I have a germanium Analogman Sun Face that I'm having some issues with picking up radio noise. Analogman suggested adding a 100pF capacitor on "the input of the board or the input jack to ground". He said "We often put a small cap right on the switch from the TO BOARD wire connection (gets connected to input jack when ON) to the GROUND connection.".
Analogman is having power and Internet issues at the moment and is taking a long time to respond so I thought I'd ask here.
Here's a pic of my pedal guts:
(https://i.imgur.com/Hhp68p0.jpg)
For GROUND I can use the input lug, but I'm not 100% certain what he means by "the input of the board or the input jack". Am I correct thinking I could wire the capacitor between the input jack ground lug and the pad on the circuitboard labelled "IN"? Or is he saying to go from the ground lug to the hot lug of the 9v power jack?
Although its should be more effective to place that cap between Q1 Base & Emitter Ground, you can place it between board IN pad and any adjacent ground point..
Quote from: antonis on August 10, 2020, 09:44:25 AM
Although its should be more effective to place that cap between Q1 Base & Emitter Ground, you can place it between board IN pad and any adjacent ground point..
I know ZERO about how/why he recommended what he did, vs your suggestion but why would what you posted be "more effective"? And you're saying to just put the cap between those two legs of Q1 (Base & Emitter Ground)?
Yes.. :icon_wink:
The closer the cap to the interference amplification device the more effective the elimination (RF shunt to GND)..
You could obtain the above by doing as suggested by Analog man (which suggestion is easily obtainable by simply removing pedal's back plate..) but there should still be a signal path AFTER bypass cap (till the Base of Q1) prone to interference reception.. :icon_wink:
Can you experiment with the two suggestions by not even soldering and just taking the cap and touching said points with the leads to see if it works? Correct me if this is not a viable test.
Quote from: Phend on August 10, 2020, 01:56:45 PM
Can you experiment with the two suggestions by not even soldering and just taking the cap and touching said points with the leads to see if it works? Correct me if this is not a viable test.
I could do it but I need to be 100% sure which legs are which on this Q1 before I try...
Although you can't do any harm, Emitter is the leg directly grounded and Base is the leg connected to 1μF negative plate and 100k feedback resistor..
Quote from: Phend on August 10, 2020, 01:56:45 PM
Can you experiment with the two suggestions by not even soldering and just taking the cap and touching said points with the leads to see if it works? Correct me if this is not a viable test.
This is a very viable test
Just be careful not to short anything with the cap legs...!
Alligator clips.
Quote from: idy on August 10, 2020, 10:53:52 PM
Alligator clips.
A bit more unthreaded than depicted into my avatar .. :icon_wink:
Quote from: Grendel2000 on August 10, 2020, 08:34:47 AM
He said "We often put a small cap right on the switch from the TO BOARD wire connection (gets connected to input jack when ON) to the GROUND connection."
That would be between the blue and black wires on the footswitch, fwiw.