Danelectro Chicken Salad Vibrato: broken bulb?

Forum dedicated to helping people debug and troubleshoot non-functional pedals or builds. Please use an clear and informative title, indicating circuit and basic problem. Don't forget to mark the issue as fixed if this is the case.
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Jwa1ky
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Post by Jwa1ky »

I have one that I would like to fix and upgrade but I haven't been able to find an incandescent bulb small enough to replace the broken one with. Any idea what would happen if I got an LED instead?

smear
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Post by smear »

the schematic on google (if correct) looks pretty similar to the eqd the depths. using the schem for the depths i bet you could adjust the circuit near the bulb to suit an led, and maybe even add an extra voice control like the depths has.

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lolbou
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Post by lolbou »

Sure the bulb's dead? Might be the power feed of the bulb being dead...
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Jwa1ky
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Post by Jwa1ky »

lolbou wrote:Sure the bulb's dead? Might be the power feed of the bulb being dead...
It probably is. My Grandpa and I did some work on it and replaced the bulb with an incandescent christmas light after taking the original bulb out and accidentally snapping the leads because the plastic around melted into them. There's now a hole where all that plastic used to be and the new bulb sticks through it. The bulb didn't even turn on when I plugged it in so i'm back to square 1. I'm hopefully going to be getting some LEDs delivered by tuesday so i'll need to try those out. Where is the power feed in the pedal though? I'm very new to this so I have no idea what to look for.

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lolbou
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Post by lolbou »

Image

See the transistor connected below the bulb? It's modulating the light intensity following the LFO voltage driving it at its base. If it's toast open, you won't have any current in your bulb, no matter what. There's no protection resistor so keep calm when adjusting the trimpot (don't turn it to 0!!). With a new 9V bulb, set depth to max and rate to min, put the trimpot on max and lower it gently so that it turns on and off correctly...

With depth at max and rate at min, you should see an oscillating voltage at the base of the transistor as well, it's worth checking..
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.

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Jwa1ky
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Post by Jwa1ky »

Yeah, the transistor is definitely fried but I believe the trimmer is too. They were both stuck together by melted plastic i assume is from the pedal's enclosure. But I was able to move the position of the pot and I moved it a tiny bit counter-clockwise and now the christmas light actually turns on and oscillates. It's super small but at least it turns on now lol.

[EDIT]: I turned it like 25 degrees clockwise from the center position and it works normally now. Thank you for the help.

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