Purpose of cap in tube voltage regulator circuit - who knows?

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lassoharp

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Does anyone know the purpose of this cap ?  And, is it critical?

The cap is a .01, connected from pin 8 of the 6SJ7  to ground in the voltage reg circuit.

Note** the cap is NOT shown on the 39B schematic.  It is present on the earlier 38 circuit but was apparently omitted from the design in later versions.  I had to post the 39B circuit since no 38 presently exists online.


Thanks,

Alan
 

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Add to that - where is most likely oscillation to occur?

I found out yesterday that the small cap was apparently not a stock component of the original design. It was not shown in either of the two SA-38 schematics (1st & 2nd revision) I viewed, nor was it listed in the parts section.

Emrr suggested that it may have been added as a field mod to cure problems related to the small lamp.
 
I have seen the neon bulb turn into an oscillator as it ages on numerous occasions.  They may have been chasing that problem. 
 

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