[Premium-Rx] R3030A keyboard debounce

[Carcia, Frank A. HS]

I confirm this as my open module with 3.3 UF had '83 date codes on the ICs.

-----Original Message-----
From: Herschel McCullough [mailto:w5mc at austin.rr.com]
Sent: Tuesday, July 01, 2003 12:00 AM
To: refmon; premium-rx at ml.skirrow.org
Subject: Re: [Premium-Rx] R3030A keyboard debounce


this is good eye for detail John..  ECNs can get pretty dry reading..
----- Original Message -----
From: "refmon" <monitor at referencevideo.com>
To: <premium-rx at ml.skirrow.org>
Sent: Monday, June 30, 2003 3:00 PM
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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