Are you in the market for an older keyboard, sir? And are you worried about it? David Etheridge consults a team of expert synth repairers to discover what problems you may run into on secondhand keyboards, how to spot them, and what they'll do to your bargain buy.

THERE'S A LOT to be said for the vintage keyboard.

The more mercenary among us may be hoarding them away for the first Christies auction of early synthesiser technology, while others may choose them for the sound they produce and the ease (or otherwise) of programming.

But if you're someone who stares at the latest MIDI-ed, parameter-wheeled, data-indexed keyboard, and longs for the days when 'every job had its own knob', an older, secondhand synth could be up your street. Alternatively, there simply might not be the dosh to provide for the most recent release. Synthesisers don't cease to work just because a new model comes out, and some real, powerful bargains can be found on the secondhand shelves, if you know where and how to look.

As a guide to the best of the last decade's technology, Julian Colbeck's book 'Keyfax 2' is unbeatable. But when you do turn up to buy a synth with an impressive spec, how do you know if it's all working? And perhaps more importantly, what bits can you get away with that are not working? To discover this we visited the Synthesiser Service Centre in London's Primrose Hill. The duo of David Croft and Ron Lebar have ripped apart and put together more synths than you've had duff MIDI leads.

Firstly, what to look for when presented with your prospective buy?

David: "It needs to look as though it's been well looked after — the worst part I would say is if it's had beer spilt over it. As far as I'm concerned that causes the most expensive damage."

Ron: "Yes, if the instrument looks as though it hasn't been cared for in that way, the chances are that it hasn't been cared for in other ways. Check if the keyboard seems loose and rattly — it probably needs to be treated with suspicion.

"On a non-programmable synth any missing presets mean that you've got some sort of electronic trouble, and you've got to allow for that when considering an instrument — either don't buy it, or buy it cheaply. The same things apply to touch sensitivity."

David: "Once you've checked everything that is a problem, the next thing to consider is the cost of fixing it. I would usually prefer to repair a more modern synth than an older one, like, say, a Yamaha CS80. That's because there's so much that can go wrong with a CS80 compared to something that only consists of one or two circuit boards. Anything with a lot of wires in like a CS80 or a Hammond is far more likely to go wrong than any of the modern equipment. Yamahas, as far as we can tell, are extremely reliable in this respect (that is the DX range), and most modern gear has improved reliability."

Ron: "To go back to older instruments, if you ever get a Hammond organ and it's got sounds missing, think about avoiding it.

"A stop missing could be a generator fault which can be fixed, but missing keys probably mean broken contacts inside the manual. If that is the case, then it's not going to be repairable as Hammond spares are no longer available. The other thing to watch for on Hammonds is severe contact trouble — either double touching or hardly ever playing contacts. It usually means that the precious metal wires running along the busbars are cut through, and they'll need replacing — replacements just aren't available. When the busbars are gone, the instrument is a write-off.

Farfisas are prone to contact trouble as well, particularly the Compact model. You just can't get at the contacts on a Compact. Later Farfisas are better in that respect, but spares again are a problem.

"If you're depending on it to earn a living, then you should treat it with respect."

David: "The later electronic organs (Roland and Korg) are much better in this respect. In fact most modern gear seems to be very reliable."

Ron: "I don't think many new keyboards of the last year have any problems. All the manufacturers are intent on staying in business and are learning by experience. They tend to use the non-metallic contact-type keyboards which are far more reliable, though more difficult to clean when they do get problems. There were experiments, that weren't very successful, with membrane contact keyboards which were a disaster. Now there are no current machines using that system."

What things do you have to look out for when considering samplers?

Ron: "First of all, make sure that the instrument can load its discs properly. Disc drives are a mechanical device, and as a result do suffer from problems like dust, maladjustment and so on. There's very little to choose between various makes because they use industry standard disc drives, like everyone else. Any disc problems will not only affect samples but they'll also prevent the system from loading properly. Computer based systems in fact stand up surprisingly well to life on the road. You can have problems with leads and plugs, and some of the keyboards are comparatively delicate, but mostly everything's very well made. The one severe problem with all equipment is sudden changes of temperature — taking gear out of a cold van and into a warm room, or vice versa. It particularly causes tuning problems on analogue synthesisers, and on computer based instruments the film of moisture may cause disc misreading, and possibly problems with the computer until it warms up."

Would it be best for the prospective purchaser to try for an ex-studio instrument?

Ron: "Generally speaking, yes. Studio keyboards will be less beaten about as a rule. Ex-hire equipment, too, can be excellent value for money, depending on who hired it. It may have been ill-treated at some stage, and had a lot of wear, but if it's mainly been hired out to studios, the chances are that it's been well treated, and is maybe only being replaced because there's a new model out. One advantage of a hire instrument is that it's essential to the hire company that the instrument works reliably, or they'll lose money. They usually do have them regularly maintained in their own interests.

"Studios don't always tend to provide the same level of servicing — it can happen that they'll wait until a particular instrument fails totally and enough people moan about it, before they'll get it seen to."

David: "Early modular synths like the ARP 2600 that we have here for repair are still favourites with some people, but unless they've used it before, they won't be attracted by it unless it's being offered really cheaply in preference to, say, a Casio. It is patchable, and some may like the visual indication, but changing sounds takes a long time. Not many people are going to use it live, although it has many possibilities in a home studio where time is not necessarily an important factor."

Finally, a few words from our heroes on general codes of practice to enable you to get the most reliable performance from your setup.

David: "A problem with computer equipment is mains spikes and/or interference in the mains supply. The principal result will be to corrupt data, or prompt the machine to do odd things if you can get it to do anything at all. More worryingly it can damage chips in areas where you wouldn't expect them to be damaged."

Ron: "If you have a number of items to be interconnected, do connect everything up in the correct sequence before applying the power. That's important, because in many cases people remove earths from selected pieces of equipment in order to get rid of hum loops. The trouble then is that many of these pieces of equipment have internal suppressors which connect to ground and put small amounts of mains power onto the chasses of equipment when not earthed. If you then make the connections, that power is dissipated through the circuitry as you connect it and can cause failure. So connect everything up first without the power, and then put the mains on last. Also, if at all possible, use a suppressed plug board, one with a line suppressor if you're using computer equipment. That'll save you losing data and corrupting memory. A modem musical instrument is physically complex and delicate, although fairly reliable, and if you're depending on it to earn a living, then you should treat it with respect, and it will probably last a lot longer for you than for any previous owners."