Labtec LCS-2612 Speakers Fix

The Major has expressed a desire to have some speakers for her home office so she doesn't have to use headphones all of the time. So an ancient set of Labtec LCS-2612 speakers were located and extracted from a bedroom of one of the tykes. They had been using them for playing music from their phones until they demanded Bluetooth speakers instead.

When I say ancient I mean it, these are from back when beige was king and arrived with an equally beige desktop computer way back when (20+ years ago). If there was a manual with them when they arrived it's now long gone.

Labtec LCS-2612 Speakers. Never the knees of the bees.

It should have simply been a matter of setting them up and connecting them to her laptop, but all was not well with them. They sounded like they were playing from the bottom of a well. The problem seemed to be at the volume controls, as when they were pressed in and turned the sound came back to normal levels. Dodgy potentiometers are a common issue.

Potentiometer diagram

Over time either crud builds up on the track and wiper or one or other of them can get oxidised. Both issues lead to patchy contact across the pot, which creates the characteristic pops and crackles that you get from a bad pot. Fortunately options are available for cleaning and restoring them so I didn't have to go straight to pulling them out and replacing them. First though I needed to get at them.

Labtec LCS-2612 external front and rear views

Removing the rear and side covers was just a matter of taking out the four cross-head screws at the back of the subwoofer to reveal more discrete components than I have seen in a while.

Labtec LCS-2612 subwoofer internal view

The pots were located at the front of the box and the front cover was secured by another set of four screws in a much more difficult position to get to than the first set. However I managed to remove them without too much bother.

Volume, treble and bass pots

Looking at the pots, the external shells were tarnished, so it seemed a safe bet that the internals were likewise affected. The first choice to make is to replace or clean. Replacement means identifying the part then sourcing a supplier. For some more specialist pots this can be a tall order, but these are not high-end parts so it was possible to locate a picture on the web.

Panasonic dual-gang 50K pot

I couldn't quite tie down a part number but at about £8 each that would come to £24 plus p&p to replace all the pots. As a similar set of secondhand speakers would come in at about the same price it didn’t seem worth either the expense or the trouble to replace them.

The next choice was to clean in situ or desolder and clean; in situ is obviously best/easiest. I needed to accomplish three actions, clean up the wiper and track of the pot, remove oxidation if present and lubricate the cleaned surfaces.

And this is where I fell down the rabbit hole. There are many contact and control cleaners out there and twice as many opinions on what is the best product or strategy to use. The market leader is about £30 a bottle, which again is a bit toppy given the replacement cost of the speakers.

So I had to venture even further into the rabbit hole. In the end it looked like trying to clean and then lubricate the pots would be the first strategy to try. Most contact/control cleaners (the ones you can buy now anyway) use naphtha or white spirit as a base, both to solvate their active ingredients and for its cleaning action. So I took a fine plastic pipette and dropped just a couple of drops into the pot housing via the notches at the tops of the pots and worked the controls for a bit.

Notch on the top of pots provides solvent access
without having to desolder component

White spirit isn't conductive so it shouldn't matter if there was a bit left behind. Even so I dried the pots out with a hair drier as sparks and white spirit aren't a good mix. Once that was complete I plugged the power in and tested the system and everything was back to nominal. So I wouldn't need to remove any oxidation this time. The next job was to lubricate the controls to stop the dry surfaces abrading the track of the pot and knackering it. Again there was a wide range of lubricants on offer…

WD-40 was mentioned quite frequently and appears to be quite a polarising topic, with some saying that it has worked fine for them for 20 years and others saying that it will wreck controls. For me it has a couple of major advantages, in that A) it is cheap and B) I have it to hand. I don't think the speakers will get that much more use and if they fall over they don't owe us anything.

So I put a couple of drops on the joint between the shaft and case of the pots and let it wick into the body of the pot. Then I rotated each of the pots from fully open to fully closed ten times and put the hair drier back on it.

Now to get the stuff back together. I ended up using a magnetic catcher to replace the screws, As you can see they were well buried and it required a Phillips screwdriver with a 10" shank to get them in and out.

Buried access to front cover fixings on a
Labtec LCS-2612 subwoofer

I also noticed that one of the struts protecting the subwoofer was broken so I solvent welded it back together with MEK as the case had ABS stamped on it. No problemo.

Broken strut on Labtec LCS-2612 subwoofer cover

So I now had the pots working smoothly and the case reassembled. But the sound was not really that good and the high ranges seemed to be missing? Back to troubleshooting mode again.

This time it looked like a problem with the feed in. Either there was another bad connection or the system wasn't processing the stereo input properly, as it looked like it was expecting a pair of L/R mono inputs. After a vain search of the cables box for a stereo to mono splitter lead it was off to eBay.

Female stereo 3.5 mm jack to a pair of male mono 3.5 mm jack plugs

Once that arrived I duly plugged it into the rear of the box. But whilst doing so I found a bad connection in one of the jack plug housings on the lead I had been connecting the laptop and speakers with. So it was at this point that I found out that the stereo-to-mono splitter wasn't required. Doh! But that is what comes of working off no manual. At least the next time they will be to hand and they weren't expensive. So the inputs labelled 1 and 2 are for two different stereo inputs. Noted.

I then swapped out the dodgy patch cable and the volume came up to expected levels. Better, but the high ranges still weren't right. Next I plugged in a pair of headphones to the jack at the front of the box and everything was good, indicating that there wasn’t a problem with the stereo output of the amplifier.

The only culprit left was the speaker and after a few runs with a stereo test program and some swapping around of the speakers it was obvious that the left speaker unit wasn't working properly.

Labtec LCS-2612 tweeter internal view

On opening it there was nothing obviously wrong (there isn't much to go wrong), so it's either the cable or the speaker. The impedance was 4.6 Ω so it wasn't an obvious fail. I would now have to replace the cable and/or the speaker, but at this point the law of diminishing returns loomed large. The Major decided that the speakers were good enough as is, so I called it at that.

JOB DONE (sorta)

Time taken: 1 hr (plus literally 2 days for contact cleaner research!!)

Cost: Cleaning materials, pennies - stereo to mono splitter cable, £2.95

Immersion Heater Issue

Due to another (as yet unresolved) issue the immersion heater for the hot water tank was needed during a recent heatwave (≥34^oC for a few days). However it had been previously noted as not working.

These are not complex pieces of equipment, with only marginally more parts than a kettle, consisting of a heating element and two temperature controlled switches (a thermostat and an overtemperature cut-out) bolted into the hot water tank and powered from the mains electricity. Generally they are used as back-up heating devices and therefore only sporadically.

Hot water tank diagram. The immersion heating element
is in red and the thermostat in grey - Source.

Our system is slightly different to that shown above in that we have an unvented cylinder with the immersion heater mounted on the side of the tank.

Baulky immersion heater

Immersion heaters are an industry standard item and ours is from an Italian company, Thermowatt. I couldn't find the exact item on their website, but given their generic nature I got close enough to get a circuit diagram.

Thermowatt circuit diagram for immersion heaters with
unipolar thermostat and safety disconnection.

The circuit diagram is pretty straightforward. So what is wrong with it? All I had from The Major is that 'it isn't working', so some general troubleshooting is required. As is commonly the case, YouTube came up with a good guide in the shape of John Ward of Flameport Electrical.

Immersion heater fault finding guide

Out with the multimeter for a bit of testing then; no issues with the fuse in the plug or the lead to the heater.

Internals of immersion heater. The thermostat control is in red and the
overtemperature cut-out is in the hole to the left of the lower brass screw.

If the unit is below its' set temperature the resistance across the live and neutral pins of the plug should be around 20 Ω, which it was,. So next, under the guise of checking that the thermostat was working correctly, I did the usual thing of twiddling the knobs and pressing the buttons and everything appeared to be working normally. Somewhat perplexed I put the cover back on and switched it back on. And lo and behold it was working.

Had it been working all the time? Had altering the thermostat set point or pressing the cut-out helped? No idea, but…

JOB DONE

Time taken: 20 minutes

Cost: £0.00

Unblocking the kitchen sink drain

Over the past month or two the kitchen sink has been draining more and more slowly, and it is now flirting with stopping altogether, making for an unsightly and unsanitary mess.

Blocked kitchen sink

Attacking it with the plunger didn't really improve the situation. So it was time to tackle the issue from both ends, so to speak.

I started first at the external drain, which had merged back into the undergrowth since the last adventure in that area.

Overgrowth regrowth

Out with the gardening gloves, shears and secateurs (I enrolled one of the tykes to do the hack and slash) and the drain hopper emerged again.

Not-so-clean drain hopper

It wasn't sparkling, but there weren't any signs that the drain was blocked (there is a grille over the drain). Pulling out the accumulated detritus and testing the drain with a bucket of water showed that everything was working OK at this end.

Cleared drain hopper

As the drain end was working, I turned to investigate from the plughole end. Once the cupboard under the sink was emptied out dropping off the U‑bend was straightforward, as this is also something I've tackled once before.

Checking the U-bend

Annoyingly it was pretty much clear, meaning that the blockage was somewhere in the permanently fixed part of the waste pipe. I gave it a bit of a hopeful rodding with a battered bottle brush that is only used for filthy jobs, but this didn't seem to make too much difference in terms how it felt to the touch. So I decided to re-attach the 90^o compression fitting on to the waste pipe but pointing upwards to use it as a funnel to pour in some drain unblocker I had to hand and left that to do its business for 30 mins.

Perhaps you are thinking that I could have just poured some drain cleaner into the sink in the first place? Possibly, but I would have had to completely fill the U‑bend with the stuff in order to get it back to the blockage further down the pipe; also the external drain hopper wouldn't have been cleared out.

After giving the unblocker some time to work I then put the piping back together, crossed my fingers, and ran some water through the system. Back to normal, thankfully. Now it just remained to clean everything back up and repack the cupboard.

JOB DONE

Time taken: 2 hours
Cost: £0.30 worth of drain cleaner

Dead maker pens

What’s this? Two dried out marker pens (can you tell that I'm working on clearing off my desk?).

Dead Staedtler Lumocolour Pens

These are Staedtler Lumocolour pens, non-permanent 316 fine point in this case. Marker pens are generally fire-and-forget items but these are marked as refillable, not something I have seen before. Ordinarily they would just get junked and replaced by new ones, but Staedtler make excellent markers, so let’s investigate.

Got a part number from the Staedtler catalogue for the refills package, which appears to be a small pot of ink that you stand the pen up in while it wicks the ink back up through the nib. The whole thing is quite neat.

Staedtler Ink Refill Station

At £8.50 on Amazon the price is OK as the pens are £1.30 a pop new (so not cheap but not too dear either). As a pot should refill 10 pens it will take 6.5 refills before buying the ink is cheaper than buying new pens, which is equivalent to buy 2 get 1 free. Although it is a reasonable deal, the downside is that I would have to buy 2 different colours and I don’t get through enough maker pens for me to feel confident that I will get 10 pens out of a refill pot before the ink goes dry. It might take 5 years to get through 5 red pens.

What to do?

I think I will sit on this one and just chuck them into the pens parts bin in case a use case for large amounts of non-permanent markers crops up.

JOB DONE

Time taken: About an hour of research
Cost: nil

Resurrection of Dead Ballpoint Pens

What is this? A couple of ballpoint pens, both not working.

No need for photos, we all know what a ballpoint pen looks like. In this case one was a freebie from Barclays Bank and the other is marked The Inn At Penn (no idea how this arrived). I know they are disposable, what isn't these days? But it's still not very environmentally friendly to chuck stuff out if it can be repaired. However in this case the amount of time I'm willing to spend on resurrecting them is very limited. WikiHow has an in depth article on what to try basically heat, pressure, solvent, or combinations thereof.

Parts of a ballpoint ink pen

The Barlcays pen first. On opening it and holding the white ink chamber up to a light bulb it appears most of the ink has gone (not that it would have had much in it in the first place). I tried scribbling furiously to get some heat into the nib in order to make the ink flow and that gave a few streaks of colour, then I tried bending over the ink chamber in order to pump the ink down towards the nib, no effect. Finally I pulled off the nib and dipped the end of the ink chamber in some acetone to get the ink moving. Still nothing, so into the pens parts bin for that one.

Next was the Inn at Penn pen. More ink was visible in this one, in fact it looked almost full. Scribbling did nothing, but bending the ink chamber over did the trick. Result.

OK 50% success rate, not too bad.

JOB DONE

Time taken: 5 mins
Cost: nil

Dead alkaline batteries

What is this? A small collection of dead alkaline batteries.

Collection of dead alkaline batteries

Although presented to me as dead they weren't all in that state, as their measured outputs ranged from 0.05 to 1.55 V (after I looked at them again I noticed that one was a rechargeable, doh!).

Measuring voltage of unloaded batteries

The C and AAAA cells can be put back to general use as OK(ish). The rest would usually be put out for recycling but I got to thinking… is there another use for them?

So, what is an alkaline battery made from?

Diagram of the internal parts of an alkaline battery

A variety of things it appears. The chemicals inside are Zn/ZnO and Mn(III) and Mn(IV) species plus some KOH wrapped up in a stainless steel can with a brass current collector. Nothing I really need to play around with at the moment, and it's not like dead batteries are hard to come by. So that's a pass on the raw materials.

When I measured the voltage of the remaining 3 AA cells they were 0.05, 0.55 and 1.12 V, indicating that they are all pretty dead, ie there was not even any juice to be recovered by using them in a less demanding item. It is possible to charge alkaline cells another couple of times with a special charger (such as this one), but generally they are pricey for what they are and are not recommended. Making one would be a nice scratch build, but that is a project for another day.

Chart to assess the remaining charge of an alkaline battery

So the answer to the question of 'is there anything else I can do with them?' is, not really. Off to the recycling bin it is then.

JOB DONE

Time taken: 5 mins
Cost: £0.00

Dr Martens Boots Shoes

Unearthed from under the bed, one pair of Dr Martens shoes.

1461 Dr Martens shoes

They appear to be a pair of 1461 Oxford style DMs; made in the original factory in Wollaston, England, before the corporate suits at Permira closed it in 2003 and shifted production to Thailand.

Originally made from German fighter planes, the brand didn't really take off until the '60s when the design was licensed and improved by R Griggs Ltd. in the UK. Initially sold as cheap and practical workwear they became counter-culture fashion items in the days of punk and ska, but are now sold mostly as a general fashion brand.

Bob Martens on the street

I don't know if these count as vintage but they are not new. They are in OK nick but I can't wear them anymore, so it's time to move them on to someone else. On inspection the only thing that needs to be done to them before sale is to clean the shoe polish off the signature yellow sole stitching around the welt.

Discoloured sole stitching due to polish

A bit of on-line research threw up a range of different methods for cleaning up the stitches, mostly revolving around the use of solvents; isopropanol, acetone and lighter fluid were all mentioned. Basically anything that will solvate the wax in the polish should work and to this end a review of Wikipedia indicates that shoe polish is a mix of wax and dyes in 70% solvent (Stoddard solvent - a form of white spirit or naphtha).

Let's compare and contrast. I applied each solvent to a single stitch with a cotton wool bud and then cleaned off the polish with another dry cotton wool bud.

Solvent

Before

After

Acetone

Isopropanol

White spirit

Overall the performance of each solvent was much the same as the others. Perhaps acetone was marginally worse at removing the polish than the other two and seemed to attack the rubber of the welt slightly, but if it is what you have to hand it will still do the job. For me white spirit is probably the first choice for this task and in total I used about 5 mL of solvent to clean the pair.

Before (L) and after (R) cleaning with white spirit

JOB DONE

Time taken: 20 minutes.
Cost: pennies for white spirit, liberated cotton buds for free.

PS The title reference is to Mr Balowski's nephew.

Freezer Gloves

Tired of almost getting frostbite while digging through the chest freezer for that bag of sausages that you know is in there… somewhere…?

I am.

I noticed that the freezer guys at Tesco were wearing something more insulating than disposable gloves but not as bulky as freezer gauntlets (yes they are £160/pair, but to be fair you can work down to -190^oC in them).

Off to eBay, which brought forth the snappily titled Thermal Insulated Winter Work Gloves Latex Coated Cold Safety Freezer Strong at £2.69 a pair including p&p.

At that price, even if they are no good at all, what can go wrong?

So I duly ordered some and they look just as naff as the ones in the picture; but they do the job. Result!

Freezer Gloves Strong

All that was needed was to sew on a couple of loops so that they could be hung up in the kitchen. I found some similar material and badgered one of the tykes to do that.

Freezer gloves hunged up

JOB DONE

Time taken: none for me, 45mins for tyke
Cost : £2.69

'Fridge Crisper Drawer repair

Somehow one of the feet of the crisper drawer has become detached.

Offending parts

It's a clean break, in a slightly awkward place, but probably not too much of a challenge. The drawer is moulded from the same styrene-acrylonitrile resin that the cup I partially repaired was made from.

OK, repair strategies? From best to worst those that I came up with were,

• Solvent weld the parts back together
• Use a contact adhesive
• Use a two part epoxy to fill whole socket and stick the foot into well
• Fit a screw (would have to be stainless steel)
• Buy a whole new crisper drawer

Why is solvent welding best? As with ordinary metal welding it physical melts and reforms the structure of the plastic.

Although it didn't work brilliantly in the repair of the plastic cup I brought out the acetone again. After brushing on the solvent and replacing the part I left it overnight to harden. The next day an exploratory wiggle to see if the bond could withstand the lateral forces created by dragging the drawer across a surface resulted in it parting again, confirming my suspicions that acetone is a bit pants for gluing SAN.

The next step was to try a MEK/DCM mix; I had seen Tensol 12 used for ABS so that seemed a good place to start. A web search threw up a few similar glues, SciGrip 16, Ventex Channel Bond and Evo-Stik ExtruFix (I would provide links for Tensol and Extru-Fix but they are made by a French company that doesn't understand the internet). All seem to have dichloromethane (DCM) as a base with 3/4 containing methyl ethyl ketone (MEK) along with a smattering of other components, probably for the purposes of wetting and/or prevention of crazing. None of them were really that cheap (£8 for 60 mL of Tensol 12 was the best price I could find) and I couldn't find anything to say that they would definitely work with SAN. After a bit of swithering (look it up) I decided to buy a litre each of the main constituents and mix my own. If it didn't work then at least I would have the solvents to hand, so not a complete waste of money.

After deciding to buy the components I tracked down a reference to solvent welding SAN in the Handbook of Plastics Joining (p.442), which suggests that MEK is the required active component and that DCM can be used if a fast drying solvent is required. All good then.

But what proportions to mix the DCM and MEK to? A rummage about in the material safety data sheets of the ABS glues gave me a place to start In the end I plumped for a 3:1 (v/v) mix, but weighed out the solvents rather than measuring the volumes as I was dealing with small amounts as a trial.

Solvent mixing

The result was positive.

Reformed part

Given the lack of effect of acetone I did splash the DCM/MEK mix about a bit and have obviously overcooked it, there is quite a bit of crazing in the foot well. But the part is certainly joined, if a tad melted. Next time I will be a bit more cautious and only brush on the required amounts. I just popped the foot back on and slid it back into the 'fridge.

JOB DONE

Time: 30 mins (with overnight setting time)
Cost: £19.44

Shower swamp - Return of the Creature from the Back Lagoon

Or no good act goes unpunished.

The shower drain is up to its old tricks again. This time instead of plungering the drain I decided to take the U-bend off to see if there was an ongoing blockage in it. Not sure why I chose this course of action but in retrospect bringing out the plunger first might have been a better idea.

The U-bend is easily accessible, as it is located in the unboarded roof of the cupboard that the fridge sits in. The drainward joint unscrewed no problem but the upstream one felt like it was attached with a liberal coating of treacle. When it came off it appeared that it had been slathered in silicone sealant.

Bodged connection to shower tray

The U-bend was pretty clean, no doubt an effect of the energetic plunger action I had applied previously, so no problem there. The receiving pipe, however, had a 'dead mouse' of matted long hair wrapped round the 90^o bend that lies after the trap (I'll spare you the pictures). I extracted this and refitted the U-bend.

On reassembly the reason for the silicone sealant became obvious. The top joint of the U-bend had been damaged at some point so it was not forming any sort of a seal and the silicone had been put into to bodge the joint. Without the silicone the range of the shower extended from the bathroom into the fridge cupboard.

Damaged seal on bath trap

Time for a new part (40mm bath trap) from our very local plumbing supplies company. Reinstallation was easier as the silicone had been removed but the joint was still weeping a bit, probably because of a slight mismatch between the thread sizes of the PVC pipe and the metal shower outlet. A bit of PTFE tape solved this problem.

Repaired bath trap

JOB DONE.

Time taken : 45 mins hands on
Cost : £5.48 for replacement bath trap

Cup issues

One of the tykes has been too rough with a plastic cup and, while it isn't dead, it is not very happy.

Cup with an internal leak

Broken drinking straw

As the first of the 3 Rs is to reduce I wanted to try and prevent another plastic cup being bought.

The first job was the straw which was missing a bit, but not too much. A quick hacksaw and then I filed it flat and removed the burrs with a round file and that sorted that.

Repaired drinking straw

The next task was to deal with the cup. How to get the water out and how had it got in?

Getting it out meant giving it the opportunity to escape the air gap that gives the cup its' insulating properties.

Non-obvious holes

Drilled 1.5mm holes at 4 and 10 o'clock

Two small holes should give the water the ability to evaporate without compromising the insulating properties of the cup too much. Then it was just leaving it for long enough to do just that.

So it sat next to the central heating boiler for a month.

OK, so how is the water getting in?

Repaired cup

It seems to have developed a crack at some point (after being dropped perhaps?). Solvent welding using capillary action to wick the solvent into the area that needs to be bonded would probably be the best option. But what solvent to use?

The first thing is to identify the plastic that the cup is made out of. In this case the retailer's website wasn't helpful but as they only rebrand stuff (and slap on a healthy margin for the service) you can find similar items out there. Alibaba is a great resource for more detailed product information as you can get direct to the manufacturer. In this case a search for 'tumbler with straw' quickly yielded a couple of identical items (bar the printing/branding) [cut down links to ali items].

In this case it appears that the plastic is SAN, which is commonly used for food-ware and is a relative of ABS. A search for suitable solvents yielded

• Acetone [propan-2-one]
• Methylene chloride [dichloromethane]
• Methyl ethyl ketone [butan-2-one]
• Ethylene dichloride [1,2-dichloroethane]
• Tetrahydrofuran [1,4-epoxybutane]

Courtesy of the AdhesiveTechnology Handbook [p.222].

I have the first three to hand, but acetone is the more pleasant to work with, so I brushed on enough to saturate the fractured area to see if that could seal up the break.

The fracture wicked up the solvent OK and it has had an effect but not a complete one. I have another fix that will use a dichloromethane/MEK mix so I will return the cup to use and try again when I tackle that fix.

JOB (sort of) DONE

Time taken : 30 mins
Cost: Pretty much nil