Weller station gone bad--how to fix?

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

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senecal@mapson.cs.ucdavis.edu

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

Kal

Reply to
Kalman Rubinson

A bad thermostat is a likely cause.

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7 days!


Michael A. Terrell
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Michael A. Terrell

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.

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.

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Dave Platt                                    AE6EO
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Dave Platt

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

Reply to
Mike W

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

Bob Stephens

Reply to
Bob Stephens

Probably so. A material's Curie point (or temperature) is the temperature at which, when heated, the material ceases to be able to support/retain a magnetic field, and any existing magnetic field is randomized.

Heating a permanent magnet above its Curie temperature demagnetizes it.

The slugs used in the Weller tips have Curie temperatures of 600, 700, or 800 degrees F (plus or minus a bit, I imagine).

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Dave Platt                                    AE6EO
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Dave Platt

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

Reply to
G.Beat

Josh -

Let's deal with your problem and Facts.

The WTCP series base only provides 24 volts - that's it - its a transformer in a base. The "brains" of the temperature control is the tip working in concert with the SW60 switch assembly The WTCP series has a unique click as the SW60 switch engages and disengages - turning the heater on and off to maintain the specific temperature engraved on the base of the removal tip.

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)
  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.

If iron exhibits identical problem - then the SW60 requires replacement (shorted closed).

All parts for this specific model (WTCPS) are available from Wessco (So. California). Wessco also just ended a 1/2 price sale on Weller "PT" series tip in November ($ 2.25 each)

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

Reply to
G.Beat

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

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Michael A. Terrell
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Michael A. Terrell

The only heat sensing element in the WTCP? series is the lump of metal at the tail end of the tip. The correct tips for this iron will have a separate bit there with a single digit stamped in it. That's normally a 7, for 700 degrees F.

The alloy of this lump is chosen to have a Curie temp of 700F and it will never change.

There is a magnet that runs down toward the tip and is attracted to the tip when the tip is below its Curie point. Once the temp reaches the Curie temp the lump no longer attracts the magnet and the magnet is pulled back upwards by a small spring. This opens a switch in the handle and turns off the heating element.

The usual problems with these are that something gets inside the sleeve behind the tip and jams the magnet so it can no longer move, or the switch contacts weld closed.

With the iron off and cold you can remove the tip retaining sleeve. When you pull the tip out you should feel the pull of the magnet and then feel the switch and magnet snap back into the barrel once the tip is too far away to attract the magnet. You should repeat this to verify that the magnet is free to move.

If you unplug the iron from the base and put an Ohmmeter on the pins of the iron, you should see the continuity come and go as you take the pin in and out.

Weller is owned by Cooper Tools and PDF files of replacement parts are available on their web site.

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----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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Reply to
Jim Adney

Mike -

Sounds like I will have to get the scanner (for Acrobat Reader creation) warned up this weekend - :-)

The Weller Tech Sheets (WTCP/ WTCPL; WTCPN; WTCPS and WTCPL) were available directly from Weller (free) -- but have not asked for them --- since the factory was moved from the Carolinas to Mexico last year.

Greg

(shipped

the

Reply to
G.Beat

Bugger me - I'm glad you lot are not troubleshooting a nuclear power station! The Weller WTCP must be one of the simplest decent temperature controlled irons on the market, mine runs 15hrs/day and does so year in / year out. Sometimes more when I forget to turn it off - the new ones dont have the neon in the mains switch so it does happen - I have

2 of them now, one on each bench...

Test procedure.

  1. Runs continually, therefore base station and element OK.

  1. Check switch - unscrew bit retainer and remove (iron off). Pull tip in and out - should hear click if switch working. If not, then switch or tip faulty.

  2. LOOK at tip, see if mangnet thingo at bottom has fallen of - if so, buy new tip (and after all the years youve had it, I wonder if it could solder anything except 2 wires together, my tips last about 3 months on average, I buy them by the half dozen). If tip defective, completely dismantle iron and remove magnet from switch assembly.

  1. If tip OK (go on, be a devil, buy a new one anyway....) then switch faulty. Buy new one.

  2. Exception to item 4 - if you have done bugger all maintenance to your iron, clean the garbage out of the barrel - it is rare for switches to fail "on" (never had one do it, as a matter of fact, but have only been using Wellers for 20 years so it COULD happen...) - use a bamboo satay skewer to clean out the crap, then follow procedure 2.

Hope this helps,

de VK3BFA Andrew (at 50, an "official old grump")

Reply to
Andrew VK3BFA

I have heard this from some other user - but I have tips that last years - BUT I only use the 700 degree tips.

A spare tip should always be available on the bench. I just repaired an older WTCPN station an the college student had placed an "ET" tip (aka tips are all the same right! - wrong) from the Weller EC1000/EC2000/WES50/WES51 models. Glowed cherry red -- changing to the proper tip -- corrected problem.

I saw my first internally shorted SW60 last year (although I think the user had wacked it against a hard surface to cause this type of damage). I also have seen a "kinked" spring -- near as I can tell -- originally assembled that way -- over a decade earlier. I never saw a heater fail as shorted (dead short - but not heating) until last year -- all previous ones failed as "open". See enough stations and you see many failures, bad operating practices and unique equipment abuse.

Reply to
G.Beat

I want it for the same reason I want manuals for all of my equipment. It saves a lot of time locating part numbers when you do a repair. I have used, and repaired, these soldering stations off and on for years, but I always had to wait for the distributor to look up the part numbers.

BTW, I don't do nuclear power, but I did build and test telemetry equipment used by NASA, including a KU band receiving system aboard the International Space Station.

The Weller stations were banned from the production line because of a surge in leakage current when the thermostat tripped in the heating element, and we were required to use irons with grounded tips that could reliably measure under three ohms from the hot tip to the electrical ground on the bench. They were replaced with Ungar "Loner" irons with electronic temperature control.

I used a spare DMM connected between ground and a piece of scrap copper to quickly test the resistance any time any of the three irons had sat idle. I used the irons so many hours a day they tips only lasted a few weeks before the iron plating was pitted, and would no longer go below three ohms. I threw out a lot of tips that could have been used in non ESD situations, but we couldn't risk someone reusing a bad tip, so they went into the recycling bin with other solder related scrap.

I have five dead Weller soldering stations I picked up that will need new irons, after someone tried to "Fix" them, and left the irons in pieces.

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6 days!


Michael A. Terrell
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Michael A. Terrell

OK - As long as we have all this Weller knowledge here, who has the secret stash of tips for the W200 iron? Yes, they made a 200 watt iron with the magnetic temperature control, but I have been unable to find parts for many years. Can't find W200 on the Weller web site.

Thanks in advance.

user

I
Reply to
BFoelsch

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.

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.

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.

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 snipped-for-privacy@mapson.ucdavis.edu, removing the reversed "nospam" first.

-Josh, AE6IQ

Reply to
Joshua G Senecal

I have picked up a number of NOS Weller items (no longer in production) this past year (from a number of sources) -- due to the relocation of the Weller production facilities in the Carolinas to Mexico.

You can call Weller (North Carolina) and ask for Mr. Larry Smith (who is Weller's product line manager and engineering support) IF Weller is no longer making the part, Mr. Smith or "Dino" who leads the repair center -- was know of a source !

Greg

many

years -

as

short -

Reply to
G.Beat

Actually Collins radio used the original TCP stations (black bakelite) on their productions lines and for repair in the 1950s and 1960s (5 of these from Collins surplus were the first ones that I repaired in

1975 - as I started college)

The original ones did not have the switch OR neon bulb ... and they ran 24 hours/day at Collins.

Darn shame, but components have changed as well as their tolerance to ESD.

I assume the later WTCPS and WTCPT models? In addition to the ESD requirement, "T" model changed the 3 amp fuse on the transformer's secondary (to protect transformer from a heater short) to a 6/10 amp fuse on the transformer primary (and an MOV across primary on some models).

Greg w9gb

Reply to
G.Beat

I don't know which model they were using. They were pulled from the production floor a year before I was hired. They were in storage in a separate building, and I was never able to get my hands on them They were probably destroyed last year when the plant was closed and moved to Pennsylvania. I kept hearing the old timers complain about the new irons because they had used the Wellers for years, and didn't like to do the extra maintenance on their "Loner" irons.

--
4 days!


Michael A. Terrell
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Michael A. Terrell

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