'70 Fulltone help

[PMcG No.6]

Hello everybody! This is my first post here and my last ditch effort to save a vero gone bad. I hope I have this in the right section.

I just started building a few months ago. My first was a Wampler Cranked AC PCB I sourced the parts myself and put in a box of my choosing. Came out pretty well. I ventured into vero-land and chose the '70 Fulltone as my first, which I am starting to regret. Seems a lot of confusion surrounding Torchy's layout as far as if it's good or not. I've searched a few forums and have a couple people helping me to figure out if I did something wrong or if it's just a sh*t layout. Anyway... The problem I have is there is no sound coming from the pedal. I've checked continuity, rechecked all my values several times, took voltage reading from the trans(BC549's), fiddled with the trim pot, built a new vero, tried the mid control mods posted HERE.... nothing has worked yet.

Here are the voltage readings I got from the trans:

Q2 = C - 5.5, B - 1.28, E - .66
Q1 = C - 1.28, B - .59, E - 0

Pedal:




Here's my guts:



The cuts for the mid mod are there. You can't see them marked because i did them after I tried the original layout first.

The layout i used: http://i47.photobucket.com/albums/f155/Leavittno6/70Fulltone_w-midmod.jpg

I'm about to give up on the '70 vero, but scruffie at FSB told me to try here and see if someone can help. I'm trying to hang on to the '70 working because my pedal already is made for a 3 knob fuzz with either a tone or mid control. If anyone can assist me I would appreciate it. Thanks.

[slacker]

Your voltages look Ok assuming the dashes are just hyphens and not minus signs and the layout looks correct to me.
I'd make an audio probe and make sure the signal is getting to the input of the circuit, and then trace it from there, hopefully that will pinpoint the problem.
Look here for how to make an audio probe http://www.diystompboxes.com/wiki/index.php?title=Debugging.

Welcome to the forum

[Solidhex]

Looks like your transistors are backwards. The layout you used is misleading, With most transistors when looking at the flat side it goes e,b,c from left to right. The way they show them in the layout is backwards.
 I'm not sure if it makes a difference but "D2" is supposed to be a 1n34 germanium diode. Looks like you used a silicon. Flip the transistors and see if it works.

--Brad

[PMcG No.6]

Your voltages look Ok assuming the dashes are just hyphens and not minus signs and the layout looks correct to me.
I'd make an audio probe and make sure the signal is getting to the input of the circuit, and then trace it from there, hopefully that will pinpoint the problem.
Look here for how to make an audio probe http://www.diystompboxes.com/wiki/index.php?title=Debugging.

Welcome to the forum

Thanks for the welcome!  I'll have to try the audio probe thing. Someone else suggested that. I just exhausted other things before I built something to test the circuit.

Looks like your transistors are backwards. The layout you used is misleading, With most transistors when looking at the flat side it goes e,b,c from left to right. The way they show them in the layout is backwards.
  I'm not sure if it makes a difference but "D2" is supposed to be a 1n34 germanium diode. Looks like you used a silicon. Flip the transistors and see if it works.

--Brad

I've tried the trans both ways and still no sound. I did it because I wasn't sure of the orientation on the original layout. D2 is a 1N34A germanium from Futurlec.

[rousejeremy]

Nice looking box.

Have you checked all the trace cuts? Also look for hairline solder connections between strips with a magnifying glass. Happens to me more than I'd like to admit.

[PMcG No.6]

Nice looking box.

Have you checked all the trace cuts? Also look for hairline solder connections between strips with a magnifying glass. Happens to me more than I'd like to admit.

Thanks. I really like the way the graphic came out. I'm currently working on a graphic for a Axis Face.

I've checked the trace cuts a few times and ran something between the tracks several times to avoid solder bridges.

[Toney]

Mate, I will make it simple for you.
Do this:

>>>>>>>>>>>>>>> Build an audio probe<<<<<<<<<<<<<<<<<<<<<<<
Parts count = 3 if you count the lead and alligator clip.

Start with signal at the input and go from there. Follow the signal from your guitar or whatever you have at he input - cd player/Mp3 players works too on mono.... when the noise stops, there is your problem (or the first problem).

Capes of mystery fall away from your shoulders.
Crisis over.     

[PMcG No.6]

Mate, I will make it simple for you.
Do this:

>>>>>>>>>>>>>>> Build an audio probe<<<<<<<<<<<<<<<<<<<<<<<
Parts count = 3 if you count the lead and alligator clip.

Start with signal at the input and go from there. Follow the signal from your guitar or whatever you have at he input - cd player/Mp3 players works too on mono.... when the noise stops, there is your problem (or the first problem).

Capes of mystery fall away from your shoulders.
Crisis over.     

Cool. I'll get on that and see what I find. Thanks.


Thanks to everyone for all the suggestions and help also.

[fuzzo]

What's the schematic to make that pedal ? the same as GGG has  under the name "fuzz face 70" ?

[slacker]

Yeah it's the same as the GGG 70s fuzzface. The GGG schematic has a couple of errors though, C2 is the wrong way round, the negative end should go to ground. The link between the top of R2 and the point where R9,R8 and R4 join should not be there.

[PMcG No.6]

What's the schematic to make that pedal ? the same as GGG has  under the name "fuzz face 70" ?

To tell you the truth, I don't know if it's the same. I'd have to check it out. Here's the one that was listed with the vero:

http://i197.photobucket.com/albums/aa131/veroboard/Commercial%20FX/Fulltone/70%20Fuzz/1970fuzz.jpg

I'm still learning how to read schematics a bit. I understand what's what, but not how to really compare it to a vero.

Nice avatar, BTW. 

[fuzzo]

yeah it's the same schemo, the 1970 fuzz GGG.

I'm gonna make one with PCB .

to compare both, check if the components are good link between tem like the schematic has. It's really simple working with stripboard.

Start in ckeking if all compenents which must go to the ground, go to the ground. Them , you stay the same thing with the V+ (resistor to collector's transistor). And you do that for all connections to see if you made mistakes.

Nice avatar, BTW.  icon_biggrin

I know

[PMcG No.6]

I've typed this twice, so I'm just pasting it here  :

Alright. I've ruled out a faulty switch because I broke it while I was trying to change some things around  :oops:. One of the poles pulled out while I was removing a wire. So, to keep running tests I've wired it up like this: The First Wrapper. I made the audio probe and discovered one thing: I get no sound from the input jack. None at all. I tested the probe first to make sure it worked. I clipped the ground to the ring on my guitar cable and touched the cap to the tip; I could hear my guitar thru my amp. So, I plug everything in, ground the probe and touch the tip of my guitar cable again... nothing. When I remove my input wire from the input jack I get sound. What the hell am I doing wrong?! :cry: I tried the tip of the cable plugged in because I tried the board first and there was no sound where the input is soldered to it. I figure I'd start at the source.

I know my layout works, willc1968 at FSB used it already. I've checked the circuit for solder bridges several times. I checked all my parts for values etc. right before I soldered them on. The trans are in the correct orientation ( I used two 2N4401's matched at 218hfe). The readings from the trans are: Q1= C-1.29, B-.57, E-0.00 and Q2= C-5.42, B-1.29, E-.69. Not sure if this info will help anyone help me, but I can supply any other info if needed.

Here's the layout I'm using now: HERE

[ItZaLLgOOd]

Sounds like your input is going to ground.  Double check the jack to make sure that its wired properly.  Try switching the wires around.

[kurtlives]

Make sure you attach the ground wire from your audio probe to the sleeve not the ring. I guess you can use the ring just remember to plug in a cable first.

Something is wrong around Q1, check the collector area.

[PMcG No.6]

Sounds like your input is going to ground.  Double check the jack to make sure that its wired properly.  Try switching the wires around.

That's what I figure, but I can't find how it's going to ground. I have the tip going to input on the board and the sleeve going to ground on the board. I even tried a new jack to make sure that wasn't it. It wasn't. Something has to be grounding the input, but I can't find it.

Make sure you attach the ground wire from your audio probe to the sleeve not the ring. I guess you can use the ring just remember to plug in a cable first.

Something is wrong around Q1, check the collector area.

Are my readings wrong from Q1? How do I check it? I get no sound with the audio probe. What exactly am I supposed to hear thru it anyway? I've never used one before.


BTW, thanks for the responses.

[PMcG No.6]

Alright... I got tired of dinking around with the audio probe so I went back to the DMM and was checking voltages again. In the image below I circled the areas I'm not getting any voltage readings. I know some areas are ground. However, I should be getting something from C3 to LEVEL-3, right? Which leads me to believe C3 is sh!t. So, I'll be replacing it tomorrow. Now... Should I be getting voltage readings from the area between C1 and input? I'm not. I get a voltage reading from the + side of C1 and nothing from the - side thru to input.

[kurtlives]

No you shouldn't be getting voltages there. What your doing is kinda pointless imo. Back to the audio probe!

Ok make sure your signal is getting to the board. Then check Q1s base, then Q1s collector, then Q2s base then finally Q2s collector.

Where or where not you get sound will narrow things down. I think you wont get any sound off of Q1s collector.

[PMcG No.6]

No you shouldn't be getting voltages there. What your doing is kinda pointless imo. Back to the audio probe!

Ok make sure your signal is getting to the board. Then check Q1s base, then Q1s collector, then Q2s base then finally Q2s collector.

Where or where not you get sound will narrow things down. I think you wont get any sound off of Q1s collector.

There is no signal getting to the board. That's the problem. I used the audio probe on every part of the board and I get nothing. I don't know why the input isn't working. I've been told it's going to ground somehow. I'm having trouble finding how.

[The French connection]

There's something strange around the trim on your vero vs the schem...Is'nt it?

Edit: You miss a jumper there!
Edit 2: ...and C2 must be swap...negative to ground.