Explosive Chef

Another Kenwood Chef A901 gets the Workshop treatment…

There’s been a steady flow of poorly Kenwood Chefs through the workshop of late and the new year started off with yet another.  A customer got in touch with reports of smoke coming from her Chef A901, a machine which had given years of faithful service to her family.  As a result, she was very keen to see what could be done.

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FixItWorkshop, Worthing, Jan’19, Kenwood Chef A901.

As usual with Chefs of this age, the 5 machine feet had deteriorated and now resembled squashed dry Blu-Tac, so had to be replaced.  I replace the feet to most Chefs that come in.  Not only do the feet prevent the machine from moving all over the place when in use, they provide a gap for air to be drawn in to the motor for cooling, so it’s essential the feet are in good condition.

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FixItWorkshop, Worthing, Jan’19, replacing the feet on a Chef A901 (others similar).

The feet are inexpensive and are easy to fit.  If you decide to replace yours, consider coating the existing ones with something like WD-40, a few days before you try to extract the centre pin or you risk snapping it off in the machine base, as it will likely be ceased.

On with the repair.  The speed control circuitry had failed, specifically a capacitor and resistor, a common problem on older machines, had gone pop.  As usual, the correct repair kit was bought and fitted. With careful soldering and a dab of heat transfer gel on the new triac and the job was complete.  Nice.

With any Kenwood Chef, I always check the motor end-float, the allowable spindle movement north and south.  The end float in this case was a little lose and required adjustment.  A small grub screw with Allen key head allows this adjustment and with a bit of trial and error, the end float was now spot-on.  Poor end float on these machines usually makes the speed control ‘wobbly’, especially at lower speeds.  With this one adjusted correctly, the motor now ran smoothly through all speeds.

Job done.  The owner of the machine was so pleased with my work, she even bought me a new packet of Custard Creams.  Fab.

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Cost of replacement: £400 and up.  Cost of repair: £11.24, plus my time and Custard Creams!

Another smoking Kenwood Chef A901E sorted in time for Christmas…just

Another Kenwood Chef gets the treatment in the Workshop

How about another Kenwood Chef story?  I know I’ve covered this machine a few times now, but I’ll try and make it as interesting as I can.  I just LOVE Kenwood Chefs.

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FixItWorkshop, December’18, Worthing, Kenwood Chef A901E on the bench.

A customer got in touch with me via the FixItWorkshop ‘contact us’ link asking if I could fix his family’s much beloved Chef.  While last in-use, it started smoking and smelling terminal.  How could I refuse.  I’m located in Worthing, but the customer was based in North London, quite a distance for a repair and would have been usually cost prohibitive using the Royal Mail.  However, using local drop-off points, carriers such as Hermes and DPD offer (slightly slower) courier services for about £7.00 one way, which starts to make more fiscal sense.  This is what we did.

I wish I’d taken a photo of the box the Chef came in, because the customer had clearly gone to a lot of effort to make sure it was well protected!

On with the repair.

The Chef has been in production many years and although they can often appear similar on the outside, they do vary on the inside, depending on the year of manufacture as small tweaks and improvements are made.  Evolution, rather than revolution, usually the backbone of any successful design.

The A901E is different from the previous A901 as it features an electronic speed controller, rather than a centrifugal affair.  While the later design is an improvement, it wouldn’t deter me from buying an earlier model; the improvement is small.

The A901E still features similar components to previous models which can and do fail, especially with age.  The subject here is about 30 years old, give or take.

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FixItWorkshop, December’18, Worthing, A901E, motor removed.

The motor on the A901E comes out quite easily; first remove the motor cover, remove the mains cable (disconnect first of course), remove the top cover, belt, then the four screws holding the motor in.  The motor then pulls down from inside, out through the gap left by the hinge.  Easy.

The motor circuit board showed traces of component catastrophe with dust and dirt left by exploding components.  Nasty.  Pre-empting the fault, I ordered a repair kit before I’d taken the machine apart, together with replacement feet as the ones on this machine were knackered.  The kit includes capacitors, resistor and triac as these are the main components that tend to fail.

These kits are available on eBay and are worth the money as they are often cheaper than buying the components separately and they contain instructions for newbies.  Here’s a little slide show showing the process.

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With the kit fitted, the motor re-installed, mains reconnected, the Chef ran well again, this time without burning or smoking.  However, all was not well as the speed control was a bit wobbly at lower speeds, which was just plain wrong.  Having worked on a good few Chefs, this problem is usually down to excess end-float on the motor spindle.  Working with the motor still in situ, the motor fan, which controls end-float could be adjusted with an Allen key.  Sorted.

Just the replacement feet to fit and after a quick clean-up, the Chef was reassembled, ready to go home.

A top tip for you.  If you intend to replace the feet on your machine and you probably should if they are old as they go hard or fall apart, then soak the area around the feet recesses with WD-40 or similar a day or so before as this will make getting the remnants of the old feet out, much easier.

Cost of a replacement:  £400 up.  Cost of repair:  £12.65 plus my time and tea.

Elna SP foot pedal went bang

Elna SP foot pedal to the metal

On the back of a previous article about a repair I did on the rather wonderful Elna SP sewing machine, a reader got in touch.  She was a genuine sewing aficionado and had several top of the range current machines, but she used the trusty Elna SP for many smaller jobs, where the other machines didn’t quite cut it.

All Elna SP machines are getting on a bit and parts are either re-manufactured, scarce or secondhand, if you can find them.  Having said all that, a well-maintained Elna will run for many years and last much longer than new metal on sale now.

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FixItWorkshop, Worthing, November’18, Elna SP Special, in action

The foot pedal on this machine had gone pop, bang, finito.  It smelled terminal.

Knowing that parts for this machine are rarer than hens teeth and I do like a challenge, I took on the job.  I’m based in Worthing, West Sussex and the machine was located in Scotland, so after a short wait, the knackered pedal arrived in the post.

The pedal is held together with four small self-tapping screws and came apart easily.  The reason for failure was two-fold.  The copper leaf contacts had arced excessively and caused major pitting in the contact strip (see slide show) and the probably ensuing resistance had caused the main resistor to overheat, causing the winding to fail.

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The contact surfaces were easy-ish to fix, or rather breathe new life into as all they needed was cleaning and re-shaping.  The resistor was a bit trickier to mend.  Getting hold of a replacement was going to be near impossible, so the only thing to do was to try and repair it.  Without that particular style of resistor, of that value, it wouldn’t work again.  Luckily, there was some excess resistance wire on the thing and I managed to twist it in to the broken section.  Soldering was not an option, since the wire was an alloy that wouldn’t take to solder and in any case, these things get hot in normal service.  I twisted both ends of the break to form a new section, while maintaining the same length of windings on the resistor, essential if I was to match or get close to the original specification.  Difficult.  Luckily, after a few goes, I managed it and the applied a little heat-conducting (and therefore dissipating) paste to the join.

With the pedal reassembled, I was only able to test it with my meter, since the sewing machine was far too heavy to post.  The pedal tested as a closed circuit (OK), which was a result.  I then had to wait for the pedal to be collected, taken back to Scotland and tested.  Fortunately, my fix worked and the machine sprang in to life, without a hitch or missed stitch.

Now, a word of caution with this one.  This is NOT the best way of mending something like this and all I’ve probably done is prolong it’s life a little longer.  There are generic sewing machine pedals that would work with this machine and will be fine, when this one fails in future, but that’s not the point.  The main thing is that something that was broken is now working and even if it’s not the best fix, at least it will run for a bit longer.  Happy days.

Cost of replacement: (generic part) £15-30.  Cost of repair, my time, a bit of solder and several cups of tea.

Kaput Bosch AL1450DV Drill Battery Charger

An old Bosch battery charger gets a new lease of life.

These chargers often lead a hard life, working in dusty, hot and noisy conditions, so I guess many of these fail in time.

This Bosch unit is fairly common among Bosch DIY drill sets and this one had died catastrophically.  With the power applied, this one refused to give the slightest charge to a drill battery, once plugged in.

After some basic testing, I decided to change four components which would have caused the other to fail in a ‘domino effect’.  The cost of the replacement parts was just shy of £10, but definitely worth saving since second-hand units seemed to be changing hands for £40 on eBay, with their condition largely unknown.  The parts (two resistors, MOSFET transistor and diode/ transistor) were readily available online.

I recorded a short video to help others who might have a similar problem with theirs…