Madbean Current Lover 2015 - Clean (no effect) Signal Only

[brucer]

Thanks Eric.  I'm a little relieved that I've at least been using the correct leads for testing!  Unfortunately, the stomp is no longer wired up.  I detached it from the PCB leads when I pulled the PCB from the enclosure.  However, it's still mounted in the enclosure and looks like the "normal"orientation (lug openings point to top and bottom of the enclosure)?





Is there anything I can check on the board to see what I've damaged or done incorrectly?

[EBK]

Check to make sure you didn't short any of those bypass pads together.

When you replaced the chips, did you replace all of them?  Where did you get your MN3007 from?

[brucer]

Thanks Eric.  I've checked all the bypass pads with a multi-meter and none of the adjacent pads are showing continuity with one another.  Re: the chips, I did replace them all with new ones from Small Bear (incl. the MN3007).

[Govmnt_Lacky]

Back again and still saying you need to explore why it is that you have 9VDC on Pin 13 of the CD4013 clock.

If you look at the datasheets, there is no logical reason why Pin 13 should have any voltage on it (same goes for Pin 12 which I can only assume is a typo on the madbean build doc) as all of the other pins for that logic have 0V 

Have you checked to see if you have a short between Pins 13 and 14 (with the chip removed) on IC4?

I'm not saying its the root of your problem BUT... it could certainly be one of the causes.

[EBK]

Please follow my bending pin 11 up suggestion from December 9th and report your voltages. 

[brucer]

Thank-you both.  I'll try my best to do as you suggested tonight.

Regarding bending up pin 11 on IC4, re-socketing, applying 9V, bending pin 11 back, re-socketing and reporting voltages, is it enough to use a 9V battery, ground the negative lead and touch the positive lead to pin 11 on IC4 just once?

(sorry for the newbie question, I just want to get it right and not make things worse) 

Thanks again.

[EBK]

Thank-you both.  I'll try my best to do as you suggested tonight.

Regarding bending up pin 11 on IC4, re-socketing, applying 9V, bending pin 11 back, re-socketing and reporting voltages, is it enough to use a 9V battery, ground the negative lead and touch the positive lead to pin 11 on IC4 just once?

(sorry for the newbie question, I just want to get it right and not make things worse) 

Thanks again.

Just run a wire from your +9v spot on your board and briefly touch it to pin 11.  Actually, though, I maintain that this is not a meaningful test.  We'll instead test the half of that chip that is actually connected to something.  More on that later. 

[EBK]

Back again and still saying you need to explore why it is that you have 9VDC on Pin 13 of the CD4013 clock.

If you look at the datasheets, there is no logical reason why Pin 13 should have any voltage on it (same goes for Pin 12 which I can only assume is a typo on the madbean build doc) as all of the other pins for that logic have 0V 

Have you checked to see if you have a short between Pins 13 and 14 (with the chip removed) on IC4?

I'm not saying its the root of your problem BUT... it could certainly be one of the causes.

I've looked at the data sheet.  Pins 12 and 13 are flip flop outputs, and one will always be logical HI (9 volts in this case), and the other will be logical LO (0 volts).  The state of those pins is determined on a rising edge of a clock pulse on pin 11.  If there never is such a rising clock pulse on pin 11, then pins 12 and 13 are left unchanged from whatever initial (arbitrary) state they are in at power up.  It is not possible for both pins 12 and 13 to be at 0 volts.  The madbeans measurements of those pins and brucer's measurements are equally valid and consistent with proper operation of that chip.  Moreover, the arbitrary nature of those pin voltages presents no possible source of error in this circuit because they are not connected to any other part of the circuit, i.e., that half of the chip is unused.

[brucer]

I've been very tied up with holidays + family, but got back to troubleshooting this circuit last night.  Unfortunately, I had little success.

Re: Govmnt_Lacky's concerns/suggestions around IC4, I confirmed that I don't have a short between Pins 13 and 14 with the chip removed (Yay!!).

Re: EBK's thoughts about flip/flopping voltages on pins 12 and 13 of IC4 by momentarily touching a 9v supply to a bent up pin 11:
- I tried once and was unsuccessful in flip/flopping pins 12 and 13 on my currently installed CD4013;
- I tried again and broke pin 11 off my currently installed CD4013 when bending it back into position (URGH!!);
- I installed the second CD4013 that I have on hand and it had the opposite pin 12 and 13 voltages from the first CD4013 that I tested.

Sooo ... not exactly the direct test of EBK's thoughts on flip/flopping pins 12 and 13, but suggestive that he's correct.

In any event, I still have clean signal only through the circuit and voltages are still the same as on the "Chip Set #2" page in my original post except that pins 12 and 13 of IC4 are now reversed.

I'd really appreciate it if anyone has some other thoughts on troubleshooting /testing/fixing this circuit as I'm at a bit of an impasse.

Thanks! 

[EBK]

I've been very tied up with holidays + family, but got back to troubleshooting this circuit last night.  Unfortunately, I had little success.

Re: Govmnt_Lacky's concerns/suggestions around IC4, I confirmed that I don't have a short between Pins 13 and 14 with the chip removed (Yay!!).

Re: EBK's thoughts about flip/flopping voltages on pins 12 and 13 of IC4 by momentarily touching a 9v supply to a bent up pin 11:
- I tried once and was unsuccessful in flip/flopping pins 12 and 13 on my currently installed CD4013;
- I tried again and broke pin 11 off my currently installed CD4013 when bending it back into position (URGH!!);
- I installed the second CD4013 that I have on hand and it had the opposite pin 12 and 13 voltages from the first CD4013 that I tested.

Sooo ... not exactly the direct test of EBK's thoughts on flip/flopping pins 12 and 13, but suggestive that he's correct.

In any event, I still have clean signal only through the circuit and voltages are still the same as on the "Chip Set #2" page in my original post except that pins 12 and 13 of IC4 are now reversed.

I'd really appreciate it if anyone has some other thoughts on troubleshooting /testing/fixing this circuit as I'm at a bit of an impasse.

Thanks!

Welcome back!  It's probably time to check out the clock circuitry, starting with pin 7 of IC6.  Then pins 1, 2, and 3 of IC4.  Then pins 2, 4, 6, 10, 12, and 15 of IC3.  Looking for a clock signal in each of these places.  Sorry about your broken IC pin.  Again, I would encourage you to actually ignore the voltages on pins 12 and 13 of that chip.  There are more meaningful tests you can perform on the pins that are actually connected to the rest of the circuit. 

[brucer]

Thanks Eric.  I appreciate your sticking with me. 

Another newbie question though (sorry): will I know I have clock signal if I hear tone when using the audio probe of my testing rig (or do I test for it in some other way)?

I tried the audio probe on the board in (S) and out (R), just to make sure the probe was working (got tone on both).  However, I get zero tone on pin 7 of IC6.  In fact, the audio probe gives me no signal on any pin of IC6, except a sound like waves washing rhythmically on a beach on pin 3.

[EBK]

Should have a varying voltage on pins 2, 3, and 7 of IC6.
If you dont, then go further back.  You said your LED is blinking, so pin 14 of IC5 is presumably good.  Check pin 10 of IC5.  Don't know what you should expect to hear with audio probe in this non-audio part of the circuit (perhaps someone else knows if that would help).  Your DMM should at least show some changing voltages.

[brucer]

Thanks Eric.  I can confirm varying voltages on all the pins that you mentioned:

- pins 2, 3, and 7 of IC6
- pins 10 and 14 of IC5
- pins 1, 2, and 3 of IC4
- pins 2, 4, 6, 10, 12, and 15 of IC3

[EBK]

Great.  I'll assume your clock circuit is still working, although check for varying voltage at pins 2 and 6 of IC2 just to make sure.  Note: I'm making a huge assumption here.  Merely having varying signals is not conclusive evidence of good clock signals.  An oscilloscope measuring pins 2 and 6 would be ideal.... 

(Another hunch: Check to see if Q1 is seated firmly in its socket.)

[EBK]

Is your clean signal making it to pin 3 of IC2?

Do you have a signal at the base and emitter of Q1?

(Trying to debug more rationally here.   )

[brucer]

Thanks Eric.  I appreciate your continued guidance.

Great.  I'll assume your clock circuit is still working, although check for varying voltage at pins 2 and 6 of IC2 just to make sure.  Note: I'm making a huge assumption here.  Merely having varying signals is not conclusive evidence of good clock signals.  An oscilloscope measuring pins 2 and 6 would be ideal.... 

(Another hunch: Check to see if Q1 is seated firmly in its socket.)

Unfortunately, I don't have an oscilloscope (and I don't know how to use one  ).  If the settings/tests are fairly straightforward, then I may be able to beg some time on one from a science teacher friend.  He says that he has some donated scopes in storage, but they haven't been used in a long time and may not be calibrated (not sure what that means ....  ).   

In the meantime, I've confirmed varying voltage at pins 2 and 6 of IC2 and that Q1 is seated firmly in its socket.

Is your clean signal making it to pin 3 of IC2?

Do you have a signal at the base and emitter of Q1?

(Trying to debug more rationally here.   )

Also, my clean signal is making it to pin 3 of IC2, but not to the base or emitter of Q1.  Does that suggest that my MN3007 is bad?

Thanks again, Bruce.

[EBK]

Also, my clean signal is making it to pin 3 of IC2, but not to the base or emitter of Q1.  Does that suggest that my MN3007 is bad?

Not necessarily.  It could be that your MN3007 is bad, but it could also (perhaps more likely) mean that your clock biasing is not correct. 

I would suggest you go through the biasing steps carefully, but instead of just listening for flanging at the output, keep checking for a signal at the base of Q1.  It is possible that your perceived problem biasing the circuit may have really been a problem with Q1 or something connected after it.

If no matter what you do, you can not get a signal at the base of Q1, then consider replacing the MN3007 and trying again.

[brucer]

Solved!  Thanks so much for your help Eric.  After replacing the MN3007 and Q1, then re-biasing I'm back to a working flanger! I'm going to give it a few days now before trying to box it up.  Very happy to have got it back up and running for now though!

[EBK]

Solved!  Thanks so much for your help Eric.  After replacing the MN3007 and Q1, then re-biasing I'm back to a working flanger! I'm going to give it a few days now before trying to box it up.  Very happy to have got it back up and running for now though!

Yay! 

[EBK]

The remaining question is: what caused it to fail when you boxed it up the last time?  I'm wondering about the DC jack....   Does it have a metal bushing?