Smoothie Voltages Bad

[mrsmith]

Hi, I'm building a Smoothie, and I'm not get any sound out of the effect when it is on. I am getting a bypass signal. I used 2N5952s (I ordered a quad set from Guitar PCB) and reversed them 180 from the silk screen as instructed. I also had a local store order me a zener diode, but they got the wrong one. They gave me a 100v 1W zener. The guy at the store told me it shouldn't matter, because I only needed to meet or exceed the values.

Well, now I'm getting some pretty high voltages for my ICs and transistors. I won't list all the voltages, but they're around 9v for most of the pin outs (0 where 0 should be), when I'm pretty sure they should be closer to 3-5.

I've reflowed all my joints, triple-checked component values, and feel foolish (total noob). I wanted to believe this guy so I could get this project running, and now I've spent several hours trouble-shooting this build. Could it just be this diode?

Any help would be greatly appreciated, thanks!

[DutchMF]

Dude, the guy that sold you that Zener has got to do his homework a bit better! The voltage on a Zener indicates the threshold, anything above that is going to be let through, in the case of the smoothie to ground. The specified 4.7V Zener makes sure that Vb is at the correct voltage. The 100V Zener they sold you doesn't do anything until the voltage reaches 100V, not gonna happen in your pedal, so your Vb is way off. As you can read in the docs, you can substitute it with a 10k resistor for about the same results. I did the same on my Smoothie, works great! Hope you can get it to work, good luck!

Paul

[mrsmith]

Thanks, man, that really helps! I guess I missed the 10k sub note in the docs.

Have the voltages I've been running through my components have done damage?

[DutchMF]

Have the voltages I've been running through my components have done damage?

Check the datasheets of the IC an JFETs you used to check their maximum ratings. My gut says you'll be ok, but I'm not sure, and those datasheets are somewhere on my other PC  And really, there's only one way to really check: try it!!!

Paul

[mrsmith]

Still no output, at all. I swapped out the 100V zener for a 10k resistor, and my pinout Vbs are good, except for pin 3 on IC 1, which is 3.

I also get .3-.5 on pinout 3 of Q1 and Q2. Is that normal?

I have no idea where to go next, any thoughts? I wish I had a signal probe! I should make one, soon.

I could easily dump the board and components and start again, but as a new builder, I'd really like to trouble-shoot this thing until it works.

[mrsmith]

Also, just to be clear, there're two ground pads on the PCB for the Smoothie, and one is for convenience, right? Both aren't used?

[mrsmith]

Well, after considerable trouble-shooting, it's working. Not sure what the problem was, but thanks for the help with the diode/10k resistor.

[GermanCdn]

Could you post a couple of pics (front and back of the PCB)?  Would give us a better vantage of things to look at/for.

EDIT: Clearly I need to stop reading the forum on my phone in the can.......congrats on getting it up and running.

[DutchMF]

Well, after considerable trouble-shooting, it's working. Not sure what the problem was, but thanks for the help with the diode/10k resistor.

That's good to hear!! Sorry for not getting back to you earlier, but sleep and work got in the way. The diode thing was really easy to spot, but trouble shooting can be a difficult undertaking. To make it easier for the tech wizards around here (I definitly do not consider myself one of them!) to help you, give this http://www.madbeanpedals.com/forum/index.php?topic=902.0 a read. I f you stick to that, you're bound to work out almost any problem you'll run in to. Now, enjoy that Smoothie!!

Paul

[mrsmith]

Thanks, Paul, I definitely need to build an audio probe!