DC power Jack issue – (solved)

[Chris]

Hey everyone!  I am having a really frustrating issue that I have not been able to figure out with a pedal that has been working for approx. 6-7 months.

So, my Super Lead build just stopped working yesterday.  No light, no power, no sound when engaged.  When i opened it up to check the voltage, i was getting nothing from the power jack, so I thought that it was a problem with the jack.  I begin to replace the jack – test the new jack – 9.44v.  Great!  Wire the jack into the pedal – again, nothing.  Checked the voltage and again it is nothing.

At this point I am completely baffled.  I un-wired and tested the jack – 9.44v…wtf?  I wired the ground and test again – 9.44v.  I replace the hot wire without soldering – nothing. Remove the wire – 9.44v again.  This is now the case with 3 DC power jacks, and I am not sure anything else to change. the issue seems to be with the +9v connection, but I’m not sure what else to do as power doesn’t seem to be getting past the DC jack.  Anyone have a similar issue?

[Chris]

[Anonymous]

To my thinking, the issue is not a faulty power jack.  It is a SHORT in the pedal circuit.  This is dropping your voltage to ground.  To confirm, unsolder the power wire form the jack and use a DMM to test continuity between the power wire and board ground.  If you have continuity, you have a short circuit.

This can be difficult to trace.  It may be a power wire soldered to an incorrect ground pad, a blown (shorted) 1n4001 diode, a component touching a ground somewhere, etc.

[Chris]

Thanks Wilkie1!  I will check those things.  I did sometimes get a slight pulse of power that would cause the led to flash on and off, so I may check the 1n4001, as I’ve checked the path and reflowed solder.  I did notice that I broke the single 9v trace so I’m wondering if I somehow damaged the footswitch pcb…

Thanks for the tips, most appreciated!

[Chris]

You know what – I just realized (as I looked unsuccessfully for the 1n4001) that I used a zener diode in this pedal as I had run out of 1n4001’s.  I am now thinking 18v got plugged into the pedal, which otherwise wouldn’t be an issue, except that the zener diode is probably only rated at 12v and I blew it.

Thanks again wilkie1!

[Chris]

I’m not sure how to edit my OP, but happy to report that replacing the blown zener with a fresh 1n4001 solved the issue.  Thanks again, wilkie1, for the help in correctly diagnosing the issue!

[Author]

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