[R-390] Crystal substitution puzzle

[Bill Hawkins]

Seems to me that crystals have a rated socket capacitance. The
newer crystals could be rated for lower capacitance. OTOH, 0.01%
seems like a lot of pull for a crystal.

Bill Hawkins


-----Original Message-----
From: David Wise
Sent: Thursday, May 14, 2009 7:10 PM

My R390A's Y411 (16MHz) has died.  Since it was cheap to try, I bought
all the wire-lead 16MHz crystals that Mouser stocks, five in all, and
put them in.
They run, but every last one of them is 1.5-2.5kHz low, which is 50% out
of spec at best.

This is five different parts, from Citizen, Fox, ECS, Abracon, and
Vishay/Dale, so it's not a bad part or a bad lot.  The original crystal,
though too weak to mix well, is right on.  It's a disappointment, as the
new ones are around $.50 each and I hoped to open up an alternate supply
for about half of our second-oscillator crystals.  I can live with the
error, but still - what's up?

Dave Wise