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Author Topic: zapped by the headphone jack?  (Read 1011 times)

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Offline Dirkjr

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zapped by the headphone jack?
« on: May 14, 2013, 03:39:17 PM »
After passing the voltage tests I used my newly assembled crack for about an hour. When I went to unplug my headphones from the crack I put one hand on the chasis plate and the other on the half inch plugg (metal). I had the volume down but the amp was still one (seeing as the volume control just affects the input  When the plugg was most of the way out I recieved a significant zap through my hands. Is this normal (cant say I have ever tried holding a grounded plate while removing the jack on any other device) or is there something seriously wrong in my wiring? If it maters when I did the voltage tests there was a constant 15mV reading on the chasis.
« Last Edit: May 14, 2013, 03:47:16 PM by Dirkjr »

Online Paul Birkeland

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Re: zapped by the headphone jack?
« Reply #1 on: May 14, 2013, 05:07:11 PM »
I'd really double check the connection of the 2.49K resistors on the headphone jack, if they aren't well connected, you can get a little DC at the output, and certainly enough to pop you a little.

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Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Grainger49

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Re: zapped by the headphone jack?
« Reply #2 on: May 15, 2013, 12:11:38 AM »
Low voltages can not be felt by a human, 15mV is low.  It is not enough to break down the resistance of your skin. 

If you were shocked it points to a problem with the safety ground.  First check the resistance of just the two leads by touching the leads together.  That gives you a zero reading for your meter.  Then check resistance from the ground lug of the power cord to the chassis plate.  It should be lower than an ohm. 

Then you should check the ground at your outlet.  The best way to do that is with one of these:

(http://i244.photobucket.com/albums/gg7/Grainger49/Bottlehead%20Equipment/Pictures%20Of%20Tools/IMG_1132.jpg)

If this doesn't tell you all is right then you need an electrician.