[sdiy] Rhythm Ace FR-2L

[Maarten Halmans]

Hi,
I fitted a couple of them with indiviual trigger inputs. Connect a 33nF cap 
to the tip of the trigger input jack, the other end of the cap goes with a 
470k resistor to ground. Connect the junction of the cap and resitor to the 
cathode of a diode. The other end of the diode goes the anode of the diode 
of each voice. These diodes are on the upper right side of the voice boards. 
This works for all voices exept for the open high-hat you can connect this 
one directly to the trigger input.  For the closed high hat you have to fit 
an extra diode between wire comming from the diode matrix and the input of 
the voice.
The voltage level of the trigger also determines the voice level.
I also fitted potmeters instead of the internal trimmers so you can change 
de decay of the voices, you have to add some extra resistors to create a 
propper range of the decay without oscillation of the voices.
Cheers,
Maarten


----- Original Message ----- 
From: "Martin Klang" <mars at pingdynasty.com>
To: "synthdiy diy" <synth-diy at dropmix.xs4all.nl>
Sent: Saturday, August 11, 2012 12:51 AM
Subject: [sdiy] Rhythm Ace FR-2L


> hi list,
>
> I'm looking for information on the Bentley/Ace Tone/Hammond Rhythm Ace 
> FR-2L.
> Ideally a service manual or schematic!
>
> I've picked up a unit, in very nice condition, and intend to add 
> individual trigger inputs.
> Separated outputs would be pretty sweet too, though probably quite tricky 
> seeing how much of the sound generator circuits seem to overlap.
>
> My scope says the sounds are triggered by +6.5v (roughly) impulses. Easy. 
> But the power rails are all negative. How does that work?!
> I have tried with straight +5v input triggers and it works ok, I just need 
> to shorten the pulse. But since I don't understand how this works I'm a 
> bit worried about messing up and killing a beautiful vintage machine.
>
> If anyone's got anything useful on this or related devices, let me know!
>
> cheers dears,
>
> /m
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