Weird Eagle Problem??

[italianguy63]

Well, I finally took some time today and started digging into my Tube Screamer project that did not work.

I found something, and was wondering if anyone else ever encountered it.

I could not find anything wrong, but pedal was passing zero signal.  Injected signal directly to output.  NOTHING.

Long story short, checked traces and found a really weird issue.  The pinout on my 2N4401 NPN was wrong.  The Base and Collector traces were swapped!  I don't know which library I used.. maybe the "stock" one or maybe GM?? But, the schematic was correct and the pinout swapped!  (Base was on pin 3).

Anybody else have a similar experience?

MC

P.S. fixed that issue, but pedal still not working.... baaahhh!

[italianguy63]

Related question:

Could the issue of the legs being swapped have caused damage to other components?  Schematic attached.

I twisted the legs on the trannys and replaced them, but still getting no signal through.

MC

[slacker]

No, swapping the legs wouldn't damage anything except maybe the transistors themselves. The worst that could happen is you'd get 9 volts on all transistor's legs but nothing attached to them would be damaged by that.

Are you getting signal anywhere?

[italianguy63]

No, swapping the legs wouldn't damage anything except maybe the transistors themselves. The worst that could happen is you'd get 9 volts on all transistor's legs but nothing attached to them would be damaged by that.

Are you getting signal anywhere?

I have not dug back into it yet.  When the legs were swapped, the signal must have been grounding out because I had NOTHING.

I have to "start over" again troubleshooting now.. but, I had already spent several hours on it.  Maybe tomorrow morning I can take another stab at it.

[Hobs]

It won't help this go round, but I suggest making your own library and saving components in it after after you confirm the pinouts. As you've learned, you can't trust the libraries. Sometimes this is because there are or were certain pinouts for a particular part, but they are different from the ones you have, even though the base part number is the same. Voltage regulators seem to be particularly prone to this.

[italianguy63]

It won't help this go round, but I suggest making your own library and saving components in it after after you confirm the pinouts. As you've learned, you can't trust the libraries. Sometimes this is because there are or were certain pinouts for a particular part, but they are different from the ones you have, even though the base part number is the same. Voltage regulators seem to be particularly prone to this.

Yeah... I usually use Bean's or GM's library... and I have not run into this before.  Live and learn!  I don't remember which library I used!?  Anyway, no body's fault but mine (Led Zeppelin).  I just learned I need to add one more layer of quality control to my PCB design (i.e. check the semi-conductor pinouts carefully!).  It is what it is.  I may start doing that and saving specific transistors and JFets in a folder someplace.  Thanks! 

Now back to troubleshooting this thing......

MC

[italianguy63]

OK.. it seems to be working.. somewhat.  Output is very low.  Going to check the transistor pinouts AGAIN to make sure I am not backwards.

In the meantime-- would someone review these voltages and see if you see anything amiss?:

IC1--
1- 4.16V
2- 4.19
3- 4.17
4- 0.3
5- 2.78
6- 4.16
7- 4.16
8- 8.41

Q1/Q2  (both read exactly the same)
E- 3.59V
B- 4.17
C- 8.40

Thanks!  MC

[italianguy63]

SOLVED.

I populated and tested another board "just in case."

Works perfectly (after the tranny leg switch)--

Thanks!

MC