Equi=Core Hum & Other Issues


I’ve owned a Core Power Tech Equi=Core 1800 for 6 months. Recently the transformer has started to hum inside the chassis. It happens when components are on and also when sources are powered down. The transformer hum is intermittent. It ranges from multiple times per day to 3 or 4 days without any hum. I never had DC on my dedicated lines before, so I picked up a Klein Tools AC/DC tester... https://www.kleintools.com/catalog/electrical-testers/electronic-acdc-voltage-tester-12-240v-ac-15-2...
and when plugged into wall receptacles it indicated overload. Line voltage is steady at 122VAC and always has been.
What am I doing wrong, and how should I test for DC on the power line?

I discovered another problem when testing the Equi=Core duplex receptacles; they indicate inverted polarity. All house outlets measure correct polarity.
I’m looking for some assistance in diagnosing this hum. I’m not sure if it’s due to DC offset or if the torroid itself is vibrating in its mounting.

I know this is becoming a long thread, but I must mention that the Equi=Core now trips the breaker at the panel when powered on. It trips several times in a row, eventually allowing power-up. This is a 20A dedicated line from a subpanel which I’ve had for years.
Any advice is much appreciated.


lowrider57
Send an email to Underwood HiFi as they bought out Equi=Core and are now manufacturing and marketing newer version. 
The Equi=Core is balanced power, therefore, we all get the indicated inverted polarity. I suggest you phone or email Walter, I'll bet he will repair or replace the unit. [email protected]
Hi Lowrider,

DC offset on an AC power line can't be measured with an ordinary multimeter, or with the device you purchased. Although after looking at the description of the device I'm not sure why it indicated an overload. Apparently it automatically senses whether the voltage is AC or DC, and I would have expected it to illuminate the LED corresponding to 120 volts AC.

It might be possible to measure DC offset to some degree of accuracy with an oscilloscope. But a better way would be to construct a low-pass filter that would remove the 60 Hz content, and use that in conjunction with a multimeter. If that might be of interest to you or anyone else reading this thread see the posts by Jea48 and me on page 2 of the following thread (assuming you have the posts sorted oldest first):

https://forum.audiogon.com/discussions/dc-offset-blocker-killer-where-to-buy-in-the-usa?page=2

In any event, good luck in getting the issue resolved.

Best regards,
-- Al
@ lowrider57

I agree with testpilot and lak , send the unit in for repair.


As for measuring DC on the mains. You cannot measure DC on the mains by connecting a regular DVM directly across the AC mains at the wall outlet. You would need to connect a low pass filter between the DVM leads and the wall outlet.
The Klien tester you bought is not a DVM by the way.

I know this is becoming a long thread, but I must mention that the Equi=Core now trips the breaker at the panel when powered on. It trips several times in a row, eventually allowing power-up. This is a 20A dedicated line from a subpanel which I’ve had for years.

Stop using the Equi=Core..... Get it repaired.

You need to hire an electrician to have the 20 amp breaker in the electrical panel replaced. That is a must!... Repeated tripping and resetting of the breaker has damaged the thermomagnetic trip unit in the breaker. In many cases the breaker just gets weaker, will trip with less of a connected load than the 20 amps it is rated for and or will not be able to handle inrush current that the breaker used to be able to handle before the repeated tripping and resetting of the breaker.

Worse case that could, can, happen now if it trips due to a high inrush current or a short circuit event of the Equi=Core unit the 20 amp breaker in the electrical panel will not trip when you try to reset it again and the breaker may explode causing major damage to the electrical panel but may also explode outward through the front of the breaker casing burning your fingers, hand, arm, and possibly your face and eyes.
Yes a defective 20 amp breaker could, can, do that........

You should never face,look, at a circuit breaker when resetting a tripped breaker. Always turn your face away from the breaker and electrical panel when pushing the breaker handle back to the ON position. In fact your body should not be in front of the electrical panel. You should be off to the side with your arm and hand extended. 

Jim

.
Thanks @lak  for that valuable information.

@almarg , I've been reading that thread.
The Klein device does register 120VAC, but the Overload LED is lit. The polarity LED's indicate normal AC, maybe the overload is due to high DC. Overload is >25vDC.
And I know not to use a multimeter, that's why I bought this device. Thanks.

@jea48 , I think I should call the electrician to address the breaker situation. The 20A breaker being tripped at every powerup has never happened before this week.
Would he be able to measure DC offset?


I should mention that this unit is one year old and was purchased used. It was manufactured by Core Power Technologies.

I'm thinking that I should start with a call to my electrician before sending the unit for service. 
I wonder if a DC blocker can be installed in this conditioner as it is in my amp.
Thanks everybody.


Equi=Core and Core Power Technologies are the same company.
@testpilot , true, but not anymore. Core Power Technologies is out of business and has been purchased by Underwood. All new sales and R&D are done at a new facility.

lowrider57 OP


I think I should call the electrician to address the breaker situation. The 20A breaker being tripped at every powerup has never happened before this week.
Would he be able to measure DC offset?

Good chance the electrician will look at you scratching his head. DC on the AC mains?

I have never head of DC on the mains causing a 20 amp branch circuit breaker to trip open.

If it where me I would pop the top cover off the unit and have look inside. Use your nose and sniff around inside. Look and smell for something that looks and smells burnt. Especially look around the top support mounting plate for the toroid transformer as well at the bottom of the transformer if it rests against the metal bottom of the unit.

Also check where the AC hot wire leaves the power switch to see if there is a DC blocker circuit/device/components between the switch and the primary winding of the toroid transformer. Hard to believe it doesn't have one. I would imagine the transformer is a 2Kva (2000 Va) rated transformer.


When you hire an electrician to change out the 20 amp breaker in the sub panel, you might ask him to have a look inside the Equi=Core unit.

Jim
.
Thanks @jea48 . I always appreciate your help.
I've read about mods where the torroid is removed from  the bottom of the chassis and a layer of cork or other substance is used for the transformer to sit upon.

I found this comment on a transformer hum thread...
Changes in acoustic buzz from a power transformer often indicate that the AC waveform is not a pure sine wave, but has harmonics. The cause of this is probably outside of your control - you may find the buzz comes and goes depending on demand on the grid. There are so many switching power supplies (including large industrial motors) that rip the **** out of a pure sinewave.

Jim, thanks for your thoughts. I'll have some time later this week to look at the conditioner. 
A massive transformer...
https://images.app.goo.gl/ZvE7yvoxRMrJcL3BA



Check both the main panel and subpanel to see if each phase is 120 volts and the neutral to ground is close to zero volts. 

Try turning off all other circuits in your home next time. :)

Did you add any new light bulbs, computers, or fancy LED lighting??
@erik_squires , nothing has changed in the house. That's why I'm so puzzled. Just sitting here one day and heard the hum; and it's loud. Today, it was present for only five minutes and system was turned off.

Thanks @gs5556. I added your advice to my list.

Erik, I do wonder how valid the case for harmonics on the AC line is. 
I could turn off my fridge for a while since it's an older unit and the compressor kicks on and off frequently. And as you know, everything shares a ground.

@lowrider

From your description though, it sounds like DC, not harmonics, and that's often caused by a switching power supply.  You didn't add a light dimmer either?? No new PC or router?

Oh Snap. Erik, I have a new router, in fact it's a couple of months old. How can that be affecting the mains...the SMPS?
Post removed 
Erik, the routers PS is on a different circuit with my computer. I need to look at my diagram of the circuit panel layout. I had the loads moved and evenly distributed at the panel.
@Millercarbon, as someone who has been here for not much more than a year you may not be aware that over the course of many years it has become abundantly clear to long-time participants that Jim (Jea48) knows more about electrician-related matters than pretty much the rest of the membership combined.

I suggest that in the future you think twice before directing insulting and completely unconstructive comments toward highly respected members (and others as well), as you have done on numerous occasions.

Regards,
-- Al

Thank heaven for @jea48 (Jim) and @almarg .
Thank you for all you do,
Jim S.
I just have a balance transformer installed in my listening room at the third floor of my house, where run a separated line from the main inlet. Whenever I turn on my pow-amp, the transformer causes a "buzz" but nothing wrong happened, I enjoy the music perfectly. One day I heard a hum noise very noticable, stop for a while, and again. I go around to check and detect that hum noise caused by the hairdryer of my wife from the first floor. Now I know every single time when she use her hairdryer.
Another, balance transformer have two "live" polarity, there is no "neutral" polarity any more.
Hairdryers are notorious for contaminating the AC line.

Well, routers usually are on 24/7, and the power requirements are minimal, so they don't usually draw enough, or cause enough DC offset to cause this.

Again, strongly suggest just turn off every single breaker except the one your conditioner is on.

 
Call me at 770-667-5633 to discuss your problem. We have seen it multiple times and in virtually every case it is DC on your line. You can call your power company and they can remove it or use our Deep=Core that removes virtually all DC on the line.
Walter
@almarg 

Your comment at 02-25-2020 4:37pm is much appreciated. Acting with civility along with integrity and character go a long way toward creating a place where others can enjoy interaction and learning. Thanks again.
Walter, thanks for getting in touch. I'll give you a call on Thursday. Tomorrow I'll be in the dental chair.
Jim

I just wanted to mention that I now have a Core Power 1800 with no issues of hum. My former Core Power 1200 unit did have an issue with hum on occasion.  One week when one of the household members was gone for a week I had no problems with hum in the unit. Well I figured out it was a curling iron left plugged in and turned on that was causing it. Never had a hum problem with themat unit again. 
Erik, what you’re saying makes sense for troubleshooting. But, since the hum issue is so random it may not present again for many hours or days.
I’m thinking that shutting off large appliances may be the way to go first, rather than sitting in the dark.

Tuffy, that’s interesting. As stated, I’ve had close to six months of flawless operation. I need to find what’s different now. I live in an old Philly rowhome so the cause could even be from a neighbor.

Plus I need to address the issue of tripping the circuit breaker.


Jim
Is this the unit you bought from myself back in May last year?
Sorry to hear you are having issues with it.
Talk to Wally, he is a true gentleman IME.
Good luck sir!
Hi Uber. These problems came out of nowhere. Like the circuit breaker tripping, there’s no way the EquiCore is overloading a 20A circuit. That’s why I think the electrician should have a look first.

Of course I'll talk to Wally.


I know this is becoming a long thread, but I must mention that the Equi=Core now trips the breaker at the panel when powered on.


Oh, I missed this entirely. Have your circuit checked. You didn’t just go through a lot of ice or rain did you? :)

But it IS possible something blew in the conditioner too. You may have a short there you didn't have before.
Jim
I would say the 20a breaker is toast, although that has already been stated.
However working in large industrial application electronics and electrical installations we get plenty of breaker trip issues ( sub contractor bad wiring, incorrect wiring, shorted cables etc).
Generally we replace ANY breaker once it has tripped 3 times in rapid succession.
Not advocating that as any sort of "golden rule" but have seen plenty of 20a breakers( we use a lot of that size in our heating panels) trip with just 15a of load after a number of rapid fire trips.
Pays to be prudent especially when the customer has just dropped 3 to 5 million on his latest toy and expects trouble free production... lol.
Uber, I plan on having the breaker inspected and replaced. I've had multiple trips in succession. 
Thanks.
DC blockers are cheap to buy and build. One can be put inside your conditioner as I have done in my BPT Balanced isolation tranny. It quieted my BPT Conditioner and my Clayton Audio amp’s transformer. No need to spend many hundreds for the Deep Core to solve a DC issue.

I populated this board and wired it inside the unit. The board has inputs from your IEC and outputs to your tranny.  You can even buy several finished options:
https://www.atlhifi.com/shop/assembled-pcbs/fully-populated-dc-blocker-pcb/

Even tiny, tiny amounts of DC can cause the tranny to buzz like crazy and it does change throughout the day in intensity. That is normal. Replace your breaker and get a dc blocker installed.


  Uber, I plan on having the breaker inspected and replaced. I've had multiple trips in succession.

I'm no expert but I do know there are two quality levels of circuit breaker. There is a "home" version and a higher quality version. Ask your electrician for the best breaker. The price may be a little more but since they are overall pretty inexpensive, it's not a place to save money. They may insist the lower priced unit is adequate for your home but this is not a circuit to run a .......hairdryer. ;-)

@Al, (almarg),

Thanks for the kind words.

I find it’s best just to ignore his posts.

Jim
lowrider57 OP3,542 posts

02-25-2020
8:45pm

Hi Uber. These problems came out of nowhere. Like the circuit breaker tripping, there’s no way the EquiCore is overloading a 20A circuit. That’s why I think the electrician should have a look first.
@lowrider57,

I assumed the 20 amp breaker is just a standard type breaker. It’s NOT a GFCI, or an AFCI, or an AFCI/GFCI combination type breaker.... Correct?



Overloading a 20A circuit?
I guess I should have ask you to be more specific on how quick, fast, after you would reset the breaker and then move the breaker handle to the ON position the breaker tripped. Immediately? Or after a short interval of time? I was thinking immediately when you would move the breaker handle to the ON position. Please clarify....

If the breaker trips immediately that would indicate a very high inrush current or a ground fault or short circuit, condition, event. In either case, event, the current could be well over 100 amps or more. Just a guess by you repeatedly resetting the breaker it temporarily clears the ground fault or short circuit. Can that happen? Yeah, if the fault is not a Bolted Fault. I get the impression you do not leave the Equi Core powered on 24/7. I noticed the unit enclosure looks sealed, there in no air vents to convection cool the power transformer. Have you ever added up all the connected loads plugged into the unit? How hot does the top cover of the unit get?

Question. Has the 15 amp circuit breaker on the Equi Core ever tripped?
Here is a closeup photo of the inside of the unit. Can’t get any simpler... Just an IEC inlet connector, on/off switch, 15 amp magnetic circuit breaker, power transformer, electrical wiring, and 4 duplex receptacles. At least that’s all I see.

Scroll down the page to the photo of the inside of the unit.
https://forum.polkaudio.com/discussion/186921/core-power-technologies-equi-core-1800-review


Last but not least we have been blaming the Equi Core unit for the cause for tripping the 20 amp breaker in the electrical panel. Did you ever remove the Equi Core unit from the wall outlet and feed your audio equipment directly from the wall outlet the way you used to? I would suggest you try that. That should rule out the problem is caused by the branch circuit wiring or the branch circuit breaker. Of course you don’t know at this point, how weak the breaker is now..... You still should try it....

Jim
.
CORRECTION:

jea483,262 posts

02-25-2020
9:25am

@ lowrider57


Stop using the Equi=Core..... Get it repaired.

You need to hire an electrician to have the 20 amp breaker in the electrical panel replaced. That is a must!... Repeated tripping and resetting of the breaker has damaged the thermomagnetic trip unit in the breaker.

So much for proof reading....

Repeated tripping and resetting of the breaker has damaged the thermomagnetic trip unit in the breaker.
That should read:

Repeated tripping and resetting of the breaker has damaged the thermal-magnetic trip unit in the breaker.


Jim
@jea48 , I'll try and answer all your questions. Here goes...
I leave the EquiCore on 24 hrs/day. My weekly schedule changes so when there's two or three days I won't be listening, I shut it down. To power up the system, I turn on the Equi=Core, then the panel breaker trips immediately. I used to repeat this procedure but the panel tripped every time I turned the EQ on. Now I stand at the panel with the EQ power switch in the on position and retry the breaker every few seconds until resetting is successful. The 20A is a standard residential breaker.

The breaker on the EQ has never tripped and the unit has always run cool. All inputs are low-current-draw components; DAC, transport, iFi reclocker, LPS with 50VA torroid, Bluesound Node. (all digital, no SMPS) Amp and preamp are on a 2nd dedicated line.

 I will swap in my old Brick Wall conditioner when I have a chance. Good idea.


Post removed 
Either you fix the Equi=Core via 
_Underwally Or fix it your self   ?
I have 2 of the same in my Australian garage in the long hope I will have these fixed. The main issue ( Going back to 2018) why my Equi=Core came promIst to ship to Australia with AUS connectors when the opposite where delivered. US connectors where delivered, to me and my electronics companion were particularly disappointed. Now where to we get the US electronics required.
Australia is not close to seeking the required connector outlets and as such seek recuperative respective knowledge to be able to apply the respective corrections to make these EQUI=COREconnectors which were ordered however came with US outlets, which obviously we cannon use.
A readily and cheap solution would be appreciated.
AMG

lowrider57 OP3,544 posts  

02-26-2020  
 4:06pm


To power up the system, I turn on the Equi=Core, then the panel breaker trips immediately. I used to repeat this procedure but the panel tripped every time I turned the EQ on.

@lowrider57

That tells me the branch circuit wiring is fine. The 20 amp breaker didn’t trip until you turned on the EQ unit using the ON/OFF switch.

It sounds like you have been tripping and resetting the circuit breaker a whole bunch of times. Not just a few times. It sounds like it was the magnetic trip device in the breaker that was tripping the breaker open. I am not sure the magnetic trip device weakens with several repeated very high inrush current and or from a ground fault or short circuit event/s. I do know the overload thermal trip device does though. You weren’t tripping the breaker on overload, imo..... You said the breaker would trip immediately.


If the secondary of the transformer was not loaded, (say by at least 50% or more), from a cold start up the primary winding would not draw all that much inrush current. No where near enough current to trip a 20 amp breaker...
Just a stab in the dark I would say the transformer is the culprit. I would also guess what ever is going on it has been progressively getting worse. I would not try use it until you have it looked at.

As for the 20 amp breaker in the electrical electrical sub panel.
Because of all times the breaker has been tripped, and then you trying to close the breaker under a load. At a very high current load I might add. Possibly at a hundred amps or more, the contacts in the breaker have to be really burnt and pitted.
Jmho, I think you are darn lucky the contacts did not weld themselves together.


Side note:
I should mention depending on the breaker manufacture the 20 amp breaker may be a SWD rated breaker. An SWD rated breaker is rated to be used as a switch to turn on and off florescent lighting like you see in a store like Target and Walmart. (Now no doubt LED)... The calculated maximum continuous connected load for a 20 amp circuit breaker is 16 amps. 80% of 20 amps. You were switching a load of maybe 100 amps or more.....

Jim
@lowrider57

For some reason the above post, I originally posted last night, was corrupted after it looked fine after I posted it. The post this morning is the same without the corrupted part as seen at the top sentence of the post last night. I then deleted the post.

With that out of the way.....

I would like you to preform a test when you get a chance. Plug a vacuum cleaner into the wall outlet of the 20 amp dedicated circuit that has been tripping the breaker. Most walk behind vacuum cleaners have a so called 12 amp motor. That means if the motor is loaded, vacuuming carpet, it will draw 12 amps, or slightly less... That is a good load test for the branch circuit wiring as well as the branch circuit breaker.

It should power up fine without tripping the breaker. But,.... there is all them breaker trips and resets.... One thing for sure if the vacuum runs just fine that clears any finger pointing at the branch circuit wiring and breaker causing the problem.


You still need to hire an electrician and have him trouble shoot your situation. At the very least have the 20 amp breaker in the sub panel replaced.
I kept forgetting to ask, what manufacturer made the sub panel and breaker?
Example, Square D? Square D QO? Square D Homeline?

The electrician will be more than qualified to look at the Equi=Core unit. You can save some money by having the top cover already removed before he looks at it. You might ask him, when you call him, if he has a Megger? If he does ask him to bring it with him.

Megger is a trade name of an insulation tester. Example of:
https://www.grainger.com/product/MEGGER-Insulation-Tester-54JH70?ef_id=EAIaIQobChMI_Pu6tfHx5wIVx0XVC...

I would also let him know what manufacture made the sub panel. On the inside of the hinged cover it should list the manufacturer as well as the model number.
That way he will know for sure he has the 20 amp breaker in his Service Van when he comes to your home. Time is money....

Jim
.
 @jea48 
Square D QO main panel,
8 space 100 amp.

Going to try to have the electrician who did the install come to the house. Will call today.
 I was planning to open up the EquiCore before his service call....
-- Should I have the audio sources hooked up so he can test it under load?
-- What type of breaker should I request he bring; a heavy duty or commercial breaker?

Good idea to try the vacuum cleaner. As always, I appreciate your time.
Jim S.



@lowrider57

Square D QO. Good Choice.

No doubt he carries a Square D QO 120 breaker in his service van. Still wouldn’t hurt to tell him the breaker is a QO 120 breaker. Only a Square D QO breaker will work in the panel.

No need to have the audio equipment hooked up to the Equi Core unit. If he needs a load you can always use pretty much anything with a cord and plug you have in your home for a load.

You might prepare a place on the dining room table for him to look at the Equi Core unit So he doesn’t have to get down on his hands and knees. Make sure he has good lighting. Natural lighting works best.

Also you might mention the transformer has a 60/120V split phase secondary winding. The two outer 120V leads are both ungrounded that connect to the duplex receptacle AC Line, Mains, contacts.
The secondary winding center tap neutral lead is bonded, grounded, to the chassis and to the equipment ground contacts on the duplex receptacle outlets.
(NEC ARTICLE 647 Sensitive Electronic Equipment.)

Jim

@jea48  Thanks for the transformer wiring info.
I'd like to keep you updated if you don't mind. Electrician appt. is Tuesday; my service order states to inspect panel and subpanel, replace the subpanel breaker, and inspect/service the Equi=Core.

I pulled the EQ out of service and will pop the top this weekend. I have a Brick Wall passive conditioner in the circuit running digital devices, no issues.
But now I'm hearing hum from the power transformer in my Atma-sphere amp. It uses the second dedicated circuit from subpanel with my preamp. I'll have to check with Ralph, the amp is supposed to have a DC blocker built in. Preamp is Audio Note using their large EI transformer.

This leads me to the question; can DC offset be measured by the electrician either at the service panel or the wall receptacles?


@grannyring , made an appt. with the electrician.
This device is highly thought of on the forums...
https://avahifi.com/products/humdinger-dc-line-blocker

Will the very large toroid in the Equi=Core 1800 be a problem for a small device such as this?