> Just picked up a used A-166 which is behaving in a way I didn't
> expect. Not sure if it is faulty or if I haven't quite understood
> how the module normalisations are supposed to work.
>
> Both sections work fine on their own - the logic operations are
> as expected.
>
> But if I patch the upper logic processor inputs, the resulting
> outputs are also present at the lower section outputs, even
> though the LEDs on the lower outputs are not showing any activity.
>
> So if I put 2 clocks into input 1 and 2 of the first section and
> take the output from, say, XOR on the second section I get the
> same outcome as I would do from taking the output from section 1s
> XOR output, even though the output LEDs are only active for section 1.
>
> Is that right
>
> Mark

That's indeed not how the module should work. The LEDs should in any case
show the states of the outputs in the right way. Maybe the output buffer
(ULN2004) is faulty and does no longer separate the channels. If the module
is new please return it to the dealer where you purchased it for replacement
or refund. If it's an older module or second hand I'd recommend to replace
the ULN2004 on the main board. It's a cheap circuit (< US$1).

Best wishes
Dieter Doepfer