"Bad" CAI302 Display

Dan Marotta wrote, On 9/17/2013 8:42 AM:
Well, calling Gary *would* be the elegant solution but I thought he
wasn't working on CAI instruments any more. I can call...

As to simply rotating the glass - that was my initial thought so I asked
Paul at Cumulus Soaring. He thought the problem was with the actual LCD
and not the front glass. So I started thinking about it... Having no
direct knowledge of LCD construction other than at the highest level, I
believe there's a back layer which contains the electronics, a layer of
the liquid crystal, probably a transparent layer in front of that with
whatever circuitry is necessary to complete the electric fields to
change the state of the crystal, and a front layer, which may be
polarized. There may be other layers which I don't think matter to this
discussion.

If it's the front layer of the sandwich, then it was incorrectly applied
during manufacture and there's no fixing it. If, on the other hand, my
imaginings are wrong and it *is* the front glass, then that should be
easily rotated. Then the only problem is the possible violation of the
electronic seal.

I don't think it's the front glass, as I can see the needle clearly
through my polarized glasses, but not the LCD.

The 302 isn't my only problem, but also the Butterfly display for
PowerFlarm, and the ClearNav display to some extent. The Becker
transponder display and the MGL radio display are not affected,
regardless of the sunglasses orientation, so they must use a different
kind of LCD.

I've dealt with the problem by punching holes in the polarized clip-ons
that I use with my prescription glasses. The holes are located low on
the clip-ons so I can see the panel while I'm looking outside. The
oblong holes are about 0.3" high and 0.4" long. Besides solving the LCD
problem, the lack of tinting makes it easier to read the instruments and
flight computer in any lighting, but especially dim light.

And, yes, I do look a little strange when wandering around the airport
with holes in my sunglasses, but it's a small price to pay for being
able to see!

--
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

Dan, you can rotate your glasses 90 degrees, if the display
becomes visable, it is the glass not the LCD on the 302.

The material in polarised sunglasses is oriented to minimise specular
reflection from water/snow surfaces. As a bonus for soaring pilots this
enhances cloud definition. Rotating sunglasses material reduces the useful
effect appreciably, so negates the benefit of polarising sunglasses.

Early production CAI302s had an LCD with the 'wrong' orientation for
polarising sunglasses, and nobody is likely to have a new batch
manufactured now.

The only practical answer is to use non-polarising sunglasses; brown tint
is good for cloud definition. A reddish tint is even better, but at the
expense of false colour which can cause problems when identifying crop
types for the field selected, and in reading paper charts.

At 04:14 18 September 2013, Doug Mueller wrote:
Dan, you can rotate your glasses 90 degrees, if the display
becomes visable, it is the glass not the LCD on the 302.

It's 45 degrees, not 90. Very strange.

And still no definite answer about whether it's the LCD waver or the front
glass that's the problem. I wear my old standby smoke colored sunglasses in
the glider and the Eagle Eyes in the car. I'd much prefer the reverse.

I sent Gary an email but no reply just yet...

"Peter Purdie" wrote in message
...
The material in polarised sunglasses is oriented to minimise specular
reflection from water/snow surfaces. As a bonus for soaring pilots this
enhances cloud definition. Rotating sunglasses material reduces the useful
effect appreciably, so negates the benefit of polarising sunglasses.

Early production CAI302s had an LCD with the 'wrong' orientation for
polarising sunglasses, and nobody is likely to have a new batch
manufactured now.

The only practical answer is to use non-polarising sunglasses; brown tint
is good for cloud definition. A reddish tint is even better, but at the
expense of false colour which can cause problems when identifying crop
types for the field selected, and in reading paper charts.

At 04:14 18 September 2013, Doug Mueller wrote:
Dan, you can rotate your glasses 90 degrees, if the display
becomes visable, it is the glass not the LCD on the 302.

Peter Purdie wrote, On 9/18/2013 5:51 AM:
The only practical answer is to use non-polarising sunglasses; brown tint
is good for cloud definition. A reddish tint is even better, but at the
expense of false colour which can cause problems when identifying crop
types for the field selected, and in reading paper charts.

At 04:14 18 September 2013, Doug Mueller wrote:
Dan, you can rotate your glasses 90 degrees, if the display
becomes visable, it is the glass not the LCD on the 302.

I found it practical to punch holes in my polarized clip-ons. That
eliminated the polarization over the area of the panel, and also the
tinting: no LCD problems, no paper chart problems (not that I look at a
chart very often). It does not solve the tinting problem for crops,
because I'm using bifocal glasses, and the holes are over the bifocal part.

I'd probably use non-polarized clip-ons if I could find them. If you
don't need distant vision correction, there are polarized "sunreaders"
available that have non-polarized, non (or lightly)-tinted inserts with
correction for reading.

http://www.amazon.com/Polarized-Bifo...reader+glasses

These look like the inserts are tinted, unlike the ones I have. Since
the inserts aren't polarized, looking at LCDs isn't a problem.

--
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

On Tuesday, September 17, 2013 5:24:36 AM UTC-5, KiloKilo wrote:
http://clearnav.net/main/cn-service.html

I may have read the http://clearnav.net/main/cn-service.html page wrong but it appears they only service the older Cambridge products.

GPS-NAV™ Datalogger
GPS-NAV™ Display
L-NAV™ Glide Computer
S-NAV™ Glide Computer
CAVII™ Variometer

Probably because they use discrete components (individual resistors, capitors, transitors, etc) or single technology ICs which they can easily troubleshoot. Not so the 302.

My $0.02.

Gary's email to me:

Hi Dan,

I was browsing rec.aviation.soaring and read about your troubles with the
302 polarization. Unfortunately it is the LCD that is polarized and not the
window glass.

As I recall, in the early production days of the 302 the first batch of LCD’s
received were not polarized correctly and nobody at CAI noticed. Once the
complaints started rolling in, the manufacturer was notified and further
shipments of the LCD’s were polarized properly. I suspect you have a very
early instrument?

In regards to replacing the LCD with the newer polarized glass, we (ClearNav
Instruments) are looking into purchasing some of Cambridge’s inventory so we
can go forward with support of the 300 Series.

Stay tuned…….

Best Regards,

Gary


"JohnDeRosa" wrote in message
...
On Tuesday, September 17, 2013 5:24:36 AM UTC-5, KiloKilo wrote:
http://clearnav.net/main/cn-service.html

I may have read the http://clearnav.net/main/cn-service.html page wrong but
it appears they only service the older Cambridge products.

GPS-NAV™ Datalogger
GPS-NAV™ Display
L-NAV™ Glide Computer
S-NAV™ Glide Computer
CAVII™ Variometer

Probably because they use discrete components (individual resistors,
capitors, transitors, etc) or single technology ICs which they can easily
troubleshoot. Not so the 302.

My $0.02.

hmmm,
and what about to ask your neighbour optician
to rotate the lenses in your glasses
instead of rotating the 302?
Supposing it should be cheaper...

The glasses are not round.


"StaPo" wrote in message
...
hmmm,
and what about to ask your neighbour optician
to rotate the lenses in your glasses
instead of rotating the 302?
Supposing it should be cheaper...

Dan:

There's a much easier way that drilling new holes. Fly the glider while lying on the wing. This turns your head sideways. Hard to reach the pedals, of course, but no new holes in the panel. Fred