7 of Dwarves kit from Fuzz Dog - debugging [SOLVED]

[Tex Gore]

Hey everyone,

I hope this is in the right place to post. I recently purchased the 7 of Dwarves kit from Fuzz Dog. I studied electronics but it was about 100 years ago, and I've forgotten much of it. I'm working to get it back, hence building this kit, but I'm hoping someone can give me a hand with troubleshooting. I have read 'R.G. Keens troubleshooting guide' as per the FuzzDog website, but I'm still struggling. Having built the pedal it's completely dead - no sound at all (not even a buzz).

So far I have:

• Checked all components - 3 times. They're correctly placed and in the right way round.
  Cleaned the excess flux off the board
  Checked my power supply and grounds are all correct
  'Bypassed' the board so check everything between guitar and amp is good - it is (I just connted signal input to out together on the board and got sound fine)
  Solder joints all look good - it was something I was pretty good at back at college

Having done all that, measuring voltages (my knowledge runs out pretty quickly here)
I get 9V at the main power in pad on the PCB (where the +ve wire is soldered....first things first right?)
I get 9V both sides of R31
The LED works
I get literally less than 1mV everywhre else - D5 (both sides), R30 etc. For example at V1 of the Voltage Regulator (IC3) I am getting 0.01 mV

I'm sure it's something obvious to you guys so a nudge in the right direction would be really great. This was supposed to be a Christmas present!

Thanks in advance

EDIT: I put a jumper between my main 9V supply and V1, and it sprung into life - however the effect is extremely weak...I can barely hear it?

TG

[deltafred]

Welcome to FSB.

It sounds like you have the protection diode D5 the wrong way round or it is faulty.

As for the low output after putting the link in I have no idea.

Edit - Or a cracked PCB track.

[Tex Gore]

Thanks deltafred - you're spot on, turned out it was D5 had failed. Replaced and now all is well as I wanted that polarity protection (I assume that's what it does anyway) but as mentioned it's a very 'light' effect - you can hear it, but not very much.

Hopefully someone else might have an idea.

[modman]

Thanks deltafred - you're spot on, turned out it was D5 had failed. Replaced and now all is well as I wanted that polarity protection (I assume that's what it does anyway) but as mentioned it's a very 'light' effect - you can hear it, but not very much.
Hopefully someone else might have an idea.

Boy £45 for an Autowah, you should have bought he Valeton Catfish and showed us the guts instead. Only €45 and at least it would work and not fall apart.
https://www.thomann.de/be/search_dir.ht ... sw=autowah

Only you can debug that circuit, it's not about having ideas.

a) you are not getting 9V at points where you should -- trace the 9V from the source that location with your multimeter. Or cut the power and use continuity check on your multimeter to check the traces. Don't proceed unless you have power everywhere it should be.
b) input a signal into the circuit, connected output to speaker. then jumper to the input to output. you should now hear unity level signal through the connected speaker. Remove the jumper from the input and follow the signal path with the jumper see where you lose it.
c) did you socket the chips or soldered them to the board? sure you didn't fry them.

[Tex Gore]

Thanks modman - I wanted to make something, it's a gift and thought it would mean a bit more. It's been a tough year for a friend of mine. And she can't complain about how bad it is.

I didn't pay anything like 45 for this.

I sorted the power issue - it was a diode.

Thanks for the idea around the jumper, I'll give it a go. And yep I used sockets for the chips and used heatsink on all the other sensitive components. I don't lose any volume through the effect to be clear - it's just too dry...not enough wah.

TG