Do you know what this capacitor is doing there?

[Wavebourn]

this is a top performer Pioneer pré amplifier...i was looking and happy to see it looks alike the Dx amplifier...but i could not understand what this capacitor is doing there.

Do you know?

Please, explain.

I don't know, but can guess: when they made a prototype suddenly found that it oscillates. They tried to find what's wrong, but could not find which ground traces go wrongly, they were out of schedule, but somebody found a workaround to stop oscillations, and got a premium... Or was not fired... Who knows...

 

[destroyer X]

Yeah folks..i am reading.... correct SY.... seems to me may switch

Thank you guys.

regards,

Carlos

................................................................................................

Now it is raining.... finally!.... 10 nice rains this month...say..more than 1 minute rain.... temperature dropping....now 25... this is delicious.

 

[Geoff H]

That is a strange one. It could be a way to shunt noise generated by D1 away from the input section.

OR detract the attention of the opposition. Have you checked the PCB to see if it as the CCT diagram?

edit: the zener should not be switching, it's a voltage stabiliser for the long tailed pair current source.

 

[destroyer X]

This depends voltage drop into the supply.... if voltage drops bellow

the zener voltage..then it will switch off.

Some folks said this is noisy...well... i could never listen that..but you know....we worry about those things.... that "just in case" theory.

Some people are very alarmist about those things... they say diodes are noisy... in special Led and zeners..also that you cannot use batteries because they are noisy too.

Well...i cannot say they are lumnatic..but i really see them green and using some kind of helmet.

regards,

Carlos