The Keyboard

To start, check that no keys are chipped, broken, or glued - all indications that the keyboard has taken hard knocks that may have caused damage to pivots, supports, buss bars, return springs, or optosensors. Now place the synth on a flat surface, and sight along the keys. An uneven keyboard often indicates excessive wear, amateurish maintenance, or uncorrected damage. Next, select or create a percussive sound and, if you're testing a polysynth, put it into 'unison' mode. Playing a chromatic scale will then reveal dodgy contacts, electrical faults, and sticking keys. Feel the notes: do they respond evenly, and are the velocity and pressure-sensitive responses (if featured) equal for all keys?

A common excuse for faulty keys is, "it's just dust on the contacts". There's a simple test for this: choose a dodgy note and play it a few hundred times. If it shows signs of resuscitation, it may be suffering from dust or slight corrosion. Only you can then decide whether to take a risk, but bear in mind that repairing a keyboard fault can be expensive. For example, the Roland D70 uses rubber contacts, and it takes hours to disassemble the synth to replace these. The time alone makes this an expensive repair, and you also should bear in mind that these parts will one day become unavailable. Another example is the Roland U20, which uses a ribbon connector underneath the keys. If a group of eight keys stop working, or if every eighth key stops working, this ribbon is damaged, and it is not a cheap component. Add the cost of the work involved... and it's likely that this low-cost synth is not economically repairable.

In contrast to these, some keyboards are simpler to access and disassemble and, in principle, are more easily repaired. The contacts on the Prophet 5, Korg Polysix and Moog Polymoog are quickly accessed, but (and this is the bad news) parts are becoming hard to obtain.

If you have a keyboard fault on a vintage organ, matters become much more complicated. Many Hammonds, Vox Continentals and Farfisas have multiple contacts per key; usually one per drawbar. This makes it much more difficult to locate a fault, and you certainly don't want to remove the keyboard from something like a Hammond C3. Furthermore, what looks like a keyboard fault may in fact be a missing signal from the tone generator. Removing and repairing this requires that you disconnect approximately 200 point-to-point wires... which is not for the inexperienced or the faint-hearted.

Fortunately, a number of older organs have keyboard adjusters that may eliminate simple problems. For example, some Hammonds have an adjuster that moves the buss bar laterally and, while this will not correct a dead contact, it may clear an intermittent note. But when it comes to keyboards the best advice is, "If in doubt, walk away".

If the keyboard works correctly, remember (where appropriate) to test the keyboard scaling: the bottom of the keyboard should be in tune with the top. Many older synths also have octave selector switches, so check these carefully. Scaling faults require professional servicing, so ask for a price reduction if it's less than perfect.

One final piece of advice about keyboards. Please don't spray contact cleaner on keyboards that use rubber contacts. For one thing, it's totally inappropriate. But more important than that, it will make the problem much worse. You have been warned!