Fuzz Face Clone Issues

[pinkjimiphoton]

hey....

if you tied one leg to the wiper, the trimmer will only go down half way.

gotta ask you what you mean by this, so as not to confuse the OP. If you tie one leg to the wiper, you will still be able to turn it all the way down. If you have 10K, you will still have the full sweep from 0 - 10K

mah bad. i do this on some things, sometimes i do the opposite. i thought that effectively halved the resistance (never measured it) so that:

tieing the third leg to the wiper is a failsafe, so that the pot can't be turned all the way down and damage something.

believe it or not, it's actually kind of the opposite. The reason you tie a lug to the wiper is so that if the wiper fails, there will still  be resistance. You won't have an open connection even after failure.
[/quote]


that's kinda what i meant, but because of my misunderstanding of the above part... you get the resistance of the pot, correct?  or am i still misunderstanding dave?

[LucifersTrip]

you get the resistance of the pot, correct?  or am i still misunderstanding dave?

yes, the failsafe is there so there is some connection even if the wiper fails, so the circuit will still work

if the failsafe wasn't there, it'd be like disconnecting the pot, so there's a good chance the circuit would be dead or sound pretty bad.

here's how beavis explains it:
http://www.beavisaudio.com/techpages/Pots/

under "The Trimmer Resistor"

[pinkjimiphoton]

thanks bro!!

[TheLeakeyWeasel]

Success and no success.  I replaced the 470 ohm resistor and BAM!  Fired up like a dream.  So, I've now successfully researched, made a prototype on a bread board, committed to perf board and then troubleshot.  Now the issue I'm running into is trying to install everything in the housing.  It seems the battery/AC plug is grounding out when it's mounted to the enclosure.  Any thoughts on that?

[Pyr0]

Did you use a metal DC jack ?
Try a plastic one like these http://www.smallbearelec.com/servlet/Detail?no=666

[TheLeakeyWeasel]

yeah it's metal. Easy enough to fix.  But now another problem...haha.  So, the fuzz face circuit has a positive ground, so maybe this is part of the issue.  For the time being I have unscrewed the power jack from the housing so it's not grounding out.  I got the pedal working when using it alone.  If I plug it in my FX chain and plug in the power my DC brick dies. All power is lost, but only when I have the input and output connected.   

[LucifersTrip]

do searches here for powering positive ground pedals. this comes up every week or two it seems

bottom line, use a battery or a separate power supply

[TheLeakeyWeasel]

Kind of figured.  I'll research.  Thanks

[pinkjimiphoton]

think about it. a pnp pedal is a POSITIVE ground. most "normal" pedals are NEGATIVE ground. when you connect positive to negative, what happens?

yep. short circuit.

if you wired the input jack as a switch to connect the battery, as soon as you plug it in, it shorts to ground.

like Lucifer's Trip says, it's own wart, or a battery. battery will have less noise, but is a bit more of a pain in the arse.

don't make the mistake i made of wiring it up with the power jack backwards (which i did run, for almost 2 years)...it will still short everything else out.

you MAY wanna look into using a charge pump if ya wanna run it in line with negative grounded pedals...then you can use the -9v side (if you wire it like that) to power the pedal.
problem solved.

highly reccomend plastic power jacks, the kind where the nut tightens externally...much easier to deal with.

add some power supply filtering to the jack, too... 100-470u cap and a 1n400X (with cathode <banded side> to +) to help eliminate hash rfi and noise from a power supply, too.

it'll sound BEST tho with carbon zinc batterys tho...less noise, and the "sag" they develop really makes the germanium sing.

[rutabaga bob]

Welcome to the forum, Leakey!   

[TheLeakeyWeasel]

Thanks for the warm welcome!! I finished out my fuzz today. I took out the power jack and hooked the battery snap up. The only issue now is the horrible gain hiss. I was doing some research and picked up a 100pF cap to drop between Q2 base and Q1 collector. We will see how it goes. I do notice the pedal gets really squishy and compressed with the 1k pot maxes and the guitar volume maxed. Looking to work all this out eventually. More reading to do!

[TheLeakeyWeasel]

As it was once said by a group of lead balloons.....Ever Onward. 

I dropped a 100pF cap between Q2b and Q1c as was suggested in one of the posts on here.  Sure enough the nasty hiss was gone!  YAY!  However...things seem to be very weak now with little lows and tinny highs.  Before I soldered to perf board it sounded really nice and growled.  Once I got it on perf and replaced the 470 resistor I cooked it worked, but hissed and was way too noisy.  Now the cap in place the hiss is gone, but the sound is weak.  Playing on clean the pedal is really tinny and a sickly sounding fuzz.  At first I thought maybe the batter was dying, but it's giving out 8.2 volts right now. 

Could there be a solder bridge causing issues that I'm not seeing?  Did 100pF cap cause this much of a change?

Q1 E:  0
     B:  5.33
     C:  .08

Q2 E:  .11
     B:  .14
     C:  6.83

Way out!   I'm getting to the point where I'm thinking of just starting over on another board.  What should the values be of all the resistors?  Measuring resistance should be done without power connected correct?  that being said....do the other components affect the reading if there is no current and I'm reading from either lead.  I can't imagine resistance being affected if I'm only measuring on either end of the resistor.

[TheLeakeyWeasel]

Success!  One of the best troubleshooting steps I ever learned was in IT.  I had a computer that wouldn't boot.  I took it apart and put it back together again and bam it worked. 

So, I did the same.  I pulled the board out of the pedal, pulled the components and put it all back together again on another perf board I bought.  So, we are all good to go now.  Maybe I'll be able to put up some sound clips for everyone. 

I was very surprised this second time around.  The fuzz definitely has some get up and go!

[LucifersTrip]

sounds great...congrats!

remember beginner mistake #1
http://www.diystompboxes.com/smfforum/index.php?topic=100073.msg880533#msg880533