TC Electronic Sustain + EQ low volume

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Stevenrb718
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Post by Stevenrb718 »

I have a vintage TC Electronic Sustain + Par. EQ that has low effect output volume. I already replaced the bad 10uf caps. The bypass signal is fine but the effect volume is significantly lower. I know this isn't inherit to this pedal, so I'm looking for a repair, not a mod. What component/area should I look to next?

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mauman
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Post by mauman »

For continuity and to assist troubleshooting, here's a thread on this pedal: viewtopic.php?t=9043

Various posts there include links to the layout, BOM, service manual and schematic. Below is Harald Sabro's redrawn schematic with his notes. I would suspect either the compressor or noise suppressor function is causing your low-volume problem, but I'm not that conversant with compressors so that's about all I can contribute.
Schematic by Harald Sabro
Schematic by Harald Sabro

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Stevenrb718
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Post by Stevenrb718 »

mauman wrote: 15 Feb 2024, 14:43 For continuity and to assist troubleshooting, here's a thread on this pedal: viewtopic.php?t=9043

Various posts there include links to the layout, BOM, service manual and schematic. Below is Harald Sabro's redrawn schematic with his notes. I would suspect either the compressor or noise suppressor function is causing your low-volume problem, but I'm not that conversant with compressors so that's about all I can contribute.

sustain_parametric_eq_no_switching.png
Yeah I'm not sure where the issue is. I've repaired one of these in the past and this one definitely has a significantly lower output. I'm not good enough with reading the schematics to tell where an amplification or something takes place. I'm guessing there's a resistor somewhere that has gone out of spec, as rare as that is.

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