Doepfer

> I'm having problems with my Doepfer A155 sequencer. I use it with the 
> A154. My problem is in the A155 first CV sequence row. Only two steps 
> of the eight actually produce voltages. I'm not sure why this is, as 
> the second CV sequence works wonderfully.

Sounds like trouble with the ribbon cable connecting everything 
together. Each step in the sequence is 'addressed' via this cable, 
using 3 binary lines (hence 2 x 2 x 2 = 8) - as you are only getting 
two steps from the top row, it sounds as though the ribbon is only 
making connection on 1 of the 3 address lines. The ribbon goes to the 
bottom board (second row), middle board (top row), and then to the 
trigger/gate board. Since the bottom row is working, the signal appears 
to be good there, so there may be a break in the cable, or the 
connector to the top row (middle board) is bad - are the trigger/gates 
working properly (which are on the end of the ribbon)?

What you could try is to place the connector for the bottom 
board/second row onto the middle board/top row, but take care to keep 
the orientation the same - just leave the bottom board unconnected, and 
see if this makes the first row work. If so, you'll need a new ribbon, 
as it is not worth trying to fix a bad one.

Also if the ICs are in sockets, check these are seated properly, 
especially the '4051 which controls the switching.

Tim