Boss CH1 chorus pedal ticking

[Ward]

Hey, I just got lumbered with this thing, when engaged it ticks to whatever speed you set the rate knob to. Is this something easy to fix or is it forked Cheers.

[soundguruman]

I would venture that it is a leaky coupling cap or a bad op amp, with DC on the output...
But overall, it's forked, for sure.

[daz]

Hey, I just got lumbered with this thing, when engaged it ticks to whatever speed you set the rate knob to. Is this something easy to fix of is it forked Cheers.

Are you using a A/C adapter or battery? If adapter, and it's not the one that boss recommends for it, i'd try a battery and if that fixes it then you need the proper adapter. Some don't have the right or any filtering and i think can cause that.

[Mark Hammer]

Most chorus pedals will use a fairly standard 2-opamp LFO to produce the modulation. That circuit produces a square wave, then turns it into a triangle wave. When it produces the square, it creates a very sudden draw on the current supply. That, in turn, creates spikes or momentùry disruptions on the power line shared by all the chips, and is heard as a tick. That's why it varies with Speed.

Boss uses an interesting trick to produce a more trapezoid rather than square wave, which should, in theory and practice, eliminate the audible tick by not making the current draw quite so sudden. Boss and most other manufacturers as well will use a low-power/current chip for the LFO to further reduce how much current is drawn when producing that square/trapezoidal wave. This is often an LM358, TL062, or TL022. Here, Boss uses a chip I am less familiar with: the M5223L. However, since it is a different op-amp from what is used in the audio path, one may safely assume they are continuuing in the tradition of using whatever reduces risk of tick the most.

There are things one can do to further reduce audible ticks, but lets first establish that the pedal you have uses the stock circuit and chips. So, does it?

[Ward]

Thanks for the replies guys,
Daz, no difference whether using boss psa adaptor or battery.
Mark, ic 4 is M5223L. This is the blue label analog version. All the wires that go to the board have been resoldered but everything else is untouched as far as I can see.

[Mark Hammer]

Just for the hell of it, find the solder pads for pin 8 on the the 5223 and the nearest accessible ground point. Tack on a 10uf electrolytic cap on the copper side of the PCB between pin 8 and gnd (positive side to pin 8). Let me know if that has any audible impact on the tick.

[Ward]

Just for the hell of it, find the solder pads for pin 8 on the the 5223 and the nearest accessible ground point. Tack on a 10uf electrolytic cap on the copper side of the PCB between pin 8 and gnd (positive side to pin 8). Let me know if that has any audible impact on the tick.

Thanks Mark, it'll be a few hours before I can get to it, I'll report back.

[Mark Hammer]

No problem. Take your time. The good thing is, it's easily reversible.

[Ward]

No problem. Take your time. The good thing is, it's easily reversible.

Managed to get at it right away Mark, no difference mate. I assume pin 8 is on the right looking at the writing? I tacked the cap on both ends just to be sure, one at a time of course, same on both, chorus was not affected nor the damn tick.

[Ward]

So I started a paypal dispute and they found in my favor, the pedal is back with the shyster and I have my money back. That's how you fix a ticking CH1.

[soundguruman]

So I started a paypal dispute and they found in my favor, the pedal is back with the shyster and I have my money back. That's how you fix a ticking CH1.

No reflection on you, but this thread is generating spam bot messages, and e mailing them from MEF to my computer.