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Organ Talk

Care & Maintenance


Electronic keyboard instruments are somewhat like cars in that maintenance can tend to be neglected if all is going well. In both cases, this policy is short-sighted for fairly obvious reasons so it seems well worth while mentioning a few points concerning the care and maintenance aspect.

The condition of the cabinet will largely determine the trade-in value of any instrument: its covering is usually a high-quality wood veneer, which can be damaged easily. Some instruments are finished in laminates similar to Formica and, although cheaper and more durable than wood, are possibly less attractive to the eye. An organ is often the focal point of a room's furnishings and should be accorded the same treatment as a good suite of furniture.

Woodwork



The owners guide may contain recommendations but otherwise a proprietary wax polish will be suitable. A secondhand instrument in dirty condition should first be wiped down with a wash leather, then given a wax polish treatment.

If a veneer is struck hard enough by anything - including a vacuum cleaner - it may lift locally. In due course this will catch on clothing or a duster and probably come adrift and a piece will get lost. At the first indication of loose veneer, mix up a small quantity of warmed Araldite and insert it between veneer and body woodwork with a thin knife blade. Press the surfaces into close contact and Sellotape the edge tightly until the epoxy resin has set. Excess resin can be taken off with a damp rag at the time or removed before the resin has fully cured.

The factory finish is often a sprayed mixture of stain and polish, so that scratches will often appear lighter than the surrounding woodwork. These call for patient work with a very fine brush (say No. 0) and a suitable wood stain to disguise the blemishes. The same brush can be used again later to apply a line of polyurethane varnish over the stain: eggshell varnish will probably be less noticeable than the gloss variety. Although dents on a level surface can be 'filled' with a blob of varnish, rubbing down the work will disturb the neighbouring finish so they are probably best ignored.

Installation



Avoid a position with nearby radiator. Heat should not affect solid-state electronics up to a point but it will damage woodwork eventually. The height of the pedals above floor level varies slightly from make to make. If the instrument can be played comfortably on a parquet floor but the pedals feel spongy in a carpeted room, cut pieces of thick plywood which will not be noticeable when placed under the ends of the console.

If the organ is constantly transported for 'gigs', cabinet work is at risk unless it uses a strong vinyl finish designed for this purpose. Shuffling down a passageway with a heavy instrument is hard work and usually results in bruised ankles. If two large pipe brackets are screwed to the back of the console, a pole can be passed through them and the organ carried in 'Sedan Chair' mode. A piano or organ trolley makes lighter work of the task, as does a tail-lift truck. Road surfaces and cornering make it essential to rope the instrument inside the van. Most organs are completely top-heavy and only a few weeks back I heard of an organ toppling over in transit, with consequent damage to the pedal-board.

Always keep the instrument's back in place when moving it as it is only too easy to damage circuit boards when trying to find a good handhold. Spring reverberation units should be locked to avoid damage when moving and owners of tone-wheel organs must lock the generators. In these earlier Hammonds, the generator assembly is suspended on coil springs: by reversing the sleeves on four bolts found under the generator shelf, the generator is pulled down into contact with the shelf for transportation. Without this precaution, the valuable (and now irreplaceable) tone-wheel generators will be free to react to every bump in the road, with consequent damage to frame and drive mechanism.

Keyboards & Controls



Relatively few commercial instruments have a fall to cover the keyboards, which does help in excluding dust from the contacts. Keys and controls are best kept clean by occasional use of a damp cloth. Unless trying to repair minor damage, abrasive polish should be avoided as it can remove the lettering from tabs and controls. Naturally, water should not be allowed to run between the playing keys but other liquids spilled accidentally can be very troublesome as they are likely to be sugary. Performers with a glass of beer perched on the keyboard cheek should definitely be discouraged: they might also be chain smokers and it is impossible to disguise cigarette burns on playing keys!

The key itself is usually a plastics casting with a metal extension to the pivot point. Though fairly robust, the key surface can become scratched. Gentle polishing with a small amount of 'Bluebell' will remove anything less serious than a major scar. In a solid-state organ, these are the moving parts and have to take punishment. Really heavy-handed players have been known to break keys: replacement by a competent serviceman will be the remedy here although a clean fracture might be suitable for the use of cyanoacrylate glue (which has no filling power).

Intermittent contacts can usually be accessed by lifting the keyboards on their hinges. As plastics are used extensively, carbon tetrachloride is not the best choice for key contacts. The precious metal surfaces (rhodium, gold or silver) can be treated with a brush moistened in methylated spirit until the fault has cleared. Tabswitch contacts are usually accessible but rocker switches often have their contacts buried in a plastics casting: sometimes it is possible to remove the rocker itself, by pushing out the pivot, so exposing the contacts inside the box.

Both the clearances and shaping of contact springs are often critical so the cleaning operation demands great care.

Circuitry



Owners of self-designed instruments will know this aspect intimately, possibly having dreamed up the whole system while having a bath! Commercial organs are not always accompanied by circuit diagrams when purchased but it is well worth trying to obtain this information even if only to be warned where CMOS devices are incorporated.

Maybe you have used 4011s, treated them with abandon and got away with it but the complex LSI devices in organs cost considerably more than 20p to replace! The connecting comb on a PCB should be regarded as an extension of the IC, so tread warily. Your nylon carpet cannot be changed in a few seconds, but it takes no time to get out of a nylon shirt and put an earthed bracelet on the wrist.

Today's trend towards digital operation results in fewer connectors. Even so, the likely cause of missing notes or functions is normally due to poor connections, so PCB sockets should be checked to ensure that vibration from the internal speaker has not disturbed them. Manufacturers sometimes use solid conductors and, if the wiring to a plug is bent too frequently, it can break inside the p.v.c. covering. If the suspect can be traced from the circuit diagram, sharp needles on the ends of a meter's probes can be used to pierce the p.v.c. and diagnose lack of continuity.

Filter components are unlikely to fail (unless the op. amp. of an active filter has given up) so that an inoperative stop is normally due to a poor connection somewhere. Missing notes can be due to connectors in mother/daughterboards systems.

Voltage regulators are normally very reliable but any failure here can cause untold damage to the rest of the circuitry. Today's sophisticated instrument requires accurate voltages for its divider/keyers, T.O.S. etc, so that any sudden surge in voltage levels can lead to a very expensive result. For these reasons it is worth checking voltages from the PSU, assuming the correct figures are known.

The earthing system, especially when stereo channels are involved, is usually complex. A form of 'pink noise' can be caused when the bare screens of adjacent coaxial cables touch each other, or a screen becomes disconnected.

Most swell controls work on the lamp and l.d.r. principle so that, if the instrument suddenly develops uncontrollable full volume, a circuit diagram is hardly required to fault-find here. Simply check that the lamp operates and that the light path to the l.d.r. is clear of dust and dirt. With a top octave synthesiser, tuning presents no problems: vibration, either from the speaker or the effects of transportation, may have shifted pitch very slightly, calling for a small adjustment, usually by means of a preset internally.

Faulty potentiometers become so because they are frequently used. The speed control of the Rhythm Unit is a likely candidate here and at the first hint of an erratic set of speeds it should be replaced (making sure the law is correct). Although it may seem desirable to leave pots and drawbars in set positions ready for the next gig, this can cause extra wear and possible noise at these points. A few rapid turns of a pot may help to clear any noise present.

Lubrication



A trace of oil on the Swell pedal pivots (and also on the pedalboard pivots if they are accessible) is a useful exercise. Leslie tone cabinets also need lubrication occasionally. Apart from the rotor and horn bearings, the motors themselves require oiling. These are fitted with porous bearings with felt oil reservoirs and it is necessary to look closely to find the oil holes: they are often underneath so it is best to remove the motor temporarily to lubricate it.

Tone-wheel generators of earlier Hammonds need to be oiled annually, filling each cup on top of the housing about three-quarters full. These are only funnels and, if filled repeatedly, the inside of the cabinet and amplifier chassis will become saturated with oil. If the generator cover is removed to carry out this operation, take great care with the capillary threads which feed oil to the motors and various shafts. Breaking them can cause the system to seize up.

Most of the foregoing is obvious and common sense, but there may be something here that eluded the reader previously. Anyway, I have no doubt that it pays to look after an instrument that can give the owner and his family so much pleasure.



Previous Article in this issue

Irmin Schmidt on his Toy Planet

Next article in this issue

Harmonics


Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.

 

Electronics & Music Maker - Aug 1981

Feature by Ken Lenton-Smith

Previous article in this issue:

> Irmin Schmidt on his Toy Pla...

Next article in this issue:

> Harmonics


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