Help my first fuzz face please.....

[Jaden]

Hi folks, I am a newbie in pedal DIY and just finished building my first Ge FF.
But I've got a problem here and been wrest led with this for a few nights.... and just so exhausted. NEED YOUR HELP!!

My problem is..

1) Bypass : Works normally, without any particular noise, perfect true bypass I think

2) Pedal on : almost no output signal, these is a very very subtle signal, if I boost it with other pedals, I can here signal but very very tiny volume...

checked with DMM...

1) Almost 0V DC current in the entire circuit when the pedal is on, but LED works
2) -9V at the battery confirmed, and no issue with battery wire
3) measured all components and they are normal..

Here's the weird part: When I remove the battery cable from the circuit and measure with DMM, I get a good -9.000 V reading. but once I connect it to the circuit, the voltage drops to almost zero (-0.2XXX V) and there's no dc current flow throughout the entire circuit.

I double checked triple checked the schematic, but I couldn't find the errors...
Please help!!!!

My wiring


Pcb layout



Thanks,

[JustinFun]

Hard to tell from the photos, but are you sure your transistors are oriented correctly? Per the PCB they should be facing in opposite directions, but it looks like they might be facing the same way on the board.

The power issue is a real red flag though, suggests something is shorting out or you've got mixed up somewhere along the line with the positive ground wiring (which is really easy to do). Check continuity to all ground points from the positive terminal of the battery, and also check the same from the negative terminal (there should be none!)

[GibsonGM]

Hi Jaden, Welcome!

This sounds like a short...a wiring error that connects power and ground (or other things that get 'skipped over', hence the term 'short circuit').   

When you're checking out the circuit the way Justin suggests, be sure to measure the resistance between the "+" and "-" across the battery snap with no battery installed (but the input jack should be plugged in!).  (Continuity - beep setting - test will do about the same for us)  The resistance should be a big number (continuity shouldn't beep).  It's ok if the resistance beings lowish and swings up, as long as it DOES go up rather fast.  You'll still have to track down Where the short is, if this is the case, but it quickly proves there is one or not.

A short from power right to ground or a low resistance will result in big draw on the battery, hence that jump down in voltage when you connect it. It can't deliver the big current a short is trying to draw from it and thus 'sags'.

[JustinFun]

but LED works

This is the smoking gun for me. As shown, the LED shouldn't work! It's connected from positive ground at the ring of the input jack to positive ground from the board/sleeves, via a current limiting resistor (which shouldn't, as shown, have any current to limit?)

[duck_arse]

2 welcomes [cause antonis won't].

when I look at your jacks, I ask myself - why hasn't he wired the ground/sleeve lugs? how does he get a common connection without the sleeves?

you need to check your sleeves. you also need to be using mono jack plugs. please link us to those exact jack sockets that we might observe the pinouts.

[JustinFun]

edited for nonsense (see below)

[JustinFun]

The green leads are connected to sleeve lugs. He's used a stereo jack for the input to switch the power to the battery (which is why the + of the battery clip is connected to the ring lug, so it connects to gnd when a mono jack is plugged in).

[/quote]

No wait, I'm wrong and Duck_Arse is right, I think.

If those aren't sleeve lugs the green leads are connected to, then there wouldn't be power to the circuit (as ring wouldn't connect to sleeve) but there would still be power to the LED! Those are switching lugs maybe? So they'd do the opposite and connect the power when the circuit was UNplugged...? Connect the green leads to the lugs actually touching the sleeves at the top of the sockets and all should be good (though I suspect the LED will stop working).

[GibsonGM]

Could well be.  When I'm using a new kind of jack, esp. the enclosed kind and it's been a while....I plug a cable in and use my DMM to determine EXACTLY which lug is to what part of the cable.  You can use a stereo cable to figure ring from sleeve.  A mistake many of us know well 

[Jaden]

OMG, you guys are so kind and friendly! It's my first posting and this community looks amazing!! Thank you so much for all your advice. I will check it all one by one and update my results. Hopefully, I can resolve my issue!

[Jaden]

Hey guys, big thanks for your input – I've made some progress. Turned out I mixed up the tip and ground in the wiring. Got that sorted, and didn't like the ground being in the middle, so I tried a new wiring layout with the 3PDT.

But now it's sounding shit... lots of noise, and those wired octave notes come with some extra grit. but It works at least but just not quite what I was aiming for. lol

[amptramp]

The noise could be interference that would disappear once the circuit is mounted in an aluminum box.

A germanium Fuzz Face has a number of things in the design that make it difficult to get repeatable results from one build to another.  Germanium transistors have a lot of leakage current that may be on a par with the base biasing current.  In fact, I have seen early transistor radios using germanium transistors that were biased by leakage current alone plus leakage from the electrolytic capacitor feeding signal to the base.  Secondly, the hfe (current gain from base to collector) has a wide variation and both leakage and gain increase with temperature.  You may have to select transistors for this task.  If you go with silicon, the leakage is about 1000 times lower but you still have gain variations that affect the signal.

You may need a bunch of transistors to get a pair that give you good results.  One other thing to do is check that you have the right pin basing diagram for the transistors you are using.  It is easy to got emitter and collector switched and that would give you low gain and noise.

[Yazoo]

It would be worth replacing the resistor to the collector of the second transistor with a trimpot so you can dial in the bias. I have had to do this on both a Fuzz Face and Tonebender build. There are lots of guides on how to do this. This one looks good:

http://guitarpoppa.com/biasing-a-fuzzbox/

[mozz]

Or replace the collector resistor on Q1 with a trim pot, that will change Q2c voltage also. 

[sinthmart]

Germanium transistors are vulnerable to overheating. And you made short conclusions. It is not right.
You can take serviceable transistors, but if you solder them with overheating, these transistors may be bad already on the board.