Tonepad's Maestro FSH-1 has a strong ticking

[gigimarga]

In my FSH, after using the TL062, i still have the ticking, but i think it's at a reasonable level...

[returntable]

Okay, now I found the time to work on this project again...
I read in another thread(don't really remember which one it was), that was also about a ticking LFO, that soldering a 100Ohm resistor in series with the power supply could help.
I tried it and it helped! at least a little. the ticking is even less, but still there.
 So maybe changing the resitor value to 150 or 200 Ohm would work? I'll try it in the next few days and let you know.

[DimebuGG]

It does tick even with TL062 but acceptable.

That UP/DOWN switch is useless I guess..

[fogwolf]

Mine ticks too. Even used shielded cables for all the off board wiring. Ugh.

I've gotten the Up/Down switch to work. It takes a lot of playing around with this pedal to get a feel for it. When you switch between the 3 different functions (S+H - Auto Wah Up + Auto Wah Down) the knobs almost always need to be re-tweaked - you can't really leave any of the knobs that the different functions share in the same position (i.e. you can't necessarily click between S+H to Filter Up or even from Filter Up to Filter Down without resetting some things or else you get no or a weak effect).

I would love to see a copy of the manual for the original if anyone has one. I know what attack & decay are but they don't seem to respond like I would expect. I've also never owned an autowah or envelope follower before, so maybe that's part of it. I'm more familiar with attack & decay in the context of an ADSR or AR type envelope for a VCF or VCA in a synth - is the envelope on an autowah an AR envelope or does it take the envelope from the audio signal? Also do attack and decay act like a slew generator in S+H mode? Doesn't really sound like it but they definitely do effect that setting as well.

EDIT - just realized the original didn't have the attack & decay settings - these mods documented anywhere?

[gigimarga]

Here I found some information about FSH-1 and mods:
http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=115&Itemid=26

On the other hand when i use mine at a higher volume i can hear the ticking even in the filter mode!!!!
So, I think that there are big problems with the design...

[fogwolf]

Yeah, depending on the settings (especially with the Range set high in up mode), I get more or less ticking as well.

Noticed that when playing in up mode, I get better response if I dial the Range setting down a bit but in down mode I get better response with it about 3/4 of the way up. Still getting a feel for setting Attack & Decay along with how hard I play. In theory I know how those settings should work, just not in this specific context, and find myself still trying to figure it out, which I will the more I play with it. It all works, though. Just wish someone could figure something out with the ticking.

[flo]

I read in another thread(don't really remember which one it was), that was also about a ticking LFO, that soldering a 100Ohm resistor in series with the power supply could help.
I tried it and it helped! at least a little. the ticking is even less, but still there.
 So maybe changing the resitor value to 150 or 200 Ohm would work?

This helps in limiting the current for the circuit that makes up the LFO. This is a bit crude method (but hey, if it helps...) and can be improved by only decoupling the power supply for the LFO circuit as was described by me at the beginning of this thread:
http://www.diystompboxes.com/smfforum/index.php?topic=69638.msg559774#msg559774
http://www.diystompboxes.com/smfforum/index.php?topic=69638.msg560013#msg560013
http://www.diystompboxes.com/smfforum/index.php?topic=69638.msg559997#msg559997

The main problem is that the sharp change in the LFO signal when it changes direction creates a sharp current/voltage spike in the circuit that is fed into the audio-path.
Try a multiple approach:
- Change the LFO opamp to a low-power one like the TL062.
- Decouple the LFO power supply from the rest of the circuit.
- Apply some current limiting (for instance with a small resistor) to the power supply of the LFO.
- Reduce the steep slope of the LFO circuit's square wave part, perhaps by adding a capacitor at a strategic place. I had good results in a ticking SmallStone by placing a 1uF capacitor between the LFO comparator part of the LFO opamp's + and - inputs...

Good luck with it!

[gigimarga]

- Reduce the steep slope of the LFO circuit's square wave part, perhaps by adding a capacitor at a strategic place. I had good results in a ticking SmallStone by placing a 1uF capacitor between the LFO comparator part of the LFO opamp's + and - inputs...

Where i must to insert the 1uF in Tonepad's schematic? The capacitor must to be electrolytical or not?

Thx a lot!

[fogwolf]

He mentions this here (it's not electrolytic): http://www.diystompboxes.com/smfforum/index.php?topic=69638.msg559997#msg559997

I'm using TL082 chip and shielded wires but like I said still getting ticking. Was waiting for someone else to try the resistor and cap to ground to isolate the LFO. Sounds like folks possibly tried that without much luck. Seems like no one has tried slewing the pulse wave for the S+H yet - maybe that would do the trick (or at least in combination with the isolation and low noise chip).

- Reduce the steep slope of the LFO circuit's square wave part, perhaps by adding a capacitor at a strategic place. I had good results in a ticking SmallStone by placing a 1uF capacitor between the LFO comparator part of the LFO opamp's + and - inputs...

Where i must to insert the 1uF in Tonepad's schematic? The capacitor must to be electrolytical or not?

Thx a lot!

[fogwolf]

I had good results in a ticking SmallStone by placing a 1uF capacitor between the LFO comparator part of the LFO opamp's + and - inputs...

One question - since when you initially suggested this you had not looked at the FSH schematic and were referencing a 741 and a different IC # in the flanger circuit you'd fixed - would this 1uf cap go between pins 5 & 6 (IC3B) or pins 2 & 3 (IC3A) or even both? And this would literally be just touching each lead of the cap directly to those leads on the IC, right (I believe you initially said you could even test this before wiring it in by just touching the caps leads to the chips inputs).

Thanks!

[returntable]

This helps in limiting the current for the circuit that makes up the LFO. This is a bit crude method (but hey, if it helps...) and can be improved by only decoupling the power supply for the LFO circuit as was described by me at the beginning of this thread:

Yes, I realized that too, but it actually does help quite a lot. Not completely, but maybe a raised value will... I'll try that.
The Problem with your Tip in the beginning of the Thread is, that it seems to me that the the LFO should already be decoupled in the Tonepad Schematic.
But maybe I've got it all wrong since I still have to learn a lot.

But If my try doesn't work, I'll try your other suggestions. Except for the different OP Amp, I've already changed that with only little success.

[flo]

Where i must to insert the 1uF in Tonepad's schematic? The capacitor must to be electrolytical or not?

Put the capacitor between pin 5 and pin 6 of IC 3b. No guarantees that it will work because it is a different LFO circuit than the SmallStone one. If it does not improve anything remove it again. It will not break anything...
Elco or not does not matter.

[flo]

would this 1uf cap go between pins 5 & 6 (IC3B) or pins 2 & 3 (IC3A) or even both?

Between pins 5 & 6 (IC3B).

And this would literally be just touching each lead of the cap directly to those leads on the IC, right (I believe you initially said you could even test this before wiring it in by just touching the caps leads to the chips inputs).

Correct, just touch the chip's pins with the capacitor leads: One on pin 5 and one on pin 6 of IC 3B.

But also combine this with the other suggestions:
- Change the LFO opamp to a low-power one like the TL062, LM358 or a TL022.
- Decouple the LFO power supply (even more) from the rest of the circuit.
- Apply some current limiting (for instance with a small resistor) to the power supply of the LFO.
- Reduce the steep slope of the LFO circuit's square wave part, perhaps by adding a capacitor at a strategic place. (well, that's covered now ... )

[flo]

The Problem with your Tip in the beginning of the Thread is, that it seems to me that the the LFO should already be decoupled in the Tonepad Schematic.

Yes, the design already shows some decoupling: 470 resistors and the 220uF capacitors for the 9V  and 8V power supplies.
But it is possible to add some more dedicated resistor-capactor power supply decoupling for the power-supply of IC 3.
Your current limiting resistor is also a good suggestion that seems to work for you. Put one in the positive - and one in the negative power supply lines for IC 3 after the decoupling.

... I'll try your other suggestions. Except for the different OP Amp, I've already changed that with only little success.

Try a combination. All the "little success" adds up...

[returntable]

Yes, the design already shows some decoupling: 470 resistors and the 220uF capacitors for the 9V  and 8V power supplies.
But it is possible to add some more dedicated resistor-capactor power supply decoupling for the power-supply of IC 3.
Your current limiting resistor is also a good suggestion that seems to work for you. Put one in the positive - and one in the negative power supply lines for IC 3 after the decoupling.

All right, I will try that in the next few days and let you know whether it wored or not.

Oh and Flo, thank you so very much for all your help with this problem, I really appreciate it!

[Eb7+9]

from the PCB we can see the clock circuit shares the same gnd leg as the filter ... try cutting the gnd trace which passes under C14 and run a second wire to the common ground between batteries to the filter cap ground ... another, you can add a huge cap between the rails of the audio filter circuit - ie., on downside of 470r filter resistors, between those two resistors ... another, you can try feeding the batteries on the other side of the 470r filter resistors - this sometimes works ... make sure your batteries are fresh / power source able to supply ample current to absorb the spikes without producing ground bump internally ... I didn't go too in depth to check for other spike leaks on the board

[flo]

Good one about the trace cut! I didn't look at the PCB...

[skiraly017]

I've been following this thread and was curious if the original FHS-1 had ticking issues as well? I haven't had the opportunity to try one.

[fogwolf]

from the PCB we can see the clock circuit shares the same gnd leg as the filter ... try cutting the gnd trace which passes under C14 and run a second wire to the common ground between batteries to the filter cap ground

I've never had to do this before - what is the best way to cut a trace on an already etched & populated board?

[flo]

I use a sharp knife and cut the trace several times at the location where I want it cut, then "scrape" the groove a bit wider to make sure the connection is completely cut.
Do not forget to "run the second wire to the common ground..." so that both parts of the trace are still connected to ground.
What you are trying to accomplish here is a "star-ground" (google it...), this should reduce the LFO having an impact on the audio-path in the filter circuit via the common ground trace.
Silly question perhaps but which schematics is being referred to when talking about C14? Tonepad's schematics uses no such indicators... I assume we are takling about the ground trace connected to IC3 pin4.