DOD FX50B switching problems (how does theier switching work?)

[Chrisq206]

I can't seem to get this thing to switch off and on normally. Their switching seems different, because just testing without the switch seems funny too. The pedal works, the light will go off an on, but I can't figure out what is making it go off and on. I had it set up so I could get it to go off and on by tapping a test lead against the inside of the case. Confusing.

[R.G.]

Schematic?

[Chrisq206]

I think it's the same as other DOD FX stuff. I was hoping find someone who knows the ins and outs on how to fix these things.

[wordstep]

http://www.geocities.jp/dgb_studio/circuit/fx50b.png
http://www.ampage.org/hammer/files/dodswitch.gif

[PRR]

IC1A IC1b is a flip-flop, a static memory cell.

C3 is a dynamic memory, holding the last-state while you tap the switch.

It is a very classic debouncer and alternate-action toggle.

> I can't seem to get this thing to switch off and on normally.

What is "normal"? This type alternate-action is very common.

Do you mean you want the mechanical switch to FORCE the setting? The old-fashioned way?

Disconnect IC1 pin 11. Run 10K from IC1 pin 3 to +9V. Run 1K from IC1 pin 3 through toggle switch to ground. When switch is ON, Q2 is on and Q3 is off; and vice-versa.

[R.G.]

If the FX50 schemo is correct, yep, that's the stock DOD CMOS flipflop, implemented with a CD4007.

I hate all the gorp around the 4007, so when I do one of these, I use a hex inverter. You only need two sections, so you get four chunks of MML (mickey mouse logic) left over to do funny things with.

PRR's right - this switch circuit is a toggle flipflop, triggered by a momentary switch.

If you are in dead earnest about digging through it in detail, post the voltages on the 4007 pins in the "LED-off" state, then short the footswitch with **one** touch of a wire and read the voltages again. The LED should have gone off when you tapped. If it didn't the CMOS chip is broken or something. They're about $0.30 each.

[wordstep]

Thanks R.G.

The MML (mickey mouse logic) really open my eyes. I just Google it.

[Chrisq206]

I just wanted it to work and maybe findout more about how the switch, nothing fancy. Great info though. I just need new switch. I had figured out the momentary thing though.