Amp Shutting Down, need help

Jim just called this thread to my attention, by posting in another thread I was participating in.

Sounds like he and Metro have made many logical suggestions, and I'm pretty baffled as well. But here are a couple of thoughts:

08-14-12: Sailcappy
I had my friend who is knowledgeable about power test the lines and he confirmed that the polarity is correct vs. the small and large slots. He also noted that none of my outlets in my apartment are wired to ground it seems the ground is left to the junction boxes alone.

08-15-12: Sailcappy
It seems that none of my outlets have separate ground wires. I will call Cary today to discuss.

1) What does this mean? Does it mean that the safety ground pin on the outlets is not connected to anything, so that the safety ground pin on the amplifier's power plug is not connected to ground through the power wiring? If so, that would be number 1 on my list of things to focus on in relation to the problem. It would also be a serious code violation and a serious safety hazard.

Perhaps the design of one of the amp's various self-protection mechanisms is such that it is not happy if the amp's chassis (which can be assumed to be connected to the AC safety ground pin on the power plug) is not properly grounded. By attaching the 50 foot extension, capacitance between the three conductors in the extension cord will result in the addition of a significant amount of capacitance between the amp's chassis and AC hot and AC neutral, which conceivably could lessen the sensitivity of the protection circuitry to the ungrounded or improperly grounded condition of the chassis.

2) I'll repeat Jim's question about how the extension cord is coiled. And an experiment I would suggest is to compare results between when it is in a coiled state and when it is stretched out as much as possible, with as much spacing as possible wherever different parts of the cord have to run in parallel with each other. That will lower the cord's inductance, and thereby reduce the filtering effects it will provide at noise frequencies. (The effects of the cord's inductance at 60 Hz will be negligible either way). So comparing results between the coiled and uncoiled configurations might help us to rule out or rule in power line noise as being related to the problem. I don't think we can totally rule out that possibility at this point, even though the problem occurs when the SR conditioner is used.

Good luck!

-- Al

Al, thanks for stopping by.

Early on, I've tried to get as much confirmation from the OP regarding his outlet wiring and grounding, and based on his two responses pertaining to his friend's testing/confirming, responded with an assumption that his outlets were grounding directly to metal wall boxes and conduit by design - negating the need for ground wiring - pending local codes (not confirmed by OP). Again, based on his knowledgeable friend's testing, can only "assume" satisfactory measurements were observed on all aspects, and though I still don't have a warm fuzzy, didn’t wish to dwell further.

I also assumed his friend owned the meter, early on, leaving the OP unable to do spontaneous additional testing if requested. Appears he does, and I'd really like *him* to re-check the voltage from the outlet's LINE (smaller slot), to the GROUND pin and report the voltage. He's previously stated there's no stray voltage between the NEUTRAL and GROUND, so I'd like him to check for "resistance" between the outlet's NEUTRAL (larger slot) and GROUND if able.

If all is up-n-up, I assumed his SR conditioner would have taken dealt with any line noise issues, so... (scratching remaining hairs)

Frank

Hi Al,

I hoped you would see my post.

As Metro04 pointed out more than likely the electrical equipment grounding conductor for the branch circuits is the metallic conduit, boxes, and fittings. Back in the 1970s that was acceptable per NEC and more than likely NYC codes. (Problem, years later, was the degradation of electrical continuity integrity from the fittings, connectors, lock nuts, and conduit couplings.

Corrosion for one, = resistance. If we have resistance then a difference of potential can exist from the grounded neutral conductor and the safety equipment grounding conductor at the branch circuit outlet device, the receptacle.

To rule any chance of noise on the safety equipment ground I would think, for test purposes, a ground cheater could be installed on the power cord of the Cary Amp.

What are your thoughts on the magnetic field of the 3rd and 5th harmonic on the relay solenoid of a magnetic breaker? I would think it would distort the actual current passing through the switch/magnetic breaker on the back of the Cary amp.

Harmonics is about the only thing I can think of that causes the Amp's magnetic breaker to trip in the OP's apartment but no where else outside of his apartment.

The fact that the 50' extension cord stops the nuisance tripping is interesting.....

I assumed the cord is coiled up and not laying out in the room. Appearance as well as being a trip hazard.

So, to me, at least two things are at play.
Size of the conductors of the cord.... Impedance....
Cord is coiled up...... inductance.....

Does that filter out harmonics or at least lessen the effect on the magnetic field of the solenoid of the magnetic trip of the breaker?

I asked the OP in a previous post if he was shutting down the Cary Amp by first pushing the power button on the front panel of the Cary putting the Amp in standby before turning off the power switch/breaker on the back of the amp. (Not doing so leaves the amp in the "Active Mode" state.)

The owners manual recommends not shutting off the amp without first putting the amp in standby.

With the problem the OP is having, unique only with his apartment, proper shutdown and power up could just be enough for the breaker to hold.

I would recommend the OP power up the amp with the 50' extension cord power off by putting the amp in "standby" first then turn off the switch/breaker.

Remove the 50' cord and plug the amp directly into the wall receptacle. Wait at least 5 minutes to power up the amp again. (Power supply caps should be bled off by then?)

I would then turn on the switch/breaker and see what happens. Hopefully the 20 second timeline will pass with no breaker trip event.

If the breaker does not trip, fingers crossed, I would not get in any big hurry to push the power button on the front of the amp that starts the sequence to power up the amp in the "Active Mode". Wait at least a few minutes or so.

If the amp does power up I would not power the amp totally down unless going on vacation or in the event of lightning storms. I would just push the power button on the front of the Cary putting the amp in standby.

Does it totally solve the OP's no.... And sad to say he would still need to keep the 50' extension cord. If he has a power outage the amp will be set to "Active Mode" and he will have to use the 50' cord to to reset the amp to standby.
Jim

I assumed his SR conditioner would have dealt with any line noise issues ....

My instinct (based on nothing specific) is to not make that assumption, especially given that detailed design information and quantitative test results appear to be unavailable for that (and most other) conditioners.

The kind of possibility I'm envisioning is that some piece of industrial-type equipment somewhere in the building, or nearby, is putting a significant voltage spike onto the AC, that repeats each cycle, and whose characteristics are such that the conditioner is ineffective against it.

Sailcappy, is there any chance that you can borrow a different conditioner from someone? Also, if by any chance you know someone who has an oscilloscope, and is knowledgeable about how to use it, a good experiment would be to view the AC waveform on it, and set it to trigger at a level a little higher than the nominal peak of the AC waveform (which is around 170 volts). Then see if it triggers, and what it captures if it does trigger.

Best regards,
-- Al

I just spoke with my friend who works for the power company and we agreed on the following:

1. Regardless of the problem with my buildings power we know they will not fix it.
2. It seems to me that some type of power regenerator is needed.
3. What do you recommend that just has one input and one output?
4. Should I go digital or analogue?

Thanks again for all your help!