Mini blow-lamp.

[petervk2mlg]

I was reading in The Radiophile for Easter 1988 about using a mini blow-lamp to repair a valve's filament connection to its pin. The benefit mentioned is that the blow-lamp can be stood on the bench leaving the hands free to manipulate the job.
Do others also use such a tool and what might be the best one for the job? On ebay I see chefs' mini blow lamps for sale. Would such a thing be suitable?

Peter

[FrankB]

I typically use either an old Weller 350W soldering gun or an old American Beauty 300 W soldering iron.
I always use flux or non-acid soldering paste also.

I would be cautious about a blow lamp, as one could possibly damage the bakelite or plastic base of the valve fairly easily.

[Radio Wrangler]

There are several types of jeweller's blowlamps which make tiny flames and there are many Valtocks out there:

https://www.youtube.com/watch?v=MD-p...=RatBikerNotts

I wouldn't recommend soldering with a flame. the temperature can so easily go far too high.

I once soldered every connection in a classic car I was rebuilding using a Valtock and a lot of care. Mains power wasn't available in an isolated garage. Afterwards I bought a 12v electric soldering iron.

A soldering iron can be mounted in something like a panavise and that leaves your hands free AND you get controlled temperature.

David

[paulsherwin]

I use a no-name small pencil torch which cost very little. You just refill it with cigarette lighter gas. It produces a small very hot blue flame which is useful for all sorts of jobs. It came with a clip on soldering bit though that hasn't seen much use.

[Radio Wrangler]

Aye. In the past I've turned new pins with a drilled hole down their centre, done a dental extraction of a broken pin's stub, soldered an extension onto the wire, epoxied the new pin in place and finally soldered the tip to the protruding wire extension. Micro surgery, but it works.

I thought the OP was just talking about resoldering the pin and the connection wire

David

[Phil G4SPZ]

Widening the discussion slightly, I use a chef's blowtorch and one of those cigarette lighter-style blowtorches. They're very handy for all sorts of jobs, particularly for heat-shrink sleeving, but not for soldering - at least not for electrical soldering.

Blowlamps are one of my other hobbies. Did you know there is a Blowlamp Society? Valtock made a soldering iron attachment for the 'Major' but it gets far too hot in use.

For soldering heavy items that need a lot of heat, especially outdoors, I still fire up a paraffin blowlamp and heat a large copper-tipped iron. The process is very easily controllable. This would, I think, be sufficient to heat the end of a large valve pin, although to be honest I've used a 100 watt Weller to good effect on the couple of occasions when I've had to do a repair of this kind.

Edit: Thanks to Peter for posting the text of the 1988 Radiophile article.

[petervk2mlg]

Hi all and thanks for the replies and ideas.
Perhaps I didn't express my question very well and hence the misunderstanding.
The problem I had in mind was where the filament wire was not making good connection to the valve's pin on the socket. The symptom shows as an ostensibly open circuit heater.
In such cases I always try resoldering the relevant pins in the hope of restoring continuity. Sometimes I've been met with success.
Obviously where a heater is actually open circuit, there is no remedy.
I attach a scan of the relevant section original article to help clarify the problem.
Peter

[petervk2mlg]

Originally Posted by petervk2mlg

The problem I had in mind was where the filament wire was not making good connection to the valve's pin on the socket.

Reading this again I realise it's also expressed badly.
The socket or valve holder naturally has nothing to do with the situation.

[mark pirate]

I've used a 100 watt Weller to good effect on the couple of occasions when I've had to do a repair of this kind.

I also use a 100w solder gun for this sort of repair, it works very well on both valve and CRT bases.

It is much better than using a small blowtorch, as it is much safer and easier to apply the heat just where you need it.

I recently had a problem with a rectifier valve, the heater had continuity but there was no connection to the anode. Resoldering the pin restored the valve to working order.

Always worth trying before condemning a valve or CRT.

Mark

[vidjoman]

Ah I see what you meant having read the article. I would describe it as the lead-out wires from the valve into the hollow pins of an octal or similar valvebase.
I have done those several times by cleaning the pin with a small file to see clean metal and also a clean spot on the tip of the wire and just use a soldering iron set to a higher than normal temperature. A problem is that if applying too much solder it may result in the solder running down the wire into the base but not being attached to the wire because of corrosion. This can then settle in the hollow base and cause a short circuit between the lead-out wires.

[boxdoctor]

I use a Weller Pyropen for this kind of task. It does produce a controllable heat which can be directed accurately at the place it is needed. Also as it is actually hot air that is doing the job, the work is not obscured by a flame. Nor is there any contamination caused by any agent that might be in a gas flame.
Easy and light to handle too. Tony

[mole42uk]

I don't want to hijack this thread, but several people have mentioned the Valtock.

I have one that seems to have been robbed of the 'wick' in both tubes. I have the original user manual, but no idea what the wicks should look like to replace them.

Can anyone help?

[GMB]

I think it was made of something like a cotton rope.

The non-blowing section had the top bit jammed full of it, with a piece hanging down to the bottom. The blowing section just had it running down the tube and again to the bottom of the cylinder.

Another way to get a tiny blow-flame from any burning source is the way chemists used to do the charcoal block test...

The blow-pipe was just a very thin tube fixed at right-angles to the main piece of tube that goes in your mouth. You put the end of the thin tube into any handy flame, then blow and the air you are injecting creates a hot flame coming out of the side of the original one.

I used to do this all the time when I was a kid, until I got a Valtock and later a propane Bunsen burner.

[Phil G4SPZ]

Hence the original term "blowing lamp", eventually shortened to "blowlamp".

[David G4EBT]

As to the original question, I've removed and replaced several loose or damaged valve-bases and invariably the wires easily come free with a 40 Watt soldering iron and solder sucker, if need be, helped by a little flux on the end of the valve pin. When removed, the wires are tarnished and need to be scraped clean and tinned before replacement. Nothing like the heat which a mouth-lamp or and other form of blowlamp - not even those little cigarette lighter powered jobbies is called for. A 'chefs' lamp' taken to a valve-base pin is WMD! If a 40 Watt iron, or maybe less, is applied to the side of a valve pin for ten seconds or so, the solder should flow into the hollow pin freely.

That aside, mouth-lamps are wonderful little things, which I hold in great affection.

I served an apprenticeship at what was then the 'Gas Board' later British Gas, joining on leaving school aged 15 in 1954. Until the early 1960s almost all domestic gas installations were of lead pipe (known as 'compo' as it had a small proportion of tin in it). The most commonly used sizes were 1/2", 5/8" and 3/4", with 1" for meter connections, and occasionally 3/8" for repairing gas light supplies (which still existed in the mid 1950s!).

Soldered joints were made exclusively with a meths mouthlamp - many times a day, so until an apprentice could make sound joints quickly, they weren't much use as a mate. Hence, we had to practice making joints day in day out in the workshop until we were judged competent to be let loose. It took most of us about a month to learn to control the flame correctly so that we didn't blow a hole clean through the pipe, which the meths flame would do with ease.

Apprentices had to make their own mouth-lamps - rather crude affairs, with a 5" length of copper pipe, an old penny soldered in the bottom, and a brass meter union filed to fit the top end and soldered in, then a wick fitted. The air pipe was made from 1/8" diam 'fridge pipe as used to connect gas refrigerators. I'm almost ashamed to attach a picture of my little lamp, which I recently passed on to forum chum just after the lamp's 60th birthday! It served me well until I was 17 and passed the intermediate C&G exam at which point we were issued with a complete tool kit including a brass mouth-lamp, which I still have today, and occasionally use for little jobs - see second pic. (It has a screw cap to prevent the meths from evaporating).

Nothing can match the control which can be exercised when using such a mouthlamp - still used extensively by silversmiths and the like. When blowing gently, a precise pencil flame arises, but when blowing hard, air is entrained into the base of the flame and boy, do those things roar! Methylated spirits is a mixture of 95% ethyl alcohol and 5% methyl alcohol, sometimes known as 'wood alcohol' as it's made from the distillation of wood. (Methyl alcohol is poisonous and is added to prevent the methylated spirits being used as cheap drinking alcohol). In the US and Canada they call meths 'denatured alcohol'.

Not too far off topic I hope.

[Radio Wrangler]

That first lamp is nothing to be bashful about. It looks quite well made.

These things produce a small, high intensity flame which is very useful when your parent metal and your filler metal are all the same stuff. Using a big flame means that everything is close to slumping into a mess on the floor by the time the things you want to happen have started to happen.

I grew up with oxyacetylene torches and learned the advantages of focused heat.

Anyway, back to valve bases... I've found a 50W Weller TCP1 fine for re-soldering pins, and a solder sucker helps.

I assume the pins were originally soldered by a dip in a solder pot.

David

[mole42uk]

Originally Posted by GMB

I think it was made of something like a cotton rope.

The non-blowing section had the top bit jammed full of it, with a piece hanging down to the bottom. The blowing section just had it running down the tube and again to the bottom of the cylinder.

Thanks for that help. I found some candlewick cotton which I used to re-wick the Valtock and it works! I tried a small bit of soft solder on an exercise piece (I train musical instrument repairers to make beautiful soldered joints on saxophones and we use test pieces for exercises) and it's really quite easy to control. Much nicer than my small butane torch.

[Tim]

I have a chef's torch, about 6" high, which will stand on it's base. It's got a "clicker" for easy lighting and can be refilled with one of those aerosols of lighter fuel. It has been employed a few times for the odd stubborn nut etc., but is mostly for starting barbeques and the garden incinerator. Very handy it is too, as the flame is quite controlable.