Help Debug an EA tremolo

[matan]

so, I tried my luck with the EA. followed the GGG because i had the parts.
http://www.generalguitargadgets.com/effects-projects/tremolo/ea-tremolo/

It works only as a volume boost, no tremolo effect at all.
Did the nesseceray research in google about my transistors pinout, triple cheked the layout before and double check it after soldering.

I followed the schematics, used the stange vero board with 4 horizontal connections and 2 vertical lines.

the schematics: (pdf) http://www.generalguitargadgets.com/pdf/ggg_eat_sc_improved.pdf

my build:
https://drive.google.com/file/d/0B79pqhKeSX-Pb3V1U3luV1ZrcFk/view?usp=sharing
https://drive.google.com/file/d/0B79pqhKeSX-Pdks1WXNHN2VSVEE/view?usp=sharing

The changes i made:
1. I didn't use a volume knob, connecting directly to output.
2. Instead of 100K reverse log pot, used a 250K linear with a 68K resistor shorting lug 1 and 3.
3. some of the resistors are 2 combined and are very close but not exact values (for exapmle: 1.5M+680K=2.18M insted of 2.2M).
4. Capacitors:
used a 473(0.047) cap instead of 0.05uf (C8)
used electrolytic caps in C2, C4, C5, C6 and C7.
the polarities may be one problem, I marked here over the original the schematics the polarities i chose based on other EA versions:
https://drive.google.com/open?id=0B79pqhKeSX-PVFAwSTMwRU5nYW8

and of course - the voltage readings (transistors numbered as in the schematics):

Q1:
E= 1.0
B= 1.52
C= 5.99

Q2:
G= 0.5
S= 0
D= 0

Q3:
E= 8.65
B= 0.55
C= 0

Q4:
G= 3.16
S= 4.8
D= 9.46

last but not least, this is a great forum and I used it alot and it helped me troubleshoot few problems without posting anything, just digging in old posts.
I have 6-7 other builds that works great and it is also thanks to all you guys here.

[matan]

Forgot to mention - I use it with home made guitars only, cigar box guitar style, piezo pickups.
All pedals and amps so far worked great for them.

[Transmogrifox]

Something is wrong at Q2 & Q3.

Q3 Emitter should be zero volts.
Q3 Collector should be moving around and hard to get a steady measurement.
Q3 Base will be near 0.6V but moving around a bit, may be hard to get a steady measurement there too, but depending on your meter the input impedance of your meter might throw off the bias and stop the LFO on its own (if it's a 1Meg input meter).  Probably Q3 base is not a meaningful measurement.

Q2 Gate should be moving around and going negative most of the time.

Guesses:
Unless you reported Q3 measurements wrong, you either have it in backward, or your power and ground traces are reversed.

If you simply reported Q3 in reverse and Q3-C is actually 8.65V but not moving around, then it's possible you have a solder bridge or "solder-hair" short across C4.

Again if Q3 was only reported incorrectly then maybe your electrolytic capacitor polarities are wrong.  I didn't view your markup because my organization blocks google drive.

[GGBB]

Not 100% sure - but I think you have the polarity of C4 wrong. So it may have failed.

[matan]

thanks u all, its very helpfull.

GGBB - that's my guess as well, will try it out.

Transmogrifox - i will check again and post a re-check. meanwhile - here are my modified schematics (with capacitors polarities) in Imgur:
http://imgur.com/97yuLGP

[duck_arse]

from your marked-up dia (go, imgur!), you don't need both C9 AND C1 fitted. this is a diagram correction that should have been made a very long time ago, but, as it happens, you have marked C1 backwards if C9 is also fitted.

C2 you've marked correct - C4 is backwards - C5 and C6 are correct, C7 is actually grounded at both ends, so will be confused if polarised, but will still work turned either direction (unless its a tantalum, and then ..... ?).

I couldn't see anything informative from your googoodrive photos. what part numbers are your transistors and fets?

I also see no-one has said welcome yet. tsk-tsk, and welcome to the forum.

[matan]

ok, so i will change C4 polarity.

Didnt understand what you said about C1 and C9 - can you be more clear, or maybe talk more NOOBish?

and no tantalums were harmed during this build....

Q1=2N3904
Q3=2N5088
Q2\Q4=N5457

[matan]

flipped C4 polarity as duck_arse and GGBB said, Q3 was reversed as Transmogrifox suggested.

It works!! You analog people rock....

BUT - I got a pulse sound coming out of my speaker even without any instrument hooked up, changing with the speed knob.
What could it be? Is it shielding issues? some reversed capacitor? maybe the fact my amp is a Ruby kind?

Also - I skipped the volume knob (25K in the original schematics), and I don't really need all the volume boost. what resistor do you suggest I start experiment with? 25K is my common sense guess, but electronics is still magic to me....

[duck_arse]

C1 is the original input cap for the EA trem circuit. C9 is the original output DC blocking cap for the fet buffer stage, Q4. when the two circuits were joined together, ONE of the caps SHOULD have been omitted. the total value of two caps in series is always less than the lower of the two values, in this case the 220nF. so the 10uf is wasted. it can be removed and the holes linked over. or the 220nF can be stretched across from R17 to R2//R3.

and, the original build article, from 1967 I think, states that C3 should be a tantalum capacitor, because of their low leakage. a leaky cap can produce thumps in the output. sometimes, messing with the values of R7 relative to R19 can help thumping.

as for the output volume, if you really don't need the volume pot, wire a temporary 20k or 25k or 50k pot where it should be, set the volume where you think it is the rightest level, then measure the resistance of the pot either side of the wiper. the 2 nearest standard-value resistors to your measures can then be soldered in instead of the pot. done.

[Transmogrifox]

Get a new cap for C4.  There is a possibility it was damaged, and even though the circuit seems to be working, it might be leaking and injecting some extra pulse into the gain control FET.

That is my best guess.

Also C1 polarity is backwards if using the 10u, but probably doesn't make a difference.

C1 polarity is correct if you short the 10uF cap.

[matan]

sorry for my late response.
you guys help alot.

what's the appropriate manners dictate after the forum help you find the problems and enlighten you?
buy everyone a round of drinks? do some summary for the next NOOB builder?  bake a cake?

[bluebunny]

what's the appropriate manners dictate after the forum help you find the problems and enlighten you?
buy everyone a round of drinks? do some summary for the next NOOB builder?  bake a cake?

Cake??       No, this:

   

[duck_arse]

cake, please.