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Re: (ET) E-15 not getting out of first speed
Larry, this reminds me of something that you might find interesting.
Several years ago the video card in my laptop failed. When this happens,
it's usually because of cracks in solder joints due to heat stress from
the card getting very hot when in use, then cooling down. On a video card
there are way too many solder joints (and way too small) for me to fix by
hand - especially since any cracks would be too small to see. So I instead
put the video card in an old toaster oven and heated it up to about 385 F
(after removing heat sinks) to remelt the solder. It's been working fine
ever since. Not sure I want to try that with card #1.... :)
It sure would be nice if card #1 had the solder lines facing the way
that's easy to access, so you don't have to remove the entire thing from
the tractor to do any work on it. It would also be nice if it were held in
by screws instead of rivets....
Mike
________________________________
Michael S. Briggs, PhD
UNH Physics Department
(603) 862-2828
________________________________
________________________________________
From: Larry Chace <RLC1 etnainstruments com>
Sent: Tuesday, May 23, 2017 8:51 AM
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) E-15 not getting out of first speed
Mike mentioned replacing card #1's C103 capacitor. That is in the
time-delay circuit for the 1A contactor (which, when fired, gives
electric speed #2). There were at least 2 different values for C103,
1uf and 50uf; the associated resistor was 2.2Mohms or 39Kohms
Replacing C103 is not a bad idea. In fact, it might be good to
closely examine all of the solder joints on that card. It is a
single-sided card (copper on just the bottom side, and the holes are
not through-plated), and vibration (what???) can cause solder
connections to break. Re-heating them with a suitable soldering iron
can make a big difference.
One possible problem is that at least some of the GE-built cards were
coated with a protective film after assembly, one that resists
soldering iron heat quite effectively.
Larry Chace, Ithaca, NY I-5 and E15
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