Wired for sound: AKG Headphones repaired

A pair of decent studio headphones dodges the bin…

Headphones are big business and global sales of these devices reach over $500m per year in the U.S. alone (quick Google search, so it must be right eh). As I’m sure you do; When I read sales figures like that, I wonder what the average life expectancy of headphones is, as I’m sure that many sets are viewed as disposable items.

Bluetooth and other wireless headphones aside, most wired headphones are fairly straightforward to mend, assuming no damage has been done to the speaker or ‘phones’ part. You just need basic tools, some patience and a fair bit of nerve… See how I got on with this pair of AKG K92s.

Make and model: AKG Headphones K92

Fault reported: No left channel

Cost of replacement: £35 when new

Manufacturer support:  0/10

Cost of parts: £0.00

My repair time: 45 mins

Tools needed: Soldering iron, small screwdrivers

Sundry items: Insulation tape, holt melt glue

Cleaning materials: N/A

Repair difficulty: 4/10

Cups of tea: 1

Biscuits: No biscuits this time, as it was lunchtime. It was cheese on toast for me, with some chorizo on top as I seem to remember, maybe a dash, just a tad, of tomato sauce- from Lidl I think…

I’d just finished the last mouthful of tea, I was getting peckish, thinking about putting the grill on, when a neighbour of mine rang the doorbell, at lunchtime -of all times.

The conversation went like this; Matt, could you have look at these old headphones for me? I was about to chuck them out and I know you like playing with old stuff like this. They used to be good, but they only work ‘one side’ now. I mean, they’ve probably had it. …Hang on I said, let me have a look, leave it with me. Famous last words.

I was quite flattered actually, as I really do like receiving work this way. When there’s little hope for something that’s probably on its way to the great scrap bin in the sky, I must admit that I especially like taking on that challenge of making something work again. Diverting the once condemned item back into full service is the thing that keeps me motivated.

On with the repair. The fault reported was ‘no sound from the left speaker’. The first thing to check with anything corded is the cord/ flex/ wire itself. While a visual check of a wire is no conclusive way of proving that it works or not, tell-tale signs of bending and chaffing can save a lot of time elsewhere. Rule out anything silly before wielding screwdrivers, I say.

Since the wire looked OK and the plug wasn’t bent, it was time to take the headphones apart. The AKG K92 headphones are simple to dismantle; just pull-off the headphone covers and the speakers are held together with just four small cross head screws, each side.

Using a multimeter set to continuity test, I was able to prove each part of the cable. The main wire from plug to headphone set proved OK, which was a good thing as it meant no replacement required (these are widely available on eBay). The headphones’ over the head band, as well as keeping things snug on ones’ noggin, also carries the signal from one side of the set to the other. If you’re still reading, I hope that makes sense. Anyway, the meter proved that it was all fine.

FixItWorkshop, Worthing, AKG K92 headphones, left channel re-wiring.

In the end, the fault lay with the main wire to headphone speaker on the left side. To be honest, I should have checked that first as that connection is always under load as it crosses a pivot point, allowing a few degrees of movement and therefore comfort for the user.

On the subject of comfort, while doing the repair, I noticed that the headband was a little torn at each end, presumably a result from many intense sonic moments. The vinyl coated band was a tricky customer to repair, but a little hot melt glue along the torn edges, soon fixed things, giving the headphones a fresh feel.

A quick remake of the connection (cut cable, re-solder) and full hi-fi was restored and the headphones were ready to blast again. Turn it up to 11.

Dinner will be served in a flash…

A Tulip A350T Electric Rice Cooker is repaired

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FixItWorkshop, Worthing, June’20, Tulip A350T 12Y1EI (to be exact).

I particularly enjoy receiving something to fix that I’ve never come across before.  Indeed, I’d never used an electric rice cooker, let alone heard of Tulip, the manufacturer of this example.  To be frank, I haven’t often thought about the popularity of electric rice cookers in general as an additional labour-saving device in the kitchen.  Clearly, I must be slipping.

This actual machine was a family treasure, which had moved around a bit and had originally been purchased in Holland and had since been converted from using a standard Euro plug to IEC/ kettle UK mains plug at some point.  All very interesting you say (maybe), but how did it end up in my workshop?

Make and model: Tulip A350T Electric Rice Cooker

Fault reported: Not working

Cost of replacement: £30

Manufacturer support:  0/10

Cost of parts: £2.00

Hours spent on repair: 1 hour

Tools needed: Screwdrivers, test meter, heat shrink, looped crimps etc

Sundry items: Cleaning materials

Repair difficulty: 3/10

Cups of tea: 2

Biscuits: Custard Cream X 2

After many years of reliable service, poor old ‘Tulip’ decided it had had enough of boiling up pilau rice and assorted vegetables and conked out.  When the owner tried to switch the cooker on, nothing happened, no light, no heat, no hope.

Most people would then usually have thrown in the towel, reached for their phone and within a couple of clicks, bought a new one on Amazon to be delivered the next day.

Perhaps it was the thought of poor old Tulip being crushed in the scrap metal pile at the tip which made the owner go online and find my website of strange domestic appliance tales instead of Amazon*…  But I’m glad they did.  *other online electrical retailers are available!

The machine is basically a large kettle with a removable bowl that holds whatever you wish to cook.  It has a thermostat for temperature regulation, a switch to change modes (cook/warm) and a safety cut-out mechanism, should something go wrong.  It was this safety system which had operated and caused the machine to fail-safe.

The design of the machine is quite simple, dare I say crude in places.  Within a few minutes, I had removed the base, exposing the wiring, switch, thermostat and other gubbins.

The earth bonding cable had melted which was the first alarm bell to ring.  Digging a little closer, the main issue revealed itself.  The heat-proof insulation on the ‘over heat’ one-shot thermal fuse had shorted out via a cracked piece of wiring on the metal casing of the unit.  Surprisingly, this had not overloaded the main plug fuse, but had heated the thermal fuse and had blown that instead.  Flash-bang, kaput.

The cooker’s switch, thermostat, element and other wiring checked out OK, so it was now worth fixing the failed system.

After purchasing a suitable replacement thermal fuse for a couple of quid, I set about installing this in place of the failed one, taking the time to upgrade the wiring harness with heat shrink to avoid a short again in future.  I removed the damaged earth and replaced it with fresh wire, securing it on to a better earth-bonded location and after some careful wire re-routing and fettling, the base of the machine was ready to be re-attached, ready for testing.  With the cooking bowl full of water and power applied, the ‘cook’ light lit up and the machine started to work.  Utter joy.  After a few cycles of heating and warming, I was satisfied that my work was done.

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Even though this device wasn’t marked as such, it’s a metal bodied Class One device here in the UK and ideally required a thorough integrety test of the safety system.  Using my newly-acquired Megger PAT150 tester, I was able to prove that the machine was compliant with current UK legislation for Portable Appliance Testing.  Ricely done.

 

 

 

The tale of Hetty & Henry

A small mix up nearly resulted in some body modification…

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FixItWorkshop, Worthing, May’20, Henry & Hetty bathing in the sunshine

Make and model: Hetty Vacuum Cleaner (HET200-22)

Fault reported: Not working

Cost of replacement: £100-£140

Manufacturer support:  10/10

Cost of parts: £21.59, inc. carriage

Hours spent on repair: 1 hour with service

Tools needed: Screwdrivers, test meter etc

Sundry items: Silicone spray, cleaning materials

Repair difficulty: 4/10

Cups of tea: 1

Biscuits: Ginger Nut X2

If only everything was as well made and built to last as a Henry (or Hetty!) hoover.  Simple as a knife and fork, with tried and tested technology, it’s a machine created by an engineer, for everyone to own, use and repair themselves, when needed.

A neighbour got in touch to say that their broken Hetty was about to be scrapped and asked if I could do anything with it.  Of course, I said.  To be honest with you all, I’m not that confident with all repairs, but I knew that in the case of this one, I should be fine as Numatic products are pretty well supported by the manufacturer. And this is the thing:

How many purchases do we make that consider; “will I be able to get parts for that one day”?

We all do it, but as a tinkerer I try and consider the longevity and likely need for replacement components when I’m considering handing over my hard earned wedge, at point of purchase.

The Hetty had been working fine, but had then conked out, mid clean.  No drama, no noise, no smoke, it had just stopped.  The owner had already checked the fuse, but that was fine (as they often are).

When things just stop and won’t restart, that symptom is often trying to tell you something and if you’re listening, capturing the way something fails and acting on the information can save you time and often money.  It’s a trick I’m always trying to perfect, although one can be caught out anytime- but that’s half the fun.

  • The machine stopped suddenly…
    • Maybe the cable broke?
    • Maybe the plug is damaged
    • Maybe a component failed quickly

Expensive things like motors tend to start making noises, run slower than usual or smell bad before failing.  They can ‘just stop’ of course, but it’s likely that there will be a build-up, so I proceeded with some confidence that the motor was probably fine.  I always check motor bearings and brushes anyway, when servicing this type of thing.

Since the mains cable and plug were fine, it was time to delve inside.  The Hetty top is simply held together with a few screws (normal cross head) which then frees the cable winder and motor assembly, when undone.

I suspected the two-speed control PCB as these can fail suddenly without warning and since I have no Numatic PCB tester (if there is such a thing), all I could do is prove the component as faulty, beyond reasonable doubt.  A quick check with my multi-meter revealed that there was no output, when connected to the mains.  Suspicious.

It is also possible to by-pass the speed control PCB on these machines, which I did.  I connected the motor up without it’s 600W/1200W control circuit in the loop and the motor spun up just fine.

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Often, I like to go direct to the manufacturer (where possible) for spare parts as you often get the truth about an appliance as well as the latest version of a part.  Often, manufacturers continue to iron out bugs and develop upgrades for spare parts as these will be fitted to the latest models.  A company such as Numatic seem to apply those upgrades retrospectively to older models too, so that all customers new and old, can enjoy the benefits.  For information; UK spec speed controller part 208436 (red) replaces part 206735 (orange) for model HET200-22.

As I couldn’t find the part I needed on any website, a quick call to Numatic UK, gave me the information I needed.  Even during Covid-19 lockdown here in the UK, the lady in Numatic’s spares department, working from her kitchen, was able to advise me on the upgraded part I now needed and arrange for it to be with me for the next working day.  If that’s not good service, I don’t know what is.  http://www.numatic.co.uk

With the new part installed, the motor spun once more, at the correct two speeds.  Happy days.

All fine then.  Not quite. 

Hetty had been supplied with a red base, not the original pink one that Hetty should have.

As we all know… no?  Just me then, Henry is red and Hetty is pink and there is a range of names and colours to choose from in the range.

When I tried to fit the Hetty top to the supplied red base, it didn’t fit.  Quite a head-scratching moment, if I’m being frank with you.  Had it never fitted? Had the owner simply just put up with it the way it was?  Had there been some kind of strange swapping incident that I wasn’t aware of?  Time to get some answers!

It turns out that my neighbour have both Henry and Hetty models and had given me the wrong base.  They had assumed they are all the same.  They’re not actually, see below.

The latest Henry and Hetty tops have a cut-out for the tool storage bracket moudling as shown on the red base above.  The earlier Hetty I had in the workshop had no such bracket in the plastic.  I did offer to modify the Hetty top I had with my Dremel saw, but this offer was declined!

With the right top and base paired up once more, I was happy, the neighbours were happy and another vacuum cleaner had been saved from being scrapped needlessly.

Time for another brew.

 

Dyson DC25 with various problems

Another Dyson dodges the dump

An email dropped into my inbox about a poorly Dyson DC25, that needed a bit of a clean up.  I said no problem, I’ll take a look.  What turned up was a vacuum cleaner that needed a bit more than a quick clean up with a J-Cloth.

Make and model:  Dyson DC25 (blue/ grey)

Cost of replacement:  £N/A, price when new £300

Cost of parts:  £6.89 (plus my time)

Hours spent on repair:  2.5 (plus testing)

Repair difficulty:  5/10

It soon became apparent, that the Dyson was quite ill.

Here’s a summary of the problems:

  1. The mains cable flex was split, exposing the internal cables risking electric shock
  2. The roller beaters would not spin
  3. Suction was limited

None of these features were useful in vacuum cleaner, so out came the screw drivers.

The mains flex damage was about 90 cms from the handle end, so rather than replacing the whole cable at about £30, I decided to shorten the one already fitted on the Dyson.  This involved removing three screws on the reverse of the handle to expose the wiring.  From there, the broken flex could be cut-out and the sound part of the flex, reattached to the Dyson’s wiring.  See below.

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The DC25 features a roller-ball, enabling the beater head to twist and turn in to tight spots on the floor.  This means that mains power must navigate the various joints and hinges on the way from the main body to the roller beaters.  A quick test revealed that the power was not getting through.  After removing one of the side covers, there was evidence of a previous repair.  One of the mains cables had broken and had then been twisted back together.  Clearly, an improvement was needed.  Using a section of repair cable, a small joint was soldered back in to place with some mains-rated heat shrink around the connection for insulation and reinforcement.  See below.

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The beater head also needed a good clean, which meant a strip-down and re-build.  All parts were cleaned, inspected and reassembled.  During that process, a small break in the beater head wiring was found, repaired and put back together.  See below.

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Finally, the machine needed a good clean up.  The main cylinder was washed, the filters washed (although I later decided to replace these) and the main seals on the vacuum system, cleaned and silicone sealed.  See below.

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During clean up, the spigot-yoke that holds the roller ball in place on one side was found to be missing.  Luckily the owner had kept this and dropped it back to me to re-fit.

This Dyson was on the brink, but with a little bit of spanner-time, it’s now ready to serve many more years.

 

 

 

 

Satellite Bass Guitar that wouldn’t go to 11.

A Fender Precision style Satellite P Bass guitar repair…

A friend of mine, who plays in a Portsmouth-based Psychedelic Garage Rock & Roll band, brought in a Satellite Bass Guitar with a few issues.  Firstly the volume control was noisy and crackly and secondly, it was a little quiet.  Not good for those moments where you need to go one higher, to eleven.

The band are:  60th Parallel

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FixItWorkshop Jan’18, Fender Precision style, Satellite P-Bass.

Opening up the compartment behind volume, tone and jack plug socket revealed messy wiring and dodgy connections.  The owner had already supplied a replacement potentiometer for the volume control, so all I had to do was replace the one fitted, re-make the poor connections and give the wiring a general tidy-up.

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FixItWorkshop Jan’18, Fender Precision style, Satellite P-Bass, wiring before work.

The guitar has Dimarzio ‘Model P’ pick-ups which can be wired many different ways, depending on the application and musical taste.  This particular guitar, circa 1976, is a Fender Precision style Satellite bass (P-Bass) and has a modified ‘through neck’.

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FixItWorkshop Jan’18, Fender Precision style, Satellite P-Bass, volume (top) and tone (bottom) controls.

Testing the guitar before commencing work revealed a slightly quiet, but mainly crackly output from the amplifier, the tone control was fine.  The owner had also complained that the bass sometimes cut-out, mid song.  Not ideal.

Removing the volume control was straightforward and only required a spanner to remove the nut, after pulling off the volume knob.  The rest of the job just involved careful de-soldering, cutting out the poor wiring and replacing it with new wiring where needed and some heat shrink to tidy things up. Having not repaired an electric guitar before, I did make a quick wiring diagram for reference!

Once completed, I hooked it up to the amplifier again which revealed a much cleaner, crackle free note.  Sadly, I can’t play the guitar, so I wasn’t able to test it properly!

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FixItWorkshop Jan’18, Fender Precision style, Satellite P-Bass, neater wiring.

Cost of a new bass:  Name a price.  Cost of the repair; about £2.00 plus tinker time.