My Arcam Alpha 9 amplifier has developed a "noisy" input select switch. Arcam tell me it's no longer available as a spare. Before I disentagle the amplifier from the rat's nest of wiring it's entangled in, how likely is it that a bit of very fine wet-and-dry and some switch cleaner is going to sort it out?
Seconded. Worth a try, and will likely sort it out again...
I would start with just switch cleaner, and see if that can fix it before going anywhere near anything abrasive.
OK, ta.
That's this weekend's job, then. :o(
Angle grinder...
I was tempted when Arcam told me the part was unavailable.
I'd not use abrasive as these things are usually silver etc plated. A decent cleaner followed by a lubricant - Servisol is the one I use.
Other thing that *might* have happened is a failed capacitor allowing DC to get to the switch.
Agree Servisol does a great job of sorting out noisy switches and volume/tone pots. Main problem is getting access on modern equipment, or rather putting it back again if you succeed.
Try reposting in sci.electronics.repair. Maybe someone there has a spare switch, or knows where to find one.
I often find it's easier to repair than replace anyway - even if by some magic a manufacturer has a part, they typical either want an incredible amount of money for it, or they want to sell you a complete sub-assembly rather than the trivial item that's actually faulty. And that's often after being given the run-around for ages, too...
If you do need to go to something abrasive, use just a piece of stiff card. Back in the good old computer days, service engineers used to use punched cards as abrasives for cleaning switches, and cleaning disk heads! They had just the right abrasiveness for such things, without damaging them.
Very interesting, I have the same problem in my Marantz. Do amps carry the same risks as CRT TVs when opened, or is disconnection from the mains sufficient?
Thanks!
Kostas
It's generally a good idea to discharge any large capacitors before working on equipment. Info here:
Which of the many Servisol cleaners do you recommend?
(Just thinking I have an old Kenwood amp that has this problem on its input selector and its volume knob)
There is not usually any extra high voltage supply in an audio amp, so nothing like the risk from a TV. There will be a few large capacitors that may be charged to 40V or so. Unlikely to zap you, but take care not to accidentally short them out.
I don't think you want any abrasives going anywhere near it. Use an air duster first. Then use switch cleaner, and nothing more abrasive than some old denim cloth.
Daniele
I don't know that particular amp, is it valve or transistor? Valve amps have supply rails of a few hundred volts but generally from a high impedance source, it'll make you jump but probably not kill you. Decent power output transistor amps have supplies around 50-0-50v but from a low impedance source this could kill.
In either case the power supply smoothing capacitors contain a fair bit of energy, enough to blow holes in the ends of screwdrivers. They should be fitted with bleeder resistors so they are discharged within a few minutes of switching off.
There isn't the EHT of 25kV about like there is in the back of a telly.
Or telephone engineers cleaning uniselectors and relay contacts.
When I worked for Granada TV rentals in the 80s we used IBM cards as service reports, this is the high-tech unit we carried.
I always used a bank-note to clean clogged VHS heads.
Yeah I agree with switch cleaning fluid. I use Servisol Super 10 Switch cleaning lubricant. I would suggest you head over to AV-Forums
Anyway...good luck!
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