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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.


128x128lowrider57
pokey77
1,269 posts
 
@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.
lowrider57's avatar
lowrider57 OP
5,417 posts
 
Walter, thanks for getting in touch. I'll give you a call on Thursday. Tomorrow I'll be in the dental chair.
Jim

tuffy72561
184 posts
 
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. 
lowrider57's avatar
lowrider57 OP
5,417 posts
 
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.

lowrider57's avatar
lowrider57 OP
5,417 posts
 
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.


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