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Hello,
First post here. I've recently acquired an SD sfx-07 a client brought me as part of a thank you for some repair work I've done for him. He said it was fried and if I could fix it I could have it. After reading about D1 being the usual suspect I pulled out the replacement and jumped it from the 9v to the + side of the filter cap. Whadya know. Turned right on! Except it still doesn't work. I'm no expert at tremolo circuits or testing IC's but I've done the following in an attempt to track down the problem. But first here are the symptoms.
Now that it's fired up the pedal passes signal through the switch via TB while the pedal is off. When I turn it on the LED's turn on and blink as expected. Well, the red one does. Yellow is on. It won't pass signal but I can hear the pulsing in the output. Without a schematic I'm having trouble tracing the signal but I've gotten this far:
Signal comes in and goes all the way to U1. Then through to U2. This is where I believe it should be coming out of pin 14. (Correct me if I'm wrong) No signal. Is U1 where the signal should be amplified? There's no difference in amplitude but signal passes.
I've tested some other IC's for voltages but don't know exactly what I'm looking for. They all seem to have voltages in various amounts.
Am I missing a step? What would you do next? I'm not going to send this in to a tech because I don't have the money. I'm capable of swapping components but need a little help understanding the method for troubleshooting this circuit, I guess.
Also, U4 has no information on it. Just a blank chip. I'm wondering what that is. Any help would be hugely appreciated. I'm broke right now and have been waiting for a tremolo pedal to come into my life for like 6 months. I was considering building one soon and then this beauty fell onto my bench. I'd love to get it working since it has all the extras. All a boy could dream for in a trem! Ok that was pure cheese. Anyway thanks in advance.
Oh! I'd like to add that the guy doesn't remember what he did but thinks he may have plugged in the wrong adaptor into it. Probably why D1 fried but what could have gone wrong next? Is it possible my matching diode could have to big a voltage drop since it's not surface mount? Is that a thing?
First post here. I've recently acquired an SD sfx-07 a client brought me as part of a thank you for some repair work I've done for him. He said it was fried and if I could fix it I could have it. After reading about D1 being the usual suspect I pulled out the replacement and jumped it from the 9v to the + side of the filter cap. Whadya know. Turned right on! Except it still doesn't work. I'm no expert at tremolo circuits or testing IC's but I've done the following in an attempt to track down the problem. But first here are the symptoms.
Now that it's fired up the pedal passes signal through the switch via TB while the pedal is off. When I turn it on the LED's turn on and blink as expected. Well, the red one does. Yellow is on. It won't pass signal but I can hear the pulsing in the output. Without a schematic I'm having trouble tracing the signal but I've gotten this far:
Signal comes in and goes all the way to U1. Then through to U2. This is where I believe it should be coming out of pin 14. (Correct me if I'm wrong) No signal. Is U1 where the signal should be amplified? There's no difference in amplitude but signal passes.
I've tested some other IC's for voltages but don't know exactly what I'm looking for. They all seem to have voltages in various amounts.
Am I missing a step? What would you do next? I'm not going to send this in to a tech because I don't have the money. I'm capable of swapping components but need a little help understanding the method for troubleshooting this circuit, I guess.
Also, U4 has no information on it. Just a blank chip. I'm wondering what that is. Any help would be hugely appreciated. I'm broke right now and have been waiting for a tremolo pedal to come into my life for like 6 months. I was considering building one soon and then this beauty fell onto my bench. I'd love to get it working since it has all the extras. All a boy could dream for in a trem! Ok that was pure cheese. Anyway thanks in advance.
Oh! I'd like to add that the guy doesn't remember what he did but thinks he may have plugged in the wrong adaptor into it. Probably why D1 fried but what could have gone wrong next? Is it possible my matching diode could have to big a voltage drop since it's not surface mount? Is that a thing?
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