General Troubleshooting Question

[Bill Mountain]

I rather enjoy troubleshooting my builds (its an opportunity to learn) but I have a quick question.

I have distortion pedal with an LED that blinks intermittently.  Not fast, just kind of random and slow.  Like a meandering on-off-on-off with no real tempo.

I know we can't diagnose it from my description but does this sound like possibly a bad ground or maybe a bad electrolytic on the power supply?

Anyone have anything similar before?

Thanks!

[GibsonGM]

Wow, neat, Bill!  LOL     Maybe it is telling you there's something up with the power supply?  Like....it is going from 7 to 9V and back again...oscillating...I would look there.  Cap working with an R somewhere...

[Transmogrifox]

Try connecting another across the supply and see if it does the same thing.  That will tell you whether the supply is meandering or if there is something in the connection to the LED.

Is it driven by an active circuit like a Millenium bypass?  Might indicate something with the diodes or the FET.

First thing is to confirm the power supply isn't meandering.  You would probably hear the effect of the PS meandering in your effect.

[Bill Mountain]

Thanks for the tips gang.

I wish I had more interesting news to share.

I thought there was something sinister going on because not only was the LED acting funny but the sound was glitchy and too quiet.

I suspected the power supply so I measured every connection and they all tested fine.

Then I decided to swap out the chip and voila it sounded fine.  So I must have had a bad CD4049UBE (which happens).  But the LED was still wonky which tells me they were separate issues.

So...I just decided to swap the LED and it works just fine now.  I even tested the old LED and it works great too.

My only guess is there was a loose connection with the 1st LED that was keyed into the tides or something.

It just goes to show you it's almost always down to craftsmanship and parts do go bad sometimes.

Thanks!