Problem with my Vox Distortion Booster V8162 clone

[hs.Dorian]

Hi people,

I'm working on this effect but it doesn't work and I really don't know why, I'm searching, thinking and nothing so I need your help!

I started to make the circuit on breadboard and it works very well but not on stripboard

The issue is poor sound, cracks (just like the battery is down but it is not), stranger things like radio transmission or a tic-tac, the input wire and the input capacitor is really sensitive, is buzzing when I'm touching them.

All of that happening on stripboard but not on breadboard. I changed all components and nothing so I hope I made a mistake when I realized the drawing.

Here schematic, drawing, pictures and sound :








https://www.dropbox.com/s/1k7eb1u2l94jlme/V8162.mp3?dl=0

Any ideas?

[GibsonGM]

Hi Dorian, welcome to the forum!  Not a rare, never heard problem, LOL.

Is your enclosure grounded?  I see you have plastic jacks, so often some provision has to be made to ensure that box gets connected to the "-" of the battery.  This will shield the circuit from RF!    That may not be all that's wrong, but it is one thing to check. 
ALL of the points marked with a ground symbol on the schematic need to be going to ground...so look and be sure.  I don't see a lot of 'info' on the stripboard drawing relating to that...

Another: are you sure you got your transistors' pinouts correct when you put them on the strip board?  It is easy to reverse, or scramble them!

If it's not those, come back and we'll go further.

[hs.Dorian]

Thanks GibsonGM

Yes the enclosure is grounded, there is two black wires from the stripboard, one to jack connectors and the other is soldered on the footswitch ring in contact with the enclosure

I checked all ground symbols are grounded :

- both jack connectors,
- negative of the battery,
- 2k7 resistor,
- negative side of the 10uF cap,
- Q1 emitter,
- the lug number 1 of the 50kB pot.

I checked the transistors :



One thing I don't understand, I have realized some fuzz face and tone bender with success; these circuits are very similar.

I have started again the stripboard the last weekend because I thought to small short circuits between coppers lines. So I have cleaned the board, checked with ohms meter and tried a new implementation but the result is the same. I'm going round and round... it's crazy!

[stringsthings]

The problem may be with your input and output jacks.  It looks like they are switching jacks.
So when you plug a cable into them, it breaks the connections that are across from each other.
This would result in parts of the circuit not being grounded.  Or an input/output left unconnected.

[hs.Dorian]

I checked jacks and footswitch, it's wired just like this :



I assume it's correct 

[GibsonGM]

Just for the heck of it, I would test that it is grounded with plugs inserted into the jacks. Then you will know for sure!   It is the simple things that usually cause us the most misery.

[stringsthings]

After a 2nd look, I see the problem.  Q2 appears to be reversed.  The emitter is the pin closest to the tab.
So the pin should be on the right side ( top view ).

[hs.Dorian]

I tested jacks with and without plugs : same result!

I'm thinking about the fact that it works on breadboard and not on stripboard so what is the difference?

This is my breadboard :


For the moment, the only difference I see is the breadboard is powered by external supply but I already have tested the stripboard circuit with this external supply so...

[hs.Dorian]

After a 2nd look, I see the problem.  Q2 appears to be reversed.  The emitter is the pin closest to the tab.
So the pin should be on the right side ( top view ).

If you look closer, the tab is on the right side for Q2 and left side for Q1.

[stringsthings]

My mistake on the Q2 tab.  I mistook the tab for the transistor lead.

I went ahead and made a vero build from your diagram and I was getting the same poor results. 
I couldn't find any faults in your diagram so I checked some voltages.  They were out of whack.
Removing the transistors and re-checking voltages revealed the problem.  Although your layout
is technically correct, voltages are leaking over into adjacent strips causing problems.
For example, I found +4V in strip 16 even with both transistors removed.  There should be 0V.
This is likely caused by +9V in strip 15 leaking over into strip 16.

It's usually a good idea to put power and ground strips close together. Here's a layout
showing separation of strips carrying power and other strips.  This layout is verified.

[hs.Dorian]

Wow I really appreciate you going to make the same circuit to help me, very nice, thanks

The +9v is leaking around the strips about 4v, it's unbelievable!!! I 've checked the diagram I did for the fuzz face which is almost the same but the +9v strip is not populated around two strips, that's why the FF works!

I won't be there this weekend so I will post my feedback next week.

Bye bye!

[hs.Dorian]

I have bad news!

First I removed the transistors and I confirm the 9V is not leaking around.

Then I use the next diagram with no success :


Finally I did the diagram from « stringsthings » :


Same result

I checked voltages and I think this is good :

[stringsthings]

The layout I posted is verified and I just plugged in my build and it's working fine.  So that suggests that there
is a problem with your build.  I checked voltages and the only significant difference was a lower voltage on the collector
of Q1.  Mine measured 0.68V with a power supply of 9.38V.

At this point, I recommend starting over with a fresh piece of vero and new components.  Although unlikely, it's possible
that a component of yours is damaged or out of spec.  If you don't have any more BC108A's, you can use ordinary 2N3904's.
Are you still getting the same results as before?  ( splatty, gated sounds )

The circuit on breadboard worked for you.  So there is something going wrong when you are moving the circuit to the veroboard.
You can find PCB's that are set up just like breadboards.  I've used these several times.

https://www.radioshack.com/products/radioshack-printed-circuit-board