The MOV (Metal Oxide Varistor) is a surge supressor whose only function
is to absorb the "kick" when the mechanical thermostat opens (or
"bounces" when closing). The one in the Weller unit (if memory serves)
clamps the voltage at about 40 volts (Transformer secondary is 24 VAC).
If it isn't working properly the thermostat contacts arc and weld shut,
causing runaway overheating.

Frank Dinger wrote:

While you're at it, check one more thing! If the problem turns out to be
welded contacts on the thermostat switch, check that the MOV across the
secondary of the transformer is still good. I had one that repeatedly
welded the contacts till I replaced the MOV and has worked for 5 years
now without a problem.

=============================
Not having such a Weller soldering iron myself ,nevertheless I am interested
in the MOV (firing) voltage against the normal operating voltage . Also , is
it DC or AC ?

Frank GM0CSZ / KN6WH

The MOV (Metal Oxide Varistor) is a surge supressor whose only function
is to absorb the "kick" when the mechanical thermostat opens (or
"bounces" when closing). The one in the Weller unit (if memory serves)
clamps the voltage at about 40 volts (Transformer secondary is 24 VAC).
If it isn't working properly the thermostat contacts arc and weld shut,
causing runaway overheating.

Frank Dinger wrote:

While you're at it, check one more thing! If the problem turns out to be
welded contacts on the thermostat switch, check that the MOV across the
secondary of the transformer is still good. I had one that repeatedly
welded the contacts till I replaced the MOV and has worked for 5 years
now without a problem.

=============================
Not having such a Weller soldering iron myself ,nevertheless I am interested
in the MOV (firing) voltage against the normal operating voltage . Also , is
it DC or AC ?

Frank GM0CSZ / KN6WH

While you're at it, check one more thing! If the problem turns out to be
welded contacts on the thermostat switch, check that the MOV across the
secondary of the transformer is still good. I had one that repeatedly
welded the contacts till I replaced the MOV and has worked for 5 years
now without a problem.
=============================
Not having such a Weller soldering iron myself ,nevertheless I am interested
in the MOV (firing) voltage against the normal operating voltage . Also , is
it DC or AC ?

Frank GM0CSZ / KN6WH

While you're at it, check one more thing! If the problem turns out to be
welded contacts on the thermostat switch, check that the MOV across the
secondary of the transformer is still good. I had one that repeatedly
welded the contacts till I replaced the MOV and has worked for 5 years
now without a problem.

Joshua G Senecal wrote:

On Fri, 19 Dec 2003, G.Beat wrote:
Wow, I didn't think that my question would generate so many responses!
Thanks everyone for your input.


The Red-Glow tells you 2 things:

1. The heater (Weller EC234) is still working (but you are shortening its
life operating in this manner - cherry red)


Well, I don't operate with it cherry red. This is the first time it's done
that--hence my knowing that something is amiss.


2. The WTCP series temperature control (which works with the "PT" tip and
the SW60 switch) is not working properly.


Recommend: Change tips. Improper tips will cause this problem.
Get a Weller PTA7 (which is the standard tip shipped with this iron).
The barrel net (BA-60 may also require replacement.


I'll take a look and see. The station came with two tips, both #7, but in
the 11-odd years I've owned the iron I've never used the second one.


I also have the Weller Tech Sheet for this model -- if you need
a copy. This has part numbers, diagrams and troubleshooting advice (shipped
with every unit new)


Actually, I would like a copy, thank you. Since I got mine at a yard sale
I don't have any documentation. Please e-mail to
, removing the reversed "nospam" first.

-Josh, AE6IQ

"G.Beat" wrote:

I also have the Weller Tech Sheet for this model -- if you need
a copy. This has part numbers, diagrams and troubleshooting advice (shipped
with every unit new)

Yes, I will consider repairing for you - but it would have to be after the
holidays.
Greg
Repairing the Weller WTCP series since 1975

I would like a copy of that, if you don't mind.

--
7 days!


Michael A. Terrell
Central Florida

On Fri, 19 Dec 2003, G.Beat wrote:
Wow, I didn't think that my question would generate so many responses!
Thanks everyone for your input.

The Red-Glow tells you 2 things:

1. The heater (Weller EC234) is still working (but you are shortening its
life operating in this manner - cherry red)

Well, I don't operate with it cherry red. This is the first time it's done
that--hence my knowing that something is amiss.

2. The WTCP series temperature control (which works with the "PT" tip and
the SW60 switch) is not working properly.

Recommend: Change tips. Improper tips will cause this problem.
Get a Weller PTA7 (which is the standard tip shipped with this iron).
The barrel net (BA-60 may also require replacement.

I'll take a look and see. The station came with two tips, both #7, but in
the 11-odd years I've owned the iron I've never used the second one.

I also have the Weller Tech Sheet for this model -- if you need
a copy. This has part numbers, diagrams and troubleshooting advice (shipped
with every unit new)

Actually, I would like a copy, thank you. Since I got mine at a yard sale
I don't have any documentation. Please e-mail to
, removing the reversed "nospam" first.

-Josh, AE6IQ

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!

It is VERY EASY to fix / repair the Weller WTCP units.

First, Are you positive you have the CORRECT TIP in this iron.

It MUST BE A Weller "PT" style tip - other Weller model tips such as the ET
series will cause this problem and damage the iron.

Greg
w9gb


"Joshua G Senecal" wrote in message
...
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.