Dick Smith T-2200 soldering station element failure

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I know there are a few Aussie and Kiwi members in here who should be familiar with this unit.
They are a rebranded xytronic station and parts are readily available.
Anyway it has not had a huge amount of use over the time I've had it, I bought it new before Dick Smith shut up shop.
In that time I had to replace the element and I suspect the issue was with the thermistor inside.
What would happen was the needle on the temperature meter would oscillate for a bit before it heated up, progressively it would get worse and either not heat up, or not stop heating and the tip would glow red.
I replaced the element and all was sweet. I have not used it much in that time over the last 3 years or so after replacing it and now I've noticed the same symptoms again!
My question is this, is there something in the electronics of the soldering station itself the cause of failure, or is it just coincidental that I've had a bad run of faulty elements?
These soldering stations were a good workhorse at my first place of work 20 years ago and we had zero issues with them.
Now before anyone says something, I do have other irons, I have a TS-80 that also has had a failed tip that burned out, am waiting for my replacement to arrive and have been making do with the T-2200 for the time being only to discover that I'm having this start to fail.
Either way, it's a good soldering station and I intend to keep it as a second unit, it's a bit of nostalgia more than anything.
Would be interested to hear if anyone else has had similar issues.

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Bump

[Chris56000]

. . .Can you post some pics & the Xytronic equivalent model please?

There might be a circuit online we can assist you with!

Chris Williams

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Apparently it's based on this model which is still made today.
Only difference being its got a digital meter.
Original model would be a 168-3C
http://www.xytronic-usa.com/shop/item.aspx?itemid=236

[seronday]

I had the same problem with my T2200 solder station with the temperature meter jumping around when first turned on and progressively becoming worse over time.

The temperature sensor that is imbedded in the barrel assembly seems to be a K type thermocouple.

At one stage I attached an external K type thermocouple sensor to the solder iron tip and connected it to the temperature sensor input on the control board.  The temperature meter and control circuit then worked correctly.
After that I fitted a replacement barrel assembly and so far that issue has not re-appeared.

Attached is a copy of my hand drawn circuit for the control board.

Regards.

[Nzoomed]

I had the same problem with my T2200 solder station with the temperature meter jumping around when first turned on and progressively becoming worse over time.

The temperature sensor that is imbedded in the barrel assembly seems to be a K type thermocouple.

At one stage I attached an external K type thermocouple sensor to the solder iron tip and connected it to the temperature sensor input on the control board.  The temperature meter and control circuit then worked correctly.
After that I fitted a replacement barrel assembly and so far that issue has not re-appeared.

Attached is a copy of my hand drawn circuit for the control board.

Regards.

That's interesting, perhaps it's a common problem?
Do you think there is a faulty batch of the things or something?
It's a bit strange how I have had two of them fail on me.
Would be interested to know if this is a common thing seen with xytronics soldering irons.
I might be available to slip in a new thermocouple inside the  barrel assembly and see how that goes.
Was just wondering if any other fault in the electronics could lead to the thermocouple failing?

[Andy Chee]

My original element had an open circuit thermocouple, heater circuit would never turn on.

But yes, years ago when I bought a replacement heater barrel from eBay, I've also encountered an intermittent oscillation in the temperature control.  I noticed when I turned the temperature control down, the oscillation would cease, and then I could turn the control back up again.

So I'm not sure whether it's possibly a temperature range calibration issue that I never performed with the new heating barrel.

[Bigfoot]

I bought one of these Solder Stations from a DSE store when they went bust some years ago for $1. The element had been unknowingly faulty in the box.  Anyhow I fixed it recently by replacing the hand piece with a Chinese YAXUN 936 50W 24V unit which can be had on Aliexpress for around $7 . These have ESD protection but you can ignore the 5th conductor . 

There are four other conductors two for heating element and two for thermocouple. You just need to get the thermocouple polarity correct. I'm satisfied with the result , it heats up correctly with the meter needle matching the dial setting.

  I dismantled the original hand piece and desoldered the incoming conductors , did the same with the new Chinese one and fed the T-2200 cable up the 936 hand piece , resoldered the conductors and reassembled.  The tips are cheap enough too at $4 per 10.