the chamber cleaning
out, and the felt filter at the rear, just before the vacuum connection
point, replacing or cleaning. Once every couple of months, it will need the
front collection chamber gasket replacing, as the silicon rubber goes hard.
Occasionally, a blob of solder will get past the filter, and lodge in the
vacuum tube. It can get sucked quite a way in, so it's worth feeling all the
way back to the vacuum pump unit, to make sure that there is nothing in
there.

About once every 6 months, I clean out the main vacuum passageways. That's
all of the solid pipe stubs that the various flexible pipes plug onto. It
includes the ones at either end of the main flexi to the iron, and also the
ones to the 'flywheel' chamber inside the base station. This also serves as
the holder for the station's own protection filter - which should be
replaced at this time, along with the exhaust filter - and the connection
point for the vacuum gauge. The final one is on the vacuum pump itself.
Despite all of the filters that are in line, all of these vacuum passageways
get clogged with solidified flux residue, which is very sticky like tar, and
needs poking out with a fine screwdriver blade, before finishing off with a
flux solvent. This clogging up of these tubes has a *very* significant
impact on the performance of the unit, and is the difference between the
thing being a pleasure to use, and a royal pain in the arse.

About once a year, I strip out the vacuum pump itself, and clean all of the
passageways, and the little rubber flap valves, which also get coated in
flux residue. Hope this helps you get a handle on how well your Pace
*should* work, as I should think that it is pretty similar to my Weller.

Arfa


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Default Desoldering question (Miller XMT welder repair)

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
r 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?
:
:i


Your desoldering tool (like most) is probably fitted with a small diameter tip
(approx 0.8mm - 1.00mm inside diameter) designed for sucking solder from around
small gauge component leads and IC pins where the tip make full peripheral
contact with the board. When the solder melts around a pin all the air passes
solely around the lead and maximum effect is achieved inside the through hole.

When you try to suck solder from around pcb mount switch terminals you have to
do it in stages because the tip doesn't have the closest contact with the pcb
for most of its tip periphery. There is usually a fair gap between the switch
terminal and the side of the mounting hole and when the solder melts and the
suction starts it will pull solder from only a small section of the hole before
the rest of the solder cools due to the air passing. There will be much more
solder around a switch terminal as well so it may take several goes working your
way around the pin.

My Hakko desoldering station has good suction but when it comes to desoldering
switches and other large terminal items I usually prefer to use my old manual
Soldapult. These only take one or two goes to remove all solder.
http://www.stanleysupplyservices.com...spx?pn=114-202


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Default Desoldering question (Miller XMT welder repair)

Ignoramus1782 fired this volley in
:
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?


Iggy, there are four things that go wrong with the Pace stations, and at
least two of them are "intentional".

In the solder collection tube is a serpentine piece of aluminum strapping
used to trap and cool the solder. That can collect so much flux and
metal that nothing can get past it in the collector.

Upwind (vacuum side) of the strap is a cotton felt plug used to prevent
droplets from passing into the vacuum line. It gets solid-filled with
flux vapor, and will fail to pass air. Just massage it in a beaker of
denatured alcohol to clean it, then thoroughly dry it before re-use.
Replace if it's too gunked up with solder chips.

Further upwind, inside the base is a pancake filter. It, too will get
rosin vapor deposited on the fabric. Once plugged, you must replace it.

Those are the three Intentional blockages -- all protection features of
the system.

The fourth area of failure is the vane pump. It has graphite vanes and
end-plates. They wear. They can be replaced easily, if you access to
the parts.

LLoyd
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Default Desoldering question (Miller XMT welder repair)

On 2008-01-30, Dave Plowman (News) wrote:
In article ,
Ignoramus1782 wrote:
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?


Obviously it should provide enough to remove molten solder from the joint.

Most desolder tools can get blocked. So check the pump with the tool
disconnected you should feel the vacuum with your finger.


I tried it last night, with the tool disconnected, as you say. I do
feel a vacuum, but it is very slight.

Also check the output air stream from the pump. Many have an
adjustable restrictor valve to set the vacuum level. If it's been
used without the proper filters it's possible the pump is dirty,
blocked or damaged. They usually strip down easily. The one Pace
I've had apart had sort of carbon vanes which move in slots to make
contact with the body by centrifugal force. If those were stuck it
wouldn't work properly.


OK. When I get time, I will take it apart and see what's wrong. The
station is usable even without this pump, since I can use my other
vacuum pump (1/3 HP Welsch DuoSeal), but, obviously, it is not as
convenient. I would even say, "it sucks".

i
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Default Desoldering question (Miller XMT welder repair)

In article ,
Bob La Londe wrote:
Two words.


Solder wick.


You don't have a proper desolder tool, then? ;-)

--
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Dave Plowman London SW
To e-mail, change noise into sound.
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On 2008-01-30, Arfa Daily wrote:
My Weller 900 desoldering station, is of exactly the same construction, and
probably similar vintage. It has a vacuum gauge on the front, that reaches a
reading of "-0.6" - so I guess that's 0.4 atmospheres - when it is working
normally. But that's the trick to it. It works extremely well when it *is*
working well. It develops enough suck to be able to hear it 'slurp' up the


Exactly what I heard with the other vacuum pump.

solder from a joint, and will readily remove solder from around IC pins in a
thru' plated hole board - an action that's notoriously difficult to achieve.


Did exactly that yesterday, worked fine with the "real" vacuum pump.

But when it's not working well, then man, it's a dog. It requires regular
maintenance of making sure that the hole in the nozzle is clear, using the
proper ream-out tool, every few sucked joints.


I used a sewing needle.

About once a week, I clear out the passage between the tip, and the
solder collection chamber, again using the proper reamer. Once a
month, it will need the chamber cleaning out, and the felt filter at
the rear, just before the vacuum connection point, replacing or
cleaning. Once every couple of months, it will need the front
collection chamber gasket replacing, as the silicon rubber goes
hard. Occasionally, a blob of solder will get past the filter, and
lodge in the vacuum tube. It can get sucked quite a way in, so it's
worth feeling all the way back to the vacuum pump unit, to make sure
that there is nothing in there.


I will check the insides, indeed. I did check suction at the unit's
outlet, there was some, but very little.

About once every 6 months, I clean out the main vacuum passageways. That's
all of the solid pipe stubs that the various flexible pipes plug onto. It
includes the ones at either end of the main flexi to the iron, and also the
ones to the 'flywheel' chamber inside the base station. This also serves as
the holder for the station's own protection filter - which should be
replaced at this time, along with the exhaust filter - and the connection
point for the vacuum gauge. The final one is on the vacuum pump itself.
Despite all of the filters that are in line, all of these vacuum passageways
get clogged with solidified flux residue, which is very sticky like tar, and
needs poking out with a fine screwdriver blade, before finishing off with a
flux solvent. This clogging up of these tubes has a *very* significant
impact on the performance of the unit, and is the difference between the
thing being a pleasure to use, and a royal pain in the arse.

About once a year, I strip out the vacuum pump itself, and clean all of the
passageways, and the little rubber flap valves, which also get coated in
flux residue. Hope this helps you get a handle on how well your Pace
*should* work, as I should think that it is pretty similar to my Weller.


OK. I think that I will try to take time to do that right.

Thanks

i
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Default Desoldering question (Miller XMT welder repair)

On 2008-01-30, Ross Herbert wrote:

Your desoldering tool (like most) is probably fitted with a small diameter tip
(approx 0.8mm - 1.00mm inside diameter)


Yes.

designed for sucking solder from around small gauge component leads
and IC pins where the tip make full peripheral contact with the
board. When the solder melts around a pin all the air passes solely
around the lead and maximum effect is achieved inside the through
hole.


Well, it does this pretty well with a real vacuum pump attached
instead of the "desoldering station pump".

When you try to suck solder from around pcb mount switch terminals you have to
do it in stages because the tip doesn't have the closest contact with the pcb
for most of its tip periphery. There is usually a fair gap between the switch
terminal and the side of the mounting hole and when the solder melts and the
suction starts it will pull solder from only a small section of the hole before
the rest of the solder cools due to the air passing. There will be much more
solder around a switch terminal as well so it may take several goes working your
way around the pin.


Somehow, to my amazement, usually one "suck" was enough per pin. The
pins were too thick to fit inside the tube, so I had to approach it
from the side, and yet, it worked out.

My Hakko desoldering station has good suction but when it comes to desoldering
switches and other large terminal items I usually prefer to use my old manual
Soldapult. These only take one or two goes to remove all solder.
http://www.stanleysupplyservices.com...spx?pn=114-202


I am confused as to how it works, do I need a separate source of heat
for that one?

thanks

i


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Default Desoldering question (Miller XMT welder repair)

On 2008-01-30, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
Ignoramus1782 fired this volley in
:
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?


Iggy, there are four things that go wrong with the Pace stations, and at
least two of them are "intentional".

In the solder collection tube is a serpentine piece of aluminum strapping
used to trap and cool the solder. That can collect so much flux and
metal that nothing can get past it in the collector.


I cleaned the tube, but there was not that much to begin with, a few
globs.

Upwind (vacuum side) of the strap is a cotton felt plug used to prevent
droplets from passing into the vacuum line. It gets solid-filled with
flux vapor, and will fail to pass air. Just massage it in a beaker of
denatured alcohol to clean it, then thoroughly dry it before re-use.
Replace if it's too gunked up with solder chips.


A great idea, I will check it.

Further upwind, inside the base is a pancake filter. It, too will get
rosin vapor deposited on the fabric. Once plugged, you must replace it.


Will check out, thanks.

Those are the three Intentional blockages -- all protection features of
the system.

The fourth area of failure is the vane pump. It has graphite vanes and
end-plates. They wear. They can be replaced easily, if you access to
the parts.


Great, last time I checked, Pace was still around. Thanks Lloyd. I
will try to approach it systematically, trying to isolate the
problem. I believe that it is something inside the unit.

i
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Default Desoldering question (Miller XMT welder repair)

"Dave Plowman (News)" wrote in message
...
In article ,
Bob La Londe wrote:
Two words.


Solder wick.


You don't have a proper desolder tool, then? ;-)


I have several solder suckers. In close quarters sometimes solder wick does
the trick, and it always works. I've got one of those big blue nasty
things, and a couple of smaller aluminum solder suckers. In close quarters
I still find myself reach for the solder wick.






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On 2008-01-30, Brent wrote:
I use the same solder station family. and am very familliar with a
bunch of the handles and their construction

the axial hole solder tips feed up into pyrex glass tube with a filter
and a wavy little peice of metal and a filter element in it within the
solder handle itself


Exactly.

the used solder never leaves the handle. It needs periodic cleaning

Thake the point where the vacuum hose meets the handle push down on it
and ot the left and it should remove itself and the glass tube for
cleaning

teh solder builds up within the tube or at the end of the iron within
the tube usually.

all the buildup can usually be bushed free with a nylon brush and the
small cylinder filter within the glass tube will likely need a
replacement

this is likely your iron or the handle construction will be similar

http://www.paceworldwide.com/documents/SX-70.pdf check page 12 for a
diagram

or

http://www.paceworldwide.com/manuals.asp

all the pace "sensatemp" type irons are cross compatible and as such i
always keep an eye open for the hot air iron, the tweezers and the
large IC vacuum handles to add on my own bench on the existing
supplies


I think that I would like to find Cirk-Grind device and also should
buy more tips. This is actually a very nice station if I get it to its
potential. I do have a manual for it also.

i
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Default Desoldering question (Miller XMT welder repair)

"Bob La Londe" wrote in message
.. .

In close quarters sometimes solder wick does the trick,
and it always works.


Any desoldering method sometimes needs a bit of fresh solder to
"loosen things up" so the solder can be sucked out of the hole.


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Ignoramus19508 fired this volley in
:
I think that I would like to find Cirk-Grind device and also should
buy more tips. This is actually a very nice station if I get it to its
potential. I do have a manual for it also.


Iggy, it's been a while since I had my Pace, but IIRC, those tips are
plated with Indium/Nickle alloy to prevent them from being wetted by or
amalgamated with the solder -- even in the bore. Thus, don't use a hard
tool to clean the bore; use a plated copper lead from a resistor, etc.
If you scratch the bore, it quickly begins to corrode and amalgamate with
solder.

I think I still have some 0.025 tips for that. If I can find them, I'll
drop 'em in an envelope.

LLoyd


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Default Desoldering question (Miller XMT welder repair)

In article ,
"William Sommerwerck" wrote:

Any desoldering method sometimes needs a bit of fresh solder to
"loosen things up" so the solder can be sucked out of the hole.


Nuts. It doesn't need fresh solder, it needs fresh flux. The fresh
solder contains the flux, but it also contains a healthy dose of what
you're trying to remove. Much better to just add a drop of flux.
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Default Desoldering question (Miller XMT welder repair)

Smitty Two wrote:

In article ,
"William Sommerwerck" wrote:


Any desoldering method sometimes needs a bit of fresh solder to
"loosen things up" so the solder can be sucked out of the hole.



Nuts. It doesn't need fresh solder, it needs fresh flux. The fresh
solder contains the flux, but it also contains a healthy dose of what
you're trying to remove. Much better to just add a drop of flux.


One might think that this would suffice, but in practice, it is
often necessary to add a little rosin-core solder to permit
wicking and better interface to the suction head. I have found
adding flux often just gums up the tip when there is insufficient
solder in the joint. This condition most often occurs for me
on large lands with heavy conductors.

Regards,

Michael
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Default Desoldering question (Miller XMT welder repair)


"Smitty Two" wrote in message
news
In article ,
"William Sommerwerck" wrote:

Any desoldering method sometimes needs a bit of fresh solder to
"loosen things up" so the solder can be sucked out of the hole.


Nuts. It doesn't need fresh solder, it needs fresh flux. The fresh
solder contains the flux, but it also contains a healthy dose of what
you're trying to remove. Much better to just add a drop of flux.


The solder in a joint can wind up having a much higher melting point and
much less wetting ability than it did when it was initially applied. That's
because it amalgamates to the material being soldered to some degree. If the
joint was the least bit overheated initially, or upon re-heating for
removal, it can be a fairly high degree.

You notice it more trying to unsweat copper plumbing. Sometimes you have to
wet the joint with some fresh solder to get it to come apart. But I've run
into the same thing taking components off of an old board.

--
Ed Huntress


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Default Desoldering question (Miller XMT welder repair)

On 2008-01-30, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
Ignoramus19508 fired this volley in
:
I think that I would like to find Cirk-Grind device and also should
buy more tips. This is actually a very nice station if I get it to its
potential. I do have a manual for it also.


Iggy, it's been a while since I had my Pace, but IIRC, those tips are
plated with Indium/Nickle alloy to prevent them from being wetted by or
amalgamated with the solder -- even in the bore. Thus, don't use a hard
tool to clean the bore; use a plated copper lead from a resistor, etc.
If you scratch the bore, it quickly begins to corrode and amalgamate with
solder.

I think I still have some 0.025 tips for that. If I can find them, I'll
drop 'em in an envelope.


Lloyd, this is awesome, thanks.

i
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Default Desoldering question (Miller XMT welder repair)

Another question. These circuit boards were originally sprayed with
some coating. I surmise that the purpose of it is to prevent
accidental shorts due to dust contamination or other debris being
drawn into the unit.

This was, in fact, a great thing, as this particular welder had so
much dust inside, that I was shocked. The amount of dust was nothing
short of incredible, maybe 5 lbs of dust settled on absolutely
everything. I took this welder out of its protective shell, vacuumed
it, and then blew the dust out using compressed air (outdoors). The
truly amazing thing, is that it was still functioning fine with all
that dust inside.

Thanks to the Miller company.

Having said that, I would like to apply that coating to the areas that
I re-soldered. What is that coating?

i


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Default Desoldering question (Miller XMT welder repair)

Ignoramus19508 wrote in
:

snip
everything. I took this welder out of its protective shell, vacuumed
it, and then blew the dust out using compressed air (outdoors). The
truly amazing thing, is that it was still functioning fine with all
that dust inside.

snip

NOooooooooo, you blew away all of the magic dust!!!! Now it will surely
self destruct when you need it the most. Never blow away the magic dust,
it annoys the tool gods..

Bill
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Default Desoldering question (Miller XMT welder repair)



Having said that, I would like to apply that coating to the areas that
I re-soldered. What is that coating?



You can buy cans of conformal coating at a good electronics shop. Vetco near
me carries it, I'm sure you can find it online as well.


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Default Desoldering question (Miller XMT welder repair)

In article ,
Bob La Londe wrote:
"Dave Plowman (News)" wrote in message
...
In article ,
Bob La Londe wrote:
Two words.


Solder wick.


You don't have a proper desolder tool, then? ;-)


I have several solder suckers. In close quarters sometimes solder wick
does the trick, and it always works. I've got one of those big blue
nasty things, and a couple of smaller aluminum solder suckers. In
close quarters I still find myself reach for the solder wick.


A solder sucker ain't the same as a desolder station. Of course solder
wick is useful but the desolder station works for pretty well everything
here. But probably too large an investment for occasional use.

--
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Dave Plowman London SW
To e-mail, change noise into sound.
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A solder sucker ain't the same as a desolder station. Of course solder
wick is useful but the desolder station works for pretty well everything
here. But probably too large an investment for occasional use.



A good compromise are those suction bulb desoldering irons, I've used one
for probably 15 years now. I never had any luck at all with the separate
solder suckers, it's too hard to apply heat and suction at the same time. I
keep wick around too, neither is a one size fits all solution.


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Default Desoldering question (Miller XMT welder repair)

In article CB4oj.962$Be.475@trndny04,
James Sweet wrote:
A solder sucker ain't the same as a desolder station. Of course solder
wick is useful but the desolder station works for pretty well
everything here. But probably too large an investment for occasional
use.


A good compromise are those suction bulb desoldering irons, I've used
one for probably 15 years now. I never had any luck at all with the
separate solder suckers, it's too hard to apply heat and suction at the
same time. I keep wick around too, neither is a one size fits all
solution.


Snag with both of those is two hands needed - which usually means rigidly
mounting the work piece.

--
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Dave Plowman London SW
To e-mail, change noise into sound.


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Snag with both of those is two hands needed - which usually means rigidly
mounting the work piece.




Not with the suction bulb desoldering iron, I'm not sure how you'd use it
two handed if you wanted to..


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In article _08oj.16738$8i.11504@trndny09,
James Sweet wrote:
Snag with both of those is two hands needed - which usually means
rigidly mounting the work piece.


Not with the suction bulb desoldering iron, I'm not sure how you'd use
it two handed if you wanted to..


I've not used one but I'd have thought trying to hold it steady on the
joint while operating the bulb with one hand might be a tad tricky?

--
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Dave Plowman London SW
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"Dave Plowman (News)" wrote in message
...
In article _08oj.16738$8i.11504@trndny09,
James Sweet wrote:
Snag with both of those is two hands needed - which usually means
rigidly mounting the work piece.


Not with the suction bulb desoldering iron, I'm not sure how you'd use
it two handed if you wanted to..


I've not used one but I'd have thought trying to hold it steady on the
joint while operating the bulb with one hand might be a tad tricky?



Not at all, you hold it in your hand with your thumb on the bulb, it's
really easy to use. I'd rather have a vacuum operated desoldering station
but this fits in my toolbox. Only real trick is to keep a fresh tip on it,
when they wear out they don't get a good seal.

http://projects.jheiv.com/images/blo...ing%20Iron.jpg


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I cant help but ask why dont you take the solder sucker device apart and
check out the problem ?

You were able to repair the welder .

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On Wed, 30 Jan 2008 09:34:29 -0600, Ignoramus19508
wrote:

:On 2008-01-30, Ross Herbert wrote:
:
: Your desoldering tool (like most) is probably fitted with a small diameter
tip
: (approx 0.8mm - 1.00mm inside diameter)
:
:Yes.
:
: designed for sucking solder from around small gauge component leads
: and IC pins where the tip make full peripheral contact with the
: board. When the solder melts around a pin all the air passes solely
: around the lead and maximum effect is achieved inside the through
: hole.
:
:Well, it does this pretty well with a real vacuum pump attached
:instead of the "desoldering station pump".

Yes, of course it will. But the desoldering station pump is NOT a specialised
1/3HP vacuum pump. It is designed as being adequate to suck solder from around
component pins ONLY when the nozzle completely surrounds the lead AND make 100%
peripheral contact with the pcb solder pad.



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"Ross Herbert" wrote in message
...
On Wed, 30 Jan 2008 09:34:29 -0600, Ignoramus19508
wrote:

:On 2008-01-30, Ross Herbert wrote:
:
: Your desoldering tool (like most) is probably fitted with a small
diameter
tip
: (approx 0.8mm - 1.00mm inside diameter)
:
:Yes.
:
: designed for sucking solder from around small gauge component leads
: and IC pins where the tip make full peripheral contact with the
: board. When the solder melts around a pin all the air passes solely
: around the lead and maximum effect is achieved inside the through
: hole.
:
:Well, it does this pretty well with a real vacuum pump attached
:instead of the "desoldering station pump".

Yes, of course it will. But the desoldering station pump is NOT a
specialised
1/3HP vacuum pump. It is designed as being adequate to suck solder from
around
component pins ONLY when the nozzle completely surrounds the lead AND make
100%
peripheral contact with the pcb solder pad.


Well Ross, I gotta tell you that I use my Weller desoldering station just
about every day, I keep the same sized tip on it with a 1mm hole at all
times. It is used both for pin sizes where the hole will fit over the pin,
as you describe, and also for any other joint that I need to get the solder
off as well. I have never had a problem with it developing enough suck to
remove solder from a joint that requires the tip to be applied in a way less
than your stated 'ideal', unless it has reached the point where it needs
servicing. I think that in common with most soldering / desoldering tools,
it depends on how often you use it, and hence how much skill in its use,
that you have developed.

Arfa


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"Bill" wrote in message
. 97.142...
Ignoramus19508 wrote in
:

snip
everything. I took this welder out of its protective shell, vacuumed
it, and then blew the dust out using compressed air (outdoors). The
truly amazing thing, is that it was still functioning fine with all
that dust inside.

snip

NOooooooooo, you blew away all of the magic dust!!!! Now it will surely
self destruct when you need it the most. Never blow away the magic dust,
it annoys the tool gods..

Bill


Oh Boy ! Now he's REALLY in trouble ... Does he not realise that the magic
smoke is kept in by this thick layer of magic dust ????

Arfa


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Default Desoldering question (Miller XMT welder repair)

Bob La Londe wrote:

"Dave Plowman (News)" wrote in message
...
In article ,
Bob La Londe wrote:
Two words.


Solder wick.


You don't have a proper desolder tool, then? ;-)


I have several solder suckers. In close quarters sometimes solder wick does
the trick, and it always works. I've got one of those big blue nasty
things, and a couple of smaller aluminum solder suckers. In close quarters
I still find myself reach for the solder wick.


None of those little solder suckers compare to a real properly
functioning desoldering station. When I spent a summer working at a
fiends stereo repair shop we had the Hako deoldering stations and I
could desolder blown output modules faster than you could even uncoil
your solder wick.
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Default Desoldering question (Miller XMT welder repair)

"Ed Huntress" writes:

The solder in a joint can wind up having a much higher melting point and
much less wetting ability than it did when it was initially applied. That's
because it amalgamates to the material being soldered to some degree. If the
joint was the least bit overheated initially, or upon re-heating for
removal, it can be a fairly high degree.


You notice it more trying to unsweat copper plumbing. Sometimes you have to
wet the joint with some fresh solder to get it to come apart. But I've run
into the same thing taking components off of an old board.


I've also noticed that I often need to add solder to make a second try
at unsoldering a component lead if the solder sucker didn't get
everything on the first try. I theorize (but can't prove) that the
extra solder is sometimes necessary to carry heat all the way down into
the plated-through hole, to melt the solder all the way through the
hole.

If the component that's being removed has nice fat copper leads, those
can carry heat pretty well (assuming you can make good enough contact
between the iron tip and the lead). But IC leads don't seem to be
terribly good heat conductors. A nice bit of liquid solder does a
better job of conducting heat from the iron tip down into the PCB hole.

Dave
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None of those little solder suckers compare to a real properly
functioning desoldering station. When I spent a summer working at a
fiends stereo repair shop we had the Hako deoldering stations and I
could desolder blown output modules faster than you could even uncoil
your solder wick.




I don't think anyone who's used one can argue against it being the superior
choice, but wick and other methods have their place, they fit comfortably in
a small portable toolbox.




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Just a little update. I found a certain adjustment that I adjusted
and the vacuum increased very substantially. I think that this station
is perfectly usable now as it is.

i
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"Dave Martindale" wrote in message
...
"Ed Huntress" writes:

The solder in a joint can wind up having a much higher melting point and
much less wetting ability than it did when it was initially applied.
That's
because it amalgamates to the material being soldered to some degree. If
the
joint was the least bit overheated initially, or upon re-heating for
removal, it can be a fairly high degree.


You notice it more trying to unsweat copper plumbing. Sometimes you have
to
wet the joint with some fresh solder to get it to come apart. But I've run
into the same thing taking components off of an old board.


I've also noticed that I often need to add solder to make a second try
at unsoldering a component lead if the solder sucker didn't get
everything on the first try. I theorize (but can't prove) that the
extra solder is sometimes necessary to carry heat all the way down into
the plated-through hole, to melt the solder all the way through the
hole.

If the component that's being removed has nice fat copper leads, those
can carry heat pretty well (assuming you can make good enough contact
between the iron tip and the lead). But IC leads don't seem to be
terribly good heat conductors. A nice bit of liquid solder does a
better job of conducting heat from the iron tip down into the PCB hole.


That's probably true, but there's also a lot of amalgamation going on.
That's why copper soldering iron tips get pitted from solder; it amalgamates
with the copper. Notice that the pasty glop on a soldering iron that isn't
continuously re-tinned (or that has an iron-plated tip) has a higher melting
temp. When you wipe the glop off and re-tin, it runs a lot easier. The same
is true in a soldered joint.

--
Ed Huntress


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Default Desoldering question (Miller XMT welder repair)

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.

You say "built in", that has the diaphragm pump in the power
supply box, or a Ped-a-Vac venturi vacuum generator that runs
off compressed air? Either way, there are likely disc-type
filters in the line that become clogged with flux residue.
The old ones had filters that you could pop open and replace the
elements in, the new ones are "non-repairable". But, I found
you can drip rubbing alcohol through the hole, let it sit a
while and repeat a couple times, allowing the alcohol to drip
out onto a paper towel. When the drips come out clean without
staining the towel, the filter is magically rejuvenated.
(Note the box may have ANOTHER disc filter hidden inside, it may
also be dirty.)

Second, there is a wad of felt in the glass tube inside the
handpiece that also becomes saturated with fine solder dust and
flux. I have not found those to be recoverable due to the
non-soluble dust. I got a bag of them with the machine, so I'm
probably set for life.

Third, the hole in the desolder tip fills with oxidized solder.
I have to rod the hole out every half hour or so when using one
a lot. I just use some handy solid wire and jam it in, twist it
around and pull it out, suddenly the "Suck" is audibly stronger.
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?

I'll bet your filters are clogged. I have a motorized one at
work and a compressed air one at home. Whenever I hav a
problem, it is the filters or the tip.

Jon
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Ignoramus19508 wrote:
Just a little update. I found a certain adjustment that I adjusted
and the vacuum increased very substantially. I think that this station
is perfectly usable now as it is.

i


This is the knob that throttles the OUTPUT pressure? Yeah, it
chokes off the outlet of the pump, thereby killing its vacuum
capability, too.

Jon
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You can easily build your own inexpensive welder.
www.green-trust.org/equipment.htm
cuhulin

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