Doepfer

Hello,

I just bought a 164-1 and a 174-1 specifically to use together with a 148 S&H, and now find that it doesn't work, and this old conversation.

I have both an older and a new A-148, and it doesn't work on either; on the newer one, it works in T&H mode as described below.

Which (old or new A-148) is easiest to modify?  And could someone please provide very detailed instructions on how to do so?  I'm not very experienced with a soldering iron.

Many thanks,
Ernst

--- In Doepfer_a100@yahoogroups.com, <hardware@...> wrote:
>
> > Indeed, T&H works correctly but S&H doesn't. Initially I had both
> > units in S&H mode.
> 
> I have checked the A-164-1/A-148 combo with A-148 in S&H mode. You are
> right: this combo does not work. The reason is the AC coupling of the A-148
> input in S&H mode in combination with the way how the gate signal is
> generated by the A-164-1 (connection to +12V via protection resistor). If
> the A-164-1 is not operated the output is open and the coupling capacitor of
> the A-148 does not discharge. The T&H does work as in this case the input of
> the A-148 is DC coupled.
> 
> I found a simple solution: solder a pull down resistor (about 100k) between
> GND and the A-148 input. The resistor can be soldered directly to the
> corresponding terminals of the socket on the bottom side of the A-148 pcb.
> The 100k resistor connects the A-148 input to GND when the button of the
> A-164-1 is not operated. Then the AC coupling capacitor of the A-148 is
> discharged as necessary. I have tried successfully an 100k resistor but I'm
> sure that any other value in the range 47k ... 220k should do the job.
> 
> Best wishes
> Dieter Doepfer
>