Fairly stretched trace/guess from shots in video,



Very hard to make out much.   

For some reason the 100k + 47n appears to be on Q1, not like the germanium ckt on the web.

Most of the resistor values are unknowns.  Pot values on the schematic are BS, volume could be 500k.

---

And just to be annoying there this:

This one is silicon,


So I could have it around the wrong way and that would explain why the supply filter if flipped.
There is a reason I chose the transistor order like I did:  the wiring and direction of
rotation of the depth pot (see video).

Quote from: soggybag on Yesterday at 03:12:21 PMOn the other forum there is a long Fuzzrite thread. At the end there is a schematic with three trans. Sounds like this is the author's idea and not taken from an original unit. But it might provide some insight.

Yes there's no concrete link between the two.

On the same page of the fsb thread is a link to the 1968 Mosrite Pro Suzz Fuzz Pedal which has three transistors.   That pedal has another pot, Attack/Sustain.  If I had to guess I'd say that pedal has an extra transistor stage at the input, the output of the input stage passes to the Attack/Sustain pot which is then wired as a volume control with a resistor in pin 1 (like a Muff control) then that passes to the input of the Fuzzrite type circuit.

The video demos the Depth pot on minimum all the way to full.  From the amount of gain it should be possible to deduce if the extra stage is for gain or not.

There's no info about the biasing of the transistors.   That's going to affect the tone.  Given it's a germanium based unit there's plenty of "opportunities" for the bias points to be all over the map!

(If you weren't aware the Germanium version uses different part values.  eg.
http://diy.smallbearelec.com/Projects/FursRite/FursRite.htm
)

Quote from: Esppse on Yesterday at 08:01:52 PMHmm, yeah that may be what is happening. Every other pedal has either an isolated power supply or a switching style power adapter.

Does anyone know where I can get a 9VAC adapter that is not Class II transformer?

Stray field is a possibility.

The way to prove it is to put some distance between the rack and the adaptor (or more precisely the transformer inside the adaptor).  Take the adaptor out of the rack and run the low voltage AC into the rack.

The problem here is the field comes from the transformer itself.   This has nothing to do with grounding or Class II circuits.  The field comes from the way a transformer works.   Some constructions of transformers have less external field than others but most wall-warts use EI core transformer and will be similar.   More expensive EI transformers have flux shorting bands but I can tell you now it would be a miracle if you found a wall-wart made like that.

The simplest practical solution is to put distance between the transformer and the sensitive circuits/cables.   You can put thick metal between the transformer and the cables and an eddy shield but is not really practical for mains frequencies it's a fair amount of effort with little guarantee it will do anything.

You can also get capacitive coupled noise from the mains wiring itself in the wall-wart to the sensitive circuits.  Usually the generall shielding on audio equipment will fend that off.

Yet another form of hum is from the cable between the adaptor and the adaptor plug.  If that cable passes over sensitive audio cables or circuits humm/buzz can couple into the audio.

From. Y beginner perspective, I see it as a low impedance output to prevent loading losses.

Hmm, yeah that may be what is happening. Every other pedal has either an isolated power supply or a switching style power adapter.

Does anyone know where I can get a 9VAC adapter that is not Class II transformer?

Most likely the transformer's magnetic field is being picked up by a sensitive circuit in one of the other pedals on the board,
I have similar problems with some of my single coil pickup guitars when I sit down to practice. I keep finding magnetic fields in unexpected places.

Finally got a Ropez populated board that had never worked, working finally.  Problem was that the wires from the speed pot to the board were tarnished enough that what looked like a proper solder joint was not.  So the Resonance seemed to do something but there was no sweep.

Once the problem was finally discovered and fixed, I went and did the mod to provide the two waveshapes of the Color switch on the Small Stone.  Then I swapped the 10k current-limiting resistor on the LFO output for 9k1 and it had the desired effect of widening the sweep (primarily extending it at the top end).  THEN, I incorporated the mod that the 6-chip Small Stone used for "automatic width adjustment", and strapped a 47uf cap from the OTA end of the resistor to ground.  That had the expected effect of reducing the sweep width once the speed got over .4hz.  Finally, wishing I had better control over sweep width I added a 5k variable resistor (pot) between the OTA end of the 9k1 resistor and the OTAs, providing about 14k of current-limiting resistance.  That additional control, with the cap to ground and the sweep-shape switch for the LFO, provided a lot of control over the feel of the sweep.  I can get nice calm bubbly phasing and ultra-wide slow dramatic sweeps.  I'm pleased.

Dare I add more?  We'll see.

Quote from: Rob Strand on Yesterday at 06:31:41 PM

Quote from: Esppse on Yesterday at 06:25:23 PMI tested all the units separately before installing in the rack. There definitely was no hum on the wah unit, but I forgot if I used that 9VAC adapter currently installed, or a different one I had laying around which was actually 12VAC, yeah risky heh but it worked well during the isolated test.

Maybe the problem is the metal wha chassis being bolted onto the rack?
Try isolating the metal wha enclosure from the rack.

I actually took that into consideration when building. It's velcroed on for isolation currently. I bought this adapter new a couple weeks ago, could it be the way this adapter is constructed or maybe I got a dud? I currently don't have a different 9VAC adapter, since I bought 2 of the Jameco ones from Amazon.

Replace the 1uF capacitors C045, 49, 50 & 51. Then check the quality of the audio on pin 14 or 15 of IC2. This is the delayed audio after it has been put back together and filtered but before it is sent into IC2's expander. You can then see what its expanded delayed audio output looks like on the pins of C045.

The 10uF caps are usually the main cause of troubles with the DD-2 and 3 delay pedals but you have changed these but do make sure that you got all of them and that you have them install with the correct polarity.

Sometimes damaged memory can cause glitch or ticking noise to be heard in the delay signal. Generally if you increase or slow down the delay rate length, the glitch repetition rate or duration changes. The only solution to this problem is to replace IC6. It is a 4 bit 64 Kb dynamic RAM and they are a bit hard to find but they can be found.

Also, check the 5 volt power rail. Make sure that it is at 5 volts and that it is clean. Check it with your oscilloscope. C019 and C027 may need to be replaced (both 47uF) if the rail is noisy.

Quote from: Esppse on Yesterday at 06:25:23 PMI tested all the units separately before installing in the rack. There definitely was no hum on the wah unit, but I forgot if I used that 9VAC adapter currently installed, or a different one I had laying around which was actually 12VAC, yeah risky heh but it worked well during the isolated test.

Maybe the problem is the metal wha chassis being bolted onto the rack?
Try isolating the metal wha enclosure from the rack.