[R-390] 390() vs 390(A), R-391

[Barry Hauser]

John wrote:
> Without a functioning autotune I would say a R-391 is definitely second to
a
> R-390 in desirability due to the fact that the autotune mechanisms add a
lot
> of extra drag to the KC tuning. It gives you about 1/4 turn of easy
turning
> before it kicks in, and then the drag is much more noticeable.

I've never noticed that.  Hmmmm.  KC positioner may need cleaning and more
super-slippery lube.

> Another item lacking here is a good 28 VDC power supply with enough oomph
to
> drive the motor. Ideally what I'd like to get or build is a fully metered
> regulated supply with adjustable current limiting, that way I'd set the
> current limit to just above what the motor normally draws and the power
> supply would go into current limit if something went wrong with the
autotune
> control and the motor hit a stop. It'd probably need at least 10,000 uF on
> the supply output to take care of the motor start-up surge current too.

I believe there's quite bit of surge current.  If I recall, when I used a
metered supply, it was something like a peak of 7amps and down to 3 amp when
spun up.  A simple supply should suffice.  You could even use a couple of 12
v. gel cells in series.  A current regulated supply would probably not be a
great idea as you'd have to set it either too low whereby it would interfere
with operation -- e.g. stall at higher mechanical resistance points -- and
afford no real protection set high enough for it to work right in the first
place.

>
> Since I needed locking keys I bought a set from Hank Arney and they look
> real sweet. I tried inserting them into the knobs and into the innards of
> the autotune and they thread in nice and smooth to a point but then appear
> to bind up before the locking handle makes it down to flush with the knob
> face. Is this normal or do they really need to be screwed in very hard all
> the way down? Since I don't have any experience with using the autotune
> section I'm taking it real cautious here, don't want to beak anything! I'd
> appreciate some advice on this.

As Roy already posted, no they should stop short of the knob. I'd guess
between 1/4 and 1/8 inch. The clutch is engaged when the rounted tip of the
key presses against the works inside.  You tighten them very firmly and test
by trying to turn the KC and MC knobs.  When sufficiently tight, it
shouldn't be possible to turn them. You don't want them slipping when the
autotuner is running.

Good luck!
Barry

>
> thanks,
> John
>
>
>
>
>
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