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Weller WTCPT tip not hot enough

Discussion in 'Electronic Repair' started by George Orwell, Aug 23, 2008.

  1. I have a Weller WTCPT soldering station with the stock TC201T handle and
    PTA7 700 degrees F. tip. It's 15 years old and hasn't seen much action. I
    was using it a lot 3 years ago but for the past 2 years it's been sitting
    cold in the garage.

    The past couple times I've used it lately the tip just didn't seem to get
    as hot as I remember. You know how it is with equipment you use for a long
    time, you get to know the behavior and what's normal. When I put the
    heated tip against the sponge, I barely get much of a sizzle. Solder barely
    melts but does melt, just barely though.

    I've gone through the troubleshooting guide Weller provides for this
    station, all appears normal. I have 27.3VAC from the power unit. Heater
    element reads 12.9 ohms. The "magnastat" opens and closes when the tip is
    inserted and removed. Unfortunately the guide doesn't cover a warm tip,
    only one that's stone cold or too hot. I don't know what else to check.

    I can hear the tip cycling when I turn on the base. It just seems that the
    heater doesn't stay on long enough like it used to. Do the tips somehow
    lose their temperature calibration? Is it time for a new soldering
    station? Any opinions on the WESD51?

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  2. Jamie

    Jamie Guest

    Lead Free Solder in use?"
  3. Jim Adney

    Jim Adney Guest

    These are great stations, but many of them have one common flaw: One
    of the crimped female pins in the base, where you plug in the iron, is
    often crimped onto solid wire, and that connection will go bad within
    about a year of reasonable use. Once that connection goes bad, it will
    heat up and destroy the plastic connector body, so the best thing to
    do is to fix it before it gives problems. When we used to buy these
    new, I would fix this in new units before they were ever turned on.

    If you have a large selection of pin remover tools you may have one
    that will work on these, but I've often had to make do with a bit of
    rolled up soda can alum sheet. It's tedious, but you really only HAVE
    to remove the one solid wire. The stranded crimps will be fine.

    Once you get the pin out, just solder it and put it back.

    My guess is that this is what's happened to your station. The power is
    being split between the heater and the connector. It's also possible
    that the switch in the iron handle is going bad. That certainly
    happens, but usually only after a lot of use.

    The Magnestat control depends on the Curie temp of the alloy in the
    little slug at the end of the tip. That will never change.

    It's a little confusing that you say you can hear the Magnestat
    control switching back and forth. This is normal, but it should only
    happen if the tip is reaching it's 700 F Curie temp. This one
    observaion makes me wonder if you're just not remembering how it used
    to work.

    Even if it doesn't happen to be the problem right now, it's still a
    good idea to solder that pin, because it will save you headaches down
    the road.

  4. You say you "can hear the tip cycling". If that's the case, it would seem
    that there can't be anything wrong with the electrical parts. The tip
    cycles based on reaching the curie temperature of the magnet.

    Have you tried a new tip?

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  5. N_Cook

    N_Cook Guest

    Remember to replace the shroud that screws on and retains the tip, it is
    part of the magnetic "circuit" and if absent causes that sort of problem.

    Also if you're careful , ie parallel jaw pliers, you can pull off the
    magnastat of a worn tip and change the temp on another good but wrong temp
  6. Eeyore

    Eeyore Guest

    I prefer 800 degrees. Always have done. Esp with small tips. The idea is to get
    the soldering done as fast as quickly, not leave the joint cooking until the
    solder finally melts.

    I've seen plenty of 'cold' / 'dry' joints arising from the use of 700F tips. I
    even told the manufacturing dept of a certain company to change to 800F tips
    for a certain process but they moaned that 'the tips wear out faster'. So the
    returns rate went up again Bloody idiots.

  7. Eeyore

    Eeyore Guest

    Well there is the issue of lead-free solder too which requires a 50C (90F) or so
    hotter tip.

  8. Eeyore

    Eeyore Guest

    Your reply address suggests you are in Italy. But why are you using dizum ?

    Are you unaware of the extra temperature required to melt the lead-free solder
    now mandated in the EU ?

  9. Arfa Daily

    Arfa Daily Guest

    Just to be clear though, only mandated for items placed on the market after
    June 2006, and which don't have a waiver. Items manufactured prior to that
    using conventional leaded solder, can continue to be repaired / reworked /
    modified with leaded solder and non RoHS compliant components. New items for
    non commercial i.e. amateur use, can still be constructed in whatever
    component and solder technology you like.

  10. Eeyore

    Eeyore Guest

    Absolutely, although we have no idea what he's soldering. I still prefer 800F
    tips for quick neat soldering.

  11. Arfa Daily

    Arfa Daily Guest

    I still use 700s because of the problem of 800s burning out quicker when
    left idling all day, but I might try 800s again, if only for the improvement
    on the dreaded lead-free. I only said about the RoHS regs because there will
    be a lot of people reading the thread, who perhaps wouldn't understand the
    implications of the legislation. A while back, there was a lot of confusion
    and misconceptions about what it meant to the service industry, not helped
    by a couple of trade bulletins on the subject which were put out by at least
    one major Jap manufacturer, and one soldering equipment manufacturer, and
    which gave entirely the wrong impression. It was this which prompted me to
    write the article.

  12. Jim Adney

    Jim Adney Guest

    No, it's not part of the magnetic circuit. The magnestat works just
    fine without the sleeve. The only problem is that without the sleeve,
    when the tip becomes non-magnetic at the Curie temp it falls out of
    the iron.
    Now THAT's a useful tip! Thanks.

  13. Jim Adney

    Jim Adney Guest

    I have to disagree. 700 F is already way above the melting point of
    the solder. If you need more heat you might want to use a larger tip,
    with greater thermal mass, but higher temps are much more likely to
    damage the board.
    Good soldering technique will not give cold solder joints, regardless
    of the tip temp. High tip temp is probably a poor way to overcome poor
    technique. Using a higher temp iron will certainly pump more heat into
    the joint in a given time, but it also results in more temp difference
    across the joint, so you may be more likely to get what looks like a
    good joint on the heated side, but with little penetration.

    We've been using Rohs solder for quite a few years now, and I don't
    have a bit of trouble with it using a 700 F tip.

  14. Arfa Daily

    Arfa Daily Guest

    I would absolutely dispute that statement

    I would suggest Jim, that it does rather depend on what exactly you are
    soldering. If you are making consistently good lead-free joints with a 700
    deg Weller tip in all circumstances, then you are doing a lot better than
    most of the major manufacturers. Since they started using the stuff, the
    service industry has seen a huge leap in bad joints - and not always in
    'traditional' places where you might expect to find them.

    Whilst you are correct in that a 700 deg tip melts lead-free solder, it does
    not do so anything like as well as it does with leaded solder. Although
    lead-free solder does not have as nice a melt / flow characteristic as
    leaded in the first place, this undesirable quality is made much worse by
    not having enough temperature on it - particularly when soldering a
    component with a high thermal inertia, such as a connector or power
    semiconductor. The fact that lead-free solder is much worse at wetting most
    of the metals commonly used in electronic circuit construction, further
    exacerbates the problem, and dictates that more aggressive fluxes are used
    in the hateful stuff. Unless these are given the opportunity to do their
    work, by allowing them to reach the temperatures they need to at the
    soldering surface, then the likely result will be a bad joint - and one
    that's invisible to the naked eye, and may not give trouble for some time,
    at that. Many bad joints in lead-free that I come across in daily work, show
    no signs of external distress at all (except that *all* lead-free joints
    look distressed), and do not respond to tapping, freezing or heating. The
    only conclusion has to be that whilst the solder has stuck ok to the copper
    pad, it hasn't to the component leg inside the joint. Probably, a classic
    example of the 'cold' joint that engineers your side of the pond, are fond
    of calling them.

    Use of a bigger tip to improve its own thermal inertia, is not an option
    these days for general electronic service work. A finely pointed conical or
    small screwdriver tip, is the order of the day. Component pin densities, and
    component placement densities, are such that only a small tip and fine gauge
    solder are appropriate in most cases, and it's just not a practical
    proposition to keep changing tips, depending on what exactly is on your
    bench at the time.

    When Weller came up with the 700 deg tip, it was with a traditional tin lead
    solder alloy in mind. It is the tip that has always been supplied with these
    irons from new. Lead-free melts at a temperature of 30 to 50 deg F higher
    than leaded, so based on Weller's determination of 700 deg being appropriate
    for leaded solder, you would have to extrapolate this thinking to come up
    with a tip temperature of perhaps 750 deg, which is what I have both my
    variable temperature controlled station, and vacuum desoldering stations set
    to, for lead-free work.

    So I'm with Graham on this one (who is, like me, experienced in daily
    soldering over many many years) in that for lots of lead-free work with a
    Weller Magnastat iron, the best combination is a small tip, but with a lot
    of heat behind it in the form of it being an 800 deg rated one. I don't
    dispute that you can make good joints in lead-free with a 700 deg tip, as I
    do it myself, but it does require very considerable care and experience to
    'do it right'. There are now more appropriate soldering tools on the market
    for lead-free work, than the good old TCP irons.

    There are some interesting notes here about why the 'standard' tips burn out
    quickly, when used with lead-free

  15. Smitty Two

    Smitty Two Guest

    I'm with Graham on this one. I threw all the Wellers in the dumpster a
    few years back (tired of fixing them all the time) but when we did use
    them we used nothing but 800 degree tips.

    Now we've got another brand of iron with dial adjustable temperature and
    keep them set at 800, also. For the hobbyist or even repair tech,
    waiting two or three seconds for a small joint to heat up might be
    acceptable, but for production work it isn't.

    And as far as board damage, higher temps are much *less* likely to
    damage the board, and the components, because dwell time is drastically

    Finally as to reduced tip life at higher temps, that cost is offset by
    increased efficiency 1000 times over.
  16. Rich Webb

    Rich Webb Guest

    On Tue, 26 Aug 2008 10:56:32 +0100, "Arfa Daily"
    Interesting phrase there: "Clean the tip on a watery swamp." That one
    required a quick mental recalibration...

    On that issue, though, what are your thoughts on the use of brass
    turnings as a tip cleaner vice a dunk in the swamp? I switched over to
    the bowl of brass a while ago and now prefer it to the damp sponge.
  17. Jim Yanik

    Jim Yanik Guest

    my own experience is that dwell time is more critical in regards to PCB
    damage.I used 800 degF tips,too.
  18. Eeyore

    Eeyore Guest

    I don't let that happen and re-tin and wipe the tip regularly. I probably
    'waste' as much solder as I use !

    Plus Farnell IIRC sells some aggressive (iron) oxide remover that can help
    restore a 'damaged' tip. It comes in a little circular tin.

    Fair comment.

  19. Arfa Daily

    Arfa Daily Guest

    I have some, and jolly good it is too, although I wonder just how much
    that's eating away at the tip, as well ...

  20. Jim Yanik

    Jim Yanik Guest

    IIRC,that has some powdered solder mixed in with the flux.
    It cleans AND tins.

    (of course,AFAIK,it's not lead-free....)
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