chunk chunk confusion, help please!!!

[Pedey]

Hello all, help please.  I built a chunk chunk and here is my issue:  bypass works, when pedal is turned on it will not pass guitar signal.  Here is the kicker... it will pass signal from a generator, music, anything I try except signal from the guitar.  I have tried multiple guitars, cables to no avail,  just get hiss.  the controls all function, as far as increasing the hiss etc.  I tried connecting the input to the board directly to the input jack with same results.  Tried a different input jack, I am at a lost as to why it will amplify any signal except guitar signal.

[GermanCdn]

Suggest you post a pic of the wiring so we can take a look at it.

[Pedey]

Here is a pic, not pretty but I have been digging through it all night.  Wired with the standard wiring from mad beans sight.  Only chages are battery - moved to ground and one ground removed at the moment.  Made no difference either way.

[jimilee]

No pic! Also, Did you bias it correctly?

[gtr2]

Voltages?


Josh

[Pedey]

sorry pic is up now, yes all J201's are biased near 4.5v, range from 4.2 to 4.4v, have not dialed them in perfectly.

[Pedey]

which voltages would you like to know?

[jimilee]

Does the LED Light up? Is your bypass and engaged volume the same from an audio generator? or is it considerably more quiet? What your getting from a genrator is an amplified signal as oppsed to your guitar which is not already amplified.

[Pedey]

LED lights up, the engaged volume adjusts with the volume pot, the circuit is amplifying the signal.  I did not check where unity gain occurs.  I also set the generator at the lowest setting that I could still hear in the amp to try to get the weakest signal possible.  It also is not frequency specific as it would pass 500 Hz to 10khz.  It almost acts like an impedance mismatch,  but I would expect to hear some signal,  even if very faint. I could not get a good signal at the IN wire on the board with the scope with the guitar but could with the generator.  Also tried a guitar with active pickups to get a .more amplified signal, and had the same results.

[jimilee]

So, I'm curious. Is the input jack wired correctly? Are your noise generators using a stereo cable vs the mono of your guitar. This is really odd.

[Pedey]

Jack should be wired correctly. Generator is stereo split into two mono.  I will scope the guitar signal and the generator tonight to see how much difference in signal strength there is.  Started with a stereo jack as per the standard wiring to have to on/off power when cable is plugged in, switched last night to a mono jack.  Have ohm out jacks and they are correct as far as tip and sleeve.  I cannot figure out why it will not do the guitar signal, but will from the generator and even my iPod playing music.

[Pedey]

Mystery solved:). Semi cold solder joint on the IN wire on the board, generator must have been strong enough to pass.  I guess for the guitar it was like a cap between the wire and the board and not enough juice to pass.   THANK YOU for all the help, ends up me being dumb:)

[jimilee]

Fantastic! Glad you got it going. What do you think?

[Pedey]

Just got it dialed in bias wise, it defintly has gain   Will have to play with it some more to see what I can squeeze out of it, but so far it sounds pretty good.  I will post my thoughts again when I have more time with it.  Hoping that I can get something close to my Ampeg 140c head, one of the great metal distortion heads IMHO, be nice not to have to haul it around all the time.  That and I am a self diagnosed pedal junkie   Thanks again for your help, great to have other people that will help out.

[jimilee]

Glad to help out, everyone here is really friendly and happy to help out. I like the chunk chunk, I have built 2 of them and aim to build a 3rd for myself this time. It will flat crank out some gain like a dual rectifier that's for sure!