Tuesday, 20 April 2021

This tool sucks! (which is good!)

One of the downsides of having vintage gear is that time takes a toll on old electronics. Quality counts, but the ravages of time can affect even the highest quality of components. I have covered fitting replacement displays (LCDs) with backlights previously (TX7, RM-1x), but I've recently been replacing electrolytic capacitors and switches, which are also sometimes the unfortunate casualties of time. Capacitors can dry out because of heat, from CPUs and power supplies, mostly. Switches just have finite numbers of cycles, and the front panel of a synthesizer can require a lot of button-pressing depending on how it is designed - 'Enter' buttons, or cursor buttons, or increment/decrement buttons, or 'Play/Stop' buttons are all candidates for repeated presses over the lifetime of a piece of gear. Some switches fail because of metal fatigue, some because of dust, and some because conductive plastic loses its flexibility over time. The switches that you get on older, vintage equipment from the 1970s and 80s tend to be 'proper' metal contact switches, and so the failure mechanism tends to be just plain old 'wear and tear' - but at least they are individually replaceable. (More modern gear can use conductive rubber switches which are made as sheets, and have to be changed all at once, trying not to get any dust underneath them. And no soldering required, usually!)

Removing thru-hole components from printed circuit boards (PCBs, but not Poly-Chlorinated Biphenols) can be tricky. You want to avoid damaging the pad or tracks, and yet you need to heat up the joint sufficiently to be able to remove as much of the solder as possible - which are a difficult pair of requirements to juggle. The key words here are:

'Removing the solder...' 

Ideally, I would have invested in two soldering stations: one for surface mount components (with a tiny soldering iron bit, a heat gun, and strong magnifiers - something like this or this or this), and maybe one for thru-hole (with built-in suction). But this isn't an ideal world: I used to have an Antex soldering iron back in the 1970s, and I have had a very basic (and a bit industrial) Weller soldering iron for many years, that really needs replacing with a more modern TS100 model. 


But at the moment, I've been struggling with an antiquated classic; the almost-all-metal RS components 544-516 model solder sucker. The sucker itself works perfectly fine, but I have been totally unable to find any replacement plastic nozzles for it - and the RS website, and Farnell, and others. all laboriously lead you down a series of labyrinthine pages that never actually lead to a replacement nozzle. 

So I have the classic problem where the end of the metal rod, sticks out of the nozzle, and reduces the suction enormously - but no obvious way of fixing it... 

I did try one of the 'affordable', part plastic, part metal alternatives from Amazon, but that has a wide nozzle, a small metal rod, and doesn't suck very well. It also has the unobtainium problem with replacement nozzles as well. 

I even reminded myself that I don't like solder wick, although I know some people who like it, and I also know some people who mis-use it to create solid ground links on digital audio boards. 

Finally, I decided to stop messing around and do what I should have done in the first place: buy a decent solder sucker (and defer the surface-mount soldering/heat gun workstation to another time). 

The Engineer package - without the solder sucker!

After some research, I found the Engineer SS-02 from Japan: an all-metal, guard-less solder sucker with a bright red plunger button, and a replaceable silicone plastic nozzle (and a spare length of tubing included) and where additional tubing sections can actually be found and bought on Amazon! 

The included tube (top), plus an extra pack of two tubes

I have to say that the combination of a flexible plastic nozzle and huge amounts of suction, is just wonderful! For removing thru-hole components, then you heat up the joint until the solder goes shiny as it melts. Then you let the molten solder spread to all of the joint (you can see it go reflective and start to move), then position the nozzle as close to the soldering iron tip as possible and press the button on the side. The plunger is pushed out by the internal spring and the red button jumps upwards as air (and solder) is sucked through the nozzle inside the sucker.  

It is an interesting balancing act. You want to heat up all of the solder in the joint so that it can be sucked out, but you do not want to over-heat the pads and the tracks they are connected to. You want to get the solder sucker nozzle as close to the soldering iron tip as you can, and yet you don't want to stress or damage the silicone rubber nozzle by over-heating it - although it does seem to withstand a lot of heat!

Then there's the longer term question of what happens to the solder? It ends up inside the solder sucker, either as tiny round spheres, or as thin streams. When you push the red button to reset the plunger, then the metal rod pushes down through the nozzle and sometimes pushes some parts of those thin streams of solder out. Some solder stays inside the sucker, and so you have to unscrew the end every so often and shake/tap out the bits of solder. The inside of the sucker also tends to get coated with remnants of flux from the joint, and this goes sticky and dark over time. 

You can't see what is happening inside the solder sucker, and so emptying it tends to happen when you can't push the plunger back down until it clicks. The internal entrance to the nozzle tends to get clogged with solder that the rod can't push through, and so then you have to empty the sucker. The more solder you remove, the more often you need to empty it, and so a good solder sucker tends to need emptying more often - which is a sure sign that it is working well!

Ideally, enough of the solder has been removed from the joint, so that the component (capacitor, switch...) is now loose. To help this process, with that third hand that you probably don't have (soldering iron in one hand, solder sucker in the other) you should be applying pressure to the component so that it comes free as soon as there isn't enough solder there to hold it in place. In practice, as soon as the solder sucker has done its suction thing, you drop it, move the iron away, and nudge the component so it comes free (the component is on the other side of the PCB, of course, which just makes it all the more challenging!). 

It's a complex ballet of movements to try and remove the solder and loosen the component, and you really need an extra hand. Trying to co-ordinate two people's hands and associated tools in the tiny space near a solder joint is very difficult, but can work with larger PCBs. Another technique is to use the soldering iron tip to jiggle the component lead as the solder is sucked away, which works better with capacitors than switches, because switches tend to have more solid connections rather than flexible leads. Flat-bladed screwdrivers or tweezers can be used to lever the component as the solder is sucked away, so that any remaining solder can't freeze and lock the component in place again. 

Some people advocate twisting the cans of electrolytic capacitors axially so that the leads break, which makes the remnants easy to remove - sometimes the lead just drops out when you heat the joint and suck the solder away. But this can damage solder resist and pads, and is difficult to do if the capacitors are tightly packed together, which is often the case. 

So the solder sucker is only a temporary home for the solder. Unfortunately, it doesn't magically disappear - the sucker moves it from the joint to inside the sucker, and you then have to empty the sucker. The next step up are solder suckers which have heated tips like a soldering iron, but they also have suction through a hole in the middle of the tip, and the solder ends up in a glass tube. Again, over time, the tube fills with tiny spheres and streams of solder, and needs to be emptied - the glass tube just makes it easier to see when you need to empty it.

In conclusion, the Engineer SS-02 is especially perfect for removing switches and capacitors from PCBs... I may have put off buying a proper suction station for another day...

Name choice

I just have to comment on the choice of brand name by the Japanese manufacturer of this solder sucker. 'Engineer' is a totally brilliant, deceptively descriptive (and tautological), choice for a brand name: these are obviously tools for serious engineers, hence the name. But there's no doubt about what the purpose of the tool is: 'Hobbyist' or 'Bodger' wouldn't be very good choices, whilst 'Professional' and 'Expert' have been so over-used that they have become mostly worthless. 'Serious'? - it just sounds like irony. So 'Engineer' is a near perfect name.

And as a final thought. It turns out that my favourite, 'go to', special purpose pliers, that I use to adjust/tweak/remove awkward small bolts/objects in tight locations, are also made by Engineer. and it is only just now that I noticed... They are PZ-57s if you are interested. 

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