I really hate my self when crud like this happens.

Thread Starter

R!f@@

Joined Apr 2, 2009
9,826
I am trying to fix an old amplifier ( model and all not important )
Issue was no power so it was a walk in the park.
Another issue was the selector was working but audio is available on only one input, so naturally I checked the selector.
It was a motorized one with rotary type selectors. ( ALPS ASD1017 )
I guess the picture will provide a better idea. ( from internet. Rest of the picture is what I am working with )
ALPS ASD1017.jpg

Guess what the I saw when I opened it up
Damaged one.jpg


The gears were missing. So somebody tried it and cannot get the gears.
So naturally I went online and found them. Bought it fixed and tested
And the inevitable happened.
Broken Again.jpg

The worm gear was so brittle, a few seconds and it went.

Now I lost a few months for this. Took a long time to find them, and when I did crap happens.
** side note..... The best part is I got the part a month ago. I was busy with work and item was small and fear of loosing it I kept it somewhere safe and when I needed it, it took me literally 2 hrs to find it. **

I cannot seem to find the worm gear now.
So now I am again stuck with this amp.

If I cannot find the worm gear, which it seems is not there online so far, I have to modify the amplifier.
Aaaaaaaaaaah!
 
Last edited:

MrSalts

Joined Apr 2, 2020
2,354
Can you carefully cut off the toothed part of the worm gear and just replace that? Use the existing worm gear. You may need to rough up the surface of the nylon for the epoxy to stick well.

I'd be afraid that ant old-stock replacement would be just as brittle.
 

Thread Starter

R!f@@

Joined Apr 2, 2009
9,826
Can you carefully cut off the toothed part of the worm gear and just replace that? Use the existing worm gear. You may need to rough up the surface of the nylon for the epoxy to stick well.

I'd be afraid that ant old-stock replacement would be just as brittle.
My idea exactly.
The 2 gears I got are new.
but the worm gear, if I am able to find one, would be an old one.

I can try to replace the tooth part the worm part won't hold for long u know.
 

MrSalts

Joined Apr 2, 2020
2,354
My idea exactly.
The 2 gears I got are new.
but the worm gear, if I am able to find one, would be an old one.

I can try to replace the tooth part the worm part won't hold for long u know.
You can try drilling two 0.8mm holes through the side of the toothed gear and into the worm gear. Then slide a pin into the hole to make a strong physical connection instead of trying to glue the nylon gear. Nylon is difficult to glue.

3D print is worth a try.
 

Lo_volt

Joined Apr 3, 2014
275
Nylon is difficult to glue.
Too true. I've never had luck gluing nylon.

That being said, I have been able to repair nylon gears by inserting a heated steel wire into the nylon. The first time I did it I used a paper clip. I clamped the gear in such a way as to hold the cracked section together. I heated the paper clip to red hot on a gas stove then pushed it into the gear across the crack. Once it cooled, I dremeled off the end of the paper clip.
 

panic mode

Joined Oct 10, 2011
2,301
not likely... consumer grade 3D prints are quite fragile since thermoplastics is pretty soft and easily wears down. but high end 3D printing using better materials could work.
 

Thread Starter

R!f@@

Joined Apr 2, 2009
9,826
This thing is too small for me to do any thing. besides it broke when I try to remove the locking clip
3D printing can be done, but I don't have one yet. And it is a steep learning curve to CAD a worm gear.

5.jpg

So I had to come up with another idea.

2.jpg

3.jpg
4.jpg

Lets see what happens.
Need to check the operating voltages.
The servo is modified for continues rotation. But it works even with 1 VDC. So time for some clever circuitry.

https://youtube.com/shorts/wMsysYJS6Qk?feature=share
 
Last edited:

Thread Starter

R!f@@

Joined Apr 2, 2009
9,826
I am wondering when did I write "crud" in the heading ??
I clearly remember "c**p ".
If a mod edit then I cannot write that way. If so, Sorry abt that.
 

Thread Starter

R!f@@

Joined Apr 2, 2009
9,826
I assembled the amp and fits nicely.
6.jpg

Checked the drive voltage from the amp and it was around 3.2VDC.
Connected the servo and it starts oscillating, naturally as the speed it too fast. Feed back response is slow, so it goes to set input and overshoots, and it come backs and overshoots.
Fix was a simpler than I thought. Just a 8.2R series resistor fixed the issue.

Now it is good as new.
Wonder how long it will hold

Check it out.

Edit : Sorry the phone was upside down. Realized too late. But you get the idea. Video was to show you guys, not for likes or anything
Regards
 
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