Volume slider testing

The Yamaha SY99 is a synthesiser combining frequency modulation synthesis (branded as Advanced FM) and sample-based synthesis (branded as Advanced Wave Memory 2) and the direct successor to Yamaha's SY77/TG77

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LittleWiggler
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Joined: Wed Jan 22, 2020 12:02 am

Volume slider testing

Unread post by LittleWiggler »

Hello all.

I recently acquired a SY99 in excellent condition. It has the backlight problem, and I am in the process of replacing it.

One issue I do have is that the output on Output 1 is roughly 1/3 of the output on Output 2.

While I have it apart I tested continuity between the 8 pins of the sliders and found that the bottom pair of contacts on the slider for output 1 do not have continuity but the bottom pair of output 2 do.

I have 2 sliders coming from syntaur (dot) com, but thought I would check with the collective here to see if I am on the right track.

Thanks!
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Miks
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Re: Volume slider testing

Unread post by Miks »

Here's a snippet of the SY99 schematic showing how the sliders are 'wired':
SY99 Volume Pots.JPG
Pin1 of VR1A&B and Pin1 of VR2A&B are all connected to AG (Analog Ground). Note that those sliders are stereo versions.
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LittleWiggler
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Re: Volume slider testing

Unread post by LittleWiggler »

Mike,
Thanks for the reply.
So far no joy in figuring out the volume difference issue. I'm hesitant to replace the slider unless I can narrow it down.


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Sutur
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Re: Volume slider testing

Unread post by Sutur »

I doubt that the slider(s) are the problem here. Usually, measuring a part while in a circuit don't give you the readouts you might expect (because of the other parts which interfere with the resistence).

Have you figured it out yet?


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