Isomagic ground loop - Should PSU be earthed?? - diyAudio
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Old 17th September 2008, 10:37 PM   #1
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Default Isomagic ground loop - Should PSU be earthed??

Hi,

I just bought some new active nearfield monitors and plugged them into my Isomagic, and the left channel has some serious ground hum.

I tried lifting the ground on the various items in the loop, but I couldn't shift it. This is strange as when plugged into my regular amp, there is no ground loop.

I then remebered that the power supply to the DAC has obvious signs of having being opened and re-glued (bought it new from Richer sounds, so I can only guess it was a returned item).

So anyway, I opened the PSU up, and there was no connection from the power input ground to the transformer.

I suspect someone had a moulded IEC mains lead and wanted to lift the ground on the DAC or something. Why else would it not be connected?

Thanks,

James
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Old 18th September 2008, 05:24 AM   #2
kevinkr is offline kevinkr  United States
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Sure there isn't something wrong with the nearfield monitors?
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Old 18th September 2008, 03:01 PM   #3
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Hi,

The monitors are fine when plugged into other sources.

Update: I soldered an earth line to the transformer from the mains lead, and now the isomagic doesn't come on anymore.

Oh well. Looks like I might be selling an Isomagic, minus a power supply.

I really want a dac that does 192khz and decent upsampling.

Cheers,

James
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Old 18th September 2008, 03:49 PM   #4
kevinkr is offline kevinkr  United States
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Quote:
Originally posted by jamesd256
Hi,

The monitors are fine when plugged into other sources.

Update: I soldered an earth line to the transformer from the mains lead, and now the isomagic doesn't come on anymore.

Oh well. Looks like I might be selling an Isomagic, minus a power supply.

I really want a dac that does 192khz and decent upsampling.

Cheers,

James
Remove the ground connection you made and check the receptacle for a blown fuse. (I expect this is a standard BSA plug?)

Check out the Zhaolu 3.0 dac it's good and not too expensive. Get it here: http://www.diykits.com.hk/ (Shipping is surprisingly reasonable.)

Good luck..
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Old 19th September 2008, 08:10 AM   #5
Puffin is offline Puffin  United Kingdom
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james. If you do decide to sell the Isomagic, I would be interested, you can email me on rhpowell(at)webandmail.co.uk
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