@barry
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I would enjoy seeing what is going on on the inside.
I was also wondering if you considered adding an extra switchable stage (like a 1″x1″ Stage 3 Booster) on the inside to account for any circuit or group of circuits that would invert the phase?
Very nice and thank you for sharing.
The MPSA18 can be used in place of BC550 in the Sabotage but if you do it must be placed backwards compared to the silkscreen. No difference in tone, just pinout. When in doubt you may also google datasheets to make sure what type a transistor is and it’s pinout. In this case it would also tell you a J113 is a JFET and not an NPN transistor so it could not be a substitute for that.
Sorry I missed this one.
The 220nF cap allows more bass frequency than can be used (with a Bass guitar) so the only real mod would be to switch that value to tighten that up when using for standard guitar which is 100n and even 22n or whatever in between pleases you. You won’t necessarily hear more Bass unless using a Bass guitar but you will be choking off Bass for a tighter, brighter guitar by moving towards 22n. That is why we have a SW1 on the Stage 3 to switch between these values at C2 and C3.
That said with a Passive Tone you can never really add Bass but you can allow more or less Bass Frequency to pass through.
OK so I deleted my first response since I was working from memory. That is what happens when you are busy packing after a new board release and throwing a Birthday Party.
I think we are mixing up transistor packs or something.
MPSA18 can be inserted in Q1 backwards if memory serves ???
Then as Wilkie points out the others Q2 etc. need to be JFETs.
Q1 may or may not be backwards depending on the transistor being used.
If it is a BC550 then it is backwards.
If it is another type of transistor then it may need to be flipped as in the photo so we will need to know what transistor is being used in Q1.
That aside there are many readings that are off like Wilkie1 said.
“What can I do?”
Simply put you can try to fix it.
If you would like us to help you troubleshoot the circuit we need clear photos and measured voltages of all transistors labeled by which Q and which lead. This circuit has been available for 8 years so you can be assured the circuit board is just fine. There is nothing wrong with the components you mentioned that I see.
2N4125 and 2N3906 are both PNP transistors with similar properties and lead orientation.
We will need the required troubleshooting info that is requested for all build issues and we will try to help.
If you do not understand voltages etc. Here is a GUIDE See pages 8-9.
I agree it is a simple matter of testing the gain and making a few minor potentiometer adjustments. When working with circuits in tandem I think a good saying is “just because it goes to 10 doesn’t mean it should”, especially for any guitarists that would not concern themselves with such things.
What a fantastic build. Well executed on the inside & out and should make a great combo for any rig. That is the kind of combo I would take to a local Jam Night and let all the players have a go at it. I would call that the “puppy dog sell” and then take orders to fund your hobby. I have certainly done it.
I would add that Billy’s link is a great source of info that is so often overlooked.
That is one of my favorite Fuzz boxes Billy! It is easy to build and requires no biasing. Beautifully smooth silicon fuzz. For the new people this Board was redesigned and rebranded a year ago as the Sriracha Fuzz and includes onboard potentiometers. Thank you for sharing. Well done!
When looking for a build guide be sure to go to the Mandatory Guides section of the forum.
Here is the direct link:
Also in the Guides Section you can find the url to the old archived site.
If you forget this just add a “.webs” after the http://www.guitarpcb
Example: guitarpcb.webs.com and it will take you to the old archived site then click on forum and you will find the Layout Gallery. Likewise if you wish to download something you may also be required to add a .webs to the url to avoid getting a url error.
In short for everyone:
The .webs after guitarpcb in the url is what separates the new site from the archived site.
Don’t forget to answer the “GRIT” question this circuit is designed to be what many call “transparent” which is a word I really do not care for as all circuits color the signal or it would be useless but I digress so if you want more “distortion” you may consider an AfterBlaster add-on board and use either J113 or for more distortion sub in a J201.
They are the same. The flat side of an LED is the cathode and the stripe side of a silicon or germanium diode is also the cathode. In the photo you can see that both the flat side of the LED and the stripe side of the diode have the same orientation. This symbol is meant to show you have an option for either LEDs or another type of diode. (Hence the extra pad for fit)
We can’t see the other side of the board to make sure you connected to the correct pad.
The Green Wire [Out] looks OK but we cannot see the Blue Wire [IN] in the photo.
