Hello!

Back in 2013, I made my first attempt to build this beast, but had no luck—possibly because I used CA3094E chips bought from Aliexpress. That might explain the failure. Now, in 2025, I tried again, this time with more knowledge and many successful pedal builds under my belt. But once again, I failed.

I bought the CA3094E again from Aliexpress at a very cheap price, and—of course—it didn't work. Before throwing the circuit in the trash, I decided to buy a batch of CA3094E chips from BANZAI Music. In an email I wrote to them, they assured me the chips were legit. But again... no success.

The thing is, the ICs from Banzai look exactly the same as one of the previous batches I bought (same side indicator, font, Intersil logo, and batch number), so I have my doubts.

I used the RobertoMasz PCB, with the BorislavGajic parts list, and with the A14 pin2 grounded. I've made a custom lm317 -  lm337 bipolar power supply with the +9 and -10 voltages correctly. At the output of the effect, I think I can hear a mix of all the voices together, but at a very, very low volume. And that's it—no filter, no resonance, and none of the envelope controls seem to be working. It seems to me that everything involving the CA3094 is not functioning.

I took some readings with my multimeter on the Banzai chip (out of circuit), using diode mode. With the positive probe on pin 4, I tested all the other pins with the negative probe and got the following readings:

PIN 1 = 0.748

PIN 2 = 0

PIN 3 = 0

PIN 5 = 0.745

PIN 6 = 0.742

PIN 7 = 0.656

PIN 8 = 0

I understand these readings may not tell the whole story, but they could give me a hint—especially if I can compare them with the readings from a known working CA3094.

So, my main request is: if anyone out there has a verified, original, legit, working CA3094E out of circuit, could you please take the same readings? Hopefully, that will guide me through this adventure.

And of course, any other help or troubleshooting protocol for this effect would be greatly appreciated.

Thanks in advance, everyone.

JEAN PAUL

Where are you located at?

Welcome. First, please don't cross-post (https://www.diystompboxes.com/smfforum/index.php?topic=132.msg1299486#msg1299486 https://www.diystompboxes.com/smfforum/index.php?topic=120180.msg1299488#msg1299488). Those other topics are old - you've done the right thing to start a new topic.

Second - I recommend you breadboard one of the test circuits provided in the datasheet and use that to test your chips.

Quote from: mozz on May 22, 2025, 10:12:15 AMWhere are you located at?

hello, I live in the city of Linares, Chile

Quote from: GGBB on May 22, 2025, 10:33:00 AMSecond - I recommend you breadboard one of the test circuits provided in the datasheet and use that to test your chips.

THanks for your answer, i don't know which one of the test circuits will be enough to check. Can you recomend me one of them?

thanks again

I can relate to your skepticism.
In a pinch, I'd just check the complimentary darlington pair to ensure that they are there. Going further, I'd check on the opamp portion to see if it's in-line with a couple of the "Typical Applications" examples in the datasheets.
Even more simple, make it a unitity gain buffer and see if the output voltage matches the input voltage.

Consider the 3094 a pimitive single channel LM13600, where many applications can be interchangeable with the proper rework and minimal value changes if any at all.
-That one is if you'd rather tinker and not run the math.

I have read they are very suspectable to static esd damage.