Yamaha CS5 Trigger mod

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Edweird79
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Yamaha CS5 Trigger mod

Post by Edweird79 » Wed Nov 15, 2017 7:27 am

Hello all,

Love my Yamaha CS5, use it in conjunction with a korg SQ-1 to trigger great sequenced bass lines. Problem I have is that if I want to play the synth in free time with my hands doing all the key on key offing, I literally have to reach around and pull out the 'trigger in' cable. This is annoying. I'd like to be able to leave the trigger in cable plugged in and have a switch on the top of the unit which lets me go between sequences or free play. It sounds relatively simple right? Any answers would be great!

Thanks, Ed

Rasputin
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Re: Yamaha CS5 Trigger mod

Post by Rasputin » Wed Nov 15, 2017 8:43 am

I'm not all that familiar with the Yamaha CS5, so I could be off-base here, but it probably is a switched mono style jack, so instead of just the traditional sleeve and tip connections, there would be an additional connector. When there's no plug inserted into such a jack, the extra contact is physically touching another pin and the switch is closed. When a plug is inserted then the contact is displaced and the switch becomes open.

Therefore: Wire up a switch to manually close them electrically even when they're physically opened by a plug.

Edit: Looking at the service manual, it seems that there should be a yellow and orange wire on the Trigger Input jack that ordinarily short together.

I don't know the circuit well enough to say what the repercussions of this would be nor if it's advisable. But that might be where to start investigating.

Extra Edit: It looks like the Trigger Out simply loops back into the Trigger In via the normally closed switch in the Trigger In jack. That means Trigger Out is always active with the Key-On data and usually passes the Key-On data to the Trigger In jack which is simply fed back into the synth. When a jack is plugged into the Trigger In, this switch is broken so the synth no longer receives its own Key-On data via the Trigger Out to Trigger In loop. Instead, the signal from the Trigger In tip plug connection is sent in place of the internal Key-On data.

Test Point #14 (TP14) seems to be the source of Key-On data. Test Point #49 appears to be the destination of Key-On data (whether internally from the synth or the Trigger In jack). So, connecting TP14 to TP49 should force all synth Key-On events to be read by the synth regardless of the state of the Trigger In jack.

This may cause the synth's Key-On data to be sent back in to the trigger output jack of any connected external trigger device, but I'm not 100% sure. That's probably something you'd want to avoid. It may require adding a diode between TP49 and (what I'm assuming to be) the yellow wire that goes to the tip connection of the Trigger In in order to prevent backfeeding.

Edweird79
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Re: Yamaha CS5 Trigger mod

Post by Edweird79 » Thu Nov 16, 2017 4:05 am

Thanks for that input, Rasputin. I'll have a little look under the hood tonight and post a reply.

Rasputin
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Re: Yamaha CS5 Trigger mod

Post by Rasputin » Sat Dec 02, 2017 11:41 pm

Any epiphanies?

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