ALPS motorized input selector (ASD-1017) repair, Pioneer A-701R

jda850

Member
Just wanted to share some info for those of you who might experience the same problem as I did.
The input selector on my Pioneer A-701R started to fail with sound dropping out and making crackling noises when changing inputs.
Eventually it failed completely and stopped switching between inputs.

The switch is a rotary type, driven by an electric motor via a small "gearbox".
It's name and number - for it is a human number, and it might as well have been 666 ;-) - is "ALPS ASD-1017", and was used in a number of Pioneers, Onkyos, Yamahas (?), and maybe others too.

The bad contact is due to oxidation of the switch contacts, but it's hard to get De-oxit inside the housing.
The failed switching is caused by a plastic gear becoming brittle with age, and eventually cracking, effectively stopping the switch from turning.
When that happens the motor might spin for a long time without stopping, or it might not move at all.

Upon opening my own switch I found this:


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I also found the associated missing portions of the gear, and removed them all.
Realizing the switch is since long out of production I considered leaving the amp at one input only, or drilling a hole in the top cover and selecting input with a screwdriver...

Then I thought about replacing it completely, with an aftermarket Chinese relay board.
I quickly abandoned that idea when I realized the amount of time and labour involved, and that it still would result in a loss of the original remote control function.

And that's when the Googling started.
I told myself that some other product, somewhere in the world, must have used a similar gear.
After more than a few hours learning everything I never wanted to know about gear modules and tooth spacing I got a hit! At least kind of:
Futaba servos for R/C toys apparently use the exact same diameter final gear, with the same number of teeth, on their S3001, 9001 and 3151 models (and a few others).

Of course there is a number of differences, thicker gear disc, other diameter shaft, rotation limiter etc...
But I decided to give it a try, since they actually sell the gear kit as a spare part for a mere 25 SEK (about $3) here in Sweden.

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This is what's included in the kit.
The one we're interested in is the one furthest to the right:

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It's hard to see in the pictures, but it has a "stopper" sticking up from the gear disc, to stop it from rotating more than 320 degrees, or something like that, when used for it's intended purpose.
I don't know if it could cause trouble in the gear's new work position, but just to be safe I cut it away using a sharp hobby knife.
At the same time i cut the shaft down to get about the same total height as the original gear.
This took some effort since the new plastic is some kind of nylon or similar that's very tough.
What's not in this picture, because I forgot to take a photo, is the next step, which is drilling a hole through the center of the gear shaft.
The metal switch axle is going to go through it all the way.

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Here's what the axle looks like.
It pulls straight out of the switch housing with a bit of force, there's nothing holding it in place but friction.

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With the gear out of the way, now is an excellent opportunity to splash a gallon or two of De-oxit down the hatch...
Actually, do that before you pull the axle, it's then very easy to turn the switch manually with a screwdriver to work the contacts.
It just goes round and round, so don't worry about breaking anything, just spin away.
And spray some more.
And turn it some more.
You get the idea.
Listen to all the inputs to verify it's clean before putting it all back together.

Also, don't worry about the position of the switch.
One of the switch decks is for position sensing, so it will move to where it should be by itself when all is done.
The only thing to keep in mind is not touching the position while the axle is pulled.
It's easy to accidentally turn one of the decks 180 degrees relative to the others, and then everything will be very wrong...

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And now it's time to play blacksmith!

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The axle is flat to keep the gear and switch decks from just spinning around freely, and we must copy that shape somehow.
There might be other ways of doing this that I haven't thought of, but this worked very well.
The diameter of the hole we drilled through the gear should be slightly smaller than the axle, by the way.

Hold the axle firmly with a pair of pliers or something, not your fingers...
Heat it for a while until it's plenty hot, a few seconds will not do! I held it to the flame for almost a full minute.
When it's hot, press it straight through the gear, this is important so it doesn't wobble when it rotates later.
You might have to re-heat it to get it all the way through, it's going all the way up to the top end.
Again, I failed to take a photo of the finished result, probably because I was so eager to see if this whole theory would work, but you get the principle anyway, right?

Otherwise I think you can see the orientation of the axle shaft relative to the new gear in this photo, when everything is back in place:

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The shaft with the gear just pops right back in place.
The fact that the new gear disc is twice as thick as the original one doesn't seem to affect the operation.
Maybe it turns a little bit slower due to a bit greater friction.
It would of course be possible to sand the gear disc down to the stock thickness, but I don't feel it's worth the effort.
And I like the thought of it being a lot sturdier than the flimsy original.

A generous dab of silicone grease also helps matters a lot.
And then it's just the end cap left. I put some grease there too.
Don't forget to twist the three little metal flaps so the cap stays on!

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Excluding the time spent on research, which you won't have to do all over, the whole operation takes an hour, tops.
This amp is well worth one hour and $3 in my opinion!

And finally, proof of life!:


 
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Thank you for the kind words!
I'm happy if I can help somebody, and in that small way giving a little bit back to this incredible forum that has helped me out so many times!

And I'd like to wish you all a happy S:t Patrick's Day! ☺
 
Hi jda850,

I just signed up here to say THANK YOU!
i diassembled my input selector and found the main gear broken ass you did.
you saved me much time, by offering a matching part.
i didn't reassembly the whole thing, because there is currently a problem getting hold of the spare gears back here in austria.
but i'm confident we'll have a happy ending here!

kind Regards,

Julian
 
Hi Julian!

Thank you for the kind words!
I'm glad that my little write-up could help you out, that's the whole reason I posted it.

You could buy the gear kit here: http://r.ebay.com/FkzrvL
It's just €5,90 and free delivery world wide + the seller has a 99,8% positive feedback score.
He/she has no association to me, I just did a quick Ebay search.

Good luck with your amp!

/Daniel
 
Nice work!

I've got a Yamaha integrated with a motorized selector switch, and it has issues.
I just assumed it was the contacts wearing out, but perhaps it uses the same(or similar) pot, and there's a gear issue.
Now I'm curious to check it out some day.
 
Neat info...

Haven't yet seen one fail, but I remember seeing motorised selectors in some upper level Sony midi/ hi density Integrateds
 
Snyggt Jobbat!

smart with the Futaba gears! i havnt met this problem as of yet but if i do! i have the work instructions right here. great work.
 
Hi jda850 Congratulations on how you solved the problem I am in possession of a PIONEER A 450 R and uses the same motorized switching system to me too the gear was broken by doing a search in the Audiokarma forum I read your post about how you got solved the problem seeing that you have transcribed where to retrieve the gear on ebay but when I click on it it sends me back to an error page kindly you could if you remember to tell me the right address to be able to buy the gear thank you so much
Greetings from John
 
Reviving rather than starting my own thread...

I need to ask, is there a set position when resoldering the ALPS switch back to the main board?

I'm awaiting a gear for my A550R ALPS motor drive gear the tiny weeny one. However I have since moved the selector dial on the front of the unit AND possibly the position of the switches after cleaning, will it reset itself? How does it know what position it's in?

IMG_20211013_000722.jpg

Perhaps related? The screw on the end maybe for selecting the correct input once set in the right location it should continue as normal.

Many thanks to whomever
 
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