[volt-nuts] New Solartron 7081

J. L. Trantham jltran at att.net
Fri May 11 03:26:00 UTC 2012

Another interesting thing is that this 7081 (S/N 000660) is equipped with
IC406 through IC411, all HM6117LP-4, 2K x 8 RAM, where as the other (S/N
001523) has only IC406 and IC410 equipped with HY6264LP-10, 8K x 8 RAM.

It would appear that the 'new' older unit (S/N 000660) has 12K of RAM while
the original (S/N 001523), later, unit has 16K of RAM.

Also, I just noticed that there is a difference in the polarities of how B1
is installed on PCB 3, the Earthy Logic Board.  Should the '+' be connected
toward the edge of the board (toward R16) or toward the middle of the board
(toward R18)?

The pictures of S/N 001523 that I took before sending it to Ametek for
calibration and to replace that battery show the '+' toward the edge of the
Earthy Logic Board and with the '+' under the '+' imprinted on the corner of
PCB 14, the Earthy Processor board, that sits just over that end of the
battery B1.

On S/N 001523, after it returned from Ametek, the '+' of B1 is toward the
center of the board.  I think it is installed backwards.  Looking at the
schematic, I think the battery is shown with the incorrect polarity (or
perhaps this is a convention in England, though B401 on PCB 14 is shown
differently).  However, there is D2, an SD3, installed in such a manner that
it protects the circuit from an inverse polarity of the battery.  Can anyone
confirm my thought that the '+' end of B1 should be toward the edge of the

Thanks in advance.


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