Here's a new one

[MAO]

Never had this happen before, need some help.

I just boxed up a PT2399 pedal that seems to be working fine, but the LED glows faintly when bypassed, and only does so when I have a guitar chord plugged into either jack.  

When I remove both cables, the LED goes completely out. Plug either one back in, the LED glows faintly.

I also found that when I connect the red meter lead to ground, and the black lead to the LED's cathode, I get the same faint glow. (diode check mode) How is that even possible?

The pedal sounds perfectly fine, no hum, noise etc. And the LED is the usual bright when the pedal is on.
Bypass sound seems fine as well. Voltages and grounds at the ICs are as expected.

Going to take a knife to the tracks and touch up all the solder joints, but hoping to get some advice as well.

Thanks,
Mike
 

[GrooveChampion]

Had that happen to me on multiple occasions, still have no idea what's going on.

[lasermonkey]

Is your LED in a bezel or glued into a hole in the enclosure?
I have found that some LEDs don't perfectly insulate the leads where they are inside the body of the device. By this I mean that the electrodes protrude slightly from the side of the LED. It's usually not visible by the naked eye and the symptoms can manifest themselves in many, head-scratching ways! Ask me how I know.......

[Travis]

Excellent suggestion lasermonkey

My other guess would be that the switch could be "bleeding". Assuming you are using the offboard wiring from the site, you could check resistance between lugs 1 and 2 with the switch in the bypass position

[MAO]

Thanks guys, really appreciate the support!

Woke up 1/2 dozen times last night with this on my mind, how crazy is that?

The LED will be peaking through, no bezel, but I believe I had the same symptoms with it free standing in mid air. The stomp switch doesn't show continuity when bypassed either.

I discovered the LED won't light in bypass mode if the cables are not attached to the guitar or amp, if I touch the tip of either cable, the LED dimly lights. I don't get it!

Thought it was crazy after all these years, and all the pedals, never seen this before. Kinda glad to hear I'm not alone. :0)

Anyway, I will swap out the LED and then the stomp switch when I get hone as a brute force attempt.
 

[MAO]

Just got in, thought I'd record a short video before I dig in again.

https://youtu.be/kpncm-cQa9g

[Hozy31]

I might be talking crap here, but could you have a short between your 9v supply and battery snap connection on your dc jack? I noticed the snap was grounding against the enclosure .

[MAO]

Thanks Hozy31! I should have mentioned the symptom is the same with a battery and with the circuit outside of the enclosure.

So it appears Travis' suspicion was correct. I haven't boxed it back up yet, but replacing the stomp switch seems to have resolved the issue.  

FWIW, here is what I found today:

I measured voltage across the LED, when on it was around 2.8v, when bypassed and no cables attached voltage was 0v. When I touched the tip of the cable, voltage dropped to a negative 6v.

In this particular circuit, the Vbias is created with 10k resistors, so there is a 20k differential between the supply voltage and ground. I'm thinking the LED probably would have remained off if the Vbias had been created with 100k resistors, giving a 200k differential between the supply and ground.

If anything changes after I box it back up I'll report back, but for now I believe it has been resolved.

Thanks again Travis and those who had the chance to respond.

MAO