Build Your Own Clone Message Board

I just assembled the BYOC Analog Vibrato. Before turning it on I plugged my guitar into it, I heard my guitar in the amp, so bypass works. I turn it on, the LED comes on, but now it just squeals noisily (high pitch). The signal from my guitar does not make it to the amp, turning any of the knobs or flipping the ramp switch has no effect. However, adjusting the trimpot marked 474 alters the pitch of the squeal, and adjusting the trimpot marked 204 alters the volume of the squeal. When I adjust the 204 trimpot to half, the squeal becomes INSANELY loud, my amp volume was almost as low as it could have been and still my left ear is numb right now. (before I managed to turn off the amp it also started making a fast wuwuwuwuwwu sound) At the bottom or top of the 202 trimpot sweep, the squeal becomes as quiet as it can go, which is a moderate volume level. I don't understand what the problem is. I double checked all of the resistor values. The transistors and ICs are all facing the right direction. All of the positive leads are in the square holes and so are the black ends of the diodes. And the rest are too simple to mess up, like using the right numbered capacitor, or wiring lug 1 to the hole marked '1'. Do I have a cold joint somewhere? Did I burnout an integrated circuit while I was soldering?(I soldered them while they were in their sockets and it didn't occur to me to put them in later) Does anyone know what could cause this sort of thing to happen? Is the solution as simple as resoldering every single connection on the board with higher heat and my fingers crossed?

Also, just before anyone mentions it, in the picture of the bottom of the circuit board, there appears to be an unsoldered joint to the left of the top potentiometer's middle lug, but I double checked and it's soldered. I resoldered it anyway just to see if it would do anything, but the same problem persists.

You need to trim some of your wiring. Go through everything and make sure nothing is touching something it shouldn't be touching.

Yes, in many cases, it really is as simple as going through and reflowing your solder joints.

The 202 trimpot should be set to the middle.

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*patience is a virtue*

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

Okay, so I trimmed the wiring and reflowed all solder joints. There is one definite change, and one new phenomenon which I haven't noticed before. Firstly, when I sweep the 202 trimpot, it doesn't become ridiculously loud anymore. Secondly, while I was adjusting the trimpot with a metal tool, I noticed that every time I touched it with the tool in my left hand, the enclosure would send a pulse of electricity into my right hand. I don't really know what this means but it seems that this is going to require some skill at problem solving considering every joint has been reflowed and every protruding wire clipped off. Hmm, my hand is starting to hurt while typing this, I better start using a different tool.

The chassis/enclosure is ground (or should be). The center wiper of the 202 pot, should have a positive voltage of up to 9VDC. So if you have one hand on ground, and you're manipulating the trim pot with a metal implement, then yes, you're going to have some current passing through you. However, it's going to be less than 9 volts and probably less than 1 amp. So unless you're using your tongue to turn this metal implement, the fact that you can actually feel a shock is a little concerning.

What are you using for a power supply?

_________________
*patience is a virtue*

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

+1 on power supply. Try a different one. AMHIK.

_________________
Twisting and tinning is for chumps.

The power supply I was using is a simple 9 volt, center negative power adapter. I unplugged it and put a 9 volt battery into the pedal. The noise is gone, and the guitar's signal makes it to the amp while the pedal is on. But now, the problem is that I only hear vibrato while my tool is in the 474 trimpot. When I take the metal tool out, the vibrato quickly fades and doesn't come back, until I touch it again with my tool. I think this means that something between that point, and the end of the circuit, is disconnected; the 474 trimpot must not be grounded. (in any 474 trimpot position, the signal is saturated to the point of distortion while there is vibrato, the 203 trimpot controls volume) (I notice there have been some typos earlier, to clarify, the second trimpot is 203, two-zero-three)

You shouldn't use just any old 9v center negative supply. It needs to be regulated and filtered. You might get away with it on some pedals, but you will eventually find some that won't tolerate it.

The 202 trimpot is the bias voltage. You want to set that so that the signal is the loudest and cleanest. This should be pretty much in the middle of its rotation or close to it. Set that and don't adjust it anymore.

There are 3 parts that make up this circuit as a whole. The first is the signal path, which includes the BBD chip (3207), which is working fine. The second is the LFO (low frequency oscillator) which makes the effect "move", which is working. The third is the clock driver. This translates the wave form from the LFO into at fluctuating delay time that make the BBD chip bend the pitch up and down. Since the effect intermittently works when you stick your metal poking stick into the delay time timer (474), we can assume that the actual click driver chip (3102) is working just fine. So the problem must be in the clock driver's support components. If you look at the schematic, you can see this section of circuit just off of R43.

My guess is that you still have a cold solder joint somewhere in there. Probably at the trimpot.

_________________
*patience is a virtue*

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