Analogman - King of Tone Mystery.....

Lithium_Grim · Post by **Lithium_Grim** » 30 May 2016, 17:16

Does anyone here know what the C12 optional capacitor is for in the rev 4 KoT? There is no mention of it in any schematic I can find (yes there is a C12 in all schematics, but the parts numbering of the schematics do not match up with the PCB).
There are 14 SMF capacitors in the picture which is the exact amount as in the schematic... Who can solve this mystery?

Picture attached!

karul · Post by **karul** » 30 May 2016, 17:49

Are you sure calling the "optional" capacitor C12? As far as I can see, component markings are under the boxes, so you're looking at the C4. Am I right ?

Ice-9 · Post by **Ice-9** » 30 May 2016, 18:07

I would have to take a guess at the marking C12 being the correct one as lining up the other components and markings it make more sense that it is C12 and not C4.
Anyhow the best way to find out what that cap is for would be to see where it connects to other components and try and fit it into a schematic, this way you will be able to work out what it does. It also may just be a left over never used component space on the pcb.

karul · Post by **karul** » 30 May 2016, 22:07

Ice-9 wrote:I would have to take a guess at the marking C12 being the correct one as lining up the other components and markings it make more sense that it is C12 and not C4.
Anyhow the best way to find out what that cap is for would be to see where it connects to other components and try and fit it into a schematic, this way you will be able to work out what it does. It also may just be a left over never used component space on the pcb.

I agree, C4 is probably the 100p in the opamp's neg. feedback loop.
C1, C2, C3 seem to be the same size, and corresponding to the schematic, I guess they are the same value, 10n. The one on top of the opamp should be 100n, and the bigger one 1u.

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ok, there's a photo in the Analogman - King of Tone, thread:
https://www.freestompboxes.org/viewtopic.php?f=56&t=6884

http://s94951552.onlinehome.us/kot.jpg

It's clear now, your "optional" is C12.

I've changed the parts numbering. It seems that C12 is treble bleed capacitor, probably in a pico range.

Lithium_Grim · Post by **Lithium_Grim** » 31 May 2016, 04:55

Great thank you for the info! Should it not be on the red channel gain though?

karul · Post by **karul** » 31 May 2016, 12:34

Lithium_Grim wrote:Great thank you for the info! Should it not be on the red channel gain though?

I'm not that familiar with this pedal. This optional capacitor is present only on one channel - and I don't know which one is the red one.

..........

Aha! Red one is left one, and this particular capacitor is present on the yellow channel. I can't see one on the red channel.