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Well, on my third build I have a problem. When powered up and turn it on the LED comes on. With the Attack all the way CW and the Sens all the way CW I can dial the trim pot and get somewhat of a swell effect. The problem is as the note sustains it start to warble and cut in and out. When picking 1/8, 1/4 notes it sounds like it is trying to work but as the note linger is starts to break up. Also when I dial the Sens back CCW the output signal gets weaker. I will post some photos.
Thanks,
-Steve

Here are some pictures

The 390 ohm resistor at R17 is switched with the 390K resistor at R21. Very common mistake. Switch those around and see where you're at....

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“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Ok, I switched them around and it seemed to correct the problem with the Sens POT having a weak signal when dialed CCW. It seems with the Sens all the way CCW I get the best swell. When I turn it past 9 o'clock I lose the swell. (which may be normal) I am still having a problem with the signal warbling distorting, cutting in and out and or completely dissipating during sustain. This happens with the Sens fully CCW to 9 O'clock. The attack POT can be turned to any position if the Sens is fully CCW - 9 o'clock, and the sustain is still not right. With the sens POT is past 9 o'clock to fully CW the sustain is fine, but there is no effect of the slow gear.
-Steve

Any Ideas?

Should I post a link to a YouTube video so you can have a better idea of whats going on?

Thanks,
-Steve

Try this: set Sens to about nine o'clock, and attack all the way CW; now adjust the trim pot for best swell. Remember to turn your guitar volume all the way up, too.

Like all envelope follower effects, the LS requires some technique - you must mute the previous note before you pick the next one.

Hope some of this helps...

Some bock ground on myself. I have been playing for and modifying guitars for 35+years. Building guitars for 5 years. I would post a link to by guitar build site but I am not sure if that is allowed on this forum.
I have a Boss Slow Gear pedal in my VG-99 system. I am familiar with how they work.

It's not that the slow gear effect is not working. IT IS THAT THE NOTE WON'T SUSTAIN. The problem is as the note sustains it start to warble and then cut out. The note will sound for about .5-1 seconds then it starts to sound phazy and then it cuts off. If I play short note that don't need to sustain for more than .5-1 sec. It sound like it is working. It just won't sustain the note.


Should I post a link to a video showing what is going on with this pedal.

Did you see my note about adjusting the trim pot? If you are confident that it is set correctly, then we need to look further into your build...

I will play around with it a little more and if I still have the sustain problem I will make a video and post a YT link to it. So you can hear what i am hearing.
Thanks,

The way this thing works is that there are two very simple unity gain buffers - an input buffer and an output buffer. Between them is a FET which shunts the signal to ground under control of a voltage derived from the envelope of the input signal.

With the Sensitivity pot turned all the way down the signal should pass through these two buffers virtually unaffected. Is that what happens ?

A side chain circuit produces the swell effect.

As you turn the Sensitivity up a voltage is generated in the side chain circuit that should follow the envelope of the input note. At the start of the note this voltage is at its maximum and then as the note decays this voltage falls to match it. The voltage is used to turn the FET T6 on, shunting the signal to ground and muting the sound at the start of the note. As the note decays the FET drain to source resistance gradually rises and the signal swells.

So it is difficult to see how you can be having problems with the decay of the note because that is where the active part of the circuit has its least effect. It suggests there may be a bias problem somewhere for the two emitter followers built around T1 and T2. I would expect the emitters of those two to be at around +4V.

Is the 0.68 tantalum cap in the right way round?

If you mean fully CCW, NO.

I get the best slow gear effect at full CCW to 8 o'clock. But the note decays rapidly. It's swells up niecly but then it just decays away. Once I reach 9 o'clock the effect of the slow gear is gone but the sustain problem is gone as well.

The Boss Slow gear I have in my VG-99 system works the way you are describing it Tark. With the snes down NO EFFECT. I have something ass backwards it seems.

http://www.youtube.com/watch?v=akqcIXCA ... e=youtu.be

Here is a link to a video I made. Let me know what your thought after viewing.
Thanks again!

This is a link to an audio file of me using the Boss Slow Gear. Sens at 3 o'clock and release/attack at 3'oclock

https://dl.dropbox.com/u/55810304/SG.wav

Hopefully we can figure out how to get this Lazy sprocket sounding like this.

Are the pots connected to their correct PCB locations? Can't confirm their placement in any of the pix.

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"It’s your soldering."

yes, they are good. I just double checked to make sure I had not switch the A100K with the B25K. But I have the B25K for attack and A100k for the sens and they are hook ed up correctly.

Your pots are not behaving as they should. Please post pics of the pots with the wires spread out so that we can clearly see where each wire is connected.

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*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

I hope this helps.

Well those pots look as though they are wired exactly per instructions to me.

I'm starting to suspect the IC. I see that it is soldered in place, and there is no easy way to get it out w/out damage. However, it may be worth the effort to remove it and put in a socket, then a new chip.

Why didn't this kit come with a socket? My wife bought me 4 kits for Christmas and this was the only kit that did not come with a socket for the IC.
I can get it out with a little patience. Is this something BYOC covers?
I would like a second opinion on this before I take the time to remove this.
Thanks,
-Steve

A faulty IC actually doesn't seem that likely, at least not to me.

The function of the IC is to amplify the input signal to the volume control side chain. It is set up to provide a huge boost of 2565 times the input. This means that even when Sensitivity control is at minimum, due to the 470 ohm limit resistor at the CCW end of the control, even 100mV pk to pk out of the guitar will produce 1.28v at the output of the op-amp. The Sensitivity does not need to be turned up by much to cause a square wave at the output of the op-amp that is hard limiting against its supply rail constraints.

It seems clear from the OPs description that the op-amp is providing gain since at least something like the slow gear effect is heard with the Sensitivity pot at the low end of its range. Op-amps are more likely to fail such that they provide little to no gain rather than some gain. It would be worth checking the voltage on the output pin of the op-amp, it should be sitting at around 4.5V.

This signal from the op-amp drives the full wave rectifier of Q3, Q4 and Q5. With Q4 and Q5 turned on they drain the voltage on C4 via R28. In turn this controls the FET which modulates the signal volume. I'll admit I am have some trouble working out exactly how it does that, I can't seem to get the biasing right.

I said in a previous post that I thought that with no signal at the input the FET in this circuit was turned OFF, allowing a signal path through the pedal and that if you turned the Sensitivity down to minimum the pedal should just pass signal without any effect. Now apart from the fact that the Sensitivity control does not completely shut off the signal to the side chain because of the limit resistor R10, I now think I was wrong about how the pedal works.

As far as I can tell, without any signal present the FET is normally turned ON, so it is shunting the signal path between the input and output buffers to ground. When an input signal is applied to the pedal the cap C9 is drained at a rate determined by the setting of the Attack pot, gradually turning the FET off, gradually allowing more signal to pass between the buffers and resulting in a note swell.

Once the input note decays below a certain point the input level is not enough to hold the FET off and it turns on, muting the signal. Your demo appears to sound at least something like this although it is possible that the FET is turning on faster than it should resulting in a rather rapid mute, but maybe this is just your note damping? For a natural decay to happen after the swell the output of the envelope follower must gradually allow the voltage on the cap C9 to rise so that the change in drain to source resistance of the FET tracks the decay.

For the mute to happen the voltage on the cap C9 has to rise and that is determined by R14, VR2 and the offset of T4 and T5 set by the trimmer VR2. If C9 was leaky or inserted reversed that might cause the problem. It might be worth replacing it, tantalums are bit more delicate than ordinary electrolytics. I'd check that the trimmer varies between 2.3V and 0V on the wiper (assuming that the zener D4 is stabilising at 5.6V) and I suppose VR2 might be faulty. It may be a question of getting the trimmer set just right.