Amp input selector

[Huge]

Slightly off topic, but ...

I have an Arcam Alpha 9 audio amplifier. The input select switch has gone very noisy, rendering it almost unusable. I've already tried squirting RS switch cleaner in it, which improved matters for a few weeks, but now it's worse than ever. Several people have recommend Deoxit switch cleaner so I have ordered some ("*How* effing much?"). Arcam say the switch is globally unavailable, which has been confirmed by several repair companies I've spoken to. Another said that dismantling the switch (which is big, complicated, well soldered to the motherboard and motor driven) is both long winded, complicated and doesn't work for any length of time.

So ... I now have a perfectly good and quite expensive (although quite old) amplifier that's unusable. Any suggestions as to where to go from here? I suppose I'm wanting to be talked into replacing it, but I'm not happy.

(What's even more irritating is that I gave away my perfectly servicable Trio KA-2000A a few months ago, so I can't play any bloody music at the moment.)

[Dave Plowman (News)]

How many inputs do you actually need? If only a few and they're all the same level (ie not including an LP pickup) you could replace the switch with a simple rotary type. Or wire out the original and use an external one.

[Dave Liquorice]

What does the switch actually do? Just audio from the various inputs (post EQ in the case of a record deck input) or does it also switch the required EQ in/out depending on the input selected?

If it's just audio could a multiple position, multiple pole rotary switch be fitted and wired to the board?

How is the motor controlled from the front panel? Rotary selector inter-locked push buttons?

[Huge]

I have 5 inputs. Including an LP pickup. :o(

[Huge]

No idea. It's very well integrated into the amp motherboard and has many connections. I guess I'll need to have a better look at it. I fear it is more complex than my limited electronics skills, though.

It's for the remote control. The motor drives the switch shaft round in the same manner as a human rotating the switch. I don't care about the motorised facility, I'd cheerfully lose that if I could get the switch to work. The only thing I do from the remote is adjust the volume which is irrelevant for this fault.

[Donwill]

Why should an amplifier input selector switch be motor driven for goodness sake, is the younger generation incapable of turning a rotary switch?? Don

[Jules Richardson]

Did they give a reason for the "doesn't work for any length of time" statement? I'm not sure what the failure mode would be such that it can be cured for a short length of time but will just re-occur?

If switch contacts have worn away, then surely you're not going to fix it at all and dismantling is pointless. If they've oxidised, then you're probably going to be able to fix it for as long as it takes to suffer oxidisation problems again - which IME with switches is quite a long time (and I'm not sure why the period would be shorter for whatever Arcam used)

Maybe the Arcam switches (as with many) are riveted or use folded-over tabs which are prone to breaking - and poor solutions might result in a switch that essentially kept on coming apart at the seams; perhaps that's what the person you spoke to meant?

Anyway, that's a long-winded way of me saying that I think you need to look at the physical design and see how easy you think it'll be to dismantle the thing - and to put it back together in such a way that it stays together :-)

cheers

Jules

[Tabby]

As said, either replace the switch with a standard nonmotorised one, or use an external switch. It should be simply a 5 way 2 pole switch. One can determine which connections are the power amp in terminals by: an audio signal fed to the right 2 will keep coming out of the speakers no matter what position the switch is in. Note that position may affect the volume a fair bit on such a test, but wont kill the signal, as long as you use a low impedance source.

If you dont understadn that at all, you could connect an external audio input selector to random switch terminals, when you hit the right ones it'll work. The downside of this is you wont be using the internal record desk pickup preamp.

NT

[Huge]

For the remote control.

Younger generation? Bwahahahahahahahahahahaha. Tosser.

[Huge]

BTW, the switch is made by a company called "Alps". They don't seem to make them any more. At least not on their web site. Perhaps I should contact them, if I can get a part number off the switch....

Could well be. I'll take the amp to pieces once the Deoxit arrives and have another look. I may be able to replace the switch with flying leads and some kind of rotary switch arrangement. After all, the amp is scrap anyway.

:o)

I feared as much.

Thanks all!

[Andy Dingley]

Angle grinder. Hack out the old switch, replace with a modern replacement, without the motor. Simples.

I'd be surprised if you even get any trouble from the record preamp input. The circuit for these input selectors is usually very simple, just a multi-way changeover.

Motorized volume controls have some use, as you can adjust them from your favourite listening position. However switching inputs usually involves disk changing, so you're up there anyway.

Make sure you use leaded solder.

[The Natural Philosopher]

Alps used to custom make switches..to special order :-(

If you are lucky some white haired old boy will know where there are a dozen tucked away somewhere.

Or the actual contact parts may be standard items - need to usually take it off the board,. unscrew a couple of bolts and pull the wafers off the shaft, and fit new ones..

[The Natural Philosopher]

Not if its quality, and has a phono amp.

You often had to disable that to prevent crosstalk when playing a record but switched to something else.

Probably it will be shorted to deck at the output EXCEPT when selected.

[John Rumm]

I had a similar problem with the volume control and input selector switch on a Kenwood KA3020, and also a noisy volume knob on a Arcam Alpha 8R.

For the Kenwood I (hushed voice) /squirted some WD40/ into the pot and the switch mechanism and worked them back and forth for a few mins. Couple of years later they are still working flawlessly.

On the Arcam I tried a similar trick but with proper contact cleaning solvent. It also worked, but has not lasted as well in the sense that some noise is creeping back into it as you rotate it.

Don't suppose it has an identical (or similar) switch right next to it for Rec Out selection? If so could they be swapped?

[Huge]

It's probably cheaper than a new amplifier. I shall try writing to them. Given that this is a common problem (Google "arcam alpha 9 switch") I might even be able to make a few quid by having a few made.

I've made a *lot* of calls/emails trying to find those WHOB. Indeed, I thought I'd found one, but when I got back to him, he no longer replies to emails or phone messages. I assume he's an ex-WHOB. :o(

It isn't a pure rotary switch. The shaft rotates but the thingy (told you I don't know much about electronics) that makes the contacts moves back and forth. The WHOB called it a "spear switch".

Too bloody true. I'm pretty ticked off about it, TBH. I don't think Arcam are going to be getting much more money from me. And so I have to open the can of worms of what to replace it with.

Perhaps I shall start hanging round the "vintage hi-fi" forums ...

[Huge]

It sure isn't a simple switch.

I'll take a photo when I open it up to apply the Deoxit.

[Huge]

Now *there's* an idea. Thank you!

[Dave Plowman (News)]

It allows remote control from a zapper.

[Tabby]

Whether thats necessary is another matter. If it proved an issue its not much of a challenge to stop the vinyl record when listening to something else.

NT

[Terry Casey]

Here's an idea for you. Provided that the switch isn't mechanically disintegrating, the problem will usually be the silver plated contacts tarnishing.

Years ago, in the days of 405 line TV, this was a common problem with the contacts in the VHF tuner unit.

The usual solution, if you'll pardon the pun, was RS Switch Cleaner - though Electrolube was better and longer lasting.

Some switches, though, defied all efforts at cleaning - particularly if the mating surfaces were inaccessible - until, one day, we found a cure. Silvo!

We applied it sparingly to the accessible parts of the contacts, then operated the switch repeatedly, as usual, to get it inside and between the mating surfaces. If the contacts could be reached, we'd apply addition pressure to really obstinate cases using a match stick. Then flush it away with switch cleaner and, after the carbon tet had evaporated, finish off with Electrolube.

If it worked without causing problems to circuitry operating at 200MHz,it won't be a problem for audio!

You could do worse than give it a try.