keithl@vice.ICO.TEK.COM (Keith Lofstrom) (09/17/88)
My trusty Cermetek 1200 modem isn't trusty anymore. When dialing out ON
WARM DAYS, it will no longer lock on the incoming carrier (apparently).
So, I borrowed a couple of malfunctioning Hayes from work for fix parts ...
Well, to make a long story short, I suspect that the problems with ALL
THREE modems are with the AMI S35212A filter chips failing in two different
ways. I remember stories of others with similar problems years past when
I did a modem survey ... so, yet another survey:
1) Do you have a 1200 baud modem that went flakey on you? Please, no
lightning or "bad as delivered" stories... they won't help isolate
the problem.
2) What were the symptoms?
a) did it get very hot, or blow the fuse?
b) did it cease to detect or lock onto carrier when dialing out?
c) does it have problems with dial-in?
d) other ...
3) If 2a), would you mind opening it up and telling me which LSI component
gets hot (besides the 5V regulator and the diode bridge, of course).
4) Special bonus questions for any modem designers out there:
a) have the AMI chips been improved upon?
b) am I barking up the wrong (fault) tree?
c) any good sources for spares?
As a result of this survey, I may order a whole bunch of repair chips.
(I have some infantile need to keep old equipment running - fear of
personal mortality, I guess)
Anyone interested?
If this has already come up, please flame via EMAIL...survey results via
email, of course. We don't want to strain our modems more than necessary...
--
Keith Lofstrom ...!tektronix!vice!keithl keithl@vice.TEK.COM
MS 59-316, Tektronix, PO 500, Beaverton OR 97077 (503)-627-4052