Build Your Own Clone Message Board

Minor problem with my analogue delay. LED resolutely stays on regardless of pedal being on or off. Pedal works fine apart from this one minor bug. Tried replacing BS170 transistor as mentioned on other posts but this has had no effect. Wondered of there's anything else any one has done to sort this one.

Thanks.

That's a strange one; usually they won't turn on. please post some pics of the LED circuit on the pcb and the footswitch wiring.

Here's a couple of photos let me know if you need others. I'm not massively bothered by the fault but if it can be fixed that would be cool.

Have you tested the dry output? Does it pass signal in both modes (effect & bypass)?

Hi,

Tested dry out works fine (ie passes signal) with effect on and when bypassed. the only thing I did notice was that when in bypass mode you can hear the clock noise changing pitch when you turn the delay time knob. Its really quite and I know this is part of analogue delay but is it right for it to be audible even when the effect is bypassed or when playing through the dry out?

Audible clocking noise in any effects pedal that uses internal oscillators usually occurs because the oscillator draws a fluctuating current through the pedals ground path. If the audio path shares any of the ground return paths with the oscillators a small signal gets injected into the audio.

There are two solutions - arrange the circuit such that in bypass the offending oscillator is turned off ... or ... re-arrange the ground paths. The best way to avoid induced signals of any kind in audio circuits is to use a star ground where every ground return is connected to a central point.
Just routing a fairly heavy piece of insulated copper wire from the oscillator ground points back to where the negative power enters the PCB may help.

Sometimes oscillator break through can be reduced by local smoothing - wiring a suitable cap across the power supply lines feeding the oscillator - even a 0.1uF ceramic may be enough to reduce very high frequency break through.

There are other possible break through paths - for example the clocking / oscillator signal may not be effectively filtered or cancelled out by the circuit it drives.

Make sure you reheat the solder joints on D7 and Q5 to make sure you don't have a bad connection there, as well the connections to lug 9 on the footswitch. If that doesn't clear it up, try replacing D7 and Q5. You should have continuity from the non-stripped end of D7 to lug 9 of the footswitch; and continuity to lug 8 should be made and broken when you click the footswitch; check on that to make sure the switch is working.


No, that shouldn't be. As Tark pointed out, there are a few things you can do to try to get rid of that. You may also just have the clock trimmer turned up too high.