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On some equipment there is some tingly feeling when touched. I bent over recently and my lower lip just barely touched the aluminum platter on my turntable. It was slightly painfull but couldnt be felt with my hands. This is just an example as I could have disconnected all its periferals to find the source.
I have a Wright-sound preamp which doesnt use an AC grounding pin on the plug (to prevent ground loops). My power amps dont have ground pins.
I also have a Mac MX110 that has an even stronger tingle.
Can bad power supply electrolytics cause this?
Follow Ups:
There are a lot of good suggestions here and even your own thoughts can electrolytics cause the hot chassis and the answer is,YES.. I have one unit now with leaky computer grade electrolytics that has the whole B+ on the chassis of 440vdc.
Also,if you have a subwoofer amplifier speaker or any amp or preamp with a switchmode power supply plugged into the same power strip as the mx-110,this can cause a hot chassis. Disconnect those if you have them and see what happens.You may need an isolation transformer.
Smell it,dust it,clean it,test it,measure it.If you miss doing this,vengeance shall follow.
the biggest challenge is to isolate where the leakage is coming from. To do this, it is best to strip the system down to the least number of components and have a way to test for leakage.
Frankly, start with the older gear first - the MX-110. Since the primary side of the transformer is not connected anywhere to ground except through the line caps (there's 2 in a single package by the AC connectors), this is a good place to start. If you have a GFI outlet in the garage, use this to determine if sufficient current is flowing in the chassis:
- Plug the MX-110 into the GFI outlet
- Set your DVM to AC Volts
- Connect one probe to the chassis and the other to the safety ground lug at the outlet. Take a reading.
- Now, reverse the plug and measure again. Note the reading.
- Next, switch to AC amps, if you can on your meter.
- Connect the probes again as above and take a reading. (Hint: if the GFI pops its safety breaker at this point, you have a problem.)
Do this with all the gear you have. That should help you get started.
My bets are on the MX-110 as I had a similar problem with tingly feelings when connecting/reconnecting things. I installed a 3-prong AC cord on it when the old one frayed badly from a dog's chewing interest and discovered that it would trip a GFI breaker. After a long and winding path of diagnosis, I discovered there was 30vAC riding on the chassis and it would kick off the breaker due to the new cord being installed. The AC line cap replacement on the primary side didn't help at all either. Turns out that the transformer was passing the AC into the metal housing. I determined this by carefully isolating the primary winding. This was done by raising the transformer enough to slide cardboard between it and the case while monitoring chassis voltages. It runs again after a visit to the rewinder.
Hope that's not your problem but I did get a lesson in isolating some nasty problems that cause ground faults.
Cheers,
David
David's got it. I'll add that you should probably have *one* component grounded with the third pin - the other gear will then have their chassis at ground through the interconnects, unless their RCA socket shields are above ground, which is not common. It's not the most robust/safest grounding, but should do. I also had an MR-71 that had almost 50V on the chassis.
WW
There is NO substitute for the live performance.
Thanks,
The MX110 isnt in my system right now. Ill work on that after I get my main sytem working right. Then after I get the MX110 working I'm going to sell it. It's not my type of preamp. I have a Wright-Sound WPL10v which sounds better.
No, line-to-chassis capacitors do this - they MIGHT be leaky, but even if not they can pass some current to the chassis. Flip the AC plug, may go away. Even better, find 'em and replace with a modern SAFETY APPROVED "Y" capacitor - .01 or .015 uF (highest value allowed by current safety standards).
Try reversing the units AC plug to see if it drops inserted the other way.
Jeff
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