Current lover weird modulation

[djaaz]

Hi guys,

I finished the current lover, tested it a few minutes. Roughly biased it.
Boxed it.

Plugged it, rebiased it.

And boom: biasing was not easy & when i turn the rate pot, i have this incredebly weird modulation: some kind of random detune on what i play.

I unboxed the pcb, checked for obvious stuff. Changed the bias trimmer. (mostly to do something)
Still the same.
It's 3:20 am now in Paris, so i'm going to bed and will check & list here the IC's voltage.

In the meanwhile, anyone have a brilliant idea?

[Scruffie]

Random Detune...you'll have to be a bit more specific, constantly across the sweep? At the ends of the sweep? Is it dropping out or does the note wobble while flanging?

I know with my first build I biased it too hot and got drop outs at the end of the sweep, the trimmers are slightly interactive so playing with them may help.

All else fails, post your voltages and audio probe.

[djaaz]

Constant yes: as soon as the rate pots moves a bit, it's immediate.
If i turn the clock trimmer counter clockwise, the detunes disappear but so does most of the sweep.

[djaaz]

Another weird stuff: i have some kind of distortion with the flange.
At 2 o'clock of the bias trimmer, this is just what i have: distortion and nothing else.

[Scruffie]

Distortion is normal on the bias, BBDs have a small window where they work and a smaller one witout distortion without using a precision trimmers, it should generally be about half way.

Out of interest 3207 or 3007? It is possible to have a working BBD but have it damaged, poor Static handling can cause this.

I do recall some issue that could occur with the diode in the lfo/clock portion of the circuit... i'll have to dig deeper, your voltages will really help though.

Modulation in the signal suggests this is a lfo/clock based issue.

[djaaz]

Thanks Scruffie!

This is the MN3007 version.

Will post the voltage tomorrow, it's now almost 4am.

[djaaz]

So here we go:

4558:

Pin   Voltage:
1.     4,56
2      4,56
3      2,28
4      0
5      4,12
6      4,54
7      4,52
8     9,08





MN3007:

1    9,07
2    4,52
3    4,45
4    0
5    0
6    4,53
7    4,86
8    4,84




LM311

1     0
2     1,2 - 4,5
3     2,14
4     0
5    9,08
6    9,08
7     8,6
8     9,08




4013BE

1    4,53
2    4,53
3    8,6
4    0
5    4,52
6    0
7    0
8     0
9     0
10   0
11   0
12   0
13    9,08
14    9,08


CD4049UBE

1     9,06
2     4,53
3     4,49
4     4,52
5     4,53
6     4,53
7     4,53
8     0
9   4,52
10   4,52
11   4,52
12   4,51
13   0
14   4,53
15   4,45
16    0

LM324N

1     4,54
2     4,54
3     4,12
4     9,08
5     1,25 - 1,8
6     1,25 - 1,8
7     2,20 - 4,90
8     1,2 - 7
9     4,08
10   3,4 - 5,1
11   0
12     4,5
13    4,15
14    3,20 - 4,90








I'm uploading a video (a bad one) of the sounds i get from it to youtube.
Will upload the link in a few minutes.

Thanks in advance for your help.

[Scruffie]

Hmm... there's something wrong with your 4049 voltages I think... Pin 12 should be around the same voltage as the rest of the pins and pin 13 should be NC.

The clock voltages on your MN3007 are also a little weird... Pins 2 & 6 should be near enough the same.
Pin 4 should be near supply voltage too...

Pin 3 of your 4558 is low, but this could be your multimeter giving an incorrect reading due to impeadance as the other voltages on it seem fine.

Look around the 4049 & 3007 for bad joints or shorts.

[djaaz]

And here's a sound sample.

http://www.youtube.com/watch?v=roaPLahzR9Y&context=C30cc84dADOEgsToPDskIpLiuhAcsvzDBgYa5fx45j

[djaaz]

Hmm... there's something wrong with your 4049 voltages I think... Pin 12 should be around the same voltage as the rest of the pins and pin 13 should be NC.

The clock voltages on your MN3007 are also a little weird... Pins 2 & 6 should be near enough the same.
Pin 4 should be near supply voltage too...

Pin 3 of your 4558 is low, but this could be your multimeter giving an incorrect reading due to impeadance as the other voltages on it seem fine.

Look around the 4049 & 3007 for bad joints or shorts.

sorry, i had misread my notes & inverted values for right side pins of every ICs, edited the voltage & going to recheck values on the mn3007.

[djaaz]

ok, checked the voltage of Pin 4 of the MN3007 and have 0V confirmed. Retraced it on the PCB and finally remembered this note from the doc, so i'm guessing 0V is ok:

"MN3007 – Omit D4, D5 and C5. Connect the square and round pins of C5 together via a jumper. This does two things: 
connects pin1 of  the MN3007 to VC via a 100R series resistor f or (nearly) f ull voltage operation and connects the VGG pin 
of the chip to ground"

[djaaz]

ok, did a bit of wandering on the pcb with an audio probe.

The "detune" modulation gets out of the MN3007 outs. Pin 7 & 8.  BUT it depends on the clock trimmer position:

If full counterclock on the trimmer is 7 o' clock, the detunes start at 8:30.

With the clock trimmer between 7 & 9, i have kind of chorus sounds but no flange.

Anyone?

[djaaz]

Hi guys, i read most of the topics on diy about Thomequee's electric mistress adaptation. Did not get most of it obviously.
Then, i just stared at the pcb and i just have no idea what to do next.
At this point, any idea to continue troubleshoot will be welcome. I will even take a suggestion to kill a black rooster during full moon seriously.

[jkokura]

Have you read all the tips and ideas http://www.madbeanpedals.com/forum/index.php?topic=902.0 there?

Jacob

[djaaz]

Almost, i think.

What i did:
I checked every resistors value with a DMM and taped them to the bom.
Did not check capacitor value (did not have a capacity meter), but double checked the value on the capacitors & taped them to the bom.

I tested it before boxing it. I think it was ok, i had some  noises but i assumed that was because it was out of the box.

Boxed it.
Wired it.
Plugged the power supply with the wrong polarity for a few second. (plugged, switched, led being off, removed the power supply)
Had this weird detune stuff.
Checked the pcb for bad solders
Tried another 4558, just in case.
Checked all ICs.
Played with the trimmers, checked the value of the trimmers. Changed the bias trimmer (measured at 80k instead of 100k)

What i noticed: at some point, i just had no effect at all. I removed the MN3007 replugged it, same behavior with the detune stuff.

Posted all the voltages on ICs.
Used the audio probe, checked in & out of the 4558 & MN3007.

I could check all components value again & i probably will. But i'm pretty confident this is not the issue.

Could the reverse polarity a few seconds have damaged one of the ICs despite the diodes?