Corrral Chorus/Boss Ce-2 help

[mnordbye]

I'm just finished building the Corrral Chorus from Tonepad, and i have an issue which i didn't find an answer to anywhere else..

I built the CE-2B, the bass guitar version, so i incorporated the effect level mod and the wet-bass mod (unswitched). My issue is that the rate pot doesn't seem to work. When i turn it, it has no effect. I can hear that the pedal has some effect, but it's very subtle. Anyone have an answer to this one?

Will post voltages if necessary.

Magnus Nordbye

EDIT: By the way, R14 is 56k, but i didn't have that on hand, so i used 47k.. Does it make a big difference?

[mnordbye]

BTW: I used a 1N914 instead of the RD11EB diode. I understand that works as a substitute here?

project: http://tonepad.com/getFile.asp?id=101

[mnordbye]

Here's the voltages:

IC1 (4558):
1 5.38                        8 9.20
2 5.38                        7 5.38
3 5.31                        6 5.38
4 0.00                        5 5.36

IC2 (TL022/TL072):
1 1.32                        8 9.20
2 9.20                        7 8.59
3 7.88                        6 1.40
4 0.00                        5 9.20

IC3 (MN3007):
1 9.03                        8 4.81
2 4.79                        7 4.81
3 4.67                        6 4.86
4 0.60                        5 0

IC4 (MN3101):
1 9.03                        8 0.60
2 4.85                        7 3.62
3 0.00                        6 7.52
4 4.78                        5 0.55

All transistors 2N5088

    Emitter:       Base:        Collector

Q1:   4.48       3.51          9.20

Q2:   4.70       4.67          9.20

Q3:   4.52       3.78          9.21

Q4:   7.84       6.88          9.03

Q5:   0.00       0.58          5.17

How does this look?

Magnus Nordbye

[ruispeeds]

I've had a similar problem, mine only started to work when i put a different 11V zener to sub the RD11EB part that i couldn't find, i tried several but only one type got to make it work.

[mnordbye]

Okay, what kind did you use? I use a standard 1N914 diode. read somewhere that it is supposed to work.. Think that might be the problem? Allthough it seems that it is only a polarity protection diode?

Magnus Nordbye

[Andre]

The  rd11 or whatever 11V zener is only there for wrong polarity-  and high voltage protection, so
it's of no influence to the rest of the circuit.
If you use a 1N914 you would still have the wrong polarity- but not the high voltage protection.

The voltage you measured on pin 2 of the TL022 is 9.2.volt.
This should be 1/2 Vcc (about 4.5V)  as it is directly connected to the voltage divider formed by R33 and R34.
I think you will have to concentrate on this part of the circuit.

André

[Fuzzy-Train]

Here's some voltages of a working CE-2... don't know if this helps at all.

[mnordbye]

The  rd11 or whatever 11V zener is only there for wrong polarity-  and high voltage protection, so
it's of no influence to the rest of the circuit.
If you use a 1N914 you would still have the wrong polarity- but not the high voltage protection.

The voltage you measured on pin 2 of the TL022 is 9.2.volt.
This should be 1/2 Vcc (about 4.5V)  as it is directly connected to the voltage divider formed by R33 and R34.
I think you will have to concentrate on this part of the circuit.

André

Ahh, suspect a solder bridge around that area then. I'll check tomorrow.

And thanks for the voltages from a working CE-2! Looking forward to finishing this.

Magnus Nordbye

[mnordbye]

I've resoldered some joints, and it seems pin 2 and 5 have the right voltages now. But now there's no sound at all. I guess i bumped something of, or miswired something.

But anyways, some of the other voltages changed also, does this look right for IC2 (Tl022/TL072)?

1. 4.60    8. 9.20
2. 4.58    7. 4.57
3. 4.58    6. 3.76
4. 0.00    5. 4.58

Magnus Nordbye

[Andre]

The voltages of pins 1,3, and 7 should be moving up and down between almost 0 and 9 V at the rate of the LFO.
If not, your LFO is still not working.

André

[mnordbye]

Ahh, i understand. I'll turn the pot and check that out. I guess something i did when rewiring the external components made the pedal have no sound.

Magnus Nordbye

[mnordbye]

I just realized the voltages on Q4 have changed to. Can this make the pedal not giving any sound at all?

New voltages (old ones further up the page):
E: 3.84   B: 3.59   C: 9.15

Anyone?
Magnus Nordbye

[mnordbye]

I just figured out that R21, which should be 47k, was 470k! I'm at work right now, so can't test it out, but do anyone see a light in the end of the tunnel for me here? 

Magnus Nordbye

[Andre]

I just realized the voltages on Q4 have changed to. Can this make the pedal not giving any sound at all?

New voltages (old ones further up the page):
E: 3.84   B: 3.59   C: 9.15

Anyone?
Magnus Nordbye

These voltages are more like the voltages of Q4 that Alex posted, so they appear to be OK.
Q4 is not in the signal path of both the dry and wet signal, so it can't stop the sound.
I guess the audioprobe could give you a clue of what stops your audio signal.

I just figured out that R21, which should be 47k, was 470k! I'm at work right now, so can't test it out, but do anyone see a light in the end of the tunnel for me here? 

Magnus Nordbye

This 470k resistor will seriously attenuate your dry signal, but i think it would still be audible.
However it does nothing in your wet signal path  so you should be able to hear the effect signal.
So, there's still something wrong there too.
Again, use the audioprobe to trace where your audio stops.

I do see a light at the end of the tunnel for you.
We will get this thing to do what it's supposed to do.

André

[mnordbye]

Thanks for all the help so far! I guess i'll report back when i've re arranged a couple of things.

Magnus Nordbye

[mnordbye]

Gah! I think i've found the problem, or should i say, all those idiotic problems!

R4, R6, R22, R24 and R30 is supposed to be 47k, but everyoneis 470k! Except for R30, which turns up at 154k on the meter.

Any quick "you've found the solutions!" comment, before i grind my teeth and change those resistors?

Oh, and btw, i measured every resistor here, and i must say, some are lower than they should in value. The metal resistors from Futurlec is supposed to be 1%, but some was way under that. The gold medal goes to a 470k resistor, which was 419k... So much for 1 %. I think i'll go for better quality resistors after this.

Magnus Nordbye

[mnordbye]

It's alive!

Changing the resistors with the wrong value was the solution. Thanks for all your help guys!

Magnus Nordbye