Green Ringer Debug

[ugly_guitar_guy]

Howdy Y'all!

So I decided today to take a shot at the Green Ringer using this layout: http://www.fredric.co.uk/misc/green%20ringer.gif

It makes a VERY squeezed sound that I really have to play super hard to get a kind of fuzzy signal out of.

Here's my readings:

Q1
C 1.44
B 1.82
E 5.21

Q2
C 5.96
B 5.21
E 3.46

Q3
C 0
B 0
E 9.42

I used germanium 1N34A diodes, and the only value on the board I didn't follow was a 51k resistor for R13 because I didn't have a 47k.

Any help here?

[ugly_guitar_guy]

I just did an audio probe, and I get fuzzy (what sounds like effected, but not very octave-y) all the way up until the Emitter of Q3, then it just dies. I tried a few different 2N5088's and it's the same thing.

Checked for traces that may be leading to ground, nothing. It's actually a pretty clean solder job for me. No idea why I'm losing it right at the very end.

[lopsided]

hey,

not sure, but either you have mislabeled Q1 and Q3 or there is something very wrong.
The voltage look backwards (for example Q3 is supposed to have supply voltage at the collector)
i am reffering to this schematic http://www.generalguitargadgets.com/diagrams/gringer_sc.gif

[ugly_guitar_guy]

hey,

not sure, but either you have mislabeled Q1 and Q3 or there is something very wrong.
The voltage look backwards (for example Q3 is supposed to have supply voltage at the collector)
i am reffering to this schematic http://www.generalguitargadgets.com/diagrams/gringer_sc.gif

I think I got my pins backwards. I always have a hard time with that for some reason.

So I guess the readings would be:

Q1:
C 5.21
B 1.82
E 1.44

Q2:
C 3.46
B 5.21
E 5.96

Q3:
C 9.42
B 0
E 0

I've also be looking at this breakdown from GGG: http://www.generalguitargadgets.com/pdf/ggg_gro_instruct.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

Q1 and Q2 look to be pretty similar in readings, but obviously Q3 is way off. I'm not understanding where both the Base and Emitter of Q3 are going to ground like that. I'll post a pic of the back of it later. Here's the front:

[lopsided]

hmm, seems like the Q3 base is the biggest problem. either it's grounded (but it doesn't seem to be probable on that layout ; continuity check?) or you have some bad joint there.
I would check the whole section between the two 0,047 caps and the Q3 base with a voltmeter. Start between the 22k resistors and look where it goes wrong.

[ugly_guitar_guy]

hmm, seems like the Q3 base is the biggest problem. either it's grounded (but it doesn't seem to be probable on that layout ; continuity check?) or you have some bad joint there.
I would check the whole section between the two 0,047 caps and the Q3 base with a voltmeter. Start between the 22k resistors and look where it goes wrong.

Yeah, I'll do another continuity check and report back later. Thanks

[ugly_guitar_guy]

Ok, so as usual it was a stupid oversight. I made a trace cut accidentally where there wasn't supposed to be one.  I bridged that, and voila I get a fuzzy sound with VERY LITTLE octave effect in the background.

So I bread boarded the transistor gain tester from geofex and found out the lowest gain 2n3906 I have is hfe 231, and the GR needs a 2n3906 with hfe between 100 and 150 to get the octave effect. How the heck can I find one that low? Do I seriously have to buy a lot of these and just hope to get one in that range?

[Jaicen_solo]

Hmm, I haven't played around with the green ringer myself, but you could potentially alter the circuit to drop the gain a little.
On the GGG schem, you could mess with R4. If you increase the resistor, you drop the gain of the first stage, which might give you what you want.
That said, I have a handful of 2N3906's from different suppliers. One supplier has gains all over 200, the other are all under 200, go figure.

[m-theory]

Fwiw, I built one of these for a buddy who has an original.  I can't recall offhand what I used for transistors...I believe I found some of the original part #'s, but as I recall, the key there was that there be one of significantly lower gain in the middle, so I would think that the part #'s in this layout would work fine.  I initially built it with germanium diodes, as the original was, but when my friend tried it out, he called it "close, but not quite there."  I got it back and replaced the germaniums with 1n914s, and when he tried it again, he said that it was spot on to the original.