Arcam Alpha 9 or Delta 290 Input Selector
By ARS, Mar 20 2014 01:40PM
On the majority of these models the motorised Alps input selector switch will have become annoyingly noisy/intermittent on most inputs if not all. The culprit is mainly down to the effects of long term sulphation of the silver plated contacts. This is despite evidence of a contact lubricant having been originally used which with time appears to have thickened or dried out thus losing it's self healing film properties. The end result when viewed under high magnification is a fine line of sulphation on the fixed contacts where they mate with the moving ones where any protection afforded by the original treatment is now non existent (if indeed it provided much in the first place) This can just be seen as fine dark lines in the first picture below. Small traces of sulphation are normally removed by the mechanical wiping action of the moving contact but clearly the Alps switch has degraded well beyond the scope of this.
Proper refurbishment is not for the faint hearted, takes several hours and requires complete removal from the circuit board. This can be time consuming to desolder with 40 or so plated through holes and all need to be completely cleared of solder before even attempting to lift the switch assembly away from the PCB otherwise you risk breaking legs off the wafers. The 4 individual sets of switch wafers can then be removed and as with the Alps switches in the Cyrus models are chemically cleaned to remove tarnishing followed by careful polishing and thorough cleaning with solvent to leave the plated contact surface in a pristine and as new condition. In an effort to improve the longevity of these switches further the contact surfaces are now gold electroplated which offers a far superior resistance to tarnishing compared to silver. This is finally topped off with a treatment of Caig DeOxit Gold which is a very high quality industry proven product and should provide long term protection and lubrication to the contact surfaces to extend the usable life of these amplifiers. As these switches are no longer available new this is the only option if you wish to prolong the life of these two models. Forum 'rumours' detailing cost saving attempts by some to squirt switch cleaner through holes in the casing are an absolute waste of time as the contacts are fully enclosed until removed as the lower photo shows (similar to attempting to wash a car locked inside a garage whilst poking the hose through the keyhole!)
If you wish to have your switch refurbished then visit the Arcam pricing page for further information.