Echo Base Modulation help?

[deadelms]

I built a veroboard layout version of the Echo Base and it works perfectly except that there doesn't seem to be any modulation whatsoever (neither of the mod pots make any audible change in sound). I've checked the wiring dozens of times, looked at the schematics, everything seems to check out. I measured the voltages at the TL072 in the LFO section, and it checks out perfectly, except that pin 8 reads 8.9V for me, while the voltage specs on page 4 of the Echo Base thread say it should only be 8V. I am using a 9.6V power supply though, so I assume that would give me that slightly higher reading (plus, 0.8v can't really matter, right?)?

Where do I go from here? I assume the depth pot and its wiring are what I should be focusing on. Any ideas?

[slacker]

First thing is to check that the LFO is actually working. You've said the voltages look Ok so are you getting changing voltages on pins 1 and 7 of the opamp? If you are then it's probably working, if not then you've got a problem with the LFO, probably a wrongly placed or incorrect value resistor or a short somewhere.

If the LFO seems to be working then put the Mod Depth pot on maximum and use your meter to trace the signal. You should be able to see the changing voltage on both sides of the 240k resistor and on the wiper and clockwise lug of the mod depth pot and both side of the 200R resistor. Hopefully doing that will tell you where the signal disappears and you can fix it.
If you get signal all the way to the base of the PNP transistor but you still don't get any modulation try replacing it or make sure there's no shorts round there.

Hope this helps