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
Its easy enough to test for. There is someone on this forum who makes AC extension outlets that have the DC Blocker built in. Just use one of those and you would know if that's what it is.
08-22-12: Atmasphere

Atmasphere,

Agree....

The Agon's members username is Gbart.

Email address, sae2300@optimum.net



>>>>

Jim, wouldn’t his other “standard 15 amp” outlets, throughout the apartment, be split up between the two incoming legs? He has tried, unsuccessfully, to energize the amp from various 15 amp locations around the apartment, though it isn’t known how they are split up.
Frank
08-22-12: Metro04

Frank,

Maybe.... But not necessarily. Back in the 1970s it was not uncommon to put most of the 15 amp convenience outlets in the living room and bedrooms on the same 15 amp branch circuit. Sailcappy had a 50/50 chance the circuit/s is/are fed from the other Line.

Sailcappy could check if the receptacle/s he plugged the amp into is fed from the same Line, leg, as the dedicated circuit.
Each breaker space down each side of the panel alternates from one Line to the other.

Example Line 1, L1, is the top breaker as well as the top breaker across from it.

2nd breaker down is fed from L2 as well as the one across from it.

And so on down each side of the panel.

Glad you brought up again that Sailcappy tried other outlets in his apartment.... Those in the living room as well as bedrooms are more than likely 15 amp branch circuits fed from a 15 amp breaker....

Sailcappy, is that correct? A 15 amp breaker? IF 15 amp, during the test, did the 15 amp branch circuit breaker ever trip?

I should mention, the breakers in the panel are thermal/magnetic type breakers.
.
Sailcappy, is that correct? A 15 amp breaker? IF 15 amp, during the test, did the 15 amp branch circuit breaker ever trip?

Not counting the two breakers for the environmental conditioners; there are two 20 amp breakers, and three 15 amp breakers. I have tried the unit on all 5 of these circuits and the Cary still tripped after 20 seconds. The breakers in the main circuit breaker box never tripped.
Sailcappy,

So during the tests on the 15 amp circuits not one of 15 amp breakers tripped. But the 15 amp magnetic breaker on the Cary amp did......

And of all the 5 circuits the amp was tested on the odds are great that at least 2 were on the other Line in the electrical panel than the dedicated 20 amp audio branch circuit.


I spent a little time researching the Synergistic Research Powercell 10se MKII power conditioner.

I never did find any detailed specification on the thing.
Must be top secrete or something.

Do you know if the thing has any built in surge protection?

Does it have an isolation transformer inside?
.
Well, one thing that seems to be clearly established at this point is that the problem is related to inrush current occurring at the 20 second point, whether its root cause is DC offset + failure of the DC block in the amp, per Ralph's suggestion (which strikes me as a clever and plausible theory), or some other kind of power anomaly, or oversensitivity of the amp's circuit breaker (even though it has been replaced once), or whatever.

And re the SR Powercell, although there is little in the way of technical detail that is available, one thing seems clear. Its design is based on different principles than most or all other conditioners.

Jim & Ralph, do you think it might be a reasonable gamble for Sailcappy invest either $215 or $239 for one of the BrickWall surge protectors, which also provide some degree of line filtering, and include a "series surge reactor current limiter; cascaded, auto-tracking dual polarity voltage limiters; dual pulse inverters," etc., with the onset of voltage clamping specified to occur 2 volts above the waveform peak. Specs here for the 2-outlet version, and here for the 8-outlet version.

I and a number of other A'goners use one, btw, with no reports of audible side-effects that I am aware of.

Regards,
-- Al
Hm. You could certainly try it. Anything that might drop the voltage a little would probably sort it out. We have ascertained that the issue relates to overpowering the breaker due to something to do with the incoming AC power.

It happens on any outlet in the area; its not related to which side of the line or whether there is leakage from another component. Its entirely to do with the power transformer and the incoming power.

I doubt that its a surge thing- it happens consistently. A surge would only show up occasionally. So I'm going with 'no, that won't help' in this case. Measured line voltage is fine so its not an over-voltage condition of any kind.

This is all assuming that the measurements are correct and the behaviors accurately reported!

Another possibility is a shorted current inrush limiter. A third possibility is that the breaker has developed some residual magnetism and no longer breaks at the right point- IOW its become too sensitive. Simple replacement of the breaker would solve that. Any one of these problems could be such that it would not show up elsewhere due to variables like line voltage and such.

For example if Cary put the unit on a variac when they tested it, the variac may well have functioned to limit the surge current enough so it was no worries. At the other field location, there could have been something with the wiring or the unit was plugged into a power strip with other gear already on it. Power strips only have one power cord, so there could have been a temporary voltage drop, eliminating the problem.

I like to go for the simplest answer as the best one so my thinking right now is the breaker itself is defective.