Weller EC1201A Soldering Handle Failure

For the last few days, my trust Weller EC1000 soldering iron (well, station) has been misbehaving: shortly after cleaning the tip, it would become covered in charred residue and slag. Today, the LED I’d hacked across the heater terminals inside the base stayed dark, even though the tip was hot, and then became sensitive to the handle position. Obviously there’s a loose wire inside, right?

So I took the handle apart by removing the two screws on the front plate:

Weller EC1201A soldering handle innards
Weller EC1201A soldering handle innards

The trick to getting the guts out is to push down on the tab inside the handle that locks the cord strain relief block into the handle. After that, everything comes apart with very little force at all.

Contrary to what I thought, the heater is in the tube surrounding the temperature sensor probe. Looking at the connector on the front of the base unit, the key is on the left side and the wires going clockwise from above the key are:

  • Yellow: heater
  • White: heater
  • Black: sensor
  • Red: sensor
  • Green: shield

I would have sworn the red & black were the heater, as they have special-looking brass/bronze/copper colored pins & sockets. Wrong again.

The temperature probe comes apart thusly:

Weller EC1201A temperature probe disassembly
Weller EC1201A temperature probe disassembly

Basically, slide the connector and ceramic-coated sensor out of the back of the black shell, then pull the spring-loaded sheath out the front.

I hoped for a laying-on-of-hands fix, but it was not to be: the tip heats while the LED (which I wired there early in the iron’s life) across the heater power remains off. But the LED blinked on intermittently with slight pressure on the iron’s tip; a bit more poking and prodding isolated an intermittent open-circuit to the ground wire just outboard of the strain relief at the handle:

Soldering iron cable failure
Soldering iron cable failure

A bit more poking & tugging isolated an intermittent high-resistance short (a few hundred ohms, more or less) to a section of cable half a foot from the base connector at the bottom of the cable’s natural loop when the iron’s in the holder.

Unfortunately, fixing all that didn’t restore the iron to life. It seems that the temperature sensor (a thermocouple?) has failed, allowing the tip to heat well beyond any rational temperature. Now that I’m looking, a cleaned solder layer turns blue with oxidation in a matter of seconds and rosin chars instantly. The temperature control knob has no effect whatsoever.

The date codes inside the box show it’s been with me since late 1982, so on a dollars-per-year basis the thing has been a bargain. A new sensor is $60, a new handle is twice that, and I think it’s time for a new iron… at less than the price of the sensor alone, I think that’s OK.

6 thoughts on “Weller EC1201A Soldering Handle Failure

    1. I just got a Hakko FX-888 and (in the US) it comes in any color combination you want, as long as you want yellow-on-blue…

      Even if it does look like a toy, it works wonderfully well!

  1. My Weller TCP201 (bought used at a yard sale in 1978) finally gave up on being reliable. I have replaced the temp probe guts only once since 1978. Last overhaul was in the 1990’s, so while it still works most of the time in an an “almost” temperature contolled manner, the flakiness and age got to me as I walked past the FX-888 at the local Fry’s.

    I’m quite happy with my Hakko unit. Fast Heat, good temperature control, at a reasonable price. The Weller is now “under the bench” as an emetrency backup unit.

    1. I’m quite happy with my Hakko unit.

      Same here. I’d have repaired the Weller, but the price differential was so daunting (and the lack of a sure fix somewhat intimidating) that I couldn’t get the project past the Financial Review Board…

  2. Does it actually use a sensor (NTC/PTC), or is it the good old simple and reliable version with the magnetic tips that, as it heats up to Curie-temperature, loses magnetism and switches a reed switch? (Magnastat, as Weller calls it).

    If it’s the last one, it’d probably only take a new reed switch. Not sure if these are easily available, but one tip I was given was to solder a.s.a.p. a diode (1N540x) across the switch. That trick greatly reduces the loads on the reed switch as it continually switches on and off again, under load. The diode ensures that in ‘off’ mode there’s still half the power available (using a transformer as supply, either the positive or negative periods); as it turns ‘on’, the current draw is much smaller.

    From someone who has been using good old Weller stations all of his professional life, he says it makes the soldering iron last for the rest of one’s life.

    1. Does it actually use a sensor (NTC/PTC)

      Yup, that’s the one. I have no idea what manner of sensor they stuffed inside the heater barrel, but the control board inside the iron has half a dozen trimpots surrounding a surprisingly small dab of circuitry. Pure solid state stuff, though, not a clicky switch anywhere.

      I cycled all the twiddlepots (breaking the lock-goop to do so), reseated all the connectors, and generally messed around with everything possible, all to no avail.

      It’s in a box, awaiting a very unlikely moment when I have nothing better to do…

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