Alesis (DM Lite) Drum kit without kick

Alesis Drum Kit gets a cheap repair.

A neighbour of mine is a talented musician in a local band and also teaches school children various instruments.  Some of his students learn the drums, which is most parent’s nightmare as any notion of a peaceful evening is shattered.  Luckily, electronic drum kits are an excellent way to learn with headphones, while keeping happy parents and neighbours.

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FixItWorkshop, Worthing, November’18, Alesis DM Lite Electronic Drum Kit
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FixItWorkshop,  Worthing, November’18, Alexis DM Lite main drum module

This kit was missing several beats and was hampering learning, so time for a visit to the workshop.  I’m no musical instrument repair specialist, but I thought that the drum kit must use electrical contacts, switches and rudimentary electrical components and I was right.

Two faults were reported; The kick/ foot pedal was intermittently not working and one of the drum pads was hardly working at all, unless you hit it with a sledge-hammer.  Time to see what was going wrong.

First up was the faulty drum pad.  Opening up the back of the pad was simplicity itself, just a few screws held the back to the pad.  Sandwiched between two halves was a sensor, a bit like a piezo flat speaker, similar to the type found in many toys with sounds.  I guess the principle here is that vibration detected by the piezo sensor is converted to analogue variable voltages by the drum kit’s circuitry.  While apart, I noticed that some of the copper detail tracks on the printed circuit board which had a standard 3.5mm jack socket (to allow a connection back to the rest of the kit) had cracked.  Looking again through my magnifying glass revealed quite a bit of damage, probably as a result of many Keith Moon wannabes.  Testing these tracks with my meter confirmed an intermittent fault, so out with the soldering iron, to repair the connection.  Plugging the pad back in, it was ready once again for more drum solos.

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Next up was the dodgy kick/foot pedal.  As the with the drum pad, the pedal would cut out intermittently.  A few screws held the pedal together, so only basic tools required.  See the slide show below for an idea of the construction.

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The fault with the pedal was similar to the drum pad.  Some of the copper detailing around the 3.5mm jack socket had failed and required some careful soldering.  I say careful, as applying too much heat at once would, likely as not, melt the casing of the socket.  One had to take care.

Once soldered, the pedal was much better.  I didn’t get a full 10/10 repair with the pedal since I think there was wear on the kick sensor, but it was an improvement none the less.

Cost of replacement:  £lots.  Cost of repair, my time, two cups of tea and some solder.

 

 

Runaway Hillbilly Golf Trolley…

Golf trolley heads for the hills…

Readers of this blog (I know there are millions of you) will recognise this golf trolley and I’m pleased to report that my first repair, the one to the motor, is still working perfectly.  However, the owner of the trolley contacted me with a (funny) problem.  Whilst recently enjoying a round of golf on the local fairway, the trolley decided to, by itself, begin to edge away from the second tee and then with some speed, head off in to the distance, without any operation of the dial switch, situated on the handle.  Whilst this seemed funny at first, I remembered that the motor on this trolley had the kind of torque that, coupled to small gearbox and wheels on a heavy frame, could do some serious damage, left unchecked.

Original photo taken in Aug’17, below.

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FixItWorkshop, Worthing, Aug’17 Hillbilly Compact Golf Trolley

Unlike many modern electric golf trolleys, it doesn’t feature GPS guidance, remote control or amazingly, a dead-man’s switch, which seems like a major safety oversight to me.  I’d have expected either a kill switch or dead-man’s switch* fitted to the handle on a trolley like this as the runaway scenario could never occur due to fail-safe nature of the switch being operated.  With one, the trolley would only run when the operators’ hand was on the handle or cut out when the kill switch is activated, as with the saftety cord mechanism, on a jet ski for example.  Perhaps the Mk2 Hillbilly Compact featured this.

*For example, a dead-man’s switch is usually fitted to something like an electric saw where the operator must old a handle-type switch to make it run.  Once the operator lets go of the handle, the motor automatically fails-safe and cuts-out.

On with the repair.  The trolley features some exposed connectors and cabling and it seemed sensible to check the continuity of the cables running up and down the handle shaft, as repeated trolley folding might have caused a problem with the wiring.  Fortunately, the cabling was OK.

The owner had mentioned that the handle, where the speed control switch is located, had got wet in the past, which made my alarm bells ring.

Opening up the handle, which only required a basic tool kit, revealed evidence of water damage and corrosion to the speed control terminals.  Luckily the owner of the trolley had stocked up on spare switches!

Removing the existing switch revealed intermittent continuity and varying amounts of resistance, which was not good.  A fault most likely to have been caused by water ingress or excessive shock.  The owner had supplied two ‘new old stock’ (NOS) switches.  Which one to fit?

From time to time, it’s downright sensible to either fit NOS or second-parts as they’re usually cost-effective and are more likely to fit over pattern parts.  But time can also affect apparently shiny parts.  This was a case in point.  I knew that the switch should vary resistance from open circuit to 10KOhms in either direction from COMM.  The old one didn’t and one of the ‘new’ parts only went to 2KOhms, so was not in specification.  Luckily, the remaining NOS switch worked fine and once refitted, and the handle reassembled, the golf trolley was ready to make the job of carrying clubs easier, once again.

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FixItWorkshop, Feb’18, Hillbilly Compact speed control switch, new and old- test NOS parts before fitting.

Cost of replacement trolley:  ££££ Cost of repair; £10 plus time.  Moral of the story; don’t assume NOS parts will work.  Test them first.