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11-15-2020 Post does not mapped to Knowledge Tree
anthony
Posts 268
Joined on 08-18-2014

Post #: 1741
Post ID: 26001
Reply to: 25997
Alligator clips
 Romy the Cat wrote:
Solder 10-15 inch 10Ga wire to you negative grounded terminal. Then begin to tough diligent points of you circuitry with other sides of your wire. You very fast will find how to bridge you ground in order to get rid of you noise. You might hold that wire in hands and just short different pars of grounds, but your hands might act as own antenna. You get the idea….


Yes, I did this just with alligator clips...very quick results...
11-16-2020 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 488
Joined on 01-07-2006

Post #: 1742
Post ID: 26003
Reply to: 26001
Thank you
Thank you very much for all the help/advise. I'm still to investigate the problem. The working hypothesis is that my phono has some GND routing problem. Will examine it with the scope and shortening method to see if that's the case.

PP does damp its filter caps noise to GND, the info I got from PP (hope can publish):

"The charger and the input AC filter circuits both connect to incoming AC and both are connected to ground  through their filter caps and therefore feed filtered noise to ground - where in a perfect ground system it would disappear from our life forever as intended."
Indeed, the noise at the output of my phono looks like charging voltage of a cap input filter (5ms base = 100Hz fundamental freq):
Output 5ms PP Online shorted MM.bmp
It is NOT present at the input RCA's and varies in amplitude depending which phono input I select (shorted MM smallest, Decca cart biggest).
Will let you know the results.



Cheers,
Jarek
STACORE
11-16-2020 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,250
Joined on 10-12-2006

Post #: 1743
Post ID: 26004
Reply to: 26003
Shield Unused Phono Jacks
Metal caps over phono stage unused RCA jacks can help with stray EMF/RFI. Cardas and others sell them.

Not saying something is wrong with the PP, just saying it doesn't take much to get noise from a phono stage, including any change in ground potential.


Paul S
11-16-2020 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 488
Joined on 01-07-2006

Post #: 1744
Post ID: 26005
Reply to: 26004
Have them
The GND noise enters somewhere past the input RCA's. And this GND noise is not the PP RFI/EMF.

RFI/EMF of PP looks like this:
Output 5ms 2mV GND lifted PP Online Decca.bmp

This one is caught by my Decca cart (phono GND lifted) but similar is present in the air, caught just by measuring cables. Time basis is still 5ms (vertical is 25x less than above). You can see the characteristic 'pumping' in regular periods (try to ignore the 50Hz hum).
That's probably the charger.



Cheers,
Jarek
STACORE
11-16-2020 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,250
Joined on 10-12-2006

Post #: 1745
Post ID: 26006
Reply to: 26005
Switched PS
Hmmm...

Whatever it is, if it's on the ground leg it "should" be possible to route it to ground before it gets in the amplifiers. Have you tried moving around a sheet of well grounded Mu metal, see if it catches and/or drops hum volume?


Paul S
11-24-2020 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 488
Joined on 01-07-2006

Post #: 1746
Post ID: 26012
Reply to: 26006
Still fighting
My exorcisms to eliminate 100Hz PP induced noise in the EndOfLife phono gave no results so far.

- I took GND from the PP socket and tried connecting it to various GND points I could access (the signal GND plane, input sockets GND, the case). This only increased the noise.

- I tried connecting different GND points within the circuit. No results.

- The noise seems larger when the PP batteries are not 100% charged, suggesting it comes from the charger working (it disappears when the PP is in the battery mode)

- On the SUT inputs, the noise changes its amplitude with changing the orientation of the signal unit  with respect to the power supply but never vanishes completely.

The last makes me suspect it might be emitted by the phono power supply and travel by the air to the signal unit. Perhaps PP excites the supply big chokes?  But then why lifting the phono ground from the PurePower eliminates the noise completely?? Cannot understand it. Will get a scope tomorrow and try seeing where the noise enters.



Cheers,
Jarek
STACORE
11-25-2020 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 488
Joined on 01-07-2006

Post #: 1747
Post ID: 26013
Reply to: 26012
Edit
 - The noise has two phases - large noise and steady state noise. Large one ocures when the PP is switched offline and then switched on. This noise depends on the input (SUT or MM) and the orientation Signal enclosure vs power supply
- When the battery is fully charged, what remains is the steady state noise - much smaller. It doesn't seem to react to anything.
- Lifting the ground (disconnecting the signal ground from the chassis) has no effect

The only conditions so far to suppress the 100Hz noise are:
- Switching PP to the battery mode
- Disconnecting phono ground from the PP ground






Cheers,
Jarek
STACORE
11-25-2020 Post does not mapped to Knowledge Tree
steverino
Posts 327
Joined on 05-23-2009

Post #: 1748
Post ID: 26014
Reply to: 26013
All signs point
to the usual suspect.
I can certainly understand your reluctance to send the unit back for repair. I would not do so myself although since I have the older model they don't even support them in theory anymore. I think you have to take it to a local tech repair shop as I do mine. Typically what fails are standard things so I am pretty sure they can find out the part which is malfunctioning. It probably won't cost more than the back and forth shipping anyway.
11-25-2020 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,250
Joined on 10-12-2006

Post #: 1749
Post ID: 26015
Reply to: 26013
"Ground" ?
Jarek, when you say disconnecting the phono ground from the PP ground stops the noise, why is it you don't just do that? Are we confusing "ground" and "neutral again? If the phono stage works quietly when its ground is disconnected, why don't you just lift it? If it's star grounded in the first place, then the ground plane dumps out via the neutral wire, already, and the safety ground would make a loop, in any case. My own phono stage uses only the neutral wire for grounding (the safety ground is lifted). What am I missing here? 

Paul S
11-26-2020 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 488
Joined on 01-07-2006

Post #: 1750
Post ID: 26016
Reply to: 26015
Reasons
Paul, ground is ground, neutral is neutral. Where they are connected I have no idea, for sure not in my equipment. The case of my phono is connected to the safety ground not to the neutral. The reasons why I'm onto this and has not listened to the system for 2 weeks already:

A) check if my phono internal wiring is ok; perhaps I have some GND problem which PP highlighted; this becomes less and less of an option now
B) check if PP is ok or faulty as steverino suggests
C) Phono connection to GND is my only connection to the safety ground and I want to keep it


Cheers,
Jarek
STACORE
11-26-2020 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,250
Joined on 10-12-2006

Post #: 1751
Post ID: 26017
Reply to: 26016
ICs
From your descriptions, it sounds like your phono safety ground makes a ground loop, or at least raise resistance for something, when you connect it to your PP. Are any of your ICs connected to ground at any point? The ICs "should" connect your components on the neutral leg, which also makes a safety ground redundant.

Best regards,
Paul
11-26-2020 Post does not mapped to Knowledge Tree
drdna
San Francisco, California
Posts 512
Joined on 10-29-2005

Post #: 1752
Post ID: 26018
Reply to: 26013
Noise on the ground connection
The way it is described, I have to agree about taking the Pure Power to a trusted local repair shop to get it scoped out.
I will just say again that repairing the Pure Power seems to fix the problems, for those who have been able to get their unit back.
If you have a oscilloscope, it would be of interest to see the waveform going across the connection between the Pure Power Ground and the Phono ground. You can also try adding a capacitive filter in the connection to see if this blocks the noise.
This can reveal more about what may be causing the noise, but as I said before it is probably best to get it to a local repair shop before catastrophic failure occurs!
:-)
Adrian
11-27-2020 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,250
Joined on 10-12-2006

Post #: 1753
Post ID: 26019
Reply to: 26016
Alternate Grounding Schemes?
I'm trying to remember if you have copper water pipes, and wondering again how these measure for ground resistance. You MIGHT be able to ground your phono stage case to a water pipe as a "bleeder". You could start by "jumping" it, then do something more permanent if it works. This would lift it off the PP, albeit there might be other electrical noise on the pipes, to begin with. I suspect this would only work if your phono stage case is isolated from you neutral in the first, but one never knows, it might work, anyway.

Best regards,
Paul S
11-28-2020 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 488
Joined on 01-07-2006

Post #: 1754
Post ID: 26020
Reply to: 26018
More
Adrian, I'm not yet convinced the PP is to blame. Also PP Richard is helping a lot to understand the issue (thank you Richard!). Now this f@#$%@%$ 100Hz noise stepped on my male ego  - want ot understand where it comes from.

I quickly cheked the signal between the PP ground and my phono. Nothing unusual: some 50Vrms of 50Hz when the PP is online, pretty much the same as between the phono and my wall GND when the phono is connected to the wall.

Interestingly, if I connect the phono and PP GND via amperemeter, it shows an AC current diminishing practically to zero (some 0.4mA). So this 100Hz noise is not from a current loop? Or this 0.4mA rms is enough? Cap coupling GND's I might try for a test, but ultimately I want to have a DC connection for safety. I was thinking of trying this GND blocking scheme, Fig. 4:  https://circuitcellar.com/resources/ee-tips/find-and-eliminate-ground-loops/
Another interesting thing I'm strugling to understand is why lifting the phono signal ground from the chassis ground has no effect on the noise. Only lifting the chassis ground from the PP ground kills it. This suggests it gets to the signal either via the air of via the supply lines (B+ and/or heater which biases the 2nd stage). I have to scope theose lines throroughly. But then again, why disconnecting GND kills it?


Pual - I checked my wall GND. First of all it is there (made tests with controlled 30mA shorts to GND - fuses worked). I was looking at the heating too but have no idea if the pipes are all metal or plastic. A bulb test will show.



Cheers,
Jarek
STACORE
11-28-2020 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,250
Joined on 10-12-2006

Post #: 1755
Post ID: 26021
Reply to: 26020
Again With the Star Grounding
Again, there is no need, even for "safety", to have a separate ground wire if everything is star grounded. Since the neutral and the safety ground connect at the service bus, running the "safety ground" back to that bus for your phono stage apparently makes a classic ground loop, at least as far as your phono stage is concerned. Double Hz of service cps is "normal" noise.

Best regards,Paul S
Page 88 of 88 (1,755 items) Select Pages:  « First ... « 84 85 86 87 88
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  What lives in Symmetric Sound?..  The beginning of our journey is ALWAYS symmetrical...  Audio Discussions  Forum     19  132827  05-28-2004
  »  New  Always check power-line polarity...  Polarity checker, for convenience...  Audio For Dummies ™  Forum     7  78898  07-10-2005
  »  New  RAAL “Water Drop” tweeter for Macondo...  Your comment takes me by surprise...  Horn-Loaded Speakers Forum     77  765763  02-16-2007
  »  New  My feelings about new exciting audio products..  Vacuumstate...  Audio Discussions  Forum     25  213891  04-30-2007
  »  New  Musique Concrete horns..  These are now sold as Kornhent products...  Horn-Loaded Speakers Forum     6  85919  06-12-2007
  »  New  Compression drivers and the “clean signal”...  The NEW “Compression drivers and the clean signal”....  Horn-Loaded Speakers Forum     14  128368  07-12-2007
  »  New  Digi Redux; Drive 1 transport and iDAT-44+ DAC..  Ha! It might have lasted FOREVER!...  Didital Things  Forum     25  170011  09-28-2007
  »  New  Metal domes..  Try the one Lansche is using...  Audio Discussions  Forum     6  62525  11-08-2007
  »  New  The power AC Outlets?..  Where to Pick Up the Gong?...  Audio Discussions  Forum     2  34109  10-31-2008
  »  New  The Avicenna's failure is the great Avicenna success!..  New life for Avicenna...  Audio Discussions  Forum     8  64150  02-03-2009
  »  New  Internet and electricity..  Suboptimal. . ....  Didital Things  Forum     1  21305  01-07-2010
  »  New  Electricity... power strips and ac improvements..  Electricity... power strips and ac improvements...  Audio Discussions  Forum     0  12830  03-30-2010
  »  New  Another example of energy..  Again With the Star Grounding...  Audio Discussions  Forum     1754  7335339  01-29-2011
  »  New  I good spot-light for a turntable?..  Reply...  Analog Playback Forum     15  118515  10-24-2010
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