First attempt at Vero... Bazz Fuss issues

[charriman]

Hi,
I decided to attempt my first build on vero.  I figured the Bazz Fuss would be a good one to try since it's a simple build.  However, simple doesn't seem to be working for me.
I've probed the signal and it's not getting past the base of the transistor.  I'm not seeing any solder bridges or anything out of sorts.
I've also checked my voltages.  Battery is showing 8.5 (i know that's low)   and i'm getting 8.2 on the collector of the transistor but nothing on the base or emitter.  Bypass works fine.
Also when engaged, turning the volume knob is giving me a crackly sound so i'm assuming theres nothing wrong with my switch wiring.
Here are some pix.
The layout i used:


Solder side:


Another solder side:


component side:


Any help would be appreciated.
Thanks!

[smallbearelec]

Hi--

It's almost surely a wiring issue. A first build should be breadboarded first and then soldered on a larger perfboard so that you have a little room in which to avoid problems. I am setting up to walk another beginner through this. If you want to follow, here is the thread:

http://www.diystompboxes.com/smfforum/index.php?topic=112626.0

[lethargytartare]

Did you cut the strips under R1 and C1?  I missed those when I built mine about a week ago.

[charriman]

Did you cut the strips under R1 and C1?  I missed those when I built mine about a week ago.

Crap... i didn't even see those cuts in the layout.  Wasn't very obvious looking at it.

[duck_arse]

I've also checked my voltages.  Battery is showing 8.5 (i know that's low)   and i'm getting 8.2 on the collector of the transistor but nothing on the base or emitter.

charri, when you say "nothing", what do you mean? 0V? don't be shy of the zero.

and please! smaller images. it takes me 3 or 4 scrolls across to see the whole panorama. and all the scrolls down to get to the across ......

[antonis]

Do I smell a reverse diode placement..?? 

[charriman]

Duck Arse... yes as in 0V on both.

Note.  I did forget the cut traces as mentioned a couple of posts above.  That has been remedied.

I've also checked my voltages.  Battery is showing 8.5 (i know that's low)   and i'm getting 8.2 on the collector of the transistor but nothing on the base or emitter.

charri, when you say "nothing", what do you mean? 0V? don't be shy of the zero.

and please! smaller images. it takes me 3 or 4 scrolls across to see the whole panorama. and all the scrolls down to get to the across ......

Do I smell a reverse diode placement..?? 

Antonis,
The black stripe on the diode is indeed facing down next to the base of the tranny.

[charriman]

one other thing.  i have a 100k resistor installed for R1 instead of the 10K in the layout.  I will change that out as after i did the cuts i missed, it dropped the collector voltage from the 8.5 to around .5 volts.  i had read somewhere that you should use 100k with a plain old 3904 and a 10k with a darlington.
The upside is that it does now pass signal but barely (you have to crank the amp and the volume pot on the pedal).  I am seeing some voltage on the base now after the cuts as well.  so i'm thinking it's the resistor that's causing that problem.

The long term solution is to completely rebuild the board with the cuts already done and the 10K for R1.

[antonis]

<i'm thinking it's the resistor that's causing that problem..>

I'm not sure about what you mean..

Your Collector voltage shoud be about two diode forward voltage drop above GND (1N914 + Vbe)
(practically your collector should stay to about 1V because of low current flow..)

Thus 8V drop to R1 (10k) and 800μA flowing via Collector & Base which are again "added" to Emmiter..
In case of 100k the current should be 80μΑ..

Your circuit's gain (Rc/Re) is about 320 which is the same in both cases...!!
(Re = 26mV/Ie(mA))

Raising Rc value leads to lower Ie at the same proportion which in turn leads to raise Re at the same propotion so the gain is kept "fixed"..

Propably there is some bad solders and/or connections on your board..
(in no case you should read 500mV at Collector...!!)

[lethargytartare]

One other thing:  when I look at your solder close-ups, I think I see some very fine bridges between the strips.  Might want to check that.  A trick I've used is to take a hacksaw blade and lightly saw in the space between the copper strips, effectively clearing out any possible solder bridges.