Print Page - sunking high pitch noise

Title: sunking high pitch noise
Post by: Marcelo on February 22, 2011, 04:47:32 AM

hi!
just finished a few projects today (rangemaster, snarkdoodle, krankosaurus & sunking). all of them sound great. but i have a problem with the sunking. although everything works fine and the sound is pretty good, there is a low but noticeable high pitch sound that it is pretty much constant, no matter the knobs position (although the frequency varies a little while fuzzing wiht hte knobs). reading a couple of articles I think it may be a 'leaky' capacitor.
However, I have no idea how to test the capacitors for leaks.
anyone had this problem before? any advise?
thank you guys!
m

Title: Re: sunking high pitch noise
Post by: jkokura on February 22, 2011, 05:28:11 AM

What kind of charge pump did you use? You need to use one that has a "scpa" at the end. That should fix your problem.

Jacob

Title: Re: sunking high pitch noise
Post by: B_of_H on February 22, 2011, 03:06:36 PM

replace the charge pump and opamps, try a different power source.

I had this happen a few times.

1 - bad charge pump
2 - bad opamp (put a 2272 in there forgetting it was a 10v max)

Title: Re: sunking high pitch noise
Post by: Marcelo on February 23, 2011, 05:01:05 AM

Thank you guys for the tip. I'll try to swaping the IC's this weekend (aaaaaaajjjjjjj too much work during the week, no time for anything). I'll let you know the outcome in case someone else has the same issue.
m

Title: Re: sunking high pitch noise
Post by: madbean on February 23, 2011, 11:52:54 AM

Quote from: B_of_H on February 22, 2011, 03:06:36 PM

2 - bad opamp (put a 2272 in there forgetting it was a 10v max)

Huh...really? Interesting. I have had no issues using that one in the SK.

Title: Re: sunking high pitch noise
Post by: oldhousescott on February 23, 2011, 02:17:21 PM

According to the TI spec sheet, it's +/- 8vdc max (16vdc rail-to-rail). Looks like it'd be fine for IC1 but not IC2.

Title: Re: sunking high pitch noise
Post by: B_of_H on February 23, 2011, 02:53:48 PM

I was just going off what info was on an old byoc od kit. It said iirc that the tl2272 could not handle 18v operation and i think i just pulled 10v max out of my rear end fwiw. :)

I do know that the chip was fried and causing the noise i got though.

Title: Re: sunking high pitch noise
Post by: madbean on February 23, 2011, 03:56:49 PM

Well....I guess mine must be special then. Or, gonna die soon.

Title: Re: sunking high pitch noise
Post by: Marcelo on February 26, 2011, 10:51:39 PM

Very impressive, you guys are good!
changed IC3 (the original was per spec, so something was probably wrong with it) and the problem went away. nice pedal!
Thank you guys for your help! you saved me from a very long and painful fishing expedition!
m

Title: Re: sunking high pitch noise
Post by: B_of_H on February 27, 2011, 01:53:40 AM

Quote from: Marcelo on February 26, 2011, 10:51:39 PM
Very impressive, you guys are good!
changed IC3 (the original was per spec, so something was probably wrong with it) and the problem went away. nice pedal!
Thank you guys for your help! you saved me from a very long and painful fishing expedition!
m

glad you got it fixed.

madbeanpedals::forum

Projects => Tech Help - Projects Page => Topic started by: Marcelo on February 22, 2011, 04:47:32 AM