FilterFX - 12dB/oct autowah thing with LP/BP/HP and 8 wave shapes

[blackieNYC]

Depth pot is fine, but I really think all the action of the Offset pot is within the first 1 volt of the 5.

But it is really great! I must box this.

[Kipper4]

If you're offset is not effective (working) you can always tie pin2 to +5 or Gnd with a series 10k.

I'd check it with the scope.
Are you getting good voltages on the offset pot ?

[blackieNYC]

Yes, I'm getting voltages but all the action seems to be under one volt.  It continues up to 5v but it seems to be all highs from one volt up. Just seems like an A-Log pot covers the range a little better. Not a big deal. 

[ElectricDruid]

Have you worked out how the Offset and Depth interact?

If you've got the depth turned up (say to 75%) then the offset will only have 25% of the range to work with, so it might look like only part of the range does anything.

If you turn the Depth down to 0%, you should be able to see the full range of the Offset. With Depth at 0%, the Offset CV allows you to sweep the output voltage over the whole range of the LFO, 0-5V.

[blackieNYC]

I get the interaction now.  I guess it's only with the depth set very shallow that the offset is more useful with a fraction of a volt on pin 2.  Like in the setting you mentioned - with the depth pot at 0%, the guts of the manual sweep are in a small area of the offset pot. I might want to go with a log pot, but either way, it's good.

[jackwithoneye]

Hi guys,
i'm having trouble with my FilterFX,
i'm having loud clicks when switching 3PDT and the resonance & filter switches
Do you have same clicks on yours, or is it quiet?

[Mark Hammer]

I get the interaction now.  I guess it's only with the depth set very shallow that the offset is more useful with a fraction of a volt on pin 2.  Like in the setting you mentioned - with the depth pot at 0%, the guts of the manual sweep are in a small area of the offset pot. I might want to go with a log pot, but either way, it's good.

That's pretty much how the "Manual" and "Depth" controls work on a number of Boss pedals.  The Depth pot essentially pans between the LFO and a DC voltage.  More of one equals less of the other.  It's done like that precisely to avoid one or the other exceeding a controlling DC beyond the capability of whatever it's modulating.

[garcho]

i'm having loud clicks when switching 3PDT and the resonance & filter switches

Most probably 2 different issues. Without providing us with any other information, it will be difficult to figure out.

3PDT true-bypass with LED indicator is a never-ending source of troubleshooting around here. There are tomes written about it online, have you looked those over? First things first: do you have pull down resistors for your input/output caps? They're listed as R2 and R13 on Tom's schematic. Are you following the schematic exactly? Are you using one of Tom's boards?

Look over the "troubleshooting sticky" here if you want anyone to really be able to help you.

[jackwithoneye]

thank you for your answer.
i checked the pulldown resistors R2 and R13 (2M2 and 100K), it's fine.
I'm building with Tom's board.

Loud Clicks (boosted by the resonance circuit) are happening when using the 3PDT, but happens too when the pedal is already on, using the switchs (resonance and filter type LP/BP/HP) or hitting (gently) the case with a piece of metal. Otherwise, the effect works fine.
I made no mod on the circuit, using the documentation.







Voltages :
STOMP LFO IC :
1 -  5.05
2-  2.43
3-  2.40 ( oscillating)
4-  4.93
5- 0
6- 3.80
7- 1.90
8- 2.90


IC1
1- 3.79
2- 3.79
3- 3.70
4- 0
5- 1.37 (??)
6- 3.79
7- 3.79
8- 7.50/7.60 (oscillating)

IC2
1- 3.79
2- 3.79
3- 3.79
4- 0
5- 3.79
6- 3.79
7- 3.79
8- 7.50/7.59 (oscillating)

TR1
C 2.3/2.5 (oscillating)
B 2.2/2.6 (oscillating)
E 5v

REG
C 5
B 0
E 7.5/7.7 (oscillating)






i've tried to resolder the switchs pins and checked the solder joints, without any success, i know it looks like a solder joint problem but i can't find it.
Do you think it can be a switch default, caused by an overheating?

[garcho]

5- 1.37 (??)

As you noted, that looks incorrect. It's also the op amp pin directly connected to the input coupling cap, which might have something to do with the pop.

happens too when ... hitting (gently) the case with a piece of metal.

Check all your grounds, and anything touching your enclosure. Definitely a clue lurking there.

Do you think it can be a switch default, caused by an overheating?

I'm not sure exactly what your mean, but basically the only component that has a chance of over-heating in this circuit is the linear voltage regulator, and that will either smoke or shut itself down before smoking and the LFO would stop working at that point. Does the LFO work?

I'm guessing there is a grounding issue.

[jackwithoneye]

Thanks for the analysis!

5- 1.37 (??)

As you noted, that looks incorrect. It's also the op amp pin directly connected to the input coupling cap, which might have something to do with the pop.

yep, something might be wrong on this part, i have no clue how to know what, but i'll try to inspect the coupling cap and the virtual ground sectors

happens too when ... hitting (gently) the case with a piece of metal.

Check all your grounds, and anything touching your enclosure. Definitely a clue lurking there.

how do i check the grounds? you mean solders and contacts or do i compare ground voltage with another power supply ground?

Do you think it can be a switch default, caused by an overheating?

I'm not sure exactly what your mean, but basically the only component that has a chance of over-heating in this circuit is the linear voltage regulator, and that will either smoke or shut itself down before smoking and the LFO would stop working at that point. Does the LFO work?
I'm guessing there is a grounding issue.

i was thinking about melting plastic parts in the switchs, but i might be wrong.
The LFO works perfectly, and if the effect does too, as long as i dont touch switches and having pops.

i'm sorry for my lack of knowledge and experience, i'm learning, thank you for your patience!

[ElectricDruid]

5- 1.37 (??)

As you noted, that looks incorrect. It's also the op amp pin directly connected to the input coupling cap, which might have something to do with the pop.

happens too when ... hitting (gently) the case with a piece of metal.

Check all your grounds, and anything touching your enclosure. Definitely a clue lurking there.

I agree with both of these points. That pin 5 shouldn't be at that voltage, so that needs to be fixed, and the fact that you can hear something when you tap the case is definitely a clue to something - that's not right.

[jackwithoneye]

thanks guyz, i'll find the source and let you know

for those interested, tom shared this interesting link about "pedal popping"
http://www.muzique.com/lab/pop.htm

[ElectricDruid]

thanks guyz, i'll find the source and let you know

for those interested, tom shared this interesting link about "pedal popping"
http://www.muzique.com/lab/pop.htm

When you contacted me, I hadn't seen this thread and I thought that was all that was going on, but the rest of the symptoms you've described above make me pretty sure that's not it - this is not a basic case of pedal popping. Something else is happening, and if you find it, you'll probably find all the noise goes away.

[PRR]

> pin 5 shouldn't be at that voltage

Meter loading? There's no reason pin 7 would lay at 3.79V by accident. It could be following pin 5. But pin 5 is biased with a 2.2Meg resistor. If we have a 1Meg meter, pin 5 falls to a third(*) of its actual rest voltage while the meter is poking it.


(*) Like 1/3.2. I can't make the numbers "come out right"; however I don't know the meter (datasheet or reality); and why half-supply seems to be 3.79V instead of 4.3V or so (weak battery?).

[jackwithoneye]

> pin 5 shouldn't be at that voltage

Meter loading? There's no reason pin 7 would lay at 3.79V by accident. It could be following pin 5. But pin 5 is biased with a 2.2Meg resistor. If we have a 1Meg meter, pin 5 falls to a third(*) of its actual rest voltage while the meter is poking it.


(*) Like 1/3.2. I can't make the numbers "come out right"; however I don't know the meter (datasheet or reality); and why half-supply seems to be 3.79V instead of 4.3V or so (weak battery?).

English is not my native language, i may have misunderstand some parts of your post , sorry for this

my Vbios voltage is 3.86v (measured between R20 and R21) not 4.5v. (device powered by a Ciocks dc7 power supply, it was 3.79v with a random testing power supply). The ciocks delivers 9.26v(600mA), the random one gives 9v
pin5 is about 1.20v ( i may have been wrong with the 1.37v, or it changed...)
VDD about 7.6v (REG1 in)
The R23 (47R) might overdrained voltage because it is a 47.9ohms, i can change it to 47-ish, but it still doesnt explain the difference, right?

As my meter doesn't go further 2M ohms, i dont get any conductivity and measure, but the R3 value is 2.2M ohms (red-red-green-yellow-brown).
i'll get a high end meter, i promise.

[garcho]

What is your source of power? Why is it 7.5 volts? It doesn't explain the issue you have, but it could be another clue. Battery? AC to DC wall adapter?

[PRR]

> What is your source of power? Why is it 7.5 volts?

He says "Vbios voltage is 3.86v (measured between R20 and R21) not 4.5v. ...Ciocks dc7 power supply,.... 9.26v(600mA), the random one gives 9v..."

Half of 9V should be more than 3.86V. Is one of the "4.7k" resistors not 4.7k? Or is something loading the Vref point?

[jackwithoneye]

> What is your source of power? Why is it 7.5 volts?

He says "Vbios voltage is 3.86v (measured between R20 and R21) not 4.5v. ...Ciocks dc7 power supply,.... 9.26v(600mA), the random one gives 9v..."

Half of 9V should be more than 3.86V. Is one of the "4.7k" resistors not 4.7k? Or is something loading the Vref point?

R20 and R21 are both 4.7K, 4.64K to be precise.
the Vref point is loaded with R23, a 47R right?
on R23 : 1.29v
on D1 :0.28V

make sense?

[ElectricDruid]

Taking a few voltages from the working unit on my workbench, the 7.6V seems to be about right. Running my pedal at 9.2V, I get a 1.2V drop across R23 (I used a 68R because I didn't have any 47Rs, so my situation is a bit worse). The pedal draws a fair bit of current (~25mA or so). This is perhaps not surprising with two optocouplers and two LEDs.

Consequently, with Vdd at about 7.8V, Vbias comes in around 3.8V. What's not right is that pin 5 voltage, which should be a lot closer to Vbias than 1.2V. Check the soldering on R3 and pin 5.

Incidentally, I now think I was being a bit exaggerated with the 2M2 values for R2 and R3. Other pedals I've done use 1M in those positions. I'm not entirely sure why I decided this needed a higher value. I was trying it out, I suppose. Anyway, it should work either way - 1M or 2M2.