One-Eyed LX1-X

[SeneX225]

Préambule: I got this Behringer LX1-X from a friend, who deemed it not working. I've decided to fix it and maybe learn a thing or two in the process.


From the first inspection three problems sprung up immediately: a missing component under left footswitch, said footswitch also missing and a power supply, which required 9V 600mA AC out.
The component turned out to be a crystal oscillator with 12 MHz frequency (value was helpfully written on the board itself) and was promptly replaced (don't mind a lung poking out, it was only way soldering would stick to the side of the oscillator).


The power supply, after a bit of searching and help from people from other thread was acquired (thanks, Craigslist!). After switching the plug so it would actually fit the socket (I sure love a very subtle difference between a 5.5x2.1 and a 5.5x2.5) I've crossed my fingers and powered the Behringer up.


To my surprise, it works! There are still problems, however: most of the present straight out do not produce any sound, the wah pedal appears to be not working and the left switch is still missing.

Therefore, I humbly ask (yet again) your help with these questions:
- What could be a reason the preset problem? Maybe the memory battery?
- What type of button the footswitch uses? I've seen it a lot of times but never actually learned what it's called.

[ElectricDruid]

Hi SeneX,

Good work so far! It sounds like you've made some progress with it.

I don't know about the presets - there's a lot of possibilities why they might not work. Perhaps you can show us a photo of the board. If there's a memory battery for the presets, it should be pretty obvious. Alternatively, there might be an EEPROM. They last a long while, but failures are not unheard of.

From your photo, the footswitch looks like be a "tactile switch". These come in various sizes and designs (through-hole, surface-mount, whatever) but there are lots of them about and they're not expensive to replace. The one on your PCB looks to be through-hole, but the size is hard to tell. You'd have to measure it with calipers. Note that what's missing is not the switch itself, but only the plastic footswitch "paddle" that presses down on it. Getting a new footswitch cover would be difficult. You could either nick one from a dead pedal of the same range, or if you were reall y lucky someone might have designed a replacment for 3D printing.

HTH

[RickL]

most of the present straight out do not produce any sound, the wah pedal appears to be not working

These two things may be related. If the presets that aren't working are just giving no sound, they may be programmed to use the wah pedal as a volume pedal. If the pedal is acting as if it is always toe up (i.e. volume down), there will be no volume, making it sound like the preset isn't working. The fact that some of the presets work indicates that this might be the problem. They will be presets that use the pedal for something else, like wah or speed control of one of the effects.

So... first make sure that the switch without the actuator is actually working. Push the tactile switch with you finger and see if it actually does anything. In preset mode it should toggle down to the next lower preset.

If it is working, perform the pedal calibration procedure. If that is the only problem, you should now hear sound out of the currently non-working presets by just moving the pedal towards toe down.

If the switch isn't working, you'll have to replace it before you can get the pedal fully functioning. Fixing it may not solve the other problems, but you'll have fixed at least one thing.

As mentioned, replacing the actuator is going to be the difficult thing. One possibility would be to replace the tactile switch with some other momentary switch, maybe mounted on a flat piece of thin metal in place of the missing actuator. If that works you might want to to replace the other, working, switch with the same arrangement, just so both switches are the same.

But now you're getting into possibly putting more time and money into the pedal than it's worth. I get why you would do it anyway (I probably would, just to prove to myself that I could) but you should at least think about it.

[SeneX225]

Note that what's missing is not the switch itself, but only the plastic footswitch "paddle" that presses down on it. Getting a new footswitch cover would be difficult. You could either nick one from a dead pedal of the same range, or if you were reall y lucky someone might have designed a replacment for 3D printing.

I looked up an identical replacement but, sadly, found nothing. What I'm going to do is find something that can actually allow the foot to reach the switch and then fashion something on top of it myself (maybe even for both switches so they would match).

These two things may be related. If the presets that aren't working are just giving no sound, they may be programmed to use the wah pedal as a volume pedal. If the pedal is acting as if it is always toe up (i.e. volume down), there will be no volume, making it sound like the preset isn't working. The fact that some of the presets work indicates that this might be the problem. They will be presets that use the pedal for something else, like wah or speed control of one of the effects.

So... first make sure that the switch without the actuator is actually working. Push the tactile switch with you finger and see if it actually does anything. In preset mode it should toggle down to the next lower preset.

If it is working, perform the pedal calibration procedure. If that is the only problem, you should now hear sound out of the currently non-working presets by just moving the pedal towards toe down.

If the switch isn't working, you'll have to replace it before you can get the pedal fully functioning. Fixing it may not solve the other problems, but you'll have fixed at least one thing.

I've taken out (as much as possible) the wah pedal board and here's what I've found:







The tactile switch, when pressed, does nothing. The actuator, as far as I can figure, is some kind of light-sensor switch triggered by a piece of plastic and I don't know if it's working or not.

[Govmnt_Lacky]

The tactile switch, when pressed, does nothing. The actuator, as far as I can figure, is some kind of light-sensor switch triggered by a piece of plastic and I don't know if it's working or not.

The tactile switch is easily replaceable. YOu can find them in a lot of places (Mouser, Newark, etc.) Just need to measure the size of it. Usually they are 6mm x 6mm OR 12mm x 12mm.

The "clear sensor" is a Photo transistor. Those are also used in the Digitech XP pedals. Replacements can be found as well.

Does the red LED light up when the pedal is on (and/or foot pedal actuated)?

From the pictures, I am speculating that the "piece of plastic" is shaded or polarized to give the illusion of changing darkness levels between the LED and the Photo transistor. On the Digitech XP pedals, the foot pedal actually increases or decreases the distance between the LED and the Photo transistor.

EDIT: Would also put some rubber pad or buffer material on the metal nut that pushes down on the tactile switch. Leaving it that way will surely cause damage to the tactile switch in the future.

[SeneX225]

Does the red LED light up when the pedal is on (and/or foot pedal actuated)?

Yes, I does light up when powered on and stays on until the power is off.

I'll find and replace the photo transistor (which, by the way, sounds pretty cool and I should definitely look up how they work) and the tactile switch, and get back to you in a couple of days.

[ElectricDruid]

Oooh, I like that foot pedal mechanism with the faded acrylic going in-between a LED and a phototransistor. There's one way to avoid your scratchy wah pot!

The idea has been around forever, at least. I had an old electric organ with a volume pedal that used a bulb and an LDR in a similar way, with a curved shade that came down between them and cut off gradually more light to the LDR. Nice to see it updated.

[Govmnt_Lacky]

I'll find and replace the photo transistor (which, by the way, sounds pretty cool and I should definitely look up how they work) and the tactile switch, and get back to you in a couple of days.

Phototransistor part number is right on the board. LPT80A

[SeneX225]

Update:

Hello! I apologize for lack of posts, it took a while for the components to arrive and I've only got them yesterday.

Unfortunately, after replacing the photo transistor, tactile button and the battery nothing changed. It works just as before, as in one or two effects in a dozen. I've noticed something that might be helpful, however: when I switch to one of the working effects it sounds one way (an overdrive, for example, that sounds soft), but when I so much as touch the wah pedal, it changes sound (same overdrive gains a lot of gain) and stays that way until I switch to another effect and back. Moving the wah again provides no further changes.

What would be the next step to figuring out what is actually wrong?