Noise from new HP48GX?

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Robert George

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Sep 17, 1996, 3:00:00 AM9/17/96
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I've just purchased a new HP48GX from EduCalc, and have been very
happy with it. One thing that is quite strange, is that there is a
faint, but discernable, high-pitched whine comming from the LCD panel.

This is undoubtably the static inverter for the AC panel. Has anyone
else noticed this noise?

Thanks!

Robert

--
Robert George Engineering Research Center
(601) 325-4585 P.O. Box 6176
http://www.erc.msstate.edu/~robert Mississippi State, MS 39762
"Skill and confidence are an unconquered army." - George Herbert


David Hirsh

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Sep 17, 1996, 3:00:00 AM9/17/96
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Almost sounds like a capacitor whine sound you get when your camera
flash is recharging. Unusual for a calculator though......

Don Meredith

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Sep 17, 1996, 3:00:00 AM9/17/96
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Robert George <rob...@erc.msstate.edu> writes:


>I've just purchased a new HP48GX from EduCalc, and have been very
>happy with it. One thing that is quite strange, is that there is a
>faint, but discernable, high-pitched whine comming from the LCD panel.

>This is undoubtably the static inverter for the AC panel. Has anyone
>else noticed this noise?

>Thanks!
>

Here we go again!!! *grin*


--
- Don Meredith _____________________________________
Mechanical Engineering
Clemson University __o
__o _`\<,_ __o

Dangermouse

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Sep 17, 1996, 3:00:00 AM9/17/96
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In article <66685df...@erc.msstate.edu>, Robert George
<rob...@erc.msstate.edu> wrote:

> I've just purchased a new HP48GX from EduCalc, and have been very
> happy with it. One thing that is quite strange, is that there is a
> faint, but discernable, high-pitched whine comming from the LCD panel.
>
> This is undoubtably the static inverter for the AC panel. Has anyone
> else noticed this noise?
>
> Thanks!
>

> Robert
>
> --
> Robert George Engineering Research Center
> (601) 325-4585 P.O. Box 6176
> http://www.erc.msstate.edu/~robert Mississippi State, MS 39762
> "Skill and confidence are an unconquered army." - George Herbert

Yes I ahve also heard the noises. I think it has to do with something more
than the inverter. It squawks like my modem when I'm doing heavy
computations.

--
™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™
™ ™
™ So what does this button do again...........Click!! ™
™ ™
™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™

Darrel Wilson

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Sep 17, 1996, 3:00:00 AM9/17/96
to Dave Arnett

Dave Arnett wrote:
>
> Robert George <rob...@erc.msstate.edu> wrote:
>
> Hiya, Robert.
>
> <snip>
> >... there is a

> >faint, but discernable, high-pitched whine comming from the LCD panel.
> >
> >This is undoubtably the static inverter for the AC panel. Has anyone
> >else noticed this noise?
>
> This is a common question, my friend. The best answer I have is below.
> It is intended to be general, for Andre Schoorl's use, so I may write
> at a more basic level than you need. (Andre - this is the third time
> I have responded to this question over the years, and it's a very
> reasonable question. Could this be a candidate for the FAQ? DA.)
>
> I will point out at the start that I am no longer on the HP48/HP38
> design team, as the entire product family was moved to our sister
> division in Singapore. I am not up to date on any changes that may
> have been made to the product since the design responsibility moved.
> However, your description of the sound seems quite familiar
>
> The guts of the HP48 keyboard are assembled from several layers of
> mylar and similar material. Some of the layers have conductive ink
> to create switch contacts. Some are insulators, with appropraitely
> located holes through which the switch contacts meet. Some are
> embossed with spherically domed areas, to provide the snap-spring
> feel when you press the plastic keys. The entire multi-layer
> sandwich is assembled onto plastic pegs on the backside of the
> HP48 top case, along with the metal chassis, and then the pegs are
> 'heat staked,' positively capturing and holding the matrix together.
>
> These parallel planes can act like a capacitive speaker. Most
> loudspeakers in home electronics are inductive: a sheet or cone moves
> because current passes through an attached coil positioned in a
> magnetic field. A capacitive speaker creates sound by moving a sheet
> or diaphragm due to electric charge forces, whether attracting or
> repelling. The HP48 keyboard has the necesary characteristics to be
> a very inefficient (therefore quiet) capacitive speaker.
>
> When the HP48 'scans' the keyboard, charges are placed on the parallel
> sheets of mylar. They tend to move as a result of the charge, and
> create a faint squeal or whine. The loudness will depend on a number
> of factors, and can vary significantly from HP48 to HP48. Some folks
> report that, on their HP48, the sound is stronger on the back than on
> the front; others report the opposite.
>
> Good Day!
> Dave.
>
> ------
> I don't speak for HP when I post here.

It is because of this reason and not a DC to DC converter? (An inductor was
my thought.......). The frequency changes with power consumption (determined
by a multimeter and ear). In any case, thanks for the info!

darrel...@bendnet.com

Sherry S Turechek

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Sep 17, 1996, 3:00:00 AM9/17/96
to

Robert George wrote:
>
> I've just purchased a new HP48GX from EduCalc, and have been very
> happy with it. One thing that is quite strange, is that there is a

> faint, but discernable, high-pitched whine comming from the LCD panel.
>
> This is undoubtably the static inverter for the AC panel. Has anyone
> else noticed this noise?
>
> Thanks!
>
> Robert
>
> --
> Robert George Engineering Research Center
> (601) 325-4585 P.O. Box 6176
> http://www.erc.msstate.edu/~robert Mississippi State, MS 39762
> "Skill and confidence are an unconquered army." - George HerbertI get the same thing...
Especially when I use codelock (dont ask me why i use it, i dont
know..) when i turn it on and it asks for my pw it screams.

Luke

Dave Arnett

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Sep 18, 1996, 3:00:00 AM9/18/96
to rob...@erc.msstate.edu, asch...@engr.uvc.ca, da...@cv.hp.com

Robert George <rob...@erc.msstate.edu> wrote:

Hiya, Robert.

<snip>
>... there is a


>faint, but discernable, high-pitched whine comming from the LCD panel.
>
>This is undoubtably the static inverter for the AC panel. Has anyone
>else noticed this noise?

This is a common question, my friend. The best answer I have is below.

John H Meyers

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Sep 18, 1996, 3:00:00 AM9/18/96
to

High-pitched noise from HP48's is normal and harmless,
has been attributed to the internal power supply.

Another tidbit for the FAQ, Andre?

-----------------------------------------------------------
With best wishes from: John H Meyers ( jhme...@mum.edu )

Robert George

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Sep 18, 1996, 3:00:00 AM9/18/96
to

Darrel Wilson <darrel...@bendnet.com> writes:

Dave Arnett was kind enough to reply to my post directly, but I have some
problems with his explaination. Namely, I've had several HP
calculators in the past, and none have ever exhibited this
high-pitched whine. Also, the noise appears to be comming from the
LCD panel itself, not the keyboard. This _would_ be indicative of a
faulty DC converter or inductor!

What concerns me even more is that my colleagues have older versions
of the 48S/G which also do not have this problem.

It certainly seems that the 48 series has gone through some aggressive
"cost engineering" since the 48 production was moved to Singapore...

Do you remember the days when an HP calculator weighed a ton and could
be dropped to the floor from desk-level without a scratch?

At any rate, thanks for all the responses!

As a cynical long-time Usenet reader, I am most impressed with the
signal to noise ratio on this group!

Robert

--
Robert George Engineering Research Center
(601) 325-4585 P.O. Box 6176
http://www.erc.msstate.edu/~robert Mississippi State, MS 39762
"Skill and confidence are an unconquered army." - George Herbert

>
> Dave Arnett wrote:
> >
> > Robert George <rob...@erc.msstate.edu> wrote:
> >
> > Hiya, Robert.
> >
> > <snip>
> > >... there is a
> > >faint, but discernable, high-pitched whine comming from the LCD panel.
> > >
> > >This is undoubtably the static inverter for the AC panel. Has anyone
> > >else noticed this noise?
> >
> > This is a common question, my friend. The best answer I have is below.

...
[snip]
...


> > When the HP48 'scans' the keyboard, charges are placed on the parallel
> > sheets of mylar. They tend to move as a result of the charge, and
> > create a faint squeal or whine. The loudness will depend on a number
> > of factors, and can vary significantly from HP48 to HP48. Some folks
> > report that, on their HP48, the sound is stronger on the back than on
> > the front; others report the opposite.
> >
> > Good Day!
> > Dave.
> >
> > ------
> > I don't speak for HP when I post here.
>

Dustin Wehmeyer

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Sep 19, 1996, 3:00:00 AM9/19/96
to


> Robert George <rob...@erc.msstate.edu> wrote in article
<6620fzg...@erc.msstate.edu>...


> Darrel Wilson <darrel...@bendnet.com> writes:
>
> Dave Arnett was kind enough to reply to my post directly, but I have
some
> problems with his explaination. Namely, I've had several HP
> calculators in the past, and none have ever exhibited this
> high-pitched whine. Also, the noise appears to be comming from the
> LCD panel itself, not the keyboard. This _would_ be indicative of a

Not on my GX, the almost imperceptible whine is definitely coming form the
keyboard NOT the display.

Darrel Wilson

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Sep 19, 1996, 3:00:00 AM9/19/96
to Robert George

Robert George wrote:
>
> Dave Arnett was kind enough to reply to my post directly, but I have some
> problems with his explaination. Namely, I've had several HP
> calculators in the past, and none have ever exhibited this
> high-pitched whine. Also, the noise appears to be comming from the
> LCD panel itself, not the keyboard. This _would_ be indicative of a
> faulty DC converter or inductor!
>
> What concerns me even more is that my colleagues have older versions
> of the 48S/G which also do not have this problem.
>
> It certainly seems that the 48 series has gone through some aggressive
> "cost engineering" since the 48 production was moved to Singapore...
>
> Do you remember the days when an HP calculator weighed a ton and could
> be dropped to the floor from desk-level without a scratch?
>
> At any rate, thanks for all the responses!
>
> As a cynical long-time Usenet reader, I am most impressed with the
> signal to noise ratio on this group!
>
> Robert

An LCD is such a low power device though-- it doesn't need a DC-DC converter
at all. Only a floresent display (LCD like though) would need that....or the
back lighting now found on some watches, but we don't have that (though it
might be nice at some times). On my HP, the noise is centered around the +-
key. Could be keyboard. Dave said the only inductor is right off the +
battery terminal. More likely though, I think it is noise comming from the
pizeo speaker in the HP. It would be very easy for this to emit noise
(background noise and current, etc.) Any other ideas?

darrel...@bendnet.com

Russell Salsbury

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Sep 20, 1996, 3:00:00 AM9/20/96
to

My keyboard also whines, but only when HPLock prompts for a password.
After I log in the whine stops.

Ryan russ...@netcom.com

John H Meyers

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Sep 21, 1996, 3:00:00 AM9/21/96
to

In article <6620fzg...@erc.msstate.edu>,
Robert George <rob...@erc.msstate.edu> writes:

> Do you remember the days when an HP calculator weighed a ton and could
> be dropped to the floor from desk-level without a scratch?

Many of those highly-indestructible calculators had all-plastic
LED displays, rather than the large glass panel required of the
HP48's LCD display; hence they had a slight advantage to begin with.

All the same, apparently some LCD's are made more shock-resistant
than others, and no doubt the HP48, even without its vulnerable glass
display, is not as sturdy as the $495 HP35 which went through a
snow-blower unharmed (per a testimonial in an HP35 brochure).

Dare we ask how the TI's (etc.) stack up, sturdiness-wise?

John H Meyers

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Sep 21, 1996, 3:00:00 AM9/21/96
to

In article <01bba66b.a84ab380$ce75...@HTS.premier1.net>,
"Dustin Wehmeyer" <dus...@hightechsolutions.com> writes:
>> Robert George <rob...@erc.msstate.edu> wrote:
>> the noise appears to be coming from the LCD panel itself...

>> Sherry S Turechek wrote:
>> Especially when I use codelock (dont ask me why i use it, i dont
>> know..) when i turn it on and it asks for my pw it screams...
> Not on my GX, the almost imperceptible whine is definitely coming from

> the keyboard NOT the display.
>> Darrel Wilson <darrel...@bendnet.com> writes:
>> Dave Arnett was kind enough to reply to my post...

Dave is just putting you on! Don't you know that HP people, much like
politicians, are trained to give out misleading "techno-babble" to try
to totally deceive you (and any eavesdropping competitors) about what's
really going on inside their products, and why?

The truth is, that to cut costs and get the product off the factory floor
seconds faster than any competitor, HP has deliberately installed BUGS
into every HP48 -- not software "bugs," mind you, but REAL bugs
(tiny mosquitos, to be exact), which have been carefully trained and
genetically "programmed" (much more cheaply than now-obsolete human product
inspectors) to crawl through the HP48 as it wends its way from the factory
to your retailer, performing final inspection and last-minute minor repairs
(using nano-technology tools) "on the fly," so to speak.

In many cases, the bugs are still carrying out their pre-programmed tasks
even after the new owner has begun using the HP48, which is why many
new owners still hear the "faint whining" coming from different parts of
their particular unit, depending on what point in the inspection route
has currently been reached.

This also explains why many trivial initial problems experienced by some
owners seem to just mysteriously "go away" with further use (proof that
this technology really works!).

The "CodeLock" library, on the other hand, interferes with the ability
to activate some of the required test routines, and often causes
considerable increase in the volume of the whine as the stymied
inspector is blocked from completing its appointed rounds.

Purchasers of units which have long been gathering dust on the shelves
of less aggressive retailers, however, usually find that the inspection
has long since been completed, and the "whine" has long gone silent.
There is also the fact that the earlier "Rev A-P" strains were not
as efficient at converting electrical energy (yes, they're battery-
powered!), and did not last as long as the latest-developed strains.

Now, the obvious reason why the HP48 case is (or at least is supposed to be)
unopenable, as so many frustrated electronic technicians have complained
about, is simply to prevent the illegal escape of the quarantined bug;
it is simply a fact required by government regulation, much as is the
RF shielding on the "official" HP cable. Most units (with "S" serial#s)
have actually been assembled in Singapore for many years, and there
is some controversy as to whether the true country of origin of the "bug"
is actually USA, which is what HP has claimed in order to allow re-entry
into US ports without the long quarantine delay otherwise required (a fact
which would obviously be self-defeating to the whole original purpose). In
fact, the sole reason for the Corvallis Division remaining open is so that
HP can justify its claim that this critical component is still made there.

The only reason that this whole issue is still being hushed up by HP is
that its world-wide patent applications are being widely rejected, as has
many times been the fate of HP technology which is so far ahead of its time.

I hope this finally sets many unresolved issues to rest, and that Andre
will take note and add these to the FAQ ASAP, so that we can stop hearing
any more of this interminable whining about HP noise, etc. which is always
a "fly in the ointment" to the smooth functioning of this newsgroup.

Thank you for your kind inattention.

"I do not speak for HP when I don't post" (and I didn't post this!)

John H Meyers

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Sep 21, 1996, 3:00:00 AM9/21/96
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