On Tue, 20 Sep 2005 01:13:50 -0700, Rex <[EMAIL PROTECTED]> wrote:
On Tue, 20 Sep 2005 00:17:36 -0500, James Meek <[EMAIL PROTECTED]>
wrote:
Hmmmm. I must have found by ohmmeter the connection between the eeprom
and the rubidium via J2-14A, not realizing they were both inputs (as I
had
concluded that the pinout was non-standard). I not sure about what I
found out about the connection of the rubidium serial output, but I seen
to recall that it doesn't just end electrically where it does visually,
but
rather "goes underground" through the inner layers of the board and
surfaces
elsewhere in the circuitry.
I'm sorry. It's late and I don't really understand that. Please tell me
what you have found connected by underground circuits or (possibly) by
circuits that I have missed.
Sorry, it was nearly a year ago that I did the circuit tracing, and before
I
could get down to being thoroughly systematic about it I was hit with an
urgent
assignment at work that required me to abandon the project.
Hauling out the board and tracing around a little again, and reviewing the
messages, I see that the reasons for confusion were that I had not
positively
identified the functions of any lines except the 15V power and ground
connections,
that I suspected the board of having an internal signal routing layer
(which I now
conclude it does not), and I probably interpreted a resistance measured
along
a sneak path through some semiconductor junctions and ground or Vcc as a
signal
path part of which was passing through a buried internal layer. When you
mentioned
the dead-ending serial output line, what sprang to my mind must have been
a false memory that conflated the sneak path with the dead-ending signal
line,
which I suspected of having another connection through the imagined
internal signal
routing layer. Another factor was that, since I know that some other
rubidiums
contain DDS circuits that are programmed through serial inputs, I was
expecting
to find a connection from the serial eeprom output to the rubidium, and
the fact
that I couldn't find a visible one made me believe all the more that the
board
had more inner layers than just the ground plane.
Sorry to have misled you by voicing such inaccurate memories.
I'm just trying to help here, and I _AM_ the person that figured out
that the rubidium box needs 5 V. You could still be stumbling trying to
figure why there is no output.
Please be specific with any new knowledge or criticism of my help.
I certainly didn't mean any criticism. Because I suspected the board of
having
an additional, internal signal routing layer, I thought I had stumbled
across a
connection not visible in the surface routing layers, which no one could
be
expected to find unless they happened to connect across the same points.
P.S. Have you tried to power it up with the info I just gave you.
No, because I have another project in progress, and put my original post
on the list only trying to be helpful to people who it seemed had bought
the units on the sawed-off board sections that had none of the peripheral
circuitry. I'll power it up this weekend and let you know what I find.
Give me some *facts* with new information or shut up. You are beginning
to annoy me.
And **** you very much for not thanking me in the previous message.
Pardon me for failing to thank you more effusively in my rushed reply.
But as I wrote, "Many thanks for this info. I was reluctant to power up
the whole board, before doing further circuit tracing" (which I hadn't
time to do).
Regards,
JM
--
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