Brassmaster clone - no sound when engaged

[bird]

I'm trying to make the perfboard version of the Maestro Bass Brassmaster clone from Effects Layouts: http://effectslayouts.blogspot.com/2017/09/maestro-bass-brassmaster.html. I didn't make any substitutions or changes to the layout (other than the pots aren't board mounted, wired to respective lugs). I got it all wired up and tested, but there's no sound when the effect is engaged. Bypass works, and the LED does light up when engaged. I tried all the switch positions and the full range of the pots, but there was no change.

I tested continuity in a bunch of places, and of course the in and out jack tips have no continuity when engaged. Ground is continuous between jacks. There isn't continuity between the legs of the 42TM018 transformer - should there be? Otherwise, continuity seems okay from my very limited experience.

I measured voltage at a bunch of points and added the values to a picture (reversed so I could follow traces on bottom of board):

When I measured the blue lines coming from F2TM018, the voltage started higher (around 0.05) then steadily dropped and settled at 0.01. I've never used a transformer in a pedal before, is this how it's supposed to be? How can I tell if that component is working correctly? I'm not sure if I positioned it correctly - the "P" on the transformer is towards the inside of the board.

Any idea what I could check for next? Thanks for the help.

[garcho]

Often the first places to check voltages are the power supply connections and semiconductors, since they're having the most fun. You did good by taking voltages but it would be better if you took voltages at each lead of each transistor. Try that and post your results.

I would check the bottom right (according to that pic you posted) chunk of your board for cold solder joints, resistor values, and solder bridges, possibly to ground. Are the transistors in sockets?

[bird]

Thanks for the tips and information, garcho. I updated the image with voltages (strangely a few changed by the Bass pot, maybe I have it in a different position?):


I don't see any visible solder bridges, and I'm not getting continuity between ground and non-ground paths, but I'll double-check for that and cold solder joints when I get my soldering station set up later.

One thing I noticed that might be different or a problem is that I have a resistor attached to the LED. So between the LED+ point on the board and the anode I have a 330R resistor (calculated as value for green LED). I'm not sure if that's supposed to be there, and I doubt that would affect the signal, but figured I'd mention in case that's wrong.

Thanks again for any suggestions.

[bird]

Uh-oh, I think I found a problem. I was following the layout diagram for all the transistors (EBC). Thanks to another post on this forum about messing those up, I re-checked mine, and I think I have the leads wrong. Could someone help confirm this with me? Here's a picture from the Mouser datasheet that for the 2N3391A transistors I used:

So mine are ECB, but I put them in following EBC, so I think that means I need to switch the B and C leads, right?

In that image, is the top diagram looking at the flat face of the transistor?

Unfortunately I didn't socket the transistors, so it'd be great if someone could confirm this before I go through un-soldering and somehow re-soldering them. Thank you!

[Slowpoke101]

Unfortunately you are going to have to de-solder all of those transistors and swap the Collector and Base leads.
The top left diagram represents looking at the flat face of the device.

Be careful when de-soldering the transistors. It is easy to damage them with excessive heat, but don't be too worried.
Good luck.

[Marcos - Munky]

So you indeed have to remove the transistors and try to swap base and collector leads. Or to swap them for ones with the correct pinout. You can use something like a 2N5088, 2N5089, BC547, BC548, BC549... just check the pinout because the 2N and the BC transistors have them in reverse when compared to each other (both have base in the middle, but one is ECB and the other one is EBC).

For the led resistor, it won't affect the signal at all. While the 330r value will work, the led will be too bright. This value was probably calculated based on the max current the led can handle, or a near max current. But you want the led to lit  just a bit and show if the effect is on or off, so you can go with the original 4.7K value and then swap it for something else if you don't like how bright the led is. I use 4.7K for all my builds, but some leds are too bright even with this value.

[duck_arse]

might we see some photos of your build, please?

[bird]

Hooray! I got it working! I replaced all the transistors and made sure the leads were in the correct orientation. I actually switched to 2N2222A transistors from SGS THOMSON/CDIL on the Tayda website. For Q5 in the effectslayout layout I used 2N5308, but had to carefully cross the B and C leads. It sounds really cool! Definitely loud and fuzzy. Lessons learned - carefully check the leads on transistors to match the layout, and transistor sockets are really helpful. I wasn't totally sure that swapped leads would cause no sound, but seems like they did in this case.

I forgot to take a picture of the board before it was all wrapped up, so I'm just attaching a picture of the outside. I tried stenciling with some spray paint and it came out a little sloppy, but overall I think it looks kinda cool.

Thanks so much to everyone that helped me figure this out! On to the next build!

[garcho]

^ nice job! I dig the graphic style, glad you got it working.

If you use sockets you might want to consider using hot glue or something like that to hold the transistors securely once you're happy with the configuration you have.