SMPS and grounding

[rickca]

52 minutes ago, JohnSwenson said:

Fortunately there is a real easy - inexpensive way to do this, it doesn't take any complex knowledge, I'm calling this the power supply grounding adapter

This is awesome, John!  It's going to be interesting to hear the impact of using this grounding adapter on things like routers/switches vs using a linear power supply.  Could I even do this with my powered studio monitors?

[rickca]

14 hours ago, JohnSwenson said:

it grounds the negative DC output of a power supply

OK here's a really stupid question.  Why don't they make SMPS with negative DC output grounded in the first place?

[rickca]

44 minutes ago, Superdad said:

Yeah, I've been wondering that for weeks now since John starting playing with this during measurement sessions.  Probably has something to do with regulatory requirements.

So to use John's grounding technique, does this mean we now need two outlets for each SMPS (unless grounding multiple SMPS from the same wire)?  I'm impossibly dense about electrical things.

[rickca]

27 minutes ago, Forehaven said:

is this doable/recommended??

https://www.computeraudiophile.com/forums/topic/37034-smps-and-grounding/?do=findComment&comment=722899

 

[rickca]

21 minutes ago, Superdad said:

While the single wire solution I present is cheaper, the Groundhog solution can do the same thing for the ISO REGEN--but only if you use it on the DC input jack of the ISO REGEN.

So that's different than grounding the downstream USB input, right?  

[rickca]

@JohnSwenson how does one use something like this from Supra

https://www.madisoundspeakerstore.com/power-cables/supra-swf-10-earthed-mains-iec-320-plug/

[rickca]

1 minute ago, Em2016 said:

 

@JohnSwenson my confusion comes from the above quote - which says for this topic, you ground the LPS-1's Mean Well Energizer's DC plug

 

 

@Superdad was talking about how to avoid dropouts when using galvanic isolation on the ISO REGEN.  That's a different goal than eliminating leakage currents which is what @JohnSwenson is addressing.  I think this is the source of the confusion.  Alex and John, please advise whether I've got this right.

[rickca]

6 hours ago, Em2016 said:

I don't think that relates to dropouts of the ISO REGEN - for dropouts, you need to ground the ISO REGEN'S USB output OR the ISO REGEN's input DC plug (LPS-1's DC plug output), since both do the same thing as both connected to the same ground of the ISO REGEN.

Yes, you're right.  So now I share your confusion.  My apologies to @Superdad and @JohnSwenson for mucking this up further.

[rickca]

3 hours ago, Superdad said:

And the SMPS grounding trick (I am now trying to source units that are already grounded--they exist--or get Mean Well to supply a custom version for us) is completely effective at shunting (getting rid of) the high-impedance leakage.

This is promising.  Is there an SMPS product line that's already grounded with a variety of volts/amps that might help me replace my other SMPS (the ones not powering an LPS-1).  Since I don't do DIY and find iFi's $50 kit obscenely priced, this would be great.

[rickca]

6 minutes ago, Superdad said:

 I am looking for pieces for $8-15 in quantity, not $22-28 or more.

OK, thanks Alex.  I understand your criteria, but even $25 is half the price of the iFi Groundhog which doesn't even include an IEC power cord and requires an extra outlet.  

[rickca]

3 hours ago, JohnSwenson said:

I do NOT recommend shielded Ethernet in most cases, leakage will go through the shield, bypassing all things I have written about blocking it, none of that works if you have connected shields.

Is BJC Cat 6A OK to use?  It's supposed to have a floating shield.

[rickca]

18 minutes ago, lmitche said:

I have lots of belden based bjc cat 6a cables and having re-terminated several, know that the cable is shielded but floating on both ends.

 

The internal structure of this cable is really something. I have no idea how they can cheaply manufacture something with this complexity.

So BJC Cat 6A is OK meaning it does not defeat John's ground shunt because it does not have connected shields, right?  I was concerned when I read his comment

I do NOT recommend shielded Ethernet in most cases, leakage will go through the shield, bypassing all things I have written about blocking it, none of that works if you have connected shields.

[rickca]

9 minutes ago, sandyk said:

 

 That is my main concern about using a direct earth instead of something like a low value 0.25W resistor (e.g.22 ohms or a little higher) which would very quickly go o/c and hopefully protect the downstream circuit.

A resistor of that value should be just as effective as a direct earth given the very high impedance leakage source.

Maybe that's why the Groundhog measures at 15 ohms as reported by @austinpop.  Is iFi smart enough to do this on purpose?

[rickca]

3 hours ago, Superdad said:

I really don't want John's based-on-engineering mod to get too mixed up in hoofy-spoofy stuff.

That's a new one.  Must be something technical and over my head.

[rickca]

OK this is too weird.

 

I had a friend modify my Mean Well SMPS to ground the negative output internally.  I plugged it in to my LPS-1.  I got no LED light on my LPS-1, and the green LED on the Mean Well was flashing (whatever that means).

 

So I took it back to him and said it didn't work.  He tries it in his workshop, and it works perfectly.  WTF?  He tells me there must be something weird about my AC ground at home.  Huh?

 

Then it occurs to me that in my test system I use an APC C5 power filter/surge protector.  As soon as I unplugged it, the modified Mean Well/LPS-1 worked perfectly in any outlet in the room.

 

My question is ... how can just having the APC C5 plugged in cause this kind of problem?  It must do something to the circuit, because the modified Mean Well/LPS-1 would not work even plugged directly into a different wall outlet in the same room.

 

Anyway, that APC C5 is going in the trash.  Now I'm using a simple Wiremold L10320.  I will still need to find a surge protection solution because I live in south Florida and we have tons of lightning storms all summer.  I'm in a rental condo so I can't do the usual whole home thing.

[rickca]

37 minutes ago, sandyk said:

Use Power Boards with VDR's in them. They are cheap enough, and should give you quite a bit of protection.

If you're talking about MOV surge suppressors ... that's what the APC C5 is that gave me the whole problem in the first case!

[rickca]

4 minutes ago, sandyk said:

 

 It seems likely that there may be a little more to it than just the use of  MOV/VDRs in the APC C5. 

Are you sure that it wasn't faulty due to previous high voltage spikes/surges ?

I agree with you, just having a device with MOVs shouldn't cause this kind of thing.  I was wondering myself if it was faulty due to previous surges.  It's plausible because I've had it for years, but the Protection On and Wiring OK indicators are both lit.  It's possible that those indicators are unreliable.

 

Question is what kind of fault would give me this problem with a SMPS with -ve output grounded?  How could it affect other outlets on the same circuit? 

[rickca]

1 minute ago, One and a half said:

John was quite specific in ruling out any power strips with surge suppression devices like Vdr, since they are usually connected to earth and they don't have gigohms resistance.  So there's leakage from them which then spreads. 

I better go back and review John's post.  I missed that point, thanks.

[rickca]

17 minutes ago, One and a half said:

Have a look here

I remember what John said about not using anything but a clean power strip with an isolation transformer.  I thought you were talking about my issue with a MOV device messing up John's recommendation to ground the -ve output of SMPS to eliminate high impedance leakage.  OK, I think I understand you now.

[rickca]

No Topaz incoming here due to WAF and space.  Maybe get an Equitech unit when we get a real house.  Anyway, we better get back to the thread topic.

 

No worries about inspections here.  It's a joke, they let people BBQ on their balconies.  This is Florida.  It's against fire code, but there are no inspections.

[rickca]

7 hours ago, One and a half said:

Some protection LEDs are always on, to tell you it's active, others it's a fault, so RTFM s'pose.

OK I RTFM.  My unit was indicating that it was functioning properly.

 

Protection On Status Indicator When lit, the C5 is functioning properly. If the light is extinguished, the C5 has been hit by a surge and the protection circuitry may be damaged.

[rickca]

I'm really impressed with the effect of grounding the -ve output of a Mean Well energizing an LPS-1.  This is definitely worth doing.

 

It's more than I anticipated.  Certainly a lower noise floor, so you can hear low level details more easily and the music seems to flow more freely.  I'm just using it with an ISO REGEN.  Also, no dropouts at all with GI on.  I have no idea if that's due to the grounding.

 

I also got rid of my surge suppressor/power filter at the same time.  Somehow it was incompatible with grounding the Mean Well.  The combined effect was really remarkable.

 

Thanks, @JohnSwenson!