Help ID'ing Green Russian Big Muff Cap

[electrosonic]

I have my friends 90's era Russian BMP apart and it seems to follow the general guitar gadgets schematic (for the Green Russian version) with the exception of the caps which parallel the 470K resistor from collector to base on the first 3 stages. (C2, C5, C8 on the schematic).



Any idea what the value of this might be? (Don't really want to take the cap out of circuit to measure it)

Thanks,
Andrew.

If anyone has one of these, I ID'd the components, the labeling is taken from the Beavis Audio BMP schematic.http://www.beavisaudio.com/schematics/Electro-Harmonix-Big-Muff-Pi-Schematic.htm

[Magnus]

Hello,
maybe this is what you are searching for 
http://www.electronics2000.co.uk/calc/capacitor-code-calculator.php

So if you enter 750 you have 75pF...


Greetings
Magnus

[electrosonic]

The schematics I have seen call for a 470K || 470pF from collector to base,  a 470K || 75pF would really shift the low pass filter higher on the gain stages. I guess I will measure it and report back.

Andrew.

Edit - my 300th post!

[Arcane Analog]

If the caps are in parallel with the 470K then they are 470pf caps on the Green and Black Russians (as welll as a few others) and usually are labeled C10, C11 and C12.

[electrosonic]

The are not obviously labelled that value. I took one out of circuit and it measured 509pF, so 490pF sounds right.

Andrew.

[Arcane Analog]

With a 5% or 10% tolerence they are probably 470pf as every schematic on the internet reads.

[AnalogPackrat]

The first line on the cap reads "H510" which is probably a tolerance code and 510pF.  The second line is probably the voltage rating--750V for ceramics is reasonable.

[Arcane Analog]

Mine has H51C not H510 - as do all the ones i have seen.

[John Lyons]

Could be 750p but typically 560p or 470p.

[Arcane Analog]

Have you measured a 560pf or a 750pf cap in a Green before, John?

[John Lyons]

Have you measured a 560pf or a 750pf cap in a Green before, John?
No, they usually are 470P. I was just saying that 470p to 560P are the typical spread.
One of the ram's head versions used 680 but that's the highest I've seen.

[Arcane Analog]

Gotcha. I was curious as to what the 470K feedback resistors were with the 560/750 feedback caps in a Green. If I recall the 680pf in the Ram's head was paired with a 470K.