CAI302 bent control knob

The control knob on my Cambridge 302 is slightly bent. It rotates OK
but will not "double click" - it sticks when pushed in and has to be
pulled out. Is it safe to try to bend it straight? Any advice on the
best way to do this?

Walter

On Dec 19, 8:53*am, Walter Weir wrote:
The control knob on my Cambridge 302 is slightly bent. It rotates OK
but will not "double click" - it sticks when pushed in and has to be
pulled out. Is it safe to try to bend it straight? Any advice on the
best way to do this?



I don't know about trying to straighten it. However, the control rod
actually goes through the panel. There should be enough wiggle room
in the mounting of the instrument so that if you loosen the 3 screws
that fix the 302 to the panel you can probably move it in a direction
which will not bind the control rod when you click it. The tighten
the 3 screws .

Tom

"Walter Weir" wrote in message
:

The control knob on my Cambridge 302 is slightly bent. It rotates OK
but will not "double click" - it sticks when pushed in and has to be
pulled out. Is it safe to try to bend it straight? Any advice on the
best way to do this?

Walter



Probably the worst way is to try to bend it back with your thumb.

Two ways I would try:

1. A 6 inch tube (aluminum, brass, steel, strong plastic) that will fit
snugly over the knob (or better yet, take the knob off and straighten
the shaft directly). Slowly force it back into position. This gives
you a mechanical advantage for the bending and allows you to control it
better with a longer moment.

(or)

2. Tap with a small mallet (carefully!)

Don't have a 302 in front of me, so I don't remember how the switch is
mounted. Assuming that it is held to the front cover or bezel with a
nut, The above should work without much danger of ripping it from the
circuit board below. Otherwise, you might have a repair waiting.

My $0.02,

Larry

The most likely cause is (as has been pinted out) that the shaft is binding
on the panel, due to a too small or not-quite-aligned hole.

Loosen the screws, and see if you can then double click, if so drill out
the relevant panel hole.

If it is really a bent shaft, have it removed and straightened by your
nearest Cambridge dealer who can reseal the instrument after reassembly -
the cost will be much lower than damaging the PCB.

"Walter Weir" wrote in message
:

The control knob on my Cambridge 302 is slightly bent. It rotates OK
but will not "double click" - it sticks when pushed in and has to be
pulled out. Is it safe to try to bend it straight? Any advice on the
best way to do this?

Walter

On 12/19/2010 6:53 AM, Walter Weir wrote:
The control knob on my Cambridge 302 is slightly bent. It rotates OK
but will not "double click" - it sticks when pushed in and has to be
pulled out. Is it safe to try to bend it straight? Any advice on the
best way to do this?

Maybe it's not really a bent shaft.

My 302 became sticky, but only in flight or in winter when it got
colder. Using the point of a pin, I put the tiniest drop of the thinnest
lubricant (LPS 1, I think) I had right at the base of the knob's shaft.
Now it works fine all the time.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl
- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what
you need to know tinyurl.com/yfs7tnz

It's off the panel so that's not the problem. There's no doubt that
it's bent. The end of the knob does an orbit when it's rotated.
Before I try anything I'm going to talk to Cambridge - but I thought
maybe I could get some good advice here. A little oil sounds like a
good idea for starters.

Walter

On Dec 20, 9:20*am, Walter Weir wrote:
*It's off the panel so that's not the problem. There's no doubt that
it's bent. The end of the knob does an orbit when it's rotated.
Before I try anything I'm going to talk to Cambridge - but I thought
maybe I could get some good advice here. A little oil sounds like a
good idea for starters.

Walter

The fact that the end of the knob does an orbit is not proof in itself
that the shaft is bent. Before you resort to anything more drastic,
remove the knob and confirm the shaft is really bent.

Removal of the knob requires teasing off the trim cap (finger nail or
knife blade) and then loosening the collet screw.

When you put the knob back on make sure there is clearance between it
and the panel when it is fully pressed in.


Andy

On Dec 20, 11:20*am, Walter Weir wrote:
*It's off the panel so that's not the problem. There's no doubt that
it's bent. The end of the knob does an orbit when it's rotated.
Before I try anything I'm going to talk to Cambridge - but I thought
maybe I could get some good advice here. A little oil sounds like a
good idea for starters.

Walter

We used the oil - bent it straight or at least eliminated the orbit -
but it still won't return when pushed in. It's usable because it can
be manually pulled out but it will have to go to the factory to be
properly fixed.

Walter