[sdiy] akai encoder

[Byron G. Jacquot]

> I have an Akai S5000 with an encoder problem. When I turn it to the
> right, sometimes everything is fine, sometimes the value goes down. I
> took out the 21 screws and touched up the solder, but that didn't
> help. I'm thinking I'll replace this thing, am I right to assume this
> is the Alpha brand encoder (318-ENC160-24P) in the Mouser catalog?
> 
> anyone ever have this problem?

I've seen this problem a few times, in several different.

It's usually due to a defect in the encoder design.  If the encoder 
output transistions and the mechanical detents all happen at the same 
point, then as the detent mechanism wears out, it's messes up the 
transitions on the output.  I think the detents were becoming 
slightly wider, making it so that the tactile "click" of the encoder 
didn't relate the the output edges.  

It reaches a point that whichever direction it's turned, the output 
value only seems to go one direction...like a ratcheting mechanism.

I saw this happen to some cheap-o encoders in a matter of weeks.

The solution was to replace the cheap encoders with more expensive 
ones, where the detents are halfway in between the output state 
changes.  I think we wound up using Alps encoders.

Byron Jacquot