soldering irons

[Nick Clarke 3Participant @nickclarke3]

Talking to a retired TV engineer – it was frequently the case for TV repairmen to leave the earth wire disconnected on their soldering irons when working on live chassis TVs – especially important when working in a workshop with others apparently.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Nick Clarke 3 on 11/11/2022 08:15:58:

Talking to a retired TV engineer – it was frequently the case for TV repairmen to leave the earth wire disconnected on their soldering irons when working on live chassis TVs – especially important when working in a workshop with others apparently.

I can think of a good reason why they did that, but it's a special case, not normally recommended.

Usually, it's better to have the tip earthed. Personal safety is one reason, another is that many modern electronic devices are easily destroyed by static electricity. Working with these, which come in anti-static packaging, it's usual to earth the operator as well!

Because there's a high-risk of damaging electronics by poking about inside live equipment with a metal rod, it's usual to disconnect and to discharge any big capacitors gently with a resistive probe before soldering anything. The heyday of TV engineers was when televisions relied on thermionic valves, that took a few minutes to warm up before a repair could be checked. Although valve circuitry is unreliable, the individual components were quite robust, so it's possible for a busy repairer to save time by diagnosing fixing certain common faults working on a live chassis. It's quite dangerous though: valve televisions operated at high voltages, with plenty of amps, without an isolating transformer, and the chassis was rarely earthed. A Radio Rentals friend described becoming stuck to the live EHT line of an early colour TV set (about 40,000V) because his muscles locked up. He was saved by a co-worker who pushed him off his stool. Got away with a deep burn, but once in a while people were hospitalised or killed.

As a general rule, "Don't mess with safety unless you understand what you're doing! " In this case, if the pros and cons of an earthed tip are a mystery, don't disconnect the earth and don't use a soldering iron on live circuits. And remember a percentage of the experts who do understand the risks get caught out occasionally.

Dave

 

Edited By SillyOldDuffer on 11/11/2022 08:55:27

[John HaineParticipant @johnhaine32865]

Posted by Hollowpoint on 10/11/2022 21:38:34:

Posted by John Haine on 10/11/2022 17:18:37:

I'm fascinated to see that the ts100 has upgradeable open-source firmware! What experience to people have with the tip life please? I have a Weller look-alike variable temp one I got from Maplin years back, the original tips only came from Maplin and by the time I needed a new one they no longer stocked the item. It does take Weller tips but the temperature control isn't so effective so their life is short. I've been thinking of a new iron for a while.

I've only had mine about 18 months but I've used it quite a lot and so far the tips are holding up well.

Thanks for the feedback!

[Mike HurleyParticipant @mikehurley60381]

An amusing soldering iron story! (yes there is one)

As a youth, after never settling into a job that interested me, I ended up working as a junior technition for an American company that supplied & maintained electro-mechanical & electronic invoicing machines ( pre office computer days). One model was quite a clever bit of electronic kit with a box of discrete components / TTL ics etc in the back. One feature was a group of indicators on the front panel, these were in place of small neons / lamps and were quite delicate. they had the habit of sticking occasionaly. Not repairable, change out – one screw 2 soldered tab connections the famous '5 minute job'.

As a first 'ouside' job, I was sent to do one locally, With my brand new tool kit in hand I confidently appeared and began to settle in front of the machine and remove the small access cover. Got my screwdriver and soldering iron to hand. At this point I should mention that many of the older mechanical electro-mechanical machines the company looked after were 110V supplied by a large auto transformer on the floor. These had 4 american-style sockets on the top. Nobody had told me about this 'feature'!

This piece of more modern kit was standard 220 UK however.

Looked at my soldering iron and noticed it had a 'funny' plug on it – no problem, I duly rewired it with a standard 13 amp plug I had in my kit on something else. Plugged it in and started to desolder the indicator, did notice the body of the iron was getting very, very hot. ( to be fair to me the boss had given me the standard toolkit used for electromechanical kit -i.e. the 110v sort, so sodering irons were designed to fit into the transformer mentioned above – but I didn't know and had never come across anything different to UK 'mains' before)

You are probably ahead of me at this point. PHUT!

The machine was in the workshop for about a week while the proper techs had to change virtually every electronic component – I was not popular to say the least! The customer wasn't very pleased either. I had to return there occasionaly over the years by which time I was fully experienced and competant – but there always seemed to be a bit of an 'atmosphere' though whenever I turned up.

Oh the confidence / ignorance of youth!

[Mike PooleParticipant @mikepoole82104]

We used to let the earth wire go on our oscilloscope as some checks needed to allow it to float, the plug top earth wire was kept very long so it could be pulled out of the plug top and be obvious to all that it was disconnected, I casually plugged the scope in but didn’t notice the flying earth had found it’s way under the plug top and was touching the live pin ( this was before shrouded pins were around). All was well until the unshrouded croc clip was in my hand and I leaned on the chequer plate of an access platform which earthed me nicely with an arm to arm shock, that certainly wakes you up! I replaced the earth after the job but it did need to to float while setting up the sin and cos supply for the inductosyn position feedback for the Numercal control system.

Mike

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I have four mains conventual soldering irons, which are an Antex 15 W precision C, a 25 W of unknown brand, and two Solons, one at 65 W and the other at 250 W, all of which the tips are earthed. I also have a Black & Decker dual 15 / 35 W and a Weller universal, both of which include a transformer that heats the tip, and only have a twin flex supply, so no earth at all. I do have a A55KJ soldering station from Maplin's and the tip on this is earthed, but my Antex pipemaster tongs don't have the tips connected to earth.

Moving on to BS1363 type plugs, many of those that have a moulded-on plug and serve a twin flex with a two-pin socket on the end, do have a plastic pin for opening the shutters on the wall sockets, just like many wall-warts have, however, it is important to know that not all of them are capable to carry a 13 A load whether they have a plastic or metal pin in the earth position, and are quite often limited to 5 A and should never have a fuse put in them higher than that stated on the pin side of the plug. Three photos shown below, first and second are twin flex with a twin socket on the end, and the third one is a three core with a Euro three pin socket on the end. The first and third photos shows the amp rating just above and to the right of the neutral pin, while the second photo shows it to the right of the earth pin, and they also show the maximum voltage as well.

Regards Nick

[Nicholas FarrParticipant @nicholasfarr14254]

Posted by Mike Poole on 11/11/2022 10:25:28:

We used to let the earth wire go on our oscilloscope as some checks needed to allow it to float, the plug top earth wire was kept very long so it could be pulled out of the plug top and be obvious to all that it was disconnected, I casually plugged the scope in but didn’t notice the flying earth had found it’s way under the plug top and was touching the live pin ( this was before shrouded pins were around). All was well until the unshrouded croc clip was in my hand and I leaned on the chequer plate of an access platform which earthed me nicely with an arm to arm shock, that certainly wakes you up! I replaced the earth after the job but it did need to to float while setting up the sin and cos supply for the inductosyn position feedback for the Numercal control system.

Mike

Hi Mike, it might have been prudent to have strapped the earth wire back to the flex with a bit of insulating tape but it's easy to realise that in hindsight. Having a bit of mains volts traveling from one arm to the next, isn't a fun experience, don't ask how I know.

Regards Nick.

[Nick Clarke 3Participant @nickclarke3]

Struggling to remember from the mists of time, but I seem to think that some mains soldering irons had isolated ceramic shafts for the bit to fit over???

[jaCK HobsonParticipant @jackhobson50760]

Posted by John Haine on 10/11/2022 17:18:37:

I'm fascinated to see that the ts100 has upgradeable open-source firmware! What experience to people have with the tip life please? I have a Weller look-alike variable temp one I got from Maplin years back, the original tips only came from Maplin and by the time I needed a new one they no longer stocked the item. It does take Weller tips but the temperature control isn't so effective so their life is short. I've been thinking of a new iron for a while.

You can customise it with your own welcome message – how useful!

Heat-up time is really fast, and takes up so little space.

I been running mine infrequently for a couple of years or so – not a hard life. New tips easy to get on amazon next day.

Dunno about heavy/prolonged use.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Nick Clarke 3, the one on my soldering station has the heating element buried in a ceramic sleeve, and the tip fits over it and is held in place by a shroud.

Regards Nick.

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