Unknown soldering iron question - UK Vintage Radio Repair and Restoration Discussion Forum

Techman · 31st Jul 2021, 6:44 pm

These two soldering irons came in a box of electrical bits and pieces from someone I know who gets given stuff and then passes on to me what he doesn't want and I was wondering what base they would have originally gone with. The chap I got them from thought they were 24 volt and I note that one of them has a label marked 'US', so would seem to indicate it to be faulty. They are fitted with 5 pin 'mic' style socket plugs and the one marked as 'US' has obviously had its wiring altered onto different pins, the other one looks to be original.

On the 'originally' wired one I'm getting around 12 ohms between pins 1 & 2 which is green and red. I'm getting around 2 ohms between pins 4 & 5 which is yellow and blue. On the probably faulty one I'm getting 2 ohms only between yellow and blue and nothing between any of the others.

Does anyone know anything about these particular irons and whether I can hook them up to make any sort of use out of at least one of them, keeping the probably faulty one for handle parts and a spare bit?

duncanlowe · 31st Jul 2021, 6:54 pm

My thoughts were Maplin. https://www.maplin.co.uk/maplin-a40k...-5055189030992

Techman · 31st Jul 2021, 7:08 pm

Well spotted! Thanks.

My guess is that the 12 ohm connection is the element and the 2 ohm connection is to a temperature sensor of some sort.

duncanlowe · 31st Jul 2021, 7:26 pm

Quote:

Originally Posted by Techman

Well spotted! Thanks.

My guess is that the 12 ohm connection is the element and the 2 ohm connection is to a temperature sensor of some sort.

My thought would have been the other way round. 2 ohms for a sensor means that any connection resistance would have a significant effect on the sensing. Whereas 2 ohms would likely increase quite fast to something reasonable for a heater (a bit like lightbulb filaments are very low resistance when cold).

MotorBikeLes · 31st Jul 2021, 7:43 pm

Get another iron to heat it up and see how the two resistances change. The one with the biggest change will be the sensor.
Be very cautious about applying 24v. I have one of the Chinese two station jobs, and a failure meant no control, and the barrel was glowing in double quick time. Followed by burn out if you don't switch off quickly.
Les.

Radio Wrangler · 31st Jul 2021, 9:19 pm

Quote:

Originally Posted by duncanlowe

My thought would have been the other way round. 2 ohms for a sensor means that any connection resistance would have a significant effect on the sensing. Whereas 2 ohms would likely increase quite fast to something reasonable for a heater (a bit like lightbulb filaments are very low resistance when cold).

2 Ohms would be OK for a thermocouple, and as that's a voltage source working into a high Z load, then cable resistance isn't important.

David

Techman · 1st Aug 2021, 1:00 pm

Thanks everyone for the thoughts and suggestions. I gently heated it in a gas flame and the 2 ohm resistance started to increase on a DMM, but I quickly noticed a '-' indication on the scale, so immediately changed to a voltage range and there was in fact an increasing voltage that went from 3mV to over 10mV during the test, so yes, it is a thermocouple that must feed back this small temperature dependent control voltage to the base that it would have been fitted to. The other 12 ohm connection did indicate a slight increase as you might expect a heating element to do when warmed up.

peterpiper · 1st Aug 2021, 1:29 pm

Hi, Its a Hakko T12 or a clone of. It needs a controller (check the net) and a 19v power supply i.e. Laptop. Great iron I've used it for 4 years

Peter

Techman · 1st Aug 2021, 1:37 pm

Hi, thanks for that information, I was wondering if anyone would know the make, I'll check it out.

Electronpusher0 · 3rd Aug 2021, 7:57 am

Quote:

Originally Posted by peterpiper

Hi, Its a Hakko T12 or a clone of. It needs a controller (check the net) and a 19v power supply i.e. Laptop. Great iron I've used it for 4 years

Peter

Agreed, cheap controller clones are available from e-bay, ali etc. Just make sure you get the right one, there is also a Hakko clone iron and controller that uses a thermistor not a thermocouple and the seller's tend to use the same number for both. I have bought several that turned out to be the opposite of what was listed.

Peter

Keith956 · 3rd Aug 2021, 8:25 am

Yes it's a Hakko clone. Also sold by RS as the RS Pro.

Beware: they can have totally different wiring of the sensor/element connections in the plug.

Also the sensor resistance is different for different versions, as I found out when trying to replace one.

31st Jul 2021, 6:44 pm	#1
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Unknown soldering iron question These two soldering irons came in a box of electrical bits and pieces from someone I know who gets given stuff and then passes on to me what he doesn't want and I was wondering what base they would have originally gone with. The chap I got them from thought they were 24 volt and I note that one of them has a label marked 'US', so would seem to indicate it to be faulty. They are fitted with 5 pin 'mic' style socket plugs and the one marked as 'US' has obviously had its wiring altered onto different pins, the other one looks to be original. On the 'originally' wired one I'm getting around 12 ohms between pins 1 & 2 which is green and red. I'm getting around 2 ohms between pins 4 & 5 which is yellow and blue. On the probably faulty one I'm getting 2 ohms only between yellow and blue and nothing between any of the others. Does anyone know anything about these particular irons and whether I can hook them up to make any sort of use out of at least one of them, keeping the probably faulty one for handle parts and a spare bit? Attached Thumbnails

31st Jul 2021, 6:54 pm	#2
duncanlowe Nonode Join Date: Jan 2016 Location: Stafford, Staffs. UK. Posts: 2,531	Re: Unknown soldering iron question My thoughts were Maplin. https://www.maplin.co.uk/maplin-a40k...-5055189030992

31st Jul 2021, 7:08 pm	#3
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Unknown soldering iron question Well spotted! Thanks. My guess is that the 12 ohm connection is the element and the 2 ohm connection is to a temperature sensor of some sort.

31st Jul 2021, 7:43 pm	#5
MotorBikeLes Nonode Join Date: Dec 2012 Location: Kirk Michael, Isle of Man Posts: 2,350	Re: Unknown soldering iron question Get another iron to heat it up and see how the two resistances change. The one with the biggest change will be the sensor. Be very cautious about applying 24v. I have one of the Chinese two station jobs, and a failure meant no control, and the barrel was glowing in double quick time. Followed by burn out if you don't switch off quickly. Les.

1st Aug 2021, 1:00 pm	#7
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Unknown soldering iron question Thanks everyone for the thoughts and suggestions. I gently heated it in a gas flame and the 2 ohm resistance started to increase on a DMM, but I quickly noticed a '-' indication on the scale, so immediately changed to a voltage range and there was in fact an increasing voltage that went from 3mV to over 10mV during the test, so yes, it is a thermocouple that must feed back this small temperature dependent control voltage to the base that it would have been fitted to. The other 12 ohm connection did indicate a slight increase as you might expect a heating element to do when warmed up.

1st Aug 2021, 1:29 pm	#8
peterpiper Tetrode Join Date: Jul 2016 Location: Renfrew, Renfrewshire, UK. Posts: 93	Re: Unknown soldering iron question Hi, Its a Hakko T12 or a clone of. It needs a controller (check the net) and a 19v power supply i.e. Laptop. Great iron I've used it for 4 years Peter

1st Aug 2021, 1:37 pm	#9
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Unknown soldering iron question Hi, thanks for that information, I was wondering if anyone would know the make, I'll check it out.

3rd Aug 2021, 8:25 am	#11
Keith956 Heptode Join Date: Jun 2019 Location: Oxfordshire Posts: 737	Re: Unknown soldering iron question Yes it's a Hakko clone. Also sold by RS as the RS Pro. Beware: they can have totally different wiring of the sensor/element connections in the plug. Also the sensor resistance is different for different versions, as I found out when trying to replace one.