Old Weller 100/140 Watt Soldering Gun

[clearchris]

Someone gave me two of these 100/140w weller soldering guns. Yes, I know it runs current right through the tip, but might be nice to really get some heat into some big wires that need to be soldered.

So, worth a place on the bench, or chuck it?

[stj]

Re: Old Weller 100/140 Watt Soldering Gun

keep it - go watch "diode gone wild" on yt to see how to do smt soldering & other rediculous shit with them!

get a few small boxes of hard rosin from aliexpress first.
you'l understand why after watching some video's

[CapLeaker]

Re: Old Weller 100/140 Watt Soldering Gun

I say it’s a keeper. Got one myself.

[clearchris]

Re: Old Weller 100/140 Watt Soldering Gun

keep it - go watch "diode gone wild" on yt to see how to do smt soldering & other rediculous shit with them!

get a few small boxes of hard rosin from aliexpress first.
you'l understand why after watching some video's

Wow, I thought he had one video on how he used a solder gun for smt, but it's just what he uses. Then I see him freehand dremel a solid pcb into a full circuit. I feel like I'm in an F1 race and I just got lapped by a guy on a unicycle.

Truly you can do a lot with basic tools if you have real skill.

[redwire]

Re: Old Weller 100/140 Watt Soldering Gun

About the Weller soldering guns, they do make a huge voltage spike when you release the trigger.
They do not have a grounded power cord (tip), so the spike does kill IC's.
The trick is to always pull the tip away from the board and then let go of the trigger. I guess adding a cap across the trigger switch could fix it too.

Second is the tip nuts have to be periodically loosened and tightened because the copper tip oxidizes and make a poor connection.
If you find the heat seems low or it's taking too long to heat up, retorque the nuts.

[megaraider]

Re: Old Weller 100/140 Watt Soldering Gun

Agree with every opinion mentioned before
Not only a keeper but a treasure
And yes, some 'old school' equipment, when used with some skill, never ceases to amaze

[eccerr0r]

Re: Old Weller 100/140 Watt Soldering Gun

How did we come to the conclusion that there's a voltage spike when the trigger is released? (Here's a interesting question that might change opinions: What is the power factor of these solder guns?)

[stj]

Re: Old Weller 100/140 Watt Soldering Gun

it's a transformer driving a shorted output, in theory it shouldnt spike

[eccerr0r]

Re: Old Weller 100/140 Watt Soldering Gun

I use my 8200N quite frequently, just that tips don't last long so cost adds up fast...
mainly use it when I don't want to wait for a pencil iron to heat up (and cool down). Takes about 10 seconds till I can start soldering.

The 8200N seems to have the first trigger stop (half pull) at 100W, and full pull is 140W. I try to stay at 100W.

[redwire]

Re: Old Weller 100/140 Watt Soldering Gun

What happened is Weller 8200 I was soldering some battery-powered gear and every time I let go of the soldering gun trigger, the gear crashed and rebooted. I thought "weird" but kept on going. Then the CMOS IC's died. Not on an ESD mat or conductive bench, everything was floating. There was no path for discharge, so I wondered how the IC's died.

I confirmed it by taking a neon lamp, one leg grounded and the other touching the soldering gun tip, while clicking the trigger, it flashes Try it for yourself.

Weller uses that solenoid-style transformer design in soldering guns and for a while in soldering stations as well. It has a shit ton of leakage inductance, flux all over the place. There is no cap across the switches to lessen arcing. I think the back-EMF gets capacitively-coupled to the tip.

Another thing I notice is automotive techs forbid the use of soldering guns when working on cars, something about damaging electronics. So someone else found out the hard way like myself that they are no good for electronics work unless you take extra precautions.

[clearchris]

Re: Old Weller 100/140 Watt Soldering Gun

I use my 8200N quite frequently, just that tips don't last long so cost adds up fast...
mainly use it when I don't want to wait for a pencil iron to heat up (and cool down). Takes about 10 seconds till I can start soldering.

The 8200N seems to have the first trigger stop (half pull) at 100W, and full pull is 140W. I try to stay at 100W.

All the cool kids on youtube seem to use 8-14ga solid copper wire as a tip. Would probably be super easy to make a tip bending jig out of some nails and a piece of wood.

[eccerr0r]

Re: Old Weller 100/140 Watt Soldering Gun

100W guns is a lot of power, very easy to destroy PCBs with it due to heat. Most automotive electronics are quite well protected from ESD for reliability purposes so I'd rather think it's the former.

Most of the energy stored in the inductor when disconnecting should have been eaten by the secondary which is near 0 ohms (i.e. the tip). There may be some other phenomenon going on, the di/dt of the tip when you turn it on and off is immense even with a single loop air core inductor (once again, i.e. the tip) coupling that could cause issues with sensitive electronics, not to mention there's always an electric arc near the tip of the gun when you turn it on and off (i.e. the trigger switch), unlike in indirectly heated soldering irons where most are either 100% duty cycle or power controlled elsewhere.

I suspect that turning one of those line power hair trimmers would have also likely caused failure, now those clearly have a lot of kickback, but fortunately electronics do not grow hair.

[redwire]

Re: Old Weller 100/140 Watt Soldering Gun

You don't keep power on constantly with a soldering gun - the tip heats up hotter and hotter and eventually overheats. So it is customary to pull and release the trigger every few seconds as you are soldering. Weller tips have a big copper end with lots of thermal mass, so it stays hot for many seconds with the trigger off.
For melting or cutting plastic rope, you are the man doing temp control lol.
They also have a duty cycle rating of 2 min on/5 min off or something like that.
This is how we soldered with them, when dinosaurs roamed the earth lol.
Don't forget to tighten and re-tighten the nuts to clear up oxide and any poor connection.

The little #222 incandescent lamp also shows secondary voltage (I think) and should not flicker or go really bright - it reveals a bad tip connection. It's a 2.25V 0.25A lamp.


No back-EMF (trigger-off, or power-step down) due to the secondary having a short as a load- assumes a perfect transformer with no flux leakage or air gap, all the magnetic energy in the core, from all of the winding.
But this is a half pop-can winding, like an I-core. There should be no spark across the switch when triggering off or down power... but... there is.

[eccerr0r]

Re: Old Weller 100/140 Watt Soldering Gun

There is spark when connecting a light bulb or any high power resistive load too...but still a large portion of the magnetic field is being passed to the tip than one would think, the power factor of these irons are real close to unity.

The incandescent lamp is a different winding, IIRC. I recall measuring the tip passing around 100 amps, and I don't recall the lamp getting much brighter with the tip missing. I'm not sure what my 8200N has installed but it isn't a #222 for some reason.

[clearchris]

Re: Old Weller 100/140 Watt Soldering Gun

Printed a stand with a trigger hold down bar. The stand seems firm, Ithink the trigger hold down bar could use some tuning, both for functionality and also for printability.

(not my design, btw)
https://www.thingiverse.com/thing:3812661

[eccerr0r]

Re: Old Weller 100/140 Watt Soldering Gun

interesting, might have to print one...I always have to put the gun top down, as it seems to hold up the best without a stand that way and most likely keeps the tip from touchdown.

Incidentally are all versions of the 8200 physically the same? I know some of them have different triggers - where if you half pull is 100W and full pull is 140W, and the other version is 140W half pull and 100W full pull?

There's the 8200, 8200N, and the 8200PK? Some seem to use set screws, and mine uses a hex nut. Heard the hex nut ones are easy to strip, so it's not as good...or is it?

BTW yours looks like it has a #222 bulb, mine and the one in the thingiverse photos have the unfocused bulb...

[clearchris]

Re: Old Weller 100/140 Watt Soldering Gun

interesting, might have to print one...I always have to put the gun top down, as it seems to hold up the best without a stand that way and most likely keeps the tip from touchdown.

Incidentally are all versions of the 8200 physically the same? I know some of them have different triggers - where if you half pull is 100W and full pull is 140W, and the other version is 140W half pull and 100W full pull?

There's the 8200, 8200N, and the 8200PK? Some seem to use set screws, and mine uses a hex nut. Heard the hex nut ones are easy to strip, so it's not as good...or is it?

BTW yours looks like it has a #222 bulb, mine and the one in the thingiverse photos have the unfocused bulb...

I can't say if that bulb was stock, these irons have truly unknown provenance, they could have come out of a trash can.

I took a closer look at my other one, and wow. No bulb, looks like the top had been broken off at some point, and somone spilled black epoxy all over the top to keep it together. If I disassemble one to make a permanent handleless bench top iron, it's going to be that one.

Before I do anything rash, has anyone ever needed to dual wield two soldering guns? 140w seems like it would do nearly anything I could find myself working on.

[eccerr0r]

Re: Old Weller 100/140 Watt Soldering Gun

As redwire says the #222 is very common on these wellers, just that mine does not. The main thing about the #222 is that it's focused so there's a bright spot, mine just spews light everywhere, dimly.

Come time the lamp burns out I'm not sure if I can even put in an LED ...

[R_J]

Re: Old Weller 100/140 Watt Soldering Gun

Just a note regarding your trigger hold down. These soldering guns have a 1:4 duty cycle, 1 min on, 4 min off, just something to consider.

[stj]

Re: Old Weller 100/140 Watt Soldering Gun

building a pwm driver for one would be interesting.