Pedal won't work without buffer

[Bernardduur]

OK, here's the weird part:

I've build a fOXX Tone Machine (2nd time) and it sounds exactly like my other...... but it has one disadvantage: it does not work without a buffered pedal in front of it. What can be causing this?

[R.G.]

Well, it's screamingly obvious that something is different about the input stage, right? I would measure all the dc voltages on at least the first set of transistors as suggested in "What to do when it doesn't work".

It is possible that there are bad solder joints, cracked traces, wrong components, incorrect pinouts, broken resistors, and all of the other maladies that happen to us in starting up a new pedal. Beyond that, there's not much that can be deduced from the info you have. Anything else would be just a blind guess.

[Bernardduur]

Sorry, I meant to say that I already checked that.... the circuit is OK, no problems there. I thought maybe it is something that happens more often and I don't know about.

Edit: I found the origin...... In some weird case my battery only worked with a buffered pedal in front. I changed the battery and now it works fine.

Weird?

[hairyandy]

Sorry, I meant to say that I already checked that.... the circuit is OK, no problems there. I thought maybe it is something that happens more often and I don't know about.

Edit: I found the origin...... In some weird case my battery only worked with a buffered pedal in front. I changed the battery and now it works fine.

Weird?

You know that is weird.  I just had a weird battery experience with my recent FTM build as well that I posted about a few days ago.  It manifested itself as a drop in volume with the octave switched in and I when I took the octave switch LED out of the loop the volume came back.  At that point I figured that the combination of two LEDs and the full circuit working was pulling too much current for the 9v.  It worked fine though when plugged into my Pedal Power 2.  Maybe though the FTM is just a current hog!?!  I raised the resistance on both LEDs (which were too bright anyway but I had been too lazy to fix) which seemed to fix it and I normally use it plugged in anyway.  Just out of curiosity Bernarddur, measure the battery that didn't work (if you didn't toss it already) and see where it is.  I'd be curious to know if this circuit in general is just really needy...

Is it possible that the buffer was changing the impedance that the FTM was seeing and this caused it to be more efficient in its current use?  That would be interesting...

[Bernardduur]

It get's even weirder.

The battery was 9. (something) volts. Good full. When I plugged it in the AC-power (don't have a 9V PSU on my bench) the voltage dropped to 0.83 volts with my guitar plugged in; the LED would not burn and in effect mode all I hear is static. Then I plugged in my guitar through my Pearl AD-08 and Pearl PH-03 into the unit (normal signal flow) and the voltage raise to 9. (something) volts, the LED burns and I have a good signal that is the same as my other build fOXX........

With a new battery or with the PSU on my pedalboard I have no issues.

[hairyandy]

Maybe it's aliens?  I'm gonna try building a mound of mashed potatoes over my FTM and see if it helps any...

[Bernardduur]

LOL

Then try to turn it on

[Processaurus]

Check the battery wiring?  It could be something is wired weird, and when you had its so the battery voltage was going down, it was shorting out the battery?