[Premium-Rx] R3030A keyboard debounce

Tue Jul 1 08:10:41 EDT 2003

hi All,
I had 1 unsealed module with a 3.3 UF cap. The goop was clear and it is used
to support 
the high mass high CG part during vibration testing. I found a bag of
180-004 key pad covers
but they are mis marked without the functions above the numbers. They must
have been rejects.
I bet there is 100 of them. I will look for a closer match.   fc

-----Original Message-----
From: refmon [mailto:monitor at referencevideo.com]
Sent: Monday, June 30, 2003 8:19 PM
To: premium-rx at ml.skirrow.org
Subject: Re: [Premium-Rx] R3030A keyboard debounce

OK, I have done the task and results are good.  These are initial results,
because as always, Rat Shack did not have what was needed...so I ended up
tacking in a 10uf cap.  The resulting 13.3uf nominal, feels a bit heavy...I
expect 10uf is good, as rev B indicates.  In any case, I absolutely cannot
get the keypad to bounce...I've done all the variations of button push I can
think of...head-on push, lazy side push, lingering push, shaky push, etc etc
etc.  My self-developed anti-bounce button push no longer works at
all...that's the fast snappy button push where you can beat the bounce and
get off the button fast enough to avoid the bounce.

So this looks good, subject to refinement to a real 10uf.  In the interest
of cleanliness and anality, I'll try to dissolve the potting goop with a
selection of dangerous, volatile solvents...as soon as I find my lighter for
illumination, I'll get started.

Who was it that had pulled his keyboard's pants down?  That is, taken the
overlay off...now all we need to do is find a super sticky, infinitely
flexible adhesive with which to adhere the baggy overlays...is the such an
animal as double-sided contact paper or similar?

Imagine, R3030A's without bouncy keypads...what a world!  Let me complete
the experiment before hacking into your own units...I'm already in deep.

John
__________________________

----- Original Message ----- 
From: "Carcia, Frank A. HS" <francis.carcia at hs.utc.com>
To: "'refmon'" <monitor at referencevideo.com>; <premium-rx at ml.skirrow.org>
Sent: Monday, June 30, 2003 01:07 PM
Subject: RE: [Premium-Rx] R3030A keyboard debounce

> Why not just hang a 6.8 UF across the potted cap and see what happens?
> 335 should be 3.3 UF and 106 should be 10 UF. It might be easier to
unsolder
> it
> and measure the value. I have a number of these modules for the 3512 and
> will check it
> out.    fc
>
> -----Original Message-----
> From: refmon [mailto:monitor at referencevideo.com]
> Sent: Monday, June 30, 2003 4:01 PM
> To: premium-rx at ml.skirrow.org
> Subject: [Premium-Rx] R3030A keyboard debounce
>
>
> Hi,
>
> Possible breakthrough here!  Read on.  Looking at my manuals for 3030A vs
> 3030, they show identical drawings for both Panel Interfaces...the base
> drawing dates are the same 1984 date... however, there are a bunch of
ECN's
> spanning 4-1-85 thru 4-11-86...but that's not it...the ECN's mostly update
> drawing references and fix typos...now the good part:
>
> The module is 2140-1116, the circuit board is 2140-2018, and the schematic
> is 2140-2418...notice there's no A, B, C shown.
>
> Tucked up in the corner of the drawing are rev A and rev B.   rev A is not
> related.  Rev B states that C2 was changed from 3.3uf/15V to 10uf/20V as
of
> date 3-8-85.  C2 is on pin 7 of U6, the keypad encoder.  The keyboard
> encoder is a 74C923.  Search 74C923...look at "ext C" on the data sheet
> internal diagram... the external C is none other than KEYBOARD DEBOUNCE!!!
>
> Now the mystery:  although my R3030A was made prior to the revB date, it
has
> a revB circuit board inside.  However, C2, which for some ungodly reason
is
> potted in shoe goop or some other potting substance, is color coded orange
> up top and green lower down on the bottom where the wires come out...it's
a
> tantalum.  I'm rusty on this, but I decode those colors to be 3.3uf.
PLEASE
> DOUBLE CHECK me on that.  Unfortunately, I cannot see any printed info on
> the body of the cap.
>
> I am up for some field surgery...does anyone know what will dissolve the
> potting stuff without eating the components and board?
>
> Based on my findings thus far, I have not opened any of my R3030
> modules...I'm trying to keep them sealed...I suspect, though, that the
3030
> has the 10uf update in place, as its manufacture date stamps are from
1986.
>
> read this over....double check my decode on the colors, pry off the module
> covers on your receivers and see what you've got.
>
> regards
>
> John
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