Seeking advice on new iron/handle for old soldering station (thermocouple sensor type)

Thread Starter

Nick_D

Joined Dec 20, 2023
2
First post here, so hopefully this is an appropriate post for this section :)


I have an old soldering station (Micron - pre 1990s) that needs a new iron (lack of tip availability, corrosion of original sleeve). The station belonged to my grandfather and is something of a sentimental piece, so I'd love to get it back into action. Will be soldering mostly through hole, and some SMD (SOT23).

The heater element measures 12 ohms (heater) and 1 ohm (thermocouple sensor). Supply from station is 24V AC, and the old handle states 48 watts.

I'd love some suggestions on what would be a good compatible replacement handle with compatible thermocouple sensor-based heater. I've seen irons such as the Yihua 907A, which I believe would work (and fits 900m-type tips) , but looks of dubious quality.

What would be a good bang for buck iron, with good tip availability that would fit my station? Can I get something decent for 50 bucks or less? I've looked around, but am a bit lost at this point.

Any advice would be greatly appreciated!

Cheers
Nick
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KeithWalker

Joined Jul 10, 2017
3,147
I built my own soldering station using the 936 soldering iron, 24V 50W from AliExpress. I have been using it for a number of years now without any problem. It cost about $5.00. It uses a type K thermocouple and should work well with your soldering station. Of course, you will probably need to change the connector. Make sure you connect the thermocouple the right way round or you will get thermal runaway!

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Dodgydave

Joined Jun 22, 2012
11,320
The 907a has a K type thermocouple and the element is 2ohms, your psu might take more current than needed, the hakko 936 has a 48 ohms element.
 

KeithWalker

Joined Jul 10, 2017
3,147
Tha Haako 936 work station is 24VAC. It works with the Haako 907 or 908 Iron. Either of those should work with the Micron controller. The 24V, 50W irons listed in AliExpress are just called "Baku 936 soldering iron". That Is the one with a K type thermocouple that I use.
 
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Thread Starter

Nick_D

Joined Dec 20, 2023
2
Tha Haako 936 work station is 24VAC. It works with the Haako 907 or 908 Iron. Either of those should work with the Micron controller. The 24V, 50W irons listed in AliExpress are just called "Baku 936 soldering iron". That Is the one with a K type thermocouple that I use.
Thanks for that information Keith! I had a quick look on AliExpress and found the Baku. Cheap too, as you said! I'll be hardwiring the iron into my station, at least with a screw terminal on the inside. How have you found tips fit with this handle?

I don't suppose you have a measure of the heater/thermocouple resistances for your iron by any chance? I can't for the life of me find any reference on the net. Likewise, the numerous A1322 replacement elements for sale - no mention of those crucial specs. I guess I could just buy a bunch and see what fits....

It's asking a lot, but if you had the time to probe your iron's plug for those numbers, I'd be super grateful.

Your station looks killer btw. Good work.

Thanks again

Nick
 

KeithWalker

Joined Jul 10, 2017
3,147
The sensing element is a thermocouple so it measures less than one ohm. K-type thermocouples all generate the same voltage per degree. What is really important is to wire it the right way round. Warm the iron up with your hand while measuring the voltage across the thermocouple. You should see a small voltage. Make a note of which wire is positive. Do the same with the old iron, so you can connect the new one correctly.
The tips are listed as 900-M. I ordered from the URL below. I have not had to replace a tip since I built the station. I use a conical tip most of the time. I made a second station for heavier duty work, using the same style handle with the larger chisel tip. You can easily change tips with this style of handle.
When you test the new iron, start with the lowest temperature setting, just in case there is a problem. Be ready to switch it off if it gets too hot. Good luck.

https://www.aliexpress.com/item/1005005338503372.html?spm=a2g0o.productlist.main.25.50de41efIm3jFS&algo_pvid=d7399d4e-4594-4ace-ac74-9265bfe41caa&algo_exp_id=d7399d4e-4594-4ace-ac74-9265bfe41caa-12&pdp_npi=4@dis!CAD!3.34!1.67!!!17.29!8.64!@2101fb1917128439125037800e6dd7!12000032663528746!sea!CA!164618267!&curPageLogUid=X4IZgdCsC4D3&utparam-url=scene:search|query_from:
 
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