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In Reply to: RE: Death wish posted by Awe-d-o-file on August 28, 2016 at 08:11:16
Charles Hansen said safety ground is a noise antenna.
Indeed he did but my recollection is that he suggested disconnecting or isolating signal ground from safety ground (earth) on the basis that the hazard posed by doing so was typically negligible in modern devices. Correct me if I'm wrong but I don't recall him ever suggesting that safety earth be disconnected from e.g. metal casework.
I agree with the basic idea - no signal ground in my audio system is connected to safety earth. The only way metal cases can rise to mains voltage is if isolating transformers fail by shorting secondary to primary. That's a very remote possibility but, should they do so, I'd expect the ECLBs to trip.
IMHO Blackdog is correct.
D
Follow Ups:
I don't have a problem with what you said. The risk is minimal though. I don't see it as a death wish. The system is unplugged when not in use. I've done other things I don't recommend like on an old NAD 2200 I took off the crap 16 gauge power cord and put on a good one wired direct to the transformer primary. This bypassed lots of stuff besides the switch and it was plugged into a switched outlet in a Monster Power device that would break the connection at 10A so a dead short would have safety but not its operating current. Again it was off unless I was right there listening. What a HUGE improvement it made.
ET
"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936
All the usual preliminary checks have been done before I posted.
Yes the noise is in both channels at the same volume, no matter where the pre volume is set, or even if the pre is disconnected. I do need to get the polarity checker yet though.
All the signal wire is bundled on one side, power wires on the other. looks OK.
I did find the grounding post, where the xformer, safety, and output signal grnds are all connected, have continuity with all the output lugs, both positive and neg.
I found this strange if not alarming, but maybe this has something to do with the output transformers. There is a wire from the board to the pos output lug, and a wire from the transformer to the same lug, per channel.
I also found paint between the grounding post and the chassis, which I removed.
This would be a fintastic amp if I could just the get hiss down...
all your help is appreciated
Now I'm confused...is it a hiss or a buzz? If it's a hiss, it's likely (but not definitively) tube related.
Do you have a cheater plug (3-prong to 2-prong adapter)? I'm not an advocate of running equipment with the safety ground removed, but on a temporary basis for trouble shooting it's worth trying. Try the cheater plug on the Jolida's power cord and see if there is any change to the buzz/hiss.
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