Shin Ei FY2 Fuzz; or look, I broke something new!

[moid]

Whoops, copy paste error!

For Q2 I was measuring from the 47K resistor lead nearest the C socket of Q2! Sorry

[duck_arse]

gah! I copied that circuit so's I could see what we was talking abaht, and you go and over the page. we want the resistances from the +9V line to the collectors, it seems you might be measuring the resistance between the socket and the nearest R leg.

[moid]

Sorry duck I will do this as soon as I can finish cooking this evening's meal. Mushroom risotto waits for no man!

[moid]

Moid jnr is sleeping now, and isn't coughing so much; thanks for the best wishes.

I return to probing (gently). 9V to Collector of Q1 = 0 ohms

9V to collector or Q2 = 100K

Touching probes together and crossing the streams results in:

DC - slowly falls to 0V
AC 0.006V
ohms - mostly 0, but flickers madly up to 500K

Does any of that make your Sherlock Holmes like mind say Electricity my dear Watson?

[duck_arse]

hmmm, I think we are getting some stream-crossings here.

WHENEVER you switch the meter to ohms or continuity or diode test, the circuit power must be OFF. otherwise it will mess the reading. if there are caps connected to the things you is probing in-circuit, they may have/hold a charge which may then discharge before your very eyes as you apply the probes, so a reading might ...... count ,,,,, but should settle. you can always short the resistor leads before you measure (safe to do, because the power is off) to discharge any caps connected to.

from the "+9V" line, you should show 22k to one collector and 147k to the other collector - also, from one collector to the other collector should show 22k + 147k = 169k. (collector = the empty socket-pin in this inst.)

maybe if you go around your board and measure each resistors value, we can shed some light on the missing ohms/volts/fuzz. we'll get there.

[moid]

Thanks for helping! The circuit was completely unpowered (not even plugged in, let alone switched on). I've just tested again and got the same figures. If I check between Q1 collector and Q2 Collector I get 0 ohms. It sounds to me that the audio is travelling into the circuit, but presumably going via the solder and ignoring half of the components? Although how that's possible is beyond me... Perfboard is very odd stuff to say the least. Duck, I'm going to order some new probes for my DMM - they have crocodile clips on the ends of them so at least they'll be able to hold steady on parts of the circuit (my current probes just have a metal spike sticking out the end of them with a very fine tip, which is often difficult to hold in place well). I tried using hook probes this evening and clipped them to the probes with crocodile clips as well... but the results were the same. Maybe new probes will give better results. If all else fails I'll try to build this on vero board again... I might measure the vero board version I built actually to see what that comes up with. Thanks for your patience, I bet this is some total rookie error

On the good news front I built a voltage doubler circuit AND IT ACTUALLY WORKED! 18V of power to two outputs, yay On the bad news front, while testing a buffer I built, I found that one of the outputs has failed at one of the capacitors (audio goes into the capacitor, but does not leave it), so I might try to remove that cap and add another to see if that fixes things.

And I'm back to work from Monday, which means soon all my pedal building will go on hold until the Christmas break And my wife has picked up the bug my son has so I'll be looking after both of them tomorrow, so not much time for any tinkering...

[moid]

interesting, when I measure the ohms across the collectors and 9V of the vero board version of this circuit (also non working) it gives me the values you noted above that I should see. So whatever is wrong with the veroboard version is busted after the transistors?

[duck_arse]

after the transistors, possible, yes. the way to find out is to disconnect the fuzz pot and tone section so's there is just the 2 trannies, their collector and base resistors. you should be able to audio probe big sigs from each collector, proving the "interesting" part of the circuit, and faulting "something else".

a point to note, if your buffer is an opamp, is the "virtual ground" node that appears at the (-) input. you will be able to measure DC volts there (or else it's prolly gone cronk) but there will never be any audio. it will magically reappear at the output, and you then need not worry.