Weller Soldering station EC2100M

I have my son's Weller EC2100M unit on my bench to take look at.

This is the one where the iron does not have the magnastat thingy and it is the Station that digitally displays temperature and the operator adjusts the temperapture from a knob on the front.

However, the temperature will not adjust. Upon switch on the unit displays the rising temperature which stops at 550C. At this point the iron tip is red hot!

I was dismayed to find a largish microprocessor inside (4 MHz clock crystal operating ok) along with another programmable 8 pin chip plus an op-amp a triac and 5 volt reg. All surface mount:-(

The regulator and triac check out ok.

Anyone got this unit and had any experience like this?

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Broken wire in the lead to the temp sensor/thermocouple ?

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** Yep - and it was always a faulty iron.

Either terminations on the cable or the temp sensor has died.

Spare heater elements and irons are normally available.

.... Phil

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Phil Allison

550C is just over 1000F, that's hot, and if the iron isn't shutting down, then you have a switch problem with in the triac circuit..

I'll give you some insight with triac's, sometimes one half inside shorts out and you'll get 59% duty to the iron and it won't show on a diode test.

Disconnect the gate to the triac and tie it off to prevent it from triggering.. See if the iron still heats. If so, replace the triac.

If it deos not heat, then walk you're way back in the gate circuit and look for something that looks like optical coupler. This maybe a 6 pin or 4 pin chip and it could be yellow packaged and some times black. using an ohm meter, check to make sure the coupler isn't shorted on the output. if that passes.. Then check for the presents of a pulse on the input side of the coupler.

One other item you want to check and that is the possible use of a snubber cap network around the triace, they some times short. I've seen poor designs use MOV's for this.

There is also the possibility the triac is connecting the common side to the wand and the wand has shorted against the common. That would be the heater element lead wires.. You can check that with a ohm meter too.


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