Amp Shutting Down, need help


I have a Cary 7.250 brand new amp that shuts down after 20 seconds in my NYC apartment. I have sent the unit back to Cary where it tests fine. I have tried the unit at my friend’s apartment and his place of work and it works fine. The unit is 100% in working order. After talking to many people I was told to attach a 50' extension cord and low and behold it worked.

The good news is that I have a dedicated 20amp circuit to this outlet. My voltage reads 118 volts and Cary said that is not a problem as the unit will work between 90 and 130 volts. I have tested for voltage on the negative lead to ground and there is no stray voltage. I have also tried the unit on other outlets in the apartment and the same problem occurs.

My mono blocks and all other components work just fine. So I’d love to hear suggestions as to how to get rid of this 50’ extension cord?

Thanks in advance.
sailcappy
Cappy, at this juncture, based on all the info you've responded with, I'll have to agree with Slikric3000's recommendation for a "line conditioner" or filtering. It's obvious the 50 foot extension cord is providing just enough filtering of noise to prevent your Cary from tripping, and based on the amount a 50 foot cord is accomplishing, you won't need much of a conditioner or filter providing you meet/exceed your amp's maximum current demands, which I couldn't locate in the owners manual.

You might also be interested in getting something for the upstream sources and preamp/processor since they would benefit the most from cleaner/stable AC. I don't have any experience with them, but you can search the Audiogon forums or other sources since I've seen this topic come up periodically regarding manufactures/models/types.

If you knew exactly what issues were plaguing your AC, you could better select what filtering topology is best suited (cost effective), then buy/treat it accordingly as there are simple products available for a fraction of cost consumer-targeted A/V types, but whatever fits your likings and wallet depth. There's quite a few manufactures making LC's; some with strictly-business cosmetics, some quite fancy with eye-candy appeal, and variances in between. Or, for a truly cost-effective option, find a high-wattage 50 ft. extention cord of color choice, coil-stack it neatly in a 8-10" diameter with cable-ties to retain shape, and hide it out of sight behind the amp. The coilded stack will even provide a higher lever of filtering. Done! Solved! (joking)

Keep us posted...
Love the colored cable idea! Not sure if I can get that by the wife factor!!!

Can you give me an idea of line conditioners vs the Syngergistic Research Telsa Powercell that i have? What do I look for in a line conditioner?
Things known.

From the Cary's owners manual.

*Uses a soft start circuit. That limits inrush current.
*Has built in DC offset filter protection. (That would be after the magnetic circuit breaker)
*Uses a magnetic trip circuit breaker. (Would not be my chose)

*Cary works fine elsewhere outside OP's apartment.
*Will not work anywhere on any branch circuit in the OP's apartment without the 50' cord attached.

*Cary will not work plugged into the Synergistic Research Powercell 10se MKII power conditioner.

More questions.

What is the conductor wire gauge of the 50' extension cord?

Is the 50' cord in a coil?
Roughly the diameter size?

A 50' coil with AC current passing through it is an air core inductor..... Inductive reactance....???

I do live in a high rise and my building said and I quote "as long as the breaker is not tripping then we do not concider you to have a problem." So much for living in a "luxury building".
Sailcappy

Well with a magnetic trip circuit breaker Harmonics can cause them to nuisance trip.

Sailcappy, you mentioned your friend works for a power company. Does he have access to test equipment to check the power quality of the power feeding your apartment?

http://www.copperinfo.co.uk/power-quality/downloads/pqug/31-causes-and-effects.pdf

Reading from the owners manual it talks about putting the amp in "standby" mode before turning it off with the switch/circuit breaker. Not doing so leaves the amp in "Active mode" state. I assume you are powering the amp down correctly.

I ask because of the test you performed where just as the breaker tripped you notice the voltage dipped from 118V to 112V. The VD, voltage drop, was due to a spike in current. Was it the protection relay switching in the Cary amp?

Can't say 100% the VD was due to the Cary or maybe due to a high current load turning on elsewhere in your apartment. Though what are the odds it happened at the same time the breaker tripped.
.
Cappy, I completely forgot about you mentioning the Cary still tripping when connected to your Syngergistic Research (line conditioner) back on 8/13, as Jea48 just recalled. So now I'm at a loss, and baffled further.

Like Jea48, I was going to ask if your friend was able to diagnose your AC health with more appropriate equipment to find out exactly what's going. That's really what needs to happen. Not that you couldn't hide the coiled extention cord in cosmetic, WAF-approved packaging - complete with a fancier output receptacle if desired. (marketing idea)

I guess I'm out of ideas for now, unless it's still ground-related, but will continue to loose a percentage of sleep each night until it's resolved.

~
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