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I have a weird issue that I'm chasing. When changing from the Ultra channel to the Crunch channel, every so often it will give a slapback muting effect. When it occurs, I can typically get it to occur a few times in a row before it goes back to working normally. It never occurs when going from Crunch to Ultra or from either dirty channel to Clean.
I scoped the signal and see that it is dropping out at the junction of K3A(5)/Q7/R27 node just before the tone stack on the schematic. I am suspecting the mute circuit and perhaps CLAMPC activating, or related to the CLAMPB signal. I do not experience the issue when going back and forth to the clean channel so I'm ruling out CLAMPA. I also was thinking it may be relay K3C not engaging fast enough. Edit: Maybe relay contact bounce, but it's not every time?
K2 and K3 are energized with the Crunch channel. K1 and K5 are energized with the Clean Channel (de-energized is Ultra by default).
Suggestions on where to scope/look next? 24VDC power supply dipping too low? Any caps? Thanks!
I scoped the signal and see that it is dropping out at the junction of K3A(5)/Q7/R27 node just before the tone stack on the schematic. I am suspecting the mute circuit and perhaps CLAMPC activating, or related to the CLAMPB signal. I do not experience the issue when going back and forth to the clean channel so I'm ruling out CLAMPA. I also was thinking it may be relay K3C not engaging fast enough. Edit: Maybe relay contact bounce, but it's not every time?
K2 and K3 are energized with the Crunch channel. K1 and K5 are energized with the Clean Channel (de-energized is Ultra by default).
Suggestions on where to scope/look next? 24VDC power supply dipping too low? Any caps? Thanks!
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