Help needed with Boss CE-2 clone project

[pgosselin]

You still need to use shielded cables for the input and output connections and be careful with internal cable layout - don't run the rate pot's cables directly over the input stages, etc. The cables still do radiate so care is required.

Unfortunately, I put the rate pot right above the output jack. I may have to shield all three of those wires, as well.

I'm going to do this in three stages. 1. shield the input/output wires. 2 shield the rate pot wires. 3. Make Slowpoke101's board mods. I'm going to test at each stage to see at what point the ticking goes away.

Fingers crossed.

Paul

[Elijah-Baley]

[...]
It does work on the Sabrotone (?) layout - proven by forum member "ponce" late last year. Solved his ticking problem immediately.

Do you know if the Sabrotone layout with the Mark Hammers's anti-ticking mod is posted somewhere?
Else, I guess I can mod it by myself.

When I said that the schematic around the TL022 in the Sabrotone was different frome the Guitar FX layout, it was because the pin connection are different, but their functions are the same. I don't know if I am clear, but it's nothing you still don't know, guys.

Boss uses the mod as well in some of their older effects, eg: CE-3 Chorus. However Boss use a 10nF cap and not a 1nF cap. It doesn't really matter what value cap you use as long as it falls between 1nF and 18nF. Too small and the wave-shaping is insufficient and too high the wave-shaping becomes excessive and causes other fun issues.

Actually, I was wondering however the Boss pedal, doesn't tick? At least I guess it doesn't tick.
Do that mod cause some changing in the sound?

You still need to use shielded cables for the input and output connections and be careful with internal cable layout - don't run the rate pot's cables directly over the input stages, etc. The cables still do radiate so care is required.

I'm not sure what do you mean. Maybe we should try to keep the rate pot wires away from other wires? Or what?

I tried to draw the Sabrotone Layout.
Tell me if there's any mistake.

[Slowpoke101]

I never found a modified Sabrotone layout with the anti-tick mod. I helped ponce modify his board by sending him highly detailed step by step procedures. I can't find those details at the moment but it is not terribly difficult to do. Basically the capacitor is connected to IC2 pins 6 & 7. Pin 6 is isolated from pin 3 (which is connected to the Vref 4.5V rail set by R33 & R34). The resistor is then connected between pins 3 & 6. The end of R31 which was connected to pin 6 now has to be connected to pin 3 (Vref).

Please note: I specified an incorrect lower value for the capacitor. It should be no lower than 10nF and not higher than 39nF.

The Boss CE-2 pedal doesn't have a noticeable ticking problem due to the actual layout used and some good power filtering. However as the pedal ages guess what they start to do? Recap the pedal and it's usually back to normal.

The mod does not change the sound of the pedal in any noticeable way. All the LFO really does is wobble the clock rate slightly which gives the chorus effect.

Routing the cables within the enclosure can cause trouble. The rate pot cables are the most annoying as there is a fair amount of voltage changes carried by the cables. Theses voltages are essentially squarewave (even after the mod) which has quite significant transition noise at the leading and trailing edges of the waveform. This noise is referred to as "ringing" and is quite rich in harmonics. All of this can be picked up (received) by the effect's input amp or input & output cables. Shielded cable is recommended for the input and output cables. There is no reason why not to use shielded cable on the rate and depth pots other than it becomes cumbersome as the cable can be quite thick.

I've had a quick look at your redo of the Sabrotone layout. Very well done. I haven't checked it for any errors yet. That will be done in the morning. Quite late here at the moment.

[Elijah-Baley]

Thanks for all these info.

I hope you can check my modded layout, though it's not so urgent for me, after your last explanation I have some doubts about my drawn.

Anyway I found a schematic of the CE-3, could be useful, I need it.

I'm looking at the two 10k resistors: R46 and R50. Then the resistor R51 100k and the cap C27, it's a 47nF, I think. Are these our anti-ticking guys?

[Slowpoke101]

A partial circuit for reference;



R46 and R50 (both 10K) make up the 4.5V Vref for the LFO. C27 (47uF) filters the Vref.

R51 (100K) and C29 (10nF) make up the anti-tick mod.

I will have a look at your modified Sabrotone layout shortly.

[pgosselin]

Hi everyone,

Sorry it has taken me so long to post about my progress on making the ticking stop in my pedal. As I was desoldering the wires to my foot switch to replace them with shielded ones, the epoxy surrounding one of the lugs on the switch got too hot and I destroyed the switch (never had that happen before). I had to order some new switches and it has taken me over a week to get them.

At any rate, the switches arrived and tonight I wired up a new one with shielded input and output wires going from the input and outputs to the switch and from the switch to the board. The result? The ticking is completely gone. Shielding those wires made the difference.

I did not have to shield the wires going to the rate pot or make Slowpoke101's mod. Although, I am keeping copies of that mod because I might need to make it someday as the caps age. Or if I build this circuit again (highly likely), I'll just incorporate it from the beginning.

Thank you to everyone who helped me get this pedal up and running. I couldn't be happier with it. I've never had a chorus pedal before and I believe this may be my favorite effect now.

Paul

[Elijah-Baley]

Great! I'm glad to hear that.
Where do you find the shielded wires? Can you give a link or show the picture of this kind of wire? I never used it, and I'm curious.

[pgosselin]

Great! I'm glad to hear that.
Where do you find the shielded wires? Can you give a link or show the picture of this kind of wire? I never used it, and I'm curious.

I picked up a spool of this very thin braided cable at Radio Shack about 30 years ago to connect the endpin jack on an acoustic guitar to the onboard preamp I built for the piezo-electric transducer pickup. Since Radio Shack is pretty much out of business, I doubt you could find it today.  Following are pictures of it so you can get a sense of scale. It is constructed very much like guitar cable. There is an inner core surrounded by an insulation sleeve, then surrounding that is braided wire and then the whole thing is covered in some kind of flexible plastic. What you do is you use the inner core for your signal wiring, but when you strip the outer casing, you carefully separate and twist all of the braided wires together then connect them to ground. The grounding wires surrounding the signal wires electrically shield them from everything else in the case. Your aluminum case, when connected to ground is one great big shield. So you're essentially shielding again inside the case.





So where to get this kind of wire today? Other on the board suggest just buying a cheap RCA cable and snipping off the plugs. The cable will be constructed the same. It's tricky stuff to strip, so be careful when prepping your wire.

Paul

[Elijah-Baley]

Thanks.
It is thinner than I thought.

[Elijah-Baley]

Hello!
Folowing the instructions of Slowpoke101 and Ponce I draw a modified Sabrotone layout. The layout is NOT verified, but the mod should work fine.
We have to check if it's drawn correctly.



The instructions I received some time ago:

Cut the vero trace at q30 (under IC2). This cuts the trace between IC2 pin 3 and 6.
Cut the vero trace at q32. This cut isolates IC2 pin 6.
The following steps are done on the solder side of your board. The resistor, capacitor and wire link are going to be mounted on the solder side. Keep the component leads as short as possible and make sure that the leads and the components do not short to anything.
Solder the 68K resistor between IC2 pins 3 and 6. This goes across the first cut you made at q30.
Solder the capacitor between IC2 pin 7 (p31) and pin 6 (q31).
Solder the insulated wire link to IC2 pin 3 (q28) and to R31 (q33). This link restores the 4.5V line going to the depth pot.

This is the CE-3 schematic, where there are the two extra components for the anti-tick mod (10nF and 100k):

[Elijah-Baley]

Sorry! You can read "64 cuts".

From 61 cuts I added, indeed, 3 more cuts, but there's also the thin cut. (See the notes).

[Elijah-Baley]

I built the original version of the Sabrotone Layout. The circuito works, no hum, no ticking. Really Sweet Chorus!

As for the Zombie Chorus I can't appreciate the vibrato mode, but maybe it's just me.
Cool the Intensity mode. Maybe the speed is not so fast, but I know how I can get it faster.

I can test it just with the guitar, I can't hear any difference between guitar and bass mode. Is it normal?