DEBUG: Hummingbird Tremolo Vero Clone

[schoolhouse905]

Hi folks. I built a EQD Hummingbird clone the other night following the layout from Tagboard:

http://tagboardeffects.blogspot.com/2013/04/earthquaker-devices-hummingbird.html#comment-form

and referenced the schematic from Effects Layout:

http://effectslayouts.blogspot.com/2015/10/earthquaker-devices-hummingbird.html

I seem to be only getting clean signal. The level pot works, but nothing from the rate and depth pot or SPDT switch.

I've checked I have all the components oriented properly, the cuts in the proper spots, continuity with my multimeter along the traces as supposed it's supposed to, the cuts properly cut the signal. I've scored between the traces with a knife and can't find any bridges (visually and checking with a multimeter). I've also gone through the circuit following the schematic and checked everything is connected properly and everything seems grounded properly.

The only substitution I made was using a j201 (I also tried a 2n25458) instead of 2n5457, and connected the pin of the level pot to ground on the board.

I'm wondering if it's possibly the 2n2646 or j201 I got off eBay? I've tried multiple of both. I've read that this transistor can't be socketed? I have the 3 transistors socketed currently.

I checked the voltages of each of the transistors, but as a beginner, am not sure exactly what I'm looking for or it's telling me about this circuit. These are the readings I was getting with the level pot at full and rate and depth pots at 0.

I have 9.00v going to the board and 100r resistor.

Q1: B2 7.47v
      E   6.65v
      B1 0.03v

Q2: C 0.00v
      B 0.62v
      E 0.00v

Q3: D 7.84v
      S 0.57v
      G 1.92v

Any help, suggestions, advice or guidance would be greatly appreciated! Thank you!

[theehman]

 Very possible it's the 2N2646.  When I built my first Trem-o-Matic pedal I had the same problem.  After some additional testing I found that not every 2N2646 will work in that circuit.  I bought a lot of them and sorted them by plugging them into the circuit to see if they worked and I think it was around half that worked (it's been years).

[schoolhouse905]

Very possible it's the 2N2646.  When I built my first Trem-o-Matic pedal I had the same problem.  After some additional testing I found that not every 2N2646 will work in that circuit.  I bought a lot of them and sorted them by plugging them into the circuit to see if they worked and I think it was around half that worked (it's been years).

Thank you so much for the reply! I was reading some of help and insight you were giving to someone else about this layout a few years back, which was very helpful trying to troubleshoot it, and also why I was starting to think it could be the 2N2646. I tried a few different ones from the small batch I got, but was afraid to try anymore in fear of damaging them. I'll try the rest and see if there's any that work.

Something I noticed with the batch of 2N2646's I got that I haven't been able to find an answer to anywhere. Looking at the datasheet, the tab on the case between E and B2 (top right photo at the top of the page https://components101.com/transistors/2n2646-pinout-datasheet). On the ones I have, the tab is on the opposite side next to B1. Is this normal?

Thanks again for your help, it's greatly appreciated!

[theehman]

Probably a difference in manufacturers.  When I updated the schematic to correct errors I used a pinout that turned out to be different from others.
If you want, I can send you a 2N2646 that has been tested in circuit and verified as working.

[schoolhouse905]

That's so kind of you, thank you! I'll send you a message.

[kaycee]

If you take a look at Moosapotamus' Skippy schematic, you will see a trimmer for what is R10 in your schematic.

http://moosapotamus.net/images/Skippy-v1-scheme.jpg

Also note the use of a 100K C taper pot for the rate.

I have found that with the trimmer, I can tune in the UJT and get the oscillator going in most cases.

[Pies]

That's so kind of you, thank you! I'll send you a message.

Did you manage to get your hummingbird working? Did swapping out the 2N2646 work?

I found a Gerber on PCB way for the Hummingbird so got a handful made up but I'm having the same issue. Sound is passing through when the circuit is engaged but the rate and depth controls have no effect on anything.

[theehman]

That's so kind of you, thank you! I'll send you a message.

Did you manage to get your hummingbird working? Did swapping out the 2N2646 work?

I found a Gerber on PCB way for the Hummingbird so got a handful made up but I'm having the same issue. Sound is passing through when the circuit is engaged but the rate and depth controls have no effect on anything.

I checked my messages and the 2N2646 I sent him did fix his problem.

[Pies]

Perfect, I've just bagged some NOS 2N2646's so hopefully they will work instead of the knock offs I got from eBay.

[Andrekp]

I had this problem when I built the Hummingbird.  I discovered that the oscillator was doing nothing.  So I built just the oscillator on a breadboard and discovered that the pin out of the transistor was different than I expected.  I turned in 180 degrees and it worked fine.  I don't remember whether it was a problem with the layout, or the supposed pinout, but there you are.  So don't toss that "bad" transistor until you are sure.