sshorepunk Posted April 20, 2020 Share Posted April 20, 2020 (edited) Hi Great little filter pedal this, but it isn’t working! it lights up when foot switch is pressed, tone changes, but it’s like it’s stuck somewhere in the envelope! i checked the pots with a meter and all good, that’s the extent of my electrical testing ability! fairly simple circuit, not sure how these things work but I believe the optocoupler is a key part? Tony Edited April 20, 2020 by sshorepunk Quote Link to comment Share on other sites More sharing options...
dannybuoy Posted April 20, 2020 Share Posted April 20, 2020 It does sound like the optocoupler could have failed based on the description. Not sure how easy they are to source but at least it looks like a relatively simple soldering job! I always wanted to mod mine to have an expression control but never quite built up the courage to hack into it! Quote Link to comment Share on other sites More sharing options...
bobbass4k Posted April 20, 2020 Share Posted April 20, 2020 Have you taken any readings on the opto? Check the LED side with the diode tester mode if you know how. You'll struggle to test the LDR side as those have massive dark resistance, but you could test the voltage while it's on if you're comfortable with live testing. Quote Link to comment Share on other sites More sharing options...
sshorepunk Posted April 20, 2020 Author Share Posted April 20, 2020 3 hours ago, bobbass4k said: Have you taken any readings on the opto? Check the LED side with the diode tester mode if you know how. You'll struggle to test the LDR side as those have massive dark resistance, but you could test the voltage while it's on if you're comfortable with live testing. I could probably do it, but ideally would want somebody who knows what they are doing bored in lockdown and want to take a look at my pedal, let me know 😎 Tony Quote Link to comment Share on other sites More sharing options...
bobbass4k Posted April 21, 2020 Share Posted April 21, 2020 (edited) I can take a looksee if you want to drop it in the post - the original vactrols are pretty rare these days and sell for stupid money (£10+ for what is a 50p part) but you can get new versions that are exactly the same for a few quid - there's very little mojo in a vactrol and that looks like a new one anyway. Drop me a PM if you fancy it - I may do it for free just so I can clean that LED bezel - the urge to take a cotton wool bud to it is overpowering... Edited April 21, 2020 by bobbass4k 1 Quote Link to comment Share on other sites More sharing options...
sshorepunk Posted April 22, 2020 Author Share Posted April 22, 2020 I was hoping for that sort of reply, will drop you a PM when I get time as I’m still working cheers Tony Quote Link to comment Share on other sites More sharing options...
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