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Messages - Matness

Quote from: derevaun on March 31, 2023, 06:13:17 AM
Forward current transfer ratio, or gain, is the main thing to find out. All of those are germanium PNP transistors and the datasheets say their gain is 70+. If that turns out to be the case, and their leakage is reasonable, they're in the zone for several fuzz and boost circuits.

Thanks derevaun!  I will pick up a TC1 at the earliest opportunity.  Very useful tool!
I realize it is less accurate for testing germanium than the method in the link you gave, so I will keep in mind what I've learned from that page too.

Sounds like these might just be perfect for building a Fuzz Face, and then I'll just need to find an additional NPN for building a Jordan Boss Tone clone.   I'm new around here, so I only just now discovered the madbeanpedals PCB store!

These are the two circuits I'd most like to build:
(Fuzz Face)
(Jordan Boss Tone)

I'll research these Toshiba transistors, buy a TC1, order madbeanpedals PCBs and shop for parts. 
I suspect I'll be back here with more questions in a few weeks or months when I'm ready to start building.

Thanks for replying!  I'm glad to have stumbled upon this great forum!
Hello forum,

I have a handful of Germanium transistors harvested from a 1960s reel-to-reel machine.
Which if any of these might be suitable for building a fuzz pedal? (see photo)

2x     2SB54
2x     2SB415
4x     2SB440
2x     2SB439

Any circuit recommendations or general tips?
I have some electronics experience but am new to building pedals.

Thanks in advance!
Thanks jimilee!

I'd just finished swapping the wires when your message came through.
The pedal now seems to function as intended, except that I have the potentiometer reversed.

I can not overstate how helpful you've been! Your guidance was hugely appreciated!
Without you pointing me in the right direction I'd still be lost!

The only other thing I'm wondering, is:  I have a collection of germanium transistors harvested from late 60s electronics which I've been saving with the intention to some day build some fuzz pedals.   To get advice on which transistors are most useful for this should I start a new thread?  If so, which sub-forum?  The "Beginner's Paradise" category, or elsewhere?

Thanks again!
Did some initial probing, results are discouraging...
With pedal switched on (LED lit) I detect (unamplified) audio at the following points:

Main board:

Switch board:
"BI", JI" and three switch lugs (see photo)

No audio at the potentiometer.   No audio from any pin of the IC or transistors.
No amplified audio anywhere.

See attached photo for clarification - I've marked points where I can detect audio with a yellow circle.

Do I have the wires between the two PCBs reversed?

I've been assuming that:
"BI" on switch goes to "OUT" on PCB
"BO" on switch goes to "IN" on PCB

Maybe I have that backwards?
Uploading schematic for convenience
Quote from: jimilee on March 28, 2023, 11:42:52 PM
Ok, we’re making progress. Were you able to reflow both sides of R4?

Audio probe is the next step.
I reflowed both sides of R4 as per your suggestion, as well as many other joints even though they all look normal.   No change at all.   I tested continuity between all GND points and chassis (all 0.0 ohms), and between all 9V DC points (0.0 ohms).   Resistance between 9VDC and GND is 4.7k...  Does that seem normal?

I also tested all resistors (not for spec, just for continuity) none are open.  Tested all capacitors (in circuit) all normal values except that one of the 10uF reads as 60uF...  Probably a quirk of the circuit, and that shouldn't result in 'no output' even if the capacitor is defective.   

I tried testing the diode in circuit, couldn't get a reading from it - 0V in both directions...  Should I pull it out and test it?  Or is that unlikely to be the culprit?   If faulty I'd have to replace it with a 1N4007 which is the only silicon diode I have on hand.

I will build the audio probe as you suggested, into the output jack of the pedal.
I have a 100nF capacitor, so no problem there.

Is there any risk of damaging the circuit if I accidentally probe the wrong spot?
I'll set up a jig for audio probing (signal source and amplifier) later on this evening and report back.
I added the resistor, now the LED does light up.

When pedal is off audio passes through unaffected.
When pedal is on there is no output at all.

Polarity of all components (electrolytics, diodes) is correct according to the markings on the boards.  I just triple-checked.  (see attached photo of PCB from Musikding website)

Orientation of IC and Transistors is correct according to the photo on the instruction sheet.

Yet still no output...

I've checked for solder points which might be close enough to arc, reflowed the joints which were questionable, brushed the surface to dislodge conductive debris, etc...

What else could it be? 

Quote from: jimilee on March 28, 2023, 08:17:08 PM
the out lug is the outermost or the bottom of the stack.

One jack is mono, one is stereo.   The stereo is the input, and the mono is the output, right?

The stereo jack is kind of strange, the bottom of the stack connects to ring, the middle of the stack connects to tip.  The top of the stack is shield as expected.   I connected the output to the tip.   

I'm thinking the jacks must be wired correctly, because with the switch off(?) audio does pass through.

Does the switch board need another DC connection?
I ran a 9VDC wire to the LED hookup on that board, but maybe I need to run one elsewhere on the same board?
Or maybe adding the resistor will complete the circuit?  I also ran a 9VDC wire to the main board.

I'll install a resistor for the LED and see what difference that makes.

Thanks for all your advice!
I'm going to wait for expert advice before doing anything, but my guesses:

- The switch board may need another 9V+ connection?
- The LED is missing a resistor of unknown value
- I may have also made a beginner mistake which will be obvious to Jimmilee

Did you check out the link I gave to the instruction sheet? 
Am I mistaken in thinking that the instructions are incomplete?

The switch PCB is double-sided, I can't follow all of the traces now that the switch is soldered but I assume that all necessary switch connections are being made by the PCB.
Additional photos (see previous post also)
Quote from: jimilee on March 28, 2023, 12:06:20 PM
Can we have some clear close up pics of where you're at? There's a lot of information the re.

See attached photos.
First photo is most useful - I drew a wiring diagram, since the real-world wires aren't so easy to follow visually.
Forum won't let me put them all in one post, so additional photos will follow in 2nd post.
So I made some guesses and seem to have guessed wrong...

I connected the ground wire DC jack ---> Output jack sleeve ---> Switch board GND ---> Main board GND.
I connected 9V+ to main board and to LED side of switch board.

Wired everything else up according to the link jimilee provided at the beginning of this thread, which all seemed to make sense...  The only thing I didn't do was make any connections between switch poles, being under the impression that the switch PCB was already making those connections...  I'll remove the board tomorrow and follow the traces to see whether this is the case or not.

Plugged in DC power and hit the switch... LED did not light up.
Plugged guitar and amp in - with pedal off(?) audio passes through unaltered...

With pedal on(?) there is no audio, and a quiet high pitched whine which which disappears when I turn the potentiometer yet won't return at any position? I unplugged it immediately rather than risk damage.

I also notice that the switch PCB seems to have an empty space for a resistor right before the LED...
Unfortunately the instructions that came with this kit don't mention or show photos of the switch PCB at all...  Its as if a page was missing - they go straight from populating the PCB to "You now have a boost pedal"!   (link to instructions)

So I'm a bit lost and will wait for advice here before proceeding.

Looks like I won't complete this project tonight, but I look forward to trying again tomorrow if I haven't fried any components...
Quote from: jimilee on March 28, 2023, 03:17:44 AM
On the switching jack, the ground is the l shaped lug. Immediately to the right is the DC power supply, to the right of that is the battery. That one isn't necessary if you don't plan on using a battery.

Thanks for that tip, I would prefer to skip the battery.

Just to make sure I understand correctly I've uploaded another photo.
You're saying that the upper lug / middle lug is the one for the DC power supply, and that I can completely ignore the lug furthest from the L-shaped one (far right in the photo)?

Quote from: jimilee on March 28, 2023, 03:17:44 AM
JI=jack in 
JO= jack out.
BI=board in
BO=board out

Excellent! Now its beginning to make sense!
I'll likely have a few more questions yet though, since this board looks too fragile to tolerate much desoldering/resoldering I want to try to get it right the first time.

I think I have the two PCBs wired together now.
Assuming that:
"BI" on the switch board = in FROM main board (wired to 'OUT' on main board)
"BO" on the switch board = out TO main board (wired to 'IN' on main board)

Quote from: jimilee on March 28, 2023, 03:17:44 AM
Extra +9vs and grounds are just helpful sometimes. You don't necessarily have to use them.

So in theory it shouldn't matter which GND or 9V+ point I choose on each board?
Duplicate connection points on the same board are redundant and purely for convenience?
Do I need to connect GND and 9V+ to both boards?  Or only one?

Your advice on this is hugely appreciated!  Thanks a lot!!!
Well, I have the potentiometer wired in now, thats at least some progress.

Quote from: jimilee on March 28, 2023, 02:42:21 AM
A switching DC jack has 3.

Took me a moment to understand, but now I get it:  When the power supply is plugged into the jack it disables the battery.  Now I just need figure out which is which... Should be able to determine that easily enough with a multimeter.

I know this shouldn't be complicated, but I'm still uncertain of how to wire up the rest.

The main board has:
1 "in"
1 "out"
3 "GND"s (ground)
2 "+9V"s

The switch board has:
"JI" = ____ in?
"JO" = ____ out?
"BI" = ____ in?
"BO" = ____ out?
Two "+9V"s
Three "GND" (ground)

Do I understand correctly that I only need to hook up one GND on each board?

Thanks for the link jimilee!  That will at least get me started!

Another question:  The DC jack has three tabs, but only two contacts, right?  So two of the tabs are internally connected?

Thanks again!