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

[brucer]

So, I built a Madbean Current Lover 2015 (http://www.madbeanpedals.com/projects/CurrentLover/CurrentLover_2015.pdf) ...
- it worked fine on my testing rig before boxing
- once boxed, it gave either silence (no signal) or ear-piercing tone when I operated the stomp switch
- probed it: faint testing rig tone when not touching the probe to the circuit and ear-piercing tone everywhere when I probed
- pulled it out of the enclosure
- checked parts and wiring
- re-ran testing rig:
   - faint testing rig tone in bypass, silence when engaged
   - probed and got input tone at input pad, but nowhere else
- took pictures and recorded voltages:







- followed Madbean forum advice:
   - checked parts and wiring
   - reflowed solder joints
   - continuity-tested and short-checked all jumpers and off-board wiring
   - replaced all ICs and transistors with new ones from Small Bear
- re-ran testing rig:
   - clean tone in bypass
   - clean tone when engaged
- recorded voltages with new chip set:



Current status: using "S" and "R" to send and return signal to the PCB from testing rig, I get a clean signal only at "R" no matter how many times I follow the biasing instructions.  Rate light is flashing.

I'm not getting any responses on the Madbean forum (http://www.madbeanpedals.com/forum/index.php?topic=23954.msg235099#msg235099).  I'd really appreciate any help or direction for further troubleshooting or fixes.

Thanks!

[EBK]

I'm looking at your voltages on pin 3 of the two 4558 chips.  Should be the same....  Somehow, your V_B is not correctly making its way from IC7 to IC1.

Double check those resistors in the lower right corner of the board.  Also check continuity between the right side of R4 and pin 3 of IC7.

And check to see if you have a measurable voltage drop across R4. Nevermind that.  You do.  Something is possibly shorting to pin 3 of IC1, causing too much current to flow through R4. 

[brucer]

Thanks for your suggestions Eric.  I really appreciate it!  I'd really like to get this circuit running again. 

Unfortunately, I've double-checked the resistors in the lower right corner of the board and verified continuity between the right side of R4 and pin 3 of IC7. 

Is there something else I could check?

[EBK]

Let me just check to see if I got this bit right:
1.  Everything worked (unboxed)
2.  You boxed it, and it stopped working.
3.  You unboxed it, and it didn't come back to life.

Correct?
I'd suggest reflowing your solder on your pots and toggle.  If PCB mounted parts are not perfectly aligned, boxing up the board can subject the solder joints to significant mechanical stress.  You may have already done the following, but I'll write it anyway: board-mounted pots and switches should be tightly mounted to the enclosure first, then the board should be soldered to them.

If that isn't the issue, we can keep thinking. 

Can you provide links to higher resolution pics?

[Govmnt_Lacky]

Mentioned this on the other forum and got no response.....

Any reason why you have 9V on Pin 13 of IC4 and 0V on Pin 12? Looks like that is either a typo or a problem.

Also, when you are reading voltages on this, make sure you do it in Filter Matrix mode. Also, turn the Rate control all the way CCW.

[EBK]

Mentioned this on the other forum and got no response.....

Any reason why you have 9V on Pin 13 of IC4 and 0V on Pin 12? Looks like that is either a typo or a problem.

Also, when you are reading voltages on this, make sure you do it in Filter Matrix mode. Also, turn the Rate control all the way CCW.

I wouldn't be too concerned about those IC4 voltages.  Those pins appear to be unused anyway, and the stated values would only be guaranteed if at least one clock pulse (one rising edge) reached the clock input (here, the clock is tied to ground).

[brucer]

Let me just check to see if I got this bit right:
1.  Everything worked (unboxed)
2.  You boxed it, and it stopped working.
3.  You unboxed it, and it didn't come back to life.

Correct?
I'd suggest reflowing your solder on your pots and toggle.  If PCB mounted parts are not perfectly aligned, boxing up the board can subject the solder joints to significant mechanical stress.  You may have already done the following, but I'll write it anyway: board-mounted pots and switches should be tightly mounted to the enclosure first, then the board should be soldered to them.

If that isn't the issue, we can keep thinking. 

Can you provide links to higher resolution pics?

Thanks for following up Eric.  Almost right ...

1.  Everything worked (unboxed)
2.  I boxed it and everything worked through testing rig before stomp and DC/IN/Out jacks were connected
3.  I connected the switches and jacks and it stopped working.
4.  I unboxed it and it didn't come back to life.
5.  I switched all ICs and it still didn't come back to life.

I didn't mount the pots or toggle in the enclosure before soldering them to the board, but I did reflow after installing the board in the enclosure (between steps 1 and 2, above).  I also checked parts and reflowed everything after step 4, above.

Not sure if these pics are higher resolution?





I'll try to take better pictures in daylight tomorrow.

Thanks again!

[brucer]

Mentioned this on the other forum and got no response.....

Any reason why you have 9V on Pin 13 of IC4 and 0V on Pin 12? Looks like that is either a typo or a problem.

Also, when you are reading voltages on this, make sure you do it in Filter Matrix mode. Also, turn the Rate control all the way CCW.

Thanks for ideas Govmnt_Lacky.  I saw your original post on MB re: website problems, but not the addition re: voltages.  Sorry.

I double-checked this evening and I've definitely got 9V on Pin 13 of IC4 and 0V on Pin 12.  Urgh.  Is it possible to trace this problem back to a source issue using my audio probe or multimeter?  I'd welcome any ideas.  Thanks again!

Oops: addition re: the switch: I've been taking voltages with pots, trims and switches set per the calibration instructions.  They say switch right which I think is flange mode, not filter matrix.  Should I retake my voltages with the switch left?

[EBK]

See above.  Your IC4 voltages are fine. 
To clarify, those two pins are locked in an arbitrary state because that flip-flop is unclocked.  Your arbitrary state just happens to be the opposite of madbean's arbitrary state.  Treat them as a logical "Don't Care" because they aren't connected to anything in the circuit.

If you really want those voltages switched (perhaps just to convince yourself that the flip-flop isn't fried), bend pin 11 up, resocket the chip, power it up and give pin 11 a 9-volt pulse.

[EBK]

More info gathering.

1. Voltages were all measured unboxed on your test rig?

2. Is there any chance at all you accidentally reversed the polarity of your DC jack when you boxed it up?  Think very carefully about this one and retrace your steps.

3. No clean signal when effect was engaged and in the box?

4.  Currently, clean signal comes through just fine at output when the effect is engaged?

[EBK]

Measure the voltage to the left of C1.  Should be 0.  (Wondering if C1 is shorting or super leaky).

[brucer]

Thanks again Eric for following up.

1. Voltages were all measured unboxed on your test rig?

Yes, all the voltages posted were measured unboxed on my test rig.

2. Is there any chance at all you accidentally reversed the polarity of your DC jack when you boxed it up?  Think very carefully about this one and retrace your steps.

I can't say there's NO chance that I reversed polarity.    I've since changed the power leads since and have no pictures of it boxed, so there aren't any obvious indicators, but I'm pretty sure I metered it boxed to verify DC and GND.  Not absolutely 100%, mind.  Would reversed polarity have caused the circuit to shriek like it did?

3. No clean signal when effect was engaged and in the box?

When it was in the box it gave either silence (no signal) or ear-piercing, shrieking tone when I operated the stomp switch ... but I wasn't sure which was engaged and which was bypass.   

4.  Currently, clean signal comes through just fine at output when the effect is engaged?

Yes, and sounds just like bypass.  The rate indicator is also blinking and changes tempo when I adjust the rate knob.

Measure the voltage to the left of C1.  Should be 0.  (Wondering if C1 is shorting or super leaky).

The left side is 0 VDC, very occasionally 0.1 VDC.

Is any of helpful?  Anything else that I should do or check?

[EBK]

Is anything currently different now connection-wise from when it originally worked, i.e., do you have a switch or jack connected now that wasn't there originally?

I should probably confess that at this point I haven't yet run you through any sort of methodical debugging procedure on this circuit. I'm shooting from the hip here, for the time being. 
But, if you don't mind this approach, I do think we are making some sort of disorderly progress. Ideally, I'd like to get things back to working unboxed and take a long pause. 

[brucer]

Is anything currently different now connection-wise from when it originally worked, i.e., do you have a switch or jack connected now that wasn't there originally?

I should probably confess that at this point I haven't yet run you through any sort of methodical debugging procedure on this circuit. I'm shooting from the hip here, for the time being. 
But, if you don't mind this approach, I do think we are making some sort of disorderly progress. Ideally, I'd like to get things back to working unboxed and take a long pause.

Getting things back to working unboxed and taking a step back sounds great.  That would be a major achievement for me!

Ooops!  EDIT: you asked about different connections from when it worked (not from when boxed).  Sorry.  Answer changed:

The only additional connections from when it worked are the 4 disconnected stomp leads other than Send and Return. 



When I had it operating, there were only jumper, DC, Send and Return leads.

[EBK]

Wait.  So, when it worked, you had send jumpered to return, and you had an input and output jack, right (no send/return jacks)?

[brucer]

Wait.  So, when it worked, you had send jumpered to return, and you had an input and output jack, right (no send/return jacks)?

Nope?  I don't THINK so?  I meant that the only leads attached to the PCB at the time it worked were the ones not crossed out in this picture:



I think the PCB In and Out are labelled S (Send) and R (Return) because the PCB jumpers them to separate solder pads for the input and output jack leads.  Does that make sense?

[EBK]

Wait.  So, when it worked, you had send jumpered to return, and you had an input and output jack, right (no send/return jacks)?

Nope?  I don't THINK so?  I meant that the only leads attached to the PCB at the time it worked were the ones not crossed out in this picture:



I think the PCB In and Out are labelled S (Send) and R (Return) because the PCB jumpers them to separate solder pads for the input and output jack leads.  Does that make sense?

It's actually making less sense.  The schematic shows 4 jacks: input, output, send, and return.  You appear to be telling me that you were not using an input or output....

I'll take a closer look later at the wiring options in the project file to see if I can figure out what you did.

[brucer]

Thanks!  The wiring diagrams posted in this thread are the ones I followed, the one with crossed out leads leads for testing and the full diagram for boxing.

[EBK]

Getting closer to understanding this board.


Looking at the bottom edge of the board, the "bypass" pads are labeled G L S + - I R O:
Ground
LED
Send
(+) LED anode
(-) LED cathode
Input
Return
Output


But, I see on the schematic what you are saying about the input and output being S and R.  So, I and O are merely the jack designations, not FX In/Out, like I assumed, and to make matters worse, S and R have nothing to do with the send and return jacks in the schematic!
This really seems to defy convention, but armed with this new understanding, I can take a better look at what you did. 

[EBK]

My current best guess as to what went wrong is that you may have had your stomp switch rotated 90° when you wired it up.  Now we just need to figure out what the consequences of that would have been....

Do you still have the stomp switch wired up?