Hi All, You know how you can look at something that appears identical
to something else a hundred times and never see the difference. Well,
that's what happened to me today. While helping a visitor determine
the model of his Kimball Electromatic, I discovered a difference
between the Model C & D. It's a diode!
I looked at the schematics and they appeared identical, but I was
just looking at them, not actually 'reading' them. In frustration,
I started reading and comparing the pages in both manuals page by page.
There it was, on page 8, Item #8, which is part of an explanation
concerning the electrical sequence: "... Tempo controls and the 540-014
diode." But on the same page, same number in the other manual, it
reads; "... Tempo controls and the 1N1220 diode."
Rushing to the schematics, I looked for diode 540-014 (which is not
a valid diode number). And again, there it was, in the exact same
location as in the other manual, BUT it wasn't marked 540-014, it was
labeled as 1N4818.
Those in electronics would undoubtedly surmise that the unit with the
1N1220 diode preceded the unit with the 1N4818, and they would be
absolutely correct. It is the Model D which contains the newer diode.
Although I don't have any reference books concerning diodes, I would
guess that the 1N4818 is a heftier diode.
Well, that's it. The 'C' has the 1N1220 and the 'D' has the 1N4818.
If there are any other differences, I've yet to find them.
John A. Tuttle
[ Manufacturers use their own in-house part numbers (like 540-014)
[ so that the buyer has some flexibility, but especially so that
[ the assembly drawing needn't be revised if the part bears a
[ different manufacturers part number. The companion parts list
[ (if prepared to MIL or DIN standard practices) should give the
[ Kimball part number and the industry part numbers which
[ can be used in the Kimball application. Of course, if Kimball
[ didn't publish the parts list it can be a big frustration when
[ the component must be replaced 20 years later! -- Robbie