News:

Forum may be experiencing issues.

Main Menu

Current Lover (MN3007) Debug Help needed

Started by MAXstruments, February 14, 2014, 08:22:31 PM

Previous topic - Next topic

MAXstruments

Project: Current Lover

Hallo,
I have an non working current lover on the table. He is really giving me a headache.
I spend more then four times the build time debugging this thing. Sadly with no success.
I read all the post on this forum regarding current lover debugging. My problem is nearly like this one:

http://www.madbeanpedals.com/forum/index.php?topic=4009.msg35687#msg35687

But there was no solution to this problem in the above thread.
I'm not ready to give up jet. Maybe someone has an idea!

Thank you for any Help
Max

Changed Values: I have a B1M rate poti mounted and a 1n914 for D2.

Problem:
Ich get only a a wet signal if the bias and clock trimmers are fully open. But its not a real flanging effect.
It also is a little distorted. All potis have some functionality.
I have to turn the volume 3/4 up to get unity gain compared to the bypassed signal. He is not boxed.

What have I Done:
I mesured all resistors. I checked all caps for their markings and verified them. I checked many times for bad soldering or bridges.
I tried to bias with 12v but R33 startet smoking. I tried different values for C18. 10pf, 15pf, 22pf, 220pf.
I noticed that pin7 and pin8 of MN3007 have only output if the bias trimmer is almost fully open.

IC Volteges (9.6v) with switch in flange mode.






IC1 (JRC4558)
1 - 4,8v
2 - 4,8v
3 - 4,2v
4 - 0,4mV
5 - 4,8v
6 - 4,7v
7 - 4,7v
8 - 9,5V
                                                         


IC2 (MN3007)
1 - 9,5v
2 - 4,7v
3 - 2,4V
4 - 0,8mV
5 - 3,3mV
6 - 4,7V
7 - 3,3V
8 - 3,4V
                                                         


IC3 (CD4049)
1 - 9,5V
2-7 - 4,7V
8 - 1mV
9-12 - 4,7V
13 - 0,3mV
14/15 - 4,7V
16 - 30mV
                                                         


IC4 (CD4013)
1/2 - 4,7V
3 - 7-8V varies
4 - 0,4mV
5 - 4,7V
6-12 - 0,4mV
13 - 9,5V
14 - 9,5V
                                                         


IC5 (LM324N)
1-3 - 4,7V
4 - 9,5V
5 - 1-2V varies
6 - 1-2V varies
7 - 1-3V varies
8 - jumps from approx. 1V to 8V
9/10 - 4,4V
11 - 0,4mV
12/13 - 4,3V
14 - 4-5V moving
                                                         


IC6 (LM311)
1 - 0,5mV
2-3 - 1-4V varies
4 - 0,6mV
5/6 - 9,58V
7 - 7-9V varies
8 - 9,58V
                                                         




Scruffie

Recently people have found that reducing the 82k resistor that feeds the bias trim can help with biasing issues, try that.
Works at Lectric-FX

MAXstruments

#2
Hey,
Thank you for the reply.
I put sockets in for R12 and tried 47k and 22k. It changes only the range of the bias but not the distorted flanging like sound.

Govmnt_Lacky

When the circuit is set to Matrix mode, and with the Rate, Feedback, and Volume pots all the way CCW....

What is your clock reading on the MN3007 Pins 2 & 6 with the Range pot full CCW? And what are they at full CW?

MAXstruments

i put the trimmers in their middle position.
Matrix Mode (switch down)
CCW : pin2 = 4,6v, pin6 = 4,6
CW: pin2 = 4,7v, pin6 = 4,6
(switch up)
CCW : pin2 = 4,7v, pin6 = 4,7
CW: pin2 = 4,6v, pin6 = 4,3

Govmnt_Lacky

Was asking for the CLOCK frequencies. Not voltages.

Does your DMM have a frequency measurement feature?

MAXstruments

I have but never used it. Here the measurements against G.

Matrix Mode (switch down)
CCW : pin2 = 301,6 kHz, pin6 = 301,6 kHz
CW: pin2 = 13,3kHz, pin6 = 13,3kHz
(switch up)
CCW : pin2 = 70 - 300 kHz moving, pin6 = 70 - 300 kHz moving
CW: pin2 = 17-200 kHz moving , pin6 = 17-200 kHz moving (sometimes it looks like it's jumping from 200kHz to 800kHz for a moment)

Govmnt_Lacky

Your clock looks quite a bit LOW.

With the pedal in MATRIX mode... set Rate, Feedback, and Volume full CCW. Set Range to full CW.

Adjust the Clock trimmer until you get about 32-35KHz on the clock pins.

Do this first and hopefully that will take care of some of the noise issues.

MAXstruments

Thank You,
i did what you suggested and was able to get it biased. The Sweet spot is around 34 KHz.
I have now flanging without distortion. Unity gain volume in 9v operation is still at 3 o clock. Is that normal?

I also have a other question. Measuring resistance in  a circuit does not always gives clear results. Right?
In circuit R35 for example reads as 100k. Why is that? Other resistors return only moving results. Is that a DMM issue?

Govmnt_Lacky

Quote from: MAXstruments on February 15, 2014, 05:12:49 PM
Thank You,
i did what you suggested and was able to get it biased. The Sweet spot is around 34 KHz.
I have now flanging without distortion. Unity gain volume in 9v operation is still at 3 o clock. Is that normal?

I also have a other question. Measuring resistance in  a circuit does not always gives clear results. Right?
In circuit R35 for example reads as 100k. Why is that? Other resistors return only moving results. Is that a DMM issue?

You can rarely measure resistance while a resistor is in the circuit. Often times you have to remove the resistor from the circuit to get an accurate measurement. So, NO.... It is not a DMM problem.

Glad to see you got it working!  ;)

MAXstruments