Doepfer

> -How "hot" are the trig/gate outputs on the A-155; does it put out the
+10V required to
> trig the 2600's envelopes? Otherwise, does anyone know if there is some
simple mod that
> could be done to the A-155 to make the trig/gate outs put out this
voltage?

The gate and trigger voltages of the A-155 are about +9V and depend a bit
upon the load as there are passive voltage dividers at the outputs which
also work as protection against short circuits. If these voltage dividers
are bypassed a higher voltage can be obtained but in this case the outputs
are no longer protected ! I'd recommend to hold the serial 1k protection
resistors (R10,13,16,19) in any case for circuit protection. But the pull
down resistors (R11,14,17,20) can be removed to obtain a higher voltage. It
should be close to +10V if they are removed.

> -I would also like to extend the cv range of the two sequencer rows to 0 -
10V to be able
> to, for example, open the 2600's filter or VCA from minimum to maximum. I
suppose this
> could be done quite easily by amplifying the cv outs through an A-133
polarizer [?], but
> has anyone tried an internal mod to the A-155 to extend the cv range?

If you are experienced with electronics the A-133 is not necessary. Simply
increase the feedback resistors (sum of R4+P9) to obtain a higher output
voltage. But for the upper row in this case the exact 1/2/4V maximum output
voltage is no longer valid !

I can send you the silk screens of the A-155 pcbs for identification of the
parts in question (use hardware@doepfer.de).

Best wishes
Dieter Doepfer