A friend of me observe several times unwanted effect on various Linn preamplifiers as follow:
Temporarly or permanently no mute-off after switching (e. g. input select), i. e. no sound.
Reasons therefore were in all cases not the MCU control boards rather one of the associated jFET transistors for shorting the signal pad, which remains in a conductive mode even after the absence of positive voltage at it's GATE pin.
After change by an appropriate replacement this unwanted effect wasn't longer present.
But at whole he observe this issue (defective jFET's) often several times.
Therefore for me rises up the question, what is the actually reason for such faults.
My friend suspects the cause to be that certain type series or batches/charges were deficiencies already in new condition.
Because I have found several defective SOT23 SMD jFETs for mute control in a Linn Exotik preamplifier - go to
https://www.diyaudio.com/forums/analog-line-level/258465-linn-exotik-da-version-lock-2.html
I want to know, which brands and types provide the best reliability for this task.
Thank you very much for an advice.
P.S.: This URL's don't provide the wanted information:
Power-on JFET mute - works perfectly, could parts be reduced?
Muting Circuits For Audio
https://www.diyaudio.com/forums/solid-state/172923-mute-circuit.html
https://www.diyaudio.com/forums/solid-state/194391-transistor-switch-audio-mute.html
https://www.diyaudio.com/forums/digital-source/114664-mute-transitors-veil-sound.html
Temporarly or permanently no mute-off after switching (e. g. input select), i. e. no sound.
Reasons therefore were in all cases not the MCU control boards rather one of the associated jFET transistors for shorting the signal pad, which remains in a conductive mode even after the absence of positive voltage at it's GATE pin.
After change by an appropriate replacement this unwanted effect wasn't longer present.
But at whole he observe this issue (defective jFET's) often several times.
Therefore for me rises up the question, what is the actually reason for such faults.
My friend suspects the cause to be that certain type series or batches/charges were deficiencies already in new condition.
Because I have found several defective SOT23 SMD jFETs for mute control in a Linn Exotik preamplifier - go to
https://www.diyaudio.com/forums/analog-line-level/258465-linn-exotik-da-version-lock-2.html
I want to know, which brands and types provide the best reliability for this task.
Thank you very much for an advice.
P.S.: This URL's don't provide the wanted information:
Power-on JFET mute - works perfectly, could parts be reduced?
Muting Circuits For Audio
https://www.diyaudio.com/forums/solid-state/172923-mute-circuit.html
https://www.diyaudio.com/forums/solid-state/194391-transistor-switch-audio-mute.html
https://www.diyaudio.com/forums/digital-source/114664-mute-transitors-veil-sound.html
.....then the jFET is shorted, but this statement does not allow any judgment regarding correct operating.
Only the additional fact, that no conducting is present (i. e. blocking of D-S pad between signal pad and GND) while neg. voltage on GATE allow correct operation.
Only the additional fact, that no conducting is present (i. e. blocking of D-S pad between signal pad and GND) while neg. voltage on GATE allow correct operation.
If the jfet is failing with a DS short, then it is being operated improperly outside of its specifications,
for example excessive drain current.
for example excessive drain current.
I cant believe Linn uses SS mute switches. I thought that was only found in cheap crap. Seriously, take a listen to a preamp or source with and without transistor mute. Probably the most noticable tweak on any equipment. If not relay switched, I always remove or bypass mute circuits. Try it and listen for yourself...
I would have to see the circuit diagram to understand how the mute is implemented. If they shorting the signal to ground then maybe so-so, but passing the signal through another device, or not as in muting, is bad for the audio signal quality. Again, I would have to see the schematic.
Yes, I also need the schematic. But an own creating from Linn's pre-amplifier "Exotik" isn't an easy task concerning time effort.