Soldering gun not heating up

[droopsnoot]

I've got a Hilka / Pro-Craft 100w soldering gun, and after using it to solder a small pinhole on a fuel tank it now doesn't work at all - doesn't heat up, and the light doesn't come on when I pull the trigger. That was the first time I'd used it, and it was probably on for a total of about three minutes.

I've tested the resistance on the bulb and it was zero, but I didn't have a small battery to hand to see if it lights - I partly expected it to light up when I stuck the resistance meter across it, but that might be misguided. Could it be that the bulb is blown and is somehow in series with the heater? It didn't seem to be wired that way - I had the side off it and the bulb seemed to just come directly off a pair of terminals on the transformer. There was nothing immediately obvious to look at - no burn marks or loose wires. I've swapped the fuse in the plug.

Any ideas, anyone? Could do with soldering my new alternator cable to the terminal and the 30w iron isn't really up to the job.

 

[brightspark]

yea check the 240v supply to transformer if theres 240v there check the output voltage if theres nowt at either it may be the switch or mains lead if theres output from transformer the element probably bust

 

[Screwdriver]

I think they are simple transformer step down devices. Low voltage high current DC output to the heating element which is just a short circuit wire. Imagine there would be a chunky diode rectifier on the output, feeding the operating lamp. So it will either be an easily fixed diode rectifier or an open circuit transformer. Then of course you would still need to establish why it blew up....

 

[the snooper]

They have a very short duty cycle if you had it on for ages it could have had it, put it to your ear does it buzz? If so make sure the tip is in one piece and has good connections

 

[brightspark]

They have a very short duty cycle if you had it on for ages it could have had it, put it to your ear does it buzz? If so make sure the tip is in one piece and has good connections

just don't burn your lughole if it decides to work

 

[droopsnoot]

Thanks all, I'll have a further play with it. It's not heating up, but to look at stuff like the tip it's almost brand new. I do wonder if I've just over-done it. I thought that if there was an issue with it being on too long it would have some kind of failsafe - my £3 hot air gun will refuse to switch on if it gets too hot, until it's cooled down a bit. I'll try to follow the current. The switch pushes on some long copper strip contacts, they all look nice and clean. I don't think it was buzzing when I tried it yesterday, though I think I was trying it when the heavens opened and I wasn't particularly listening.

 

[anjum]

Check the resistance across the mains lead (unplugged obviously). With the switch on there should be a low resistance, if it's open circuit then there's either an internal fuse or the thermal fuse in the primary has blown, in which case it's a door stop.
If this is the case, you can open the case up and confirm across the primaries of the transformer directly, then maybe there's a slim chance you can identify and replace the transformer with an identical one.

 

[droopsnoot]

Yes, it's the pistol-grip style. I'll have a go this afternoon and see what I find.

 

[the snooper]

Thanks all, I'll have a further play with it. It's not heating up, but to look at stuff like the tip it's almost brand new. I do wonder if I've just over-done it. I thought that if there was an issue with it being on too long it would have some kind of failsafe - my £3 hot air gun will refuse to switch on if it gets too hot, until it's cooled down a bit. I'll try to follow the current. The switch pushes on some long copper strip contacts, they all look nice and clean. I don't think it was buzzing when I tried it yesterday, though I think I was trying it when the heavens opened and I wasn't particularly listening.

if i remember correctly the duty cycle for them is something like 10 secs on 10 secs off might even be more off time

 

[the snooper]

Erm...

View attachment 86018

i knew it was short on time couldnt remember off time

 

[droopsnoot]

Ah, if mine had that written on it, that might have been a help.

It's dead, though - I've tested the various bits of it that I can test and there's nothing going on inside. The cable is OK, the switch is OK. Thanks for the help, I'll look for a replacement and use it for shorter times.

 

[123hotchef]

is there not a thermal fuse inside it?

 

[droopsnoot]

I couldn't see anything other than a few copper contacts (for the switch), a couple of connector blocks, and the transformer. I lifted the transformer out of the case to see if there was anything underneath, but there wasn't. So if it has one, it's hidden very well. I'll try to take a photo later on in case I'm being blind.

In truth I only picked it up because I needed a bit more power to unsolder and re-solder my alternator wires, and hadn't realised there was this time limit on the usage. So if I'm looking for a replacement, it's probably a good idea to look for a 100w iron rather than gun presumably?

 

[droopsnoot]

Interesting - I tried the pencil one which is marked at 30W, and it's not up to heating the new wire enough to tin the end if I hold the iron under the wire and play the solder on the top - it's 97/030 50A wire. They were both part of a Hilka kit that I've had for some time, so it's very possible they're at the bottom end of the quality scale, though the iron has been fine for anything else I've used it on. Melting the original might be an issue as I'm not sure what the manufacturer used to put it together - it's always possible it's some kind of braze rather than solder - but I can remove that mechanically.

 

[xmetal]

I always prefer the 60/40 lead solder as it has a lower melting point than lead-free. That makes life easier when the iron is struggling. I use a Weller TCP 45W too. I tend to prefer to use a portable gas soldering iron when I need more heat or when I'm working away from the bench.

 

[droopsnoot]

I bought one of the Aldi pencil butane solder guns earlier in the week, which has been useful at melting some old solder that my electric iron won't touch. Not bad for £14.99, though they didn't have the butane for it.

 

[Cobbler]

I bought one of the Aldi pencil butane solder guns earlier in the week, which has been useful at melting some old solder that my electric iron won't touch. Not bad for £14.99, though they didn't have the butane for it.

I bought one of those a while ago, it came up in the reduced bin at a fiver. The pound shop has the gas at, yes, a pound. I only bought it 'cos I thought it might be handy & it's turned out I've used it quite a bit, they are very good, I use it in preference to the electric one.

 

[droopsnoot]

I only find stuff in their clearance bin that I either didn't want, or buy another one for "just in case". Still, it solved a problem and by the sound of it will continue to be useful. I didn't think of the pound shops for gas, I went to a local Co-op who said "no, we don't keep it, not many places do now" and then to a tobacconists. Aldi had some tins of Butane at four for £4.99, but they were for camping stoves and I didn't get the idea they'd have the right connector. I'll remember the pound shop when I run out though, cheers.

 

[xmetal]

Beware though, I've had butane that doesn't like burning... That'll learm me for buying it from the pound shop Went and got some swan branded gas from tesco and that worked fine.

Yes I've come across some like that too.

 

[droopsnoot]

I can't think of any shop around who sells tobacco products that doesn't sell the refill canisters of butane (along with zippo fuel, flints and all that).

I was surprised as well, but I only tried the local one and he didn't go to the trouble of opening the sliding door to have a look.

Noted on the pound shop stuff, the can I bought was only £2-odd so not worth the saving if it's rubbish.