Slow Loris

[Axe_34]

Hi everyone.

I'm having an issue with my Slow Loris build.

It works in bypass but when engaged it makes some weird noises (I'm uploading a video as I type and will post in about 15 minutes or so).

The controls seem to be doing what they should be -- when I turn up the volume, the noise gets louder, when I turn up the gain it gets rattier (plus you can see the LEDs clipping) and when I turn the filter, the noise gets shriller or fatter, depending on which way I turn it.

Here's a picture of the voltages I'm getting. As you can see, I'm getting nothing on the right side of the IC.

As for the transistor, when I probe the middle leg, the voltage starts at around 2 and continues to climb as long as the probe is attached to it.

Here are some photos.









Any ideas? If not, I may just desolder the whole thing and start from scratch.

Thanks in advance for any help. 

[Axe_34]

And here's the video...

[greysun]

I know this isn't helpful at all, but those are some pretty cool noises - LOL.

One thing I'm noticing is that you don't have a ground at your 9v - not sure if that has something to do with it or not, but you may also have a bad/wrong type IC. I'd also triple check your parts list.

I had a problem with mine at the transistor and the cap that feeds it, but that doesn't seem to be your issue here.

have you flipped the switch into other positions to see if sound comes through okay there?

(keep in mind, I'm a noob - but a noob with circuit bending friends that show me things that make these noises all the time. Usually they get these noises by getting bad parts or feeding bad parts into good schematics, hehe).

[angrykoko]

Check for solder bridges where I have circled in the attached, it's hard to tell in the picture, you may be ok but they just looked odd.

[Axe_34]

Thanks guys. I appreciate the suggestions.

I know some guys at Harmony Central Effects who would probably pay good money for my noise generator. 

I have grounded it at the 9v since that video was taken -- no change.

I reflowed all the joints and desoldered the suspected bridge points -- no change.

I'm suspecting the IC. I've got another on order from Pedal Parts Plus. Hopefully that will sort it out.

[mgwhit]

If you've got 0V on IC1:pin3 and Q1:gate, you may have a problem in the VB section of your power supply.  Your C11 appears to be correctly oriented, but I did notice that you used 10K resistors for the voltage divider at R10 and R11.  Technically, that should create the same reference voltage as 100K's, but the difference in current might be affecting the op amp.  Can you take a voltage reading on the positive lead of C11?

You may be right about the op-amp being bad, but you could also have a bad JFET.  If you've got another 2n5457, I'd try that first.

[Axe_34]

If you've got 0V on IC1:pin3 and Q1:gate, you may have a problem in the VB section of your power supply.  Your C11 appears to be correctly oriented, but I did notice that you used 10K resistors for the voltage divider at R10 and R11.  Technically, that should create the same reference voltage as 100K's, but the difference in current might be affecting the op amp.  Can you take a voltage reading on the positive lead of C11?

You may be right about the op-amp being bad, but you could also have a bad JFET.  If you've got another 2n5457, I'd try that first.

Wow -- great catch on the resistors! Swapped them out and I've got correct voltages everywhere but still the same weird sounds. They get more pronounced when I chopstick the JFET. I think he might be the culprit.