Tag: Vibraphone

Premier 751 Vibraphone refurbish (part 1) (Job No: 1205)

This set of vibes needed a bit of tlc, or in other words a complete overhaul.

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There are a couple of issues that the customer specified that need to be looked into:  it’s really rickety and unstable, and the motor keeps snapping belts.

Whilst I was stripping the instrument down to service the parts, I drew up a long list of other problems.  Some faults I repair immediately, whilst other issues I put to one side to be looked at in isolation.

For instance:
The speed controller has been taken apart by someone and re-assembled incorrectly, so there was a bolt floating loosely around the main terminal block  which should be securing it.  Idiots!
The mains power lead going into the transformer housing has a slice through the insulation (on both the live and neutral (brown and blue) wires).

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Along with a couple of other issues on the motor wiring, means that the whole lot was removed to be looked at later, because whoever did it was trying to kill someone!

What I tend to do is overhaul the frame first.  This is both because it is big and takes up most of the bench, but also so that everything else gradually gets put onto it until I have a complete instrument ready to be checked.

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The photo above is looking down the length of the instrument at the low end.  You will have to zoom in.  I put a straight edge on top of it to show that it is bent all over the place.  This not only looks bad, but the deformation is primarily where the legs attach (probably one reason why the instrument wobbles badly).  Straightening this is a good job to do on a cold morning – I have a forming bar, a hammer, an anvil and a pair of strong arms…

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This never comes out perfectly, but it certainly gets close to straight, and once it is put back on the instrument, it will no longer be that noticeable.

The story continues in: 1205: Premier 751 (part 2)

Premier Vibe Motor Conversion (Job No: 1101)

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This is a replacement motor unit made for a Premier 751 vibraphone.  The on/off switch, and potentiometer are on fly leads so that they can be fit either side of the leg hinge, on the underside of the high end transom.  The grey box contains the speed control PCB, capacitor, and various connectors, with an IEC socket fitted so that the power cable can be removed.

The motor carriage is made to fit 750 & 751 vibes, but will probably fit older models.  Like everything I make, it has been designed to overcome problems that I have had to repair many times.  This carriage is not only strong enough to actually hold the motor, but will actually stiffen the note rails and their joining piece.

Locating the pot and on/off switch to the end frame avoids the normal difficulties experienced when bowing the notes, and the leg hinge will offer protection to the components during transportation.

The grey box is the brains.  The IEC socket was a moment of realisation during conversation with the customer.  By using a standardised socket as opposed to permanently wired, prevents straining or damaging the cable which occurs when winding it around the instrument, and makes replacement simple.  In fact finding a replacement cable on a gig is now simplicity; just borrow the cable one powering the kettle, or pc, or guitar amp, etc, etc.  Additionally, there is now no need for anyone other than myself to open that grey box!  Finally, there are two small holes on the side, the small one is the power led on the PCB, the larger one is access for the trimming pot which can be used to increase the maximum speed, so can be ignored.

To fit it, six holes need to be drilled, four for the motor carriage and one each for the pot and power switch. Then its just a matter of routing the cable.

Vibraphone Motor (Job No: 892)

Annoyingly the motor and speed control unit I had in stock just didn’t work. I had to design a removable motor unit for a vibe, and the motor assembly was at its core. To make matters worse the speed controller has been dropped by the manufacturer, so I now have an entirely new system to fit into an existing design. The final added layer of complexity is that I have to modify the new controller in order to achieve the same usability.

Having been shopping, I now have everything I need:
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B&H vibe tuning (Job No: 1070)

A set of vibe notes in for tuning.

On the graph, the X axis are the notes – this vibe goes from C to F.  The Y axis are the cents above and below the zero line which is at A=440 Hertz.  The fundamental pitch is the blue line which is generally flat (to be expected as the instrument is marked A=439Hz).  However the red line is the 2nd Harmonic, and as can be seen it goes from massively sharp in the lower octaves of the instrument, to massively flat in the higher notes.

To bring the notes into tune both of these lines should read zero.

 

Ross Vibraphone (Job No: 1064)

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This vibe is in to fix a motor problem, however there are more problems; broken note rail, and a dreadful repair that someone has done to the frame which means that the diagonal braces don’t even reach the connection socket

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Plus welding commonly known as “bird shit” which aptly describes its appearance and strength. What is more, whoever did it left sharp bits of spatter, and a sooty mess.
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The electrical side:
The first problem is in the plug, the fuse is loose in its holder, the sort of problem that starts fires. Secondly, despite the speed control being housed in a metal box, there is no earth cable. I’m not an electrician, but I thought that this was illegal, common sense dictates that an earth connection would be a good idea, and the motor manufacturer does use an earth wire in their controllers.
Finally, the wiring in the mains connector to the circuit board is not soldered, so those wires could have come out at any point to make the casing live.
Whoever repaired this instrument before shouldn’t be trading!

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The Frame Repair
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I started by cutting away the bad repair to leave the two legs ready for a fixing bracket to be made.

At the same time I have to make a new square bush that prevents the leg from wobbling.
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Then the completed legs were assembled, the frame jury rigged into position, so that the new bottom bar can be cut at the correct length.
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Over the years I have done this countless times. My design has evolved, but the basics remain; the frame is the structural element, built to withstand the rigours of use. The keyboard bed just sits on top. The reason is simple – its more expensive to repair the keyboard bed.

Once the bottom bar is fitted, and the rest of the frame components made, everything is assembled ready for welding.

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Finally I need to make a new rod to connect the damper to the pedal, to replace the sorry example that was on the instrument.

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Job Completed
Here is the finished article; new base frame, new motor and controller, new damping mechanism.
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