Green Russian Muff troubleshooting

[vicfiveleven]

Hello everyone, this is a vero problem and hopefully a lot of you have encountered it.  This is the 2nd time I've built this pedal and the first one had no problems. This is the layout I followed: http://tagboardeffects.blogspot.com/2012/06/ehx-green-russian-big-muff.html?m=1

Problem is that after a day of not playing it, it works fine. Then after a minute or two it starts.  It's a scratchy sound like when you have a loose jack on your guitar.  The sound can be heard only when turned on.

Is this a grounding issue?  This happened to a Ts9 clone I made but the sound did not go back for some reason.  I noticed that the sound will be there when I box it, but was not there before when I tested it before boxing.  This has only happened twice to me and this time the sound doesn't go away.  Any ideas?

edit: changed the title to Green Russian Muff Troubleshooting. Sorry. Omg Mods I am so sorry, I am actually talking about this green russian vero I am fixing. And at the same time I am also troubleshooting a BE-OD vero.. But this problem is about the green russian not the BeOD. My apologies. Sorry to Jack for the confusion.

[vicfiveleven]

Okay, so update: I took the vero off and found no trace of any cold solder joint or accidental bridge and was grounded correctly.  Put them back in and I was about to check the power jack if it was faulty when I noticed that the ground and 9v wires touched, BUT only on the insulated part.  I separated them both and... I don't know why the heck but the scratching/buzzing stopped!  I sticked them back and buzz was there again... Probably cold solder joint on either/both the ground and 9v lugs? Reflowed the two lugs and sticked the wires and buzz again.. So I just shrink tubed and separated them both. Could it be a faulty dc power jack? Faulty wire insulation? lol  But it works perfectly now.  *sigh*.. Just like my dev problems. Code doesn't run: Why won't it run?!  Code runs: Why did it run?!

[JackSkellington]

I'd like to built it, too.
Did you got any noise or oscillation problem? Someone did, unfortunately.

[vicfiveleven]

Jack, no noise at all except for noise when you crank the sustain knob. I'm curious because I don't have that much experience yet and I've read it a lot of times, but what is oscillation in dirt pedals? What does it sound like? Maybe I've encountered it but didn't know.

But another update: I played it earlier for about 5-10 mins and unfortunately the scratching came back but not as loud and as much as before. Kept playing it and then signal suddenly went very low. You'd have to crank both pedal and amp volume to hear it sputtering like a pedal not properly biased or something. Also, I found out that my tone pot is not exactly 100K. More like 59K. Never buying pots from that local store again. Going to probe this today. Hopefully I can get to who ever is giving me this buttache.

[JackSkellington]

I can't help you about your pedal, except, how do you know that the tone pot is 59k? Did you measured it while it's mounted in the circuit? In this case, probably it could be influenced by other resistors and capacitor.

The oscillation is about an high pitch whine/squeal that engages when the gain is high. Sometime it can goes away taming some high end. But I guess sometime this change a bit the sound of the pedal.

[vicfiveleven]

I just noticed I called the topic Be-OD. lol nope I must've been half asleep. this is for a green russian muff. What the hell was I thinking?! It's a muff. Green russian. Sorry. lol.

Jack: I took it off. it measured 59-62k kept going up and down even when not turned. nope this doesn't sound like oscillation. But yeah, I've also built that BE-OD. And no noise too.

I probed and i first thought it was the pair of diodes at Q3. It went silent for a while then came back again. So after probing, I caught it at Q1. Very faint scratching at the background. At Q1 base, it is quite but when it goes thru 470p cap and 470k resistor it is there. just really faint. gets amplified I guess after it reaches Q2. I've changed Q1 with another 5089 and even a bc550c but it's still there. Scored between strips and still there.