[sdiy] Need help understanding a schematic !

Mike Bryant mbryant at futurehorizons.com
Sat Dec 11 01:16:09 CET 2021

Look on U10/4 and see if the signal is there in any mode.  Then look at the input to U10 on pin 14 for a slower PWM signal

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Jean Bender via Synth-diy
Sent: 11 December 2021 00:06
To: synth-diy at synth-diy.org
Subject: [sdiy] Need help understanding a schematic !

Hi !
I have to repair a boss sps-10. The unit works when used in delay mod, but nothing when used as pitch shifter.
But i also discovered that the tuner output is not working when the effect is on, in delay mod or pitch shifter one. The output is only working when the effect is powered but not engaged.
When i look at the scheme, i don"t get the way it's built, nor i can see where i could find a faulty part. I assume some transistor is not working and i'm looking for a voltage problem, but i'm a bit confused with the way some parts are wired together.

Would someone here agree with explaining me how the different parts of this effect work together ?
Actually i know how to troublecheck with my scope and multimeter, but i stuck on how are working the remote effect input and tuner output.

Thanks for your help !

here is a link to the schematics and service manual !
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