Kay tremolo is killing me! Allmost solved...

[syndromet]

I'we built the kay tremolo from Dragonfly's layout, but I cannot get it to work. Feels like I have been looking for mistakes on this thing for hundreds of hours, and from probing I have found that I have no signal after the first cap. I don't understand why there should be no signal here. Anyone understand what may be wrong?? I'm using 2n5089's but that should not have anything to say on this.

Added a litle pic to show where it all ends, just follow the nice green line...

[jxoco]

maybe you can post what the voltages are on the 3 pins of the first transistor.

that seems to give helpers an extra hint.

[syndromet]

Voltage is good... 
Battery gives 8.8 V
I got 8.76 at collector of the first Transistor, and 0v at both base and emitter.

I also get 0v after the 470k resistor.
This looks completly wrong to me....
Don't understand why.

[jxoco]

Voltage is good... 
Battery gives 8.8 V
I got 8.76 at collector of the first Transistor, and 0v at both base and emitter.

I don't think that the base should be zero, there is a voltage divider from the +9v to the base, is that the 470k your mentioning, and then from the base to the ground, is that a 43K?
You would expect the base to be at (9/(470+43)) * 43 which looks to be .75

Transistor is crap?

[Transmogrifox]

Measure the resistance to ground (battery negative lead).  It sounds like this node is shorted to ground somewhere.

Also make sure that the 47k resistor from +9V actually has a good solder joint to both +9V and the base by measuring the resistance from the lead on the top of the board to the copper strip where it is supposed to be soldered (on the bottom of the board).

You could also confirm by measuring the voltage on the leads of the resistor with the pedal powered on.  When it's working, the power side lead should be the battery voltage, and the transistor base side lead should be about .7 Volts.  The collector should be somewhere between 3 and 6 Volts.


EDIT:
oh, and take a knife and scrape between each strip.  Sometimes during soldering, you'll cause hair-thin solder bridges to form between leads and traces...and they're very hard to detect just by looking at the board. Sometimes a simple scrape solves all your problems 

[343 Salty Beans]

try replacing the cap?

Sometimes the simplest solutions are the ones we overlook.

[R.G.]

... what to do when it doesn't work...

See the sticky.

[syndromet]

I scraped betwin the leads, and everything got a little better ( I think).... I now get 0.09 V at the base, using the 470 ohm resistor for voltage devider, as shown in the schematic. Actualy I'm using a 82k and a 390k in series, but that should not matter. I tried using only the 82k resistor, wich gave me 0.45 at the base. Still no sound with either the 470k or the 82k.


Still stuck on this thing.

oh, R.G, I used the sticked thread. Helped me solve some problems there, but I still didn't get it to work.
Thanx for all the help guys.

[syndromet]

UPDATED
I found out i had the pinout wrong on all transistors... Thats What happen when you don't keep your head cool. That helped a lot, as I can hear the tremolo from the circuit. Still no guitar sound, though.... Still seems to be something wrong at the base of the first transistor, as it only measures 0.09V. Why?



Here is the checklist to fill out:
1.What does it do, not do, and sound like?
I can hear the tremolo going, and the speed change with the rate knob. No guitar is getting through.

2.Name of the circuit =
Kay tremolo from dragonfly

3.Source of the circuit (URL of schematic or project) =
layout: http://aronnelson.com/gallery/album20/KAY_TREMOLO
Schematic: http://www.generalguitargadgets.com/diagrams/kaytrsc_original.gif

4.Any modifications to the circuit? Y or N
Used a 82k and a 390k in series to replace the 470k resistor. Used a electrolytic cap instead of the tantulum.

5.Any parts substitutions? If yes, list them.
Usen a 82k and a 390k in series to replace the 470k resistor. Used a electrolytic cap instead of the tantulum.

6.Positive ground to negative ground conversion? Y or N
Nope

7.Turn your meter on, set it to the 10V or 20V scale. Remove the battery from the battery clip. Probe the battery terminals with the meter leads before putting it in the clip. What is the out of circuit battery voltage? =>
9.37 V

Now insert the battery into the clip. If your effect is wired so that a plug must be in the input or output jack to turn the battery power on, insert one end of a cord into that jack. Connect the negative/black meter lead to signal ground by clipping the negative/black lead to the outer sleeve of the input or output jack, whichever does not have a plug in it. With the negative lead on signal ground, measure the following:
Voltage at the circuit board end of the red battery lead =
9.36V

Voltage at the circuit board end of the black battery lead =
0V

Now, using the original schematic as a reference for which part is which (that is, which transistor is Q1, Q2, etc. and which IC is IC1, IC2, C1, and so on) measure and list the voltage on each pin of every transistor and IC. Just keep the black lead on ground, and touch the pointed end of the red probe to each one in turn. Report the voltages as follows:

Mesaured from left to right on the Dragonfly layout
Q1
C =9.32V
B =0.09V
E = 0V

Q2
C=0.01V
B=0.51V
E=0.01V

Q3
C=0.01V
B=0.51V
E=0V

Q4
C=0.94V
B=0.68V
E=0V


There you have something more to work with. Hope someone can help me get this thing up and go!

[Transmogrifox]

There's something backwards.   Either your transistors all all in the circuit backwards, or you're mixing up the naming of collector and emitter.  The Emitter is the side (schematically) with an arrow.  For this circuit all the emitters should be 0V.  Who knows...maybe your battery is hooked up backwards.  I have kicked myself for overlooking simple things like that before.

Starting from right moving toward left in the schematic you posted:
Q1 = input amplifier transistor
Q2,Q3 = gain divider transistors
Q4 = LFO transitor

Q1 should measure somewhere near 0.6V or 0.7V from base to emitter.  The collector should be somewhere between 3 and 6 Volts.
Q2 and Q3 should be as you measured them.
Q4 collector voltage should be moving around, and the base will be moving around to a lesser degree.  What you measured, though, looks ok.

The only thing that can be recommended for Q1 is to sit on the pot with the circuitboard in your hand and admire it artistically.  Maybe you'll notice something obvious in the process.

[syndromet]

The only thing that can be recommended for Q1 is to sit on the pot with the circuitboard in your hand and admire it artistically.  Maybe you'll notice something obvious in the process.

I sure did. As I'm slightly colour-blind, i suddenly realised that what I thought was a 47k resistor ptoved to be a 4k7. Futurlec had packed it in a bag labeled 47k, and I was sure this was right. Man those orange and red lines on resistors are hard to tell from eachother. I'll go home and correct this, and see if things get anny better.

[343 Salty Beans]

on a side not, a handy addition to your repair arsenal is an audio probe...MAN, mine has helped me out.

I don't know where the link is, but you can find it on GEO.



I'm not sure if it says so, but the cap attaches to the tip, and the alligator to the sleeve. Then plug the guitar cord into an amp (set the amp at a lower volume, parts of some circuits get really loud) and touch the lead of the cap along the traces of the circuit while having a friend play your guitar. good luck.

[syndromet]

on a side not, a handy addition to your repair arsenal is an audio probe...MAN, mine has helped me out.

I don't know where the link is, but you can find it on GEO.



I'm not sure if it says so, but the cap attaches to the tip, and the alligator to the sleeve. Then plug the guitar cord into an amp (set the amp at a lower volume, parts of some circuits get really loud) and touch the lead of the cap along the traces of the circuit while having a friend play your guitar. good luck.

Thanx for the tip.I have already built an audio probe. That's what made me find where the problem was in the first place.
Changing the resistor helped a lot. I put a 47k in place of the 43k in the voltage divider. Now I actualy have sound, and there is a lot of good tremolo in it. However, I have a gating problem hven playing the strings hard. That is because there is to much voltage goes to the collector of the first resistor, right? Or could this be an effect of using a 47k instead of a 43k?

Thanx a lot for the help, guys. Guess I have learned quite a loc from this project.

[343 Salty Beans]

From my little bit of experience, it just sounds like your transistors are getting mis-biased (voltage from playing hard?). Maybe it's the few substitutions you did, or just a not-so-hot layout (I've never built the Kay, I wouldn't know). Maybe you could replace the biasing resistors with about double-valued pots/trimpots, twiddle them and play until you're getting the right sound when you play hard, soft, or whatever, use your multimeter to measure the resistance, then throw the right resistors in. Or you could just measure the voltages as you get a friend to slam on the strings and then do calculations? It's a little extreme and time-consuming, so maybe try it if all else fails before ya shelve it for a rainy day.

Correct me if I'm wrong, more experienced/knowledgeable people.

[Transmogrifox]

Use your volt meter and make sure that the Q1 collector voltage is between 3 and 6 volts.  If it's less than 3V, then make the 47k resistor smaller until comes somewhere between 3 and 6 volts (preferably ~5V). 

If it's already somwhere between 3 and 6 volts, then the gating is coming from the other two trannies...but it really sounds to me like a mis-biased Q1.  Should be an easy fix.