GGG Shin Ei Fuzz Clone, help debugging non-functioning first build

[rompler808]

Hi All,

Just started in DIY, working my way through the Make Electronics book and figured I would try building a pedal. First time through its not working so I asking here for some advice.  Thanks!

I built the full kit for the Shin Ei FY-2 Companion Fuzz from General Guitar Gadgets.http://www.generalguitargadgets.com/effects-projects/fuzz-tones/shin-ei-companion-fuzz/

Wiring Diagram:
http://www.generalguitargadgets.com/pdf/ggg_secf_lo.pdf
Schematic:
http://www.generalguitargadgets.com/pdf/ggg_secf_sc_bst.pdf

The full kit included the pcb, parts and a 150bb enclosure. I followed the project pretty much to the letter, no deviations. I use a Weller WCTCP and was pretty careful to use copper clips as heat-sinks when I was soldering in sensitive components (transistors, caps).  No chips for this build. Knowing what I know now, I think I would've opted for a bigger enclosure than the 150BB.

The bugs:

• The pedal makes no sound when  switched on, except for a little faint  line noise. Bypass seems to be working as signal is dead silent when the pedal is in bypass.
• The LED never lights up. I did use copper clips to avoid frying it when I soldered wires to its leads.

I followed the useful checklist posted here https://www.diystompboxes.com/smfforum/index.php?topic=29816.0. Below is what I found. I did all my readings with an NT DT-9205A DMM. I am pretty much in the noob phase still, so if something looks totally off please let me know.

Testing with a 9v  battery, battery voltage at: 9.44

Per the checklist, I plugged in a guitar cable into both the input and output, and put the negative lead of my DMM on the ring lug of the input.

Voltage at the circuit board end of the red battery lead (9V) = 9.45

Voltage at the circuit board end of the black battery lead (G)  = 9.26

Q1:
C 3: 9.43
B 2: 7.72
E 1: 9.26

Q2:
C: 9.30
B: 8.32
E: 9.37

Q3:
C: 9.44
B: 9.30
E: 9.33

The datasheet for 2N3904. (https://www.sparkfun.com/datasheets/Components/2N3904.pdf)
Max ratings should be:
Collector-Base V: 60
Collector-Emitter V: 40
Emitter Base V: 6

Z1:
C: 9.36
A: 9.45

Note: I did find a bad connection on Terminal 2 of the volume pot going to V2 on the circuit board (peeking out, like an orange Loch Ness Monster in photos of the build). I will solder that back in and try it again and report back here if that solves anything.

Below are photos, sorry for poor iPhone 5s quality. Thanks much!






Top of PCB:




Bottom of PCB (solder connections):






Pots:


Faintly you can make out the LED in the center of photo. Theres about 1/4" of exposed wire on the both wires connecting this. Plus I think I may have fried it.


Jacks and footswitch:

[Mark Hammer]

Those transistors whose emitter goes directly to ground should most certainly NOT be measuring over 9V.  At first blush, it looks like V+ is somehow also connected to ground.

[PRR]

Welcome.

Excellent report.

The stand-out issue is that ALL of your voltages "are 9V", or so very close as makes no real difference.

We "expect" a lot of points to be "near zero". Why else does a battery have two legs?

So I'd be looking for a broken connection in the wiring to the negative end of the battery.

Many pedals use the INPUT jack to break the neg-leg when not playing, a fool-proof OFF switch. You need a plug in the jack.

[rompler808]

Thanks for the feedback Mark and PRR. I will check that connection from the negative to the battery.

[aelling]

I dunno if it's what is causing your problem, but I believe you have the 1N400x diode in backwards.

[patrick398]

Is there a reason for omitting C10, R17, and the Jumper connection?

[patrick398]

Oh i've just read the build doc, ignore me.

I dunno if it's what is causing your problem, but I believe you have the 1N400x diode in backwards.

I think you're right

[duck_arse]

can I ask - why are your boxcaps not pushed down and standing square on the board? also, the pot w/ the purple and black wires has nothing connected to the wiper. is that the red wire waving to us in the pics?

and welcoem. < that's a rare special one.

[bluebunny]

So I'd be looking for a broken connection in the wiring to the negative end of the battery.

The screen connection on the stereo jack looks like it didn't get hot enough to make a good joint (turn your iron up).  Looks kinda pasty.  Compare it with the ring joint which looks much nicer: shiny and concave.  This could account for no -ve connection.

[bluebunny]

can I ask - why are your boxcaps not pushed down and standing square on the board?

. . . was pretty careful to use copper clips as heat-sinks when I was soldering in sensitive components (transistors, caps).

I'm guessing these are related?  Caps aren't (too) heat sensitive and don't need to be heatsinked while you're soldering.

[Govmnt_Lacky]

I dunno if it's what is causing your problem, but I believe you have the 1N400x diode in backwards.

Nailed it!

Although.. it might just fix part of the problem but, it is definitely in backwards.

[rompler808]

Yes. Thanks to all the input i got here, I got it working.

• First I reversed that diode.
• I reconnected the orange wire that was hanging out to the VOL pot (poor solder joint).
• Then went about desoldering all the connections to ground that were mentioned here or otherwise looked weak. The desoldering wick really came in handy.
• That and I managed to rip the anode leg out of the LED, so luckily I had a spare.
• After that I plugged the battery in, put plugs into the inputs, got the DMM out, and lo and behold, all the emitter legs of the Transistors came up at 0.00!

This project had some setbacks, even before it got to the bench. The powder coated enclosure I bought didn't have enough room for the battery, for instance.

Two last questions on this build:

• I sticking with battery based builds until I get enough chops to work with mains power. I was wondering, is there a way to test if its safe to plug this into an adapter?
• The screws they gave me for the enclosure are 3/8" long, dont quite fit so I have to use a battery to keep it closed for now. Any suggestions on sizes for the screws?

Thanks so much again for the input. Debugging is the hardest part and the input I got here gave me enought info to get me over the finish line.

Cheers!
Seamus

[mth5044]

Glad you got it working!

For the screws - I'm surprised GGG would intentionally send the wrong screws. Perhaps ask and see if there was a screw up?

For your power adapter question, using a power supply like a 1spot or Godlyke is nothing to worry about. They keep the mains voltage far away from you and your pedal and  transforms it into 9VDC at the outlet. If you were talking about making your own 9V power supply, then I'd suggest not doing it, but spare the environment and switch to 9V adapters ASAP.

[Mark Hammer]

I've made a bunch of these, including one that was a prize here some years back, and can recommend a bunch of simple mods that can provide a little more usability without sacrificing the stock sound.  Most are illustrated below.

1) The .047uf cap in parallel with the 100k resistor reduces bottom end.  Lift either end of that cap for more bass.

2) The .1uf (100nf) cap to ground forms a lowpass filter in tandem with the 10k resistor.  Between that filter, and the 1000pf cap, that forms a midscoop filter, allowing low bass and treble to pass to the volume pot.  If you lift one end of the 1000pf cap, you're left with just the lowpass.  If you sub a 47k fixed resistor for the 1000pf, you let the full bandwidth of the signal pass to the output.  The lowpass section is still in effect, such that it adds some additional bottom.  So what I did was use a SPDT on-off-on toggle to select the 47k, the 1000pf or nothing in addition to the lowpass.

3) Breaking the connection between the .1uf cap and ground, or simply inserting a resistance of a few kilohms, lifts the midscoop, restoring a lot of the "throatiness" of the unit

4) Finally, you will note that the pot is wired differently here than stock.  Not a mod, per se.  I just find that it gives a little more contrast between the min and max fuzz settings.

Pick and choose any of these that strike you as useful.  It's a fun circuit.

[rompler808]

Thanks for the mod recommendations Mark!

[Govmnt_Lacky]

For the screws - I'm surprised GGG would intentionally send the wrong screws. Perhaps ask and see if there was a screw up?

I see what you did there... 

[pinkjimiphoton]

a backwards diode would make ground almost 9volts, so yeah, if its backwards thats likely the issue.

Oh i've just read the build doc, ignore me.

I dunno if it's what is causing your problem, but I believe you have the 1N400x diode in backwards.

I think you're right

[pinkjimiphoton]

can I ask - why are your boxcaps not pushed down and standing square on the board?

. . . was pretty careful to use copper clips as heat-sinks when I was soldering in sensitive components (transistors, caps).

I'm guessing these are related?  Caps aren't (too) heat sensitive and don't need to be heatsinked while you're soldering.

true, generally they don't. but some will give up the ghost if overheated too much, usually the monolythic ceramics are the only ones i've ever had "melt" on me tho. use a hot iron and be quick. no more than 3 seconds on and you should be fine.

diodes and transistors of the GE variety are REAL easy to kill if ya get 'em too hot. but most everything else is fairly forgiving if you're quick.

i usually use too high powered of an iron, i forget, 45 or 60 watts, but make sure i'm there just long enough to make the joint.

glad ya got it sorted out!! welcome to the forum, and the best addiction you'll ever find