Super Hard On that doesn't feel like working (Debugging)

[leopoldoghost]

Hello there,

i am now trying to build a Zvex Super Hard On, due to his ease of construction   and because it should sound pretty good.

Introduction: i am building this effect on a stripboard, with no switching yet, so it's always on as long as the battery is connected, no enclosure yet, so it's quite noisy, tho, i included an led.


now, copypasting from the Aron thread: DEBUGGING - What to do when it doesn't work


Behavoir: big cut in frequency and volume, sound very compressed and NOT boosted at all, the knob crackles but it doesn't affect the sound in any significant way.

Name: ZVex Super Hard On

Circuit Source: http://tagboardeffects.blogspot.com/2010/07/zvex-super-hard-on-updated-version.html

layout on stripboard

Circuit Modifications/Part Subtituitions:

- C5K potentiometer changed with a B5K potentiometer

- 5,1kohm resistor changed with a 4,7kohm resistor in series with a 330 ohm resistor (4,95Kohm, inside the 5% tolerance of the 5,1kohm)

- minor layout modifications (input spot moved to a more confortable location on the board, same for the LED connection)

Positive/Negative Ground: Negative Ground (as the original)

Some photos:

for better understanding of the Voltages section:



Wiring and board:




Top Of The Board:



Soldering Side:



Soldering Side Silhouette:





Voltages (yay):

Out of circuit battery voltage: 8,68V

*clips black lead to ground*

+9 Volt spot on the board (battery clip red lead) 8,42V

(the north/south is merely visual reference; the north is "higher" than the south)

C1 North 0V
    South 3,71V

C2 Negative 0V
    Positive 4,66V

C3 Negative 0V
    Positive 8,42V

R1 North 8,43V
    South 4,66V

R2 North 0V
    South 3,72V

R3 North 4,66V
    South 3,72V

R4 North 0V
    South 0v

Zener Diode Anode: 0V
                   Cathode: 3,72V

bs170 D: 4,66V
          G: 3,70V
          S: 3,65V

Pot (full counterclockwise) (5kohm) 1: 0V
                                                       2: 0V
                                                       3: 3,65V


i've double-double checked my transistor pinout, my elecrolytic capacitors polarity and the ground connection

and here is a video of me playing through the non-working effect:

http://www.youtube.com/watch?v=MYN2KzuveBA



hope this is enough for you big-mindeds to spot the bug and please, instead of just: "X is faulty, replace it", i would really appreciate an answer like: "X is faulty, because [...], replace it"

Thanks a lot for your support and for your wise teachings, they won't be in vane  

[stallik]

1st thing I  can see is the wiring of the pot. Pins 1&2. Should be connected.....

[leopoldoghost]

they are connected by a small piece of wire visible in this photo (good eyes required)

[Jazznoise]

Those transistor voltages are probably wrong.

Check and double check for bridging or shorting with your multimeter. Best way to fix any found cases is to either cut between tracks (I use a stanley knife, but I'm insanely careful and not recommending this. Most people use a scribe.) or to droll a hole in the copper using one of those PCB screwdrivers (A screwdriver with a small drillbit in it, you can make one yourself or pick one up. Either is fine).

For future reference, don't solder entire tracks. I use veroboard alot and it's a cruel mistress, only solder where there is a connection. Try and keep connections close together so you can solder them all in to the one spot. It's all about minimising the risk of shorts or faulty connections. I can't say I'd spot cold solder joint on that layout there's so much tin!

[stallik]

Old eyes, never noticed the link. I normally take a circuit layout to show the pot wiring from beneath i.e the way you would view it when mounted in site a box. This would mean that the link should be between the other 2 pins?
EDIT: Ignore me!  somebody's having a senior moment & it might be me.....

[R.G.]

First, thank you for providing information and links to the reference material. That makes this process much easier.

b]Out of circuit battery voltage[/b]: 8,68V
Battery voltage good, if not new and fresh (which is about 9.5V for alkaline).

+9 Volt spot on the board (battery clip red lead) 8,42V
Under load, it doesn't sag too much. Also OK.

C1 North 0V      South 3,71V
C1 is not shorted, as the voltages on both ends are different.

C2 Negative 0V      Positive 4,66V
Same comment.

C3 Negative 0V      Positive 8,42V
Same comment

R1 North 8,43V      South 4,66V
Same comment.

R2 North 0V      South 3,72V
Same comment.

R3 North 4,66V      South 3,72V
Same comment. However, the gate of the MOSFET should be practically an open circuit, and so the voltage difference across R2 should be about the same as the voltage difference across R3 and it is not. The gate should be essentially an open circuit to DC, and not affect this. C1 and Z1 should also be effectively open circuits to DC. Something attached to the "gate" contact is pulling the gate to the the "source" contact.

R4 North 0V      South 0v
This is expected.

Zener Diode Anode: 0V                     Cathode: 3,72V
Z1 is not shorted.

bs170 D: 4,66V            G: 3,70V            S: 3,65V
Gate and source are not exactly the same voltage, as they would be with a solder short, but the source is not near ground. It takes something like 1.5-3V between the gate and source to turn a BS170 on, and the difference between gate and source is only 50mV. Therefore, the BS170 is not working normally. It is odd that the difference between gate and source is 50mV, not a short. My first inclination is to think the device is inserted with the pins incorrectly placed, but you say you have already checked this. There are (at least) two manufacturers of the BS170 who put the pins in different places, so it's important to check the datasheet for the manufacturer who made your specific device.

My other guess is that the BS170 has a damaged gate.

Pot (full counterclockwise) (5kohm) 1: 0V  2: 0V   3: 3,65V
*IF* the pot is actually 5K ohms (I mention this because I sometimes get pot values wrong, using 50K instead of 5K, etc.) then 3.65V/5k = 730uA is flowing through it. There are other possible scenarios, such as the pot being open or very high resistance, and the voltage at the source forcing the terminal to be at 3.65V. It is best to check the resistance of the pot from 1 to 3 with your meter set to resistance measuring.

[Dom D]

A lot of people sub the BS170 with the 2N7000 and they have different pinouts. Is there any chance you did this? Not likely, but just an idea.

[John Lyons]

Super Hard On that doesn't feel like working

Try this.

[armdnrdy]

John,

I had the same exact thought after reading the words "feel" "super hard on" and "working" in the same heading!

[Pyr0]

^^^   

[Jdansti]

^^^^ Thanks a lot, John! (sarcastic tone) 

My wife walked up behind me just as I had scrolled down to your post and asked what the hell I was doing.    Soooo... I had to explain the Super Hard On (which didn't help) and explain your joke (which didn't help either) while trying not to laugh (but I couldn't, which really didn't help matters) as she lasered a hole through me with her eyes.

Couldn't you have just said, "try the little blue pill"?   

Thankfully you didn't post the photo of the Fuzz Box Girl with her pedals in front of her!!! 

This would have been about the only time that I wish the photo would have been Markebee's gorilla boy!

[Eric.nail]

I'd personally scrap the project. I'v tried that vero layout three different times and it's sucked every one of them. I don't know why but i'v never got it to work correctly with that layout.

Spring for the extra few bucks in knobs and pots and do the upgraded super duper 2 in 1. You'll love it twice as much. Two SHO pedals in one with a master knob. A tad bit of extra wiring, but absolutely worth it for the overall volume cut/extra boost channel for over driving.

[leopoldoghost]

Super Hard On that doesn't feel like working

Try this.

Jhon, you got it all  


thanks to R.G for your complete analysis of my numbers,

what i understood from your post is that if something is faulty, that's the mosfet (btw, it actually is an honest and genuine bs170)



(maybe broken gate; almost-shorted; does bad thinghs with the other component's voltages)


or the pot [between 1 and 3 is 4,89kOhm in the fully counterclockwise position, the same when i measured all the voltages (they change if i turn the pot clockwise)]

about the super duper, that's my final goal, but being a noob, i tought it was a bit pretentious try a double stombox, so i went for the half-version and, if that would have been succesful, i would have coupled it with another one and some exra wiring into a super-duper.

if you (Eric) had bad experiences with the same layout, i feel better with my self esteem, but i would like to dig it some more, and see if the bug lays somewhere else.

i would like to know if there is any risk that i accidentally blow out my mosfet (i heard that they are pretty susceptible to static electricity)
i read that i should socket it, but at the moment my sockets are over, any suggestion?

thanks a lot for your teachings and support  


BTW, i' ve found the datasheet for my transistor, but i can't really understand most of the things written there:

http://www.futurlec.com/Transistors/BS170.shtml

[Perrow]

This would have been about the only time that I wish the photo would have been Markebee's gorilla boy!

Where's d'Astros sausage on a fork when you need it

[anchovie]

(maybe broken gate; almost-shorted; does bad thinghs with the other component's voltages)

That picture above made you almost type "thighs", didn't it? 

[leopoldoghost]

That picture above made you almost type "thighs", didn't it? 

I am discovering aspects of myself that i wasn't even far from imagine

[Jdansti]

@Leopoldoghost-when I work with mosfets, before I remove the part from its anti static package or foam, I hold the board in one hand, making sure my fingers are touching across multiple traces including the ground, and I use the other hand to remove the part from its package and insert it into its place on the board or socket.  I think that this method is similar to wearing an anti static wrist strap. It's worked for me so far, although I might just be lucky.

[John Lyons]

Just trying to help guys. 

[R.G.]

@Leopoldoghost-when I work with mosfets, before I remove the part from its anti static package or foam, I hold the board in one hand, making sure my fingers are touching across multiple traces including the ground, and I use the other hand to remove the part from its package and insert it into its place on the board or socket.  I think that this method is similar to wearing an anti static wrist strap. It's worked for me so far, although I might just be lucky.

Two quick-and-dirty techniques are to either
(1) Wear cotton clothes and take off your shoes and socks before working on MOSFETs or CMOS
or
(2) go into your bathroom to work, and turn on the shower with hot water spraying. This runs the humidity up. Static electricity can't form to any degree in humidity over about 50%.

[oldschoolanalog]

My wife walked up behind me just as I had scrolled down to your post and asked what the hell I was doing.    Soooo... I had to explain the Super Hard On (which didn't help) and explain your joke (which didn't help either) while trying not to laugh (but I couldn't, which really didn't help matters) as she lasered a hole through me with her eyes.

Jeez John; now you are going to have to get some Kevlar full body armor so you can continue DIYing.   

Where's d'Astros sausage on a fork when you need it

Here!

You did ask...
@DA: Your royalty check is on the way...