Build Your Own Clone Message Board

So this is my 3rd build but 1st non functional one. It powers on and gets signal in bypass and switched on, but there is no effect and all the knobs and the switch do nothing.

I did not receive the 3rd 15K resistor in my kit so I put a 22k (closest radio shack had) in the last 15k slot, but I would not think that would make it totally non functional?

I screwed up a lot on this one and had to replace several components along the way including all the tall caps as I didnt know what the bag of short ones were for at the time, so I wasnt totally surprised when it wouldnt work. Take a look and tell me what you think.

here's the rest

The Vibrato is a fairly complex build and your pictures are too small to be of much use.

You might check using a multimeter that all the chips are getting their supply voltage. And while you are at it check the chips are in the right sockets and the right way around.

Using an audio probe to trace the signal through the circuit to see where it gets lost would seem like the next step.

Isn't the long inline chip supposed to be on the bottom of the board or was that just for the original version?

Yes the BA6110 VCA in-line chip is supposed to be mounted under the board - the PCB silkscreen even labels it that way. However since it is an in-line chip mounting it on top of the board does not change the order in which the pins connect to the rest of the circuit so I can't see it causing a problem.

I can't see why that instruction is given - normally it would be because the chip would otherwise occupy space that is needed for something else. But I cannot see anything that takes up that space.

I suppose it is still possible that top mounting that chip cause some sort of problem.

The only explanation I can see is that the Version 1 PCB had a tracking error that was rectified in the instructions by two track cuts and a wire link fitted across the top of the board. Changing the location of that chip to under the PCB seems to make adding that link a little easier and presumably was the solution selected to fix the first run of PCBs.

The later PCBs it seems do not have the error and do not require track cuts or the link, but the instructions were left to install the chip on the underside, even though there was no longer a reason to do so.

Yep, you're right. I thought about it after posting that the same pins go through the same pads regardless of which side it is mounted on. Doesn't seem like it would make any difference.