Using old tips?

[Kevman]

Years ago, my grandfather was the machinist at the manufacturer of the world's first portable ultrasound machine, the Site-Rite. Anyway, one day they threw out 2 soldering stations- an edsyn 951sx and a Weller TC202. My grandfather grabbed them, gave my dad the Edsyn and kept the Weller.

The Edsyn has since proven itself throughout much of my dad and I's mad science, but I was just given the Weller, as my Grandfather is in a home now.

Like I said, the base is a TC202. I can't find any markings on the iron itself other than its 42W. It appears to work OK, but  solder appears to just bead off of the tip like water off a freshly waxed car. There's a total of four tips and I've only tried one so far.

Is there anything I should do to such old tips to make them solder-worthy again? Or just use them as they are? Or throw them out and buy new ones? Is it even it worth it? I think 'm going to have to disassemble it to get it clean again (I think it sat in a room that was getting drywalled...) Is there anything else I should do to get it working well?

I really like the iron itself- it has an excellent feel and the cable is superduper supple. But its not temp adjustable like the Edsyn, and the one strain relief appears to be going bad...

By the way, there's more, much older electronics to be found. You may see some interesting pictures/teardowns in the future. 

[sleemanj]

Tip cleaner paste.

Or, flux, scrub in brass wool, flux, solder, scrub, flux, solder, scrub, repeat until you get it clean

[Ian.M]

https://physics.ucsd.edu/neurophysics/Manuals/Weller%20Tech/Weller%20Tech%20Sheet%20WTCPR.pdf

They are great irons - not as versatile as a temperature controlled solder station but a real bench workhorse.   Unfortunately the iron plating on the bits tends to oxidize if you don't look after them (e.g. leave them on a long time without use or freshening the solder on the bit, and it can then be a right PITA to retin the bit without resorting to abrasives that will destroy the plating.  If the plating is damaged, like any bare copper bit it will erode fairly quickly, so don't use a file or abrasive unless you are prepared to order a new bit the same day, though that's a perfectly reasonable thing to do to an otherwise unusable bit to hold you over till the new bit arrives.

They use magnastat bits that control the temperature and the optimum temperature bit for most purposes is one ending -7.  -6 don't get hot enough for general soldering and -8 are so hot they have a short life so should be switched off immediately after use though a chunky 5mm PTDD-8 bit is very useful to have for transformer and heatsink tags and for screening cans if you don't also have a 100W weller soldering gun.

The SW60 magnetic switch assembly in the handpiece becomes unreliable with age and tends to suffer from burnt contacts.  Its the first suspect for failure to heat if power is present.   It is however serviceable - dismantle the handpiece, remove the cover from the contact end and dress the contacts with a folded strip of fine wet&dry paper then clean thouroughly with switch cleaner - and spares are still available at a price.  If I was still running a Weller TCP iron and the switch became unreliable, I think I'd rewire with a 4 wire cable and plug then fit a SSR or TRIAC in the base unit so the switch no longer has to carry the approx 2A heater current.

[BurningTantalum]

Ian M. -
I too had that idea of the triac in the base unit of a Weller, but I never found any 4 core flexible cable, preferably silicone.
I loved the Weller TCPs - we used them at work and mine was switched on at 08.30 and off at 16.30 5 days a week for years. The only failure was the contacts in the little yellow switch. We could swap the irons in the factory stores for a new one whenever we needed to, so I had a heap of spares at home but the handle was a tight squeeze to get the connectors back inside when dismantled for a new switch block.
 I regret having a clear out and tossing the irons and bases. The iron stand was probably the best ever design (the worst being the Antex...) - the iron could be 'tossed' back into the plastic funnel many thousands of times with no ill effects. The production shop used them too so they must have been resilient.
BT

[Ian.M]

Fore core flex in silicone *is* available.  Here's some 7.6mm stuff from RS: http://uk.rs-online.com/web/p/multicore-industrial-cable/7142283/
The problem is finding a supplier of the appropriate diameter range with a cut reel who'll sell by the meter. . . .

[Kevman]

All 4 tips that I have are 8s- which I guess is too hot? Does that mean 800F?

I opened it up with the intention of gutting so I could scrub the case without worry- but I think its a little too late to worry about harming the insides....

 

This is pretty bad. Even the case screws are rusty. Is this transformer even safe? I'm kinda regretting turning it on before opening it up.  I guess it works...

I've never seen a transformer built like this, either. Its like its just a core clamped around 2 coils...?

[Ian.M]

That looks pretty fugly, and is likely to be due to a previous user wetting the sponge in-situ and flooding the base.   As it works, the damage probably hasn't compromised the insulation.   An insulation test is obviously called for, and if it passes that, I would suggest treating the rust on the core using boiled linseed oil or better Owatrol if you have any handy to stabilise it and prevent further deterioration. As far as possible, keep it off the windings.  Once its cleaned up as much as possible and treated the insulation should be checked again.   You should also check earth continuity to the shaft of the iron and fix any bad connections if its more than an ohm or so.

The standard bit a Weller TCP iron comes with is a PTAA-7 and the cooler 700 deg F bit is certainly far easier to keep tinned.  *IF* it survives a soak test after the above, you might treat it to one!

Post a closeup of the four bits taking care to show the flat surface if any have one and we may be able to suggest something less drastic than taking a file to them.

[Kevman]

Hey guys,
    I know this is bump but I've finally gotten around to fixing this thing up. Check out the updated pix below. I scraped most of the rust off with a paint scraper and cleaned the rest off with a brillow pad. I then linseed oiled the core. The core turned out to a single large sheet of steel wrapped into a coil.

Most of the what I thought was dirt on the outer casing turned out to be damage so it looks as good as its going to get.

I also have the best pic I could take of the 4 tips. Sorry, I don't have a macro lens or anything like that.

However, there's a more pressing issue than the tips right now- I don't think the temp control is working. My Fluke thermocouple is only specified to 750F so I measured it with my infared thermometer and read over 900F. It was a little all over the place, though (small target), so I hooked up a Kill a Watt to it and looked for the power consumption to fall when it cycled off. No such thing happened- just a straight 52 watts falling to 48 as it heated up.

I guess I have to take the handle apart and have a look. If it looks OK inside I'll guess I'll just try another tip.

[Ian.M]

That has cleaned up very nicely - at a previous employer, I used worse for several years!

The two tips on the left look to be FUBAR - the iron plating on the conical section between the tip and the shank appears to have corroded through.  the second from right looks possible - if the dark crud on the face of the bit is superficial and cleans up with a fibreglass abrasive pencil.  The one on the right is probably the best one.

You can confirm whether or not the temperature control is working by either measuring the transformer output voltage or current.  The voltage rises by a volt or two when the magnastat switch in the iron opens. If you don't see it cycling (period around a minute or so idling in the rest), either the magnastat switch contacts have welded or the switch shaft with its little magnet on the end is seized in the center of the heating element.  Some care is required when dismantling the iron as the plastic frame that holds the contact tags and grips the cord has two locating pegs that are supposed to clip into holes in the heating element flange, and they are usually cooked to the point of breaking off, and the three p0lastic bosses in the handle shell that the screws through the flange go into are often also cooked and split/broken.  The element wiring is also rather fragile and great care must be taken not to yank on it when tilting the frame to the side so you can slide the magnastat switch out of the element.

[Kevman]

I've already had it apart and back together. Didn't think to snap any pics, though. Everything is still intact, and the switch contacts looked like new inside. I cleaned them up a little but I don't think it needed it.

I think that measuring the consumption at the wall almost has to work for measuring the cycling- I can't imagine the quiescent power consumption of the transformer being very much.

The hot end of the magnaswitch is very magnetic- is it supposed to be?

[Richard Crowley]

The hot end of the magnaswitch is very magnetic- is it supposed to be?

Yes, that is how it regulates the temperature. The back-end of the tips are made of an alloy with a different Curie Temperature (or Curie Point) for each temperature.  For example your tip that says "800F" has a Curie Point of 800 degrees Farenheit (425 deg C)

Another approach is to use magnetized soldering tips which lose their magnetic properties at a specific temperature, the Curie point. As long as the tip is magnetic, it closes a switch to supply power to the heating element. When it exceeds the design temperature it opens the contacts, cooling until the temperature drops enough to restore magnetisation. More complex Curie-point irons circulate a high-frequency AC current through the tip, using magnetic physics to direct heating only where the surface of the tip drops below the Curie point.[3]
https://en.wikipedia.org/wiki/Soldering_iron#Temperature-controlled_soldering_iron

I have an old Weller soldering station just like that and it is still going string with tips that are several decades old.

[Kevman]

Nope, Its definitely not working- even with a different tip. The whole tip and part of the retainer has started to glow...

[Ian.M]

If you carefully pop the plastic cover off the end of the switch assembly, the contacts should be open with no bit fitted or the switch assembly removed from the heater, and closed with a cold bit fitted, or with the far end of the switch assembly flat against a chunk of iron or mild steel.   

If the contacts are welded, pry them apart with a sharp knife and dress smooth.

If its seized, it *may*  be possible to free it up by applying a few drops of penetrating oil to the rod vanishing into the switch shaft, gripping the nut holding the moving contact and gently working it in and out.  If you succeed in freeing it up, you *MUST* wash all the penetrating oil out with no residue contact cleaner. A trace of PTFE dry lube applied to the rod may be beneficial. 

[Kevman]

Ok, it was definitely in the closed position with no tip. I'll have to go back in.

have to wait for it to cool back down, though.

[Kevman]

Well, after much fighting and cursing and begging and grabbing of brass with pliers, I finally have it cycling. 



I don't know how long its going to last, though. The rod barely moves, so there's little margin for the contacts to work with. You can hear it clicking, though.

 I guess I'll try using the surviving two (one is completely torched from me testing it for cycling) tips for a while and if it keeps working I'll order some 700F tips for it. If not I'll probably toss it- It seems hard to justify spending $35 for a switch when a brandy new hakko fx-888d can be had for $90.

Thanks for the help!

BTW, it consumes 7 watts when the heater is off, 50 with it on.

[Ian.M]

Its normal for the <expletive> switch to barely move, and replacements aren't made as well and may not last.

There's a topic about modding a TCP iron and base to add a TRIAC to vastly extend switch life, without changing the cord/plug here: http://www.vintage-radio.net/forum/showthread.php?t=67035. In addition to the TRIAC, I would add a LED in the base to indicate element power on.  A simple half wave rectifier, a small reservoir cap so it doesn't flicker, and the usual series resistor would be needed.  That way you can spot if the LED stops cycling, and if it jams on, shut it off before it glows!

Check the resistance of the iron, heater to earth at its plug with the bit fully up to temperature to see if there is any leakage that could cause problems for the TRIAC before conversion. Worst case, a SSR may be needed with a 10K resistor across its 'coil' terminals to reduce its sensitivity.