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Cyrus One Amp Rotary Listening Input Selector Switch

Last response: in Home Audio
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January 10, 2011 3:30:39 AM

Hello,
My Beloved Cyrus One Amp (purchased new over 20 yrs ago has, for the first time ever, developed a problem! Intermittently dropping or part-dropping a channel: either left or right, and mostly when set on 'CD-Listen'. The location of this intermittent and variable fault was driving me batty until a lucky observation put me onto the selector switch and dicky contacts. The 65mm long aluminium switch housing is an inverted U in section and Strong. Looking into the open rear end shows a travelling block driven back and forth by the large 35mm diameter rotary finger knob, exposing some contacts when fully forward.
Question: How to get at and clean the contacts? The housing looks un-rip-offable and the two 4mm holes in the top surface do not show mounting screws exposed by any positioning of the slider.
I am reduced to poking alcoholic cotton buds up the back end and I don't expect positive and lasting results, although an enema or colonic cleanse of some sort seems the only option! A contact-cleaning tip from an old-hand mainframe computer tech was to use a lead pencil eraser. But physical access required.
Help Help :)  JohnR
Anonymous
January 10, 2011 8:19:45 AM

I have a Cyrus of similar vintage and mine has the same problem -- I dismantled it and tried using some contact lubricant/cleaner on the input switching but no improvement. So the likely solution is replacing the switch (which may have to be done at the factory, assuming they still have parts).
Mine also has slippage on the posts connecting the front panel to the switches, the mains switch linkage has failed and the phono stage doesn't seem to work -- age is taking its toll !

Cyrus is a nice amp -- but I have an even older Japanese made Marantz which is faultless.
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January 18, 2011 4:00:05 AM

Thanks for the prompt reply Fihart. As a fallback option if all else (read "my DIY efforts") fails, then the 'Record Selector' which is an identical switch - can be pressed into service - I never use it.

I shall keep you posted. By the way, my magnetic-tipped screwdriver casually laid across the switch, twitched, to my huge surprise. The housing is steel !! I know the unit and componentry is reputedly 'militarized' but this is way over the top - and makes getting into the contacts that much more interesting :-)
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February 11, 2011 3:12:45 PM

I've put up with this problem for years, twiddling the rotary switch to try & hit the 'clear' spot; & have just had another go at curing it. This time I squirted servisol switchcleaner/lubricant into the rear end of the selector switch (still in situ, on the board) & wiped the contacts with cotton buds & paper towel poked in with a cocktail stick. Having assembled & connected it up I now find it all works without any crackling or signal loss to either channel. Success! but for how long?
Hoping this helps,
DM
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February 13, 2011 1:14:13 AM

me thinks a rotary cutting tool like a dremel should help you get into the switch.
but being careful not to allow the cutting disk to go all the way through the metal because you dont know what kind of damage you might cause if you cut something inside.

sounds like a job for a lit-up magnifying glass.
i would say its best to cut as deep as possible without allowing the cutting disk to go through the metal.. then use some kind of acid to lay inside the cut to help finish the cut.

seems like major surgery to something very important.
i would probably look for a replacement switch.
just because the switch is still functional.. that doesnt mean the resistance readings are accurate.
you might find that the resistance has changed and the signal to noise ratio suffers.
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Anonymous
February 13, 2011 4:47:14 AM

@ anwaypasible Do you own one of these Mission Cyrus amplifiers ?
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Anonymous
February 13, 2011 5:19:17 AM

@JRNZ


Thanks for the suggestion: ('Record Selector' which is an identical switch - can be pressed into service - I never use it).
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February 13, 2011 5:56:28 AM

Quote:
@ anwaypasible Do you own one of these Mission Cyrus amplifiers ?


what does owning the amplifier have anything to do with fixing a switch?

i mean..
thats breaking the following rules:

•Hijack a topic
•Hate speech (abusive)
•Disrupt the natural flow of forum discussion (any variant)
•Harass, embarrass or insult other users

i've done nothing wrong and dont see why such insult has been raised.
there wasnt any problem with the last switch advice i gave, and the same logic has been applied to this switch scenario.
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February 13, 2011 9:32:26 AM

You classify someone asking if you own a Mission Cyrus amplifier as hate speech? My good man, you must be a very difficult person to converse with.
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February 13, 2011 11:47:28 AM

throwing off the discussion to single-out an irrelavent question for the sake of boosting or degrading something is hate speech.

thats like asking an auto mechanic if they have a drivers license.
the key principle is using the wrench.

perhaps you assumed i was insensitive to abuse.
but the fact is, i am consciously aware and have had more than i can chew.
i'm at body trembling and forgetting things, as well as making wrong choices when acting without thinking.
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March 4, 2011 5:40:28 PM

Its just a ALPS Switch > jou can try to clean it with KONTAKT 60 - cleaner ( every good electronic shop have it, but after 20 years its better to replace the two (input - output switches...the are the same ) switches. Regards
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April 24, 2011 10:11:51 PM

amorfati said:
Its just a ALPS Switch > jou can try to clean it with KONTAKT 60 - cleaner ( every good electronic shop have it, but after 20 years its better to replace the two (input - output switches...the are the same ) switches. Regards


I've had the same problem with my Mission Cyrus amp for years. Anyone come up with a good solution or way to clean them? I've tried spraying electronics cleaner and dabbing alcohol in them multiple times and the effects are temporary. I don't think we can get the cleaner into the guts of the switch.

What's the ALPS part number, and does someone have a source (link)? I think both my switches are dirty so just swapping them won't solve anything.
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May 9, 2011 10:12:52 AM

I have a Cyrus 2 circa 1986 and my on/off switch has just failed.
I opened it up and the push switch hits a rod about 80mm long that rotates to make a connection. The rod is parallel to the front of the amp and it's all made of plastic which has broken at the supports.
Does anyone know where I can get replacement parts?
The amp has all the annoying little issues that you write of but I love it and if I can get it swtched on again Ill try some of your suggestions.
Allan
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