NEED HELP TS808 Clone NOT WORKING

[jolly]

This is my first attemt at a build and im haveing problems (of course) and i havent had any luck debugging it. PLEASE HELP!!!

1.What does it do, not do, and sound like? = Sound when in bypass mode no sound when effect is on
2.Name of the circuit = Tube screemer
3.Source of the circuit (URL of schematic or project) = www.generalguitargadgets.com
4.Any modifications to the circuit? Y or N = NO
5.Any parts substitutions? If yes, list them.
6.Positive ground to negative ground conversion? Y or N = 20k tone pot 1mb drive pot
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? =>
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 =8.87
Voltage at the circuit board end of the black battery lead =0.00

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:

Q1
C =8.05   
B =8.04
E =8.73

Q2
C=8.73
B=8.02
E=8.01

IC1 (or U1)
P1 4.45     p6 4.44
P2 4.45     p7 4.43
P3 4.43     p8 8.72
p4 0
p5 4.44
p6 4.44

D1
A (anode, the non-band end) = 4.44
K (cathode, the banded end) = 4.43

D2
A = 4.43
K = 4.44

[Seljer]

something is wrong with your transisitors, the base and emitter voltages are way to high

[jolly]

do you think i need to replace them?

[blues]

Hi Jolly,
Check your resistors 510k are connected to the ref voltage( Vr) . Correct voltage of your Vr= 1/2 U batt( your @ 4.435V if your Vbatt=8.87V.
Check also transistor pinout( BCE) .Please note that the base pin is not the middle lead of the transistor.
Good luck
blues

[jolly]

thanks blue i check the resistor and it was 8.04 on one side and 4.44 on the other side on both 510k  resistor and now i  think it is the transistors, now in the parts layout i used the pinout was C B E and B is the middle. Ive used an audio probe and traced the signal to the transistor and i get very week sound out of E pinout B pinout (the middle leg)  but no sound out of C, and C is the one that carries the signal from Q1 to Q2. the transistors im useing are c1815 out of an old broke ts-9 with a maxon board. now im really stumped, i think im useing the right transistors but if B isnt supposed to be the middle pin do i criss cross the legs so B is the middle pin to match the layout?
sorry if this is a stupid question im just a noob

[fixr1984]

Here
And Here
If you look at these data sheets of a c1815 transistor compared to a 2n3904
you can see that the pin out is different. That may be the problem. I think that what
Blues meant by saying that B is not the middle leg

[jolly]

so far no luck. anybody got anymore ideas on what it might be?

[Seljer]

you might have fried the old transistors when you were salvaging them out from the older board. I'd defintely get some new ones and try them in there

[jolly]

well Ive changed both transistors q1 and q2 with new 2N3093 NPN they have the correct pinout as far as matching up with the parts layout (E B C) and Ive used an audio probe and i get single to the transistor but nothing past it. Ive tried to flip the pinout to see if Ive got them in backwards and switch the input and output to see if it was backwards and I'm still coming up with the same thing . anymore ideas ? Ive hit a wall, heres an up date on what im getting now.

1.What does it do, not do, and sound like? Sound when in bypass mode no sound when effect is on
2.Name of the circuit = Tube screemer
3.Source of the circuit (URL of schematic or project) = www.generalguitargadgets.com
4.Any modifications to the circuit? Y or N = NO
5.Any parts substitutions? If yes, list them.
6.Positive ground to negative ground conversion? Y or N = 20k tone pot 1MB drive pot
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? =>8.67
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 =8.66
Voltage at the circuit board end of the black battery lead =0.00

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:

Q1
C =8.65   
B =1.26
E = .71

Q2
C=8.65
B=3.35
E=2.86

IC1 (or U1)
P1 4.25   
P2 4.37     p7 4.25
P3 4.26     p8 8.63
p4 0
p5 4.25
p6 4.25

D1
A (anode, the non-band end) = 4.36
K (cathode, the banded end) = 4.24

D2
A = 4.25
K = 4.24

[R.G.]

The first transistor's base and emitter are 'way too low.  The base should be up at maybe 4V and the emitter should be at about 3.5V. Something is wrong with either the circuit you're measuring or the way you are measuring it. Q2 and the opamp look OK.

[jolly]

i remesured the transistors and now they both read the same Q1 C=8.4 B=1.0 E=.4 E Q2 C=8.4 B=1.0 E.4 . does anybody know what might be causeing them to read so low? or is this right?

[jolly]

i remesured the transistors and now they both read the same Q1 C=8.4 B=1.0 E=.4 E Q2 C=8.4 B=1.0 E.4 . does anybody know what might be causeing them to read so low? or is this right?

[R.G.]

The voltages are not right.

As I said, the bases should be up around 4V or so.

Either (a) your reference voltage is incorrect, or (b) it's not getting to the transistors.

Measure the DC voltage from ground (with the black lead of the DMM)  to both sides of
(1) R2
(2) R12
(3) R9
(4) R13

and post them back. That should tell us which is the problem.

[jolly]

ok i think i got it right, and heres what ive got . why is r13 0.0?
r2=4.19--  1.09
r12=4.18-- 1.08
r9=4.17-- 4.17
r13=0.0-- 0.0

[R.G.]

r9=4.17-- 4.17
r13=0.0-- 0.0

ooops.... sorry. I meant to type in R10, not R13. R13 is 0-0 because it's a pulldown resistor, intended to hold both ends at 0V.

The reason I had you do this is that I suspect trouble with your bias voltage. This is generated by R9 and R10, and used by the base of both Q1 and Q2. What you should see on
R9 is that one end is the battery voltage and one end is half the battery voltage. R10 should show one end at half the battery voltage and the other end at 0V. This is because R9 and R10 are in series across the battery voltage as a voltage divider. They are the same value, so half the battery voltage, more or less, should appear in the middle.

It almost appears that the bias voltage is working correctly, because you report 4.x V at one end of each bias resistor for both transistor, and its the same voltage as appears on R9. However, both ends of R9 should not have the same voltage; one end ought to be battery voltage, the other the bias voltage. I think there was a measurement error there.

Can you remeasure both ends of R9 and R10 to make sure?

But in the meantime, the best guess now is that the transistors.

Here's how the transistors are supposed to work. They are both connected as emitter folllowers, which means that their collectors are tied to some high(ish) voltage and the signal is applied to the base, and comes out on the emitter. In this connection, the input impedance (that is, how little currrent the input eats per volt of input signal) is quite high. The emitter is pulled to ground by the 10K resistor from it to ground, but is pulled up by the trickle of base current from the 510K base resistor. The base eats just enough current from the base resistor to pull the emitter up to within 0.6V of the base, because as a silicon PN junction, that is about all the voltage you can ever put across it. As long as there is enough current available to the base, the emitter will always be pulled up to 0.6V less than the bias voltage.

Yours are not doing that. The emitter is remaining low, and pulling the base down with it. How can that happen?
(1) The resistor to ground at the emitter may be so small that the base can't get enough current through the 510K resistor to pull the emitter up. If the emitter voltage was 0V, we would know that the emitter was accidentally shorted to ground. Since it's not 0V, that puts the problem back to the base. If the emitter resistor is not 10K, but perhaps 1K or some other low value, it might show what you see here. Check the resistor value carefully.
(2) The base-emitter could be shorted. In this case, the base is trying to pull up the emitter resistor by itself, and getting no help from the transistor amplifying action. But in this case the base voltage and emitter voltage would be exactly the same. They're not, so that's not the problem.
(3) The base might not be able to get enough current through the bias resistor. We know this to be true. The 510K resistor has 4.1V on one side and 1V on the other. That means that there is 3.1v/510K = 6uA of current going through it. The emitter voltage is 1.0V. If the emitter resistor really is 10K, that's 100uA. The transistor is then displaying a gain of only 100/6 = 16.7. So the transistor is working... kind of. If the transistor were in the circuit backwards, this might be the case. Bipolar transistors do work if you put them in backwards, but they have very low gain and the now-backwards base-emitter junction which is acting like a collector base junction breaks over at maybe 7V. But sometimes that isn't catastrophic in a 9V circuit. So the "510K" resistor may be higher than 510K, perhaps 5.1M. Or the transistor could be damaged, or inserted backwards.
(4) There might be external interference. The capacitors before the base or after the emitter may be shorted and pulling these points down. You would check this by using your DMM to test for resistance across the cap. It should be more than 5M.
(5) There could be a consistent error in measurement of the voltages. I do this to myself all the time, so I remember to check for it.

The bottom line here is that if
(a) the reference voltage is set up correctly  - 10K/10K and a bypass cap - and
(b) the resistor values on base (510K) and emitter (10K) are correct and
(c) the transistor has a gain over 100 and has the right leads stuck in the right holes and
(d) the capacitors after the emitters and before the bases are not pulling these points down
(e) there is not a soldering or circuit board short or open

it is going to work. The fact that both transistors do the same thing points to something systematic wrong, like transistors inserted incorrectly or a wrong-value resistor rather than a broken cap or solder problem. Chances are that would only be on one of them.

[jolly]

i found some typical noob mistaks with 2 caps and one resistor  "each had one leg in the wrong hole"  i now have have a overbearin hiss and a weak sound. any ideas on how to fix that??

[jolly]

got that one figured out, another noob mistake my transistors were in backwards. !!!!IT WORKS!!!! and don't sound too bad a little noise tho how do i quiet it down ? any suggestion's ?  oh and thanks for the help guys!

[R.G.]

Congratulations!

On the hiss - bipolar transistors can be made permanently noisier by reverse breaking down their base emitter junctions even once.

If the hiss is a real problem, I would put in new low noise devices, like the 2N5088.