11/23 clock issue

Noel Chiappa jnc at mercury.lcs.mit.edu
Thu Feb 5 19:41:00 CST 2015

    > From: Brent Hilpert

    > Well, try removing W1 to isolate the output of the xtal oscillator E15
    > from inverter input pin E4.4.

Thanks! Too late to try it today, but first thing tomorrow..

It seems like every time you answer one of my queries, I smack my forehead
and say 'That's an excellent idea! Why didn't _I_ think of that!?!?' :-)

    > If you're not familiar with them, E15 is an integrated xtal oscillator,
    > not just a crystal - the crystal and oscillator logic are both in that
    > can

I'm not familiar, so thanks for the tip. Wonder where I'll find one if that's
what's bad... :-)

    > Could also (with W1 removed) pull E4.4 hi/lo while watching the
    > inverter output E4.16 to see if it responds correctly with the
    > inversion.

Since it's a tri-state, I may need to hit the enable somehow. Oh, wait, I
see, it's hard-wired on via a pull-down. (I wonder why they needed a
pull-down? And I wonder what the test point is there for?) And I guess I need
like a 5K series pull-up resistor to +5, right? (Ground I can just tie
directly, right?)

Anyway, thanks again for the help - very, very useful.


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