RadioBanter - Weller station gone bad--how to fix?

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Weller station gone bad--how to fix?

Weller sells, through distributors, replacement parts. I suggest that
you replace the temp-sensing tip element, as a start.

Kal

On Thu, 18 Dec 2003 08:32:49 -0800, Joshua G Senecal
wrote:

Hi all,

I have a Weller WTCPS soldering station with a 201U power supply and 201P
iron, using a 700 degree F tip. Last night I powered it up in preparation
for soldering some connectors, and a few minutes later I saw that the tip
and metal shaft of the iron were glowing red-hot.

Any ideas as to what is causing this, and will it be cheap to fix? Are
there any checks I can do to diagnose the problem? Or should I just dump
the thing and buy a new one? I bought the station over 11 years ago, in
practically new condition, at a yard sale for $5, so I got my money out
of it, but if a reliable fix is cheaper than purchasing a new soldering
setup I'd rather go that route.

Thanks!

-Josh, AE6IQ

Joshua G Senecal wrote:

Hi all,

I have a Weller WTCPS soldering station with a 201U power supply and 201P
iron, using a 700 degree F tip. Last night I powered it up in preparation
for soldering some connectors, and a few minutes later I saw that the tip
and metal shaft of the iron were glowing red-hot.

Any ideas as to what is causing this, and will it be cheap to fix? Are
there any checks I can do to diagnose the problem? Or should I just dump
the thing and buy a new one? I bought the station over 11 years ago, in
practically new condition, at a yard sale for $5, so I got my money out
of it, but if a reliable fix is cheaper than purchasing a new soldering
setup I'd rather go that route.

Thanks!

-Josh, AE6IQ

--

Remove the reversed "nospam" in the address.

A bad thermostat is a likely cause.
--
7 days!

Michael A. Terrell
Central Florida

Hi all,

I have a Weller WTCPS soldering station with a 201U power supply and 201P
iron, using a 700 degree F tip. Last night I powered it up in preparation
for soldering some connectors, and a few minutes later I saw that the tip
and metal shaft of the iron were glowing red-hot.

Any ideas as to what is causing this, and will it be cheap to fix?

I would guess that the fault lies in the iron, not in the station base.

If I recall correctly, the station base is simply a stepdown
transformer. It plays no part at all in the temperature regulation.

The temperature is regulated via a rather elegant (I think)
implementation in the iron. At the base of each tip, there's a slug
of a ferromagnetic material. The properties of this slug are
controlled during manufacture, so that it will change from a magnetic
to a nonmagnetic state at a specific temperature (e.g. 700 F).

Inside the shaft of the iron there is a switch with a magnet on the
end. When the tip is below its transition temperature, the magnet is
attracted to the ferromagnetic slug on the back of the tip, the switch
is pulled forwards, the contacts close, and current flows through the
iron's heating coils. When the tip reaches its desired temperature
the ferromagnetic slug becomes non-magnetic, the magnet in the shaft
"loses its grip", the switch is pulled backwards by a spring, the
contacts open, and the current to the heating coil is interrupted.
You can hear (and feel) a gentle "thick" when the magnet switch pops
back and forth.

It's a nice negative-feedback system. It allows the use of a rather
high-amperage heating coil and transformer (which can heat up the tip
quickly when powered on, and restore heat taken out of the tip by the
soldering process), and yet allows any of several temperature ranges
to be selected by changing the tip. It seems to be quite robust...
I've heard very few reports of failure.

It seems that you have a failure. I would guess that the switch has
failed... either it's become jammed, or the spring has broken due to
metal fatigue. [It's possible that the ferromagnetic slug has somehow
magically changed its properties and now has a transition temperature
several hundred degrees higher, but that seems _very_ unlikely to me!]
In any case, the heating coils are running full-time - you've got no
temperature regulation - because the switch isn't opening.

Are
there any checks I can do to diagnose the problem? Or should I just dump
the thing and buy a new one?

You can probably replace the switch (or, worst case, the whole
iron-and-handle assembly) for rather less than the cost of a new
station. The transformer and line cord, and whatever tips you may
have purchased, are almost certainly OK.

It might be worth disassembling the iron, and seeing if a sharp "rap"
on the side of the iron shaft will dislodge the switch.

If not, you could check with Weller to find out about getting a
replacement switch. The current incarnation of this product is the
WTCPT, using a TC201T iron. Mouser sells the complete TC201T iron for
around $72 (roughly half their cost for the whole station). The SW60
switch for this iron sells for around $26 - you'd probably need to
check with Weller to confirm that this switch is the same one used
in (or is compatible with) your older 201P iron.

$26 to restore this station to full life would be a very worthwhile
investment. I spent about $100 for a WTCPT iron close to 15 years ago
and have never regretted it. I used to go through cheap $15-$25 irons
every couple of years, through cheap tips a lot faster than that, and
I'd burn up components (or have difficulty getting a clean joint) and
cuss a lot. The WTCPT hasn't hiccoughed even once, and I have yet to
have to replace the original tip which came with it.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On Thu, 18 Dec 2003 18:08:22 GMT, "Michael A. Terrell"
wrote:

Joshua G Senecal wrote:

Hi all,

I have a Weller WTCPS soldering station with a 201U power supply and 201P
iron, using a 700 degree F tip. Last night I powered it up in preparation
for soldering some connectors, and a few minutes later I saw that the tip
and metal shaft of the iron were glowing red-hot.

A bad thermostat is a likely cause.

Agreed, had it happen myself. Not sure about the specific model but
ISTR the thermostat is in, and indivisible from, the element.

The "bit" has a lump of Iron with certain temperature chararistics (
peltier effect ? ). When the temperature exceeds the Iron magnetic
ability the element switch, ( with a magnet on the actuating arm ),
drops out until the Iron, ( this is the Iron on the bit ), regains its
magnetic ability.
KISS in its best form. I have managed to "unstick" the magnet before
now, but its a bugger to do.
Sorry I can't describe the operation in a more scientific language,
but I'm sure someone will ba able to... ;-)

hth Mike W, G8NXD

The temperature is regulated via a rather elegant (I think)
implementation in the iron. At the base of each tip, there's a slug
of a ferromagnetic material. The properties of this slug are
controlled during manufacture, so that it will change from a magnetic
to a nonmagnetic state at a specific temperature (e.g. 700 F).

Inside the shaft of the iron there is a switch with a magnet on the
end. When the tip is below its transition temperature, the magnet is
attracted to the ferromagnetic slug on the back of the tip, the switch
is pulled forwards, the contacts close, and current flows through the
iron's heating coils. When the tip reaches its desired temperature
the ferromagnetic slug becomes non-magnetic, the magnet in the shaft
"loses its grip", the switch is pulled backwards by a spring, the
contacts open, and the current to the heating coil is interrupted.
You can hear (and feel) a gentle "thick" when the magnet switch pops
back and forth.

I've heard this sort of Iron referred to as a "Curie Point" Iron. Is this
the same thing?

Bob Stephens