Amp Shutting Down, need help

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!

Jim, I didn't see your last post until just now; sorry. I guess it must have gone up just a few seconds before my last post.

You've offered lots of good thoughts and suggestions. My only further comment is that while I'm not particularly familiar with magnetic breaker characteristics, I'm skeptical that relatively low order harmonics are to blame. The reason I say that, and I could be wrong, is that I doubt that the inductance of a coiled 50 foot extension cord would be significant enough to have much effect at those kinds of frequencies. Keep in mind that the inherent inductance of each individual conductor (hot and neutral) will be significantly reduced by the fact that the other of those conductors is in close proximity. Coiling will increase the inductance, of course, but it will be multiplying an amount that is much less than if just one of the two current-carrying conductors were present in the cord.

So my guess, and as I say I could be wrong, is that as I suggested earlier there is some sort of higher speed transient that is present, that repeats each cycle and that is being reduced by the extension cord's inductance. Or, alternatively, perhaps the capacitance between the safety ground conductor of the extension cord and the other two conductors is providing some sort of filtering action at high frequencies, or is somehow affecting something in the amp by adding capacitance between the chassis and the AC inputs.

08-20-12: Sailcappy
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?

Why invest in a power regenerator, and perhaps risk introducing side effects that on occasion have been reported to result from them (such as compromised dynamics), when you already have a solution that appears to work adequately?

And if a regenerator is to be selected, it would seem preferable to first have as good an understanding of the cause of the problem as possible. Meaning, IMO, that the measurements and experiments suggested by me, Frank, and Jim should be addressed first. Such as the simple ground measurements Frank suggested, the comparison I suggested of results with the extension cord coiled and uncoiled, and the suggestions in Jim's last post.

Otherwise we're taking a shot in the dark. Which we may end up taking anyway, but it would be prudent to minimize that likelihood as much as possible.

Regards,
-- Al

Thank you for reminding me of proper trouble shooting techniques. Last night I had one to many and when my friend and I got around to dealing with this issue we both just said screw it just purchase a regenerator. And we went back to drinking. LOL.

Moving forward instead of referring to my friend as the guy who works for the power company I will use his first name which is Ken.

Back to the problem:

1. I uncoiled the extension cord and the Cary powered on without a problem. So it works both coiled and uncoiled.
2. The 50’ extension cord has the following information imprinted on the jacket 16/3. I assume that means 16 gauge times three wires. The jacket diameter is 5/16”. I’d have to cut the cord to get the actual gauge of the wire.
3. I have tried it with shorter extension cords from 3 feet to 20 feet with approximately the same diameter and it does not work.

“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?”

4. Not sure what you are asking the 15amp breaker which is the on/off switch for the breaker trips it to the off position when I noticed this drop. Remember this happends after i go from standby mode to Active mode.

"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.”

5. Ken confirmed that all of my outlets in the apartment are grounding directly to metal wall boxes and conduit by design - negating the need for ground wiring including the circuit breaker box.

"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."

6. Voltage from the “smaller" slot to the "ground" slot is 118 volts.

7. Resistance (Using the Omega setting on the volt meter) between Neutral (Large Slot) and Ground slot jumps between 13 and 17 units.

"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. 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."

8. I tied a ground cheater plug with the stock power cord and the problem occurred.

"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."

9. The breaker only trips after I take the unit out of standby mode and put it into “Active Mode”. I am powering the amp in the following manner. I first turn the circuit breaker switch from the off position to the on position. I then press the button on the front of the unit which takes it out to standby mode into the Active Mode”. Without the extension cord the 15 amp ON OFF circuit breaker switch on the back of the unit trips to the off position. After it switched to the off position I put the unit back into standby mode (pressing the front button to standby) and start the process over again. Not sure if your reccomendation is valid.

"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."

10. Ken is working on getting a oscilloscope to test

11. I don’t know anyone in NYC to borrow a different power conditioner. I will ask a dealer to see if they will assist.

2. The 50’ extension cord has the following information imprinted on the jacket 16/3. I assume that means 16 gauge times three wires.

Correct...

The cord impedance is limiting inrush current through the magnetic breaker of the Cary amp when the amp goes active.....

“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?”
jea48

4. Not sure what you are asking the 15amp breaker which is the on/off switch for the breaker trips it to the off position when I noticed this drop. Remember this happends after i go from standby mode to Active mode.
Sailcappy

The on/off switch/breaker is for FLA protection of the amp.
Short circuit and or overload condition.

The protection relay switches the amp from standby to active mode which I would assume sends power from the power supply to the power amps circuitry. The protection relay circuitry should also protect the speakers from damage in the event of amplifier malfunction.

Test.
With the 50' cord connected volume control set at minimum turn on the switch/breaker. With your ears close to the amp push the power button on the front of the amp. (Standby to active). More than likely you will hear a click/s.... That is the protection relay/s changing state.

"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."
jea48

9. The breaker only trips after I take the unit out of standby mode and put it into “Active Mode”. I am powering the amp in the following manner. I first turn the circuit breaker switch from the off position to the on position. I then press the button on the front of the unit which takes it out to standby mode into the Active Mode”. Without the extension cord the 15 amp ON OFF circuit breaker switch on the back of the unit trips to the off position. After it switched to the off position I put the unit back into standby mode (pressing the front button to standby) and start the process over again. Not sure if your reccomendation is valid.
Sailcappy

When the breaker trips all power on the load side of the breaker is disconnected from the Cary amp. Pushing the standby push button on the front panel will not do anything. As I read the owners manual the amp is still in active mode.

From the owners manual.

"Power Button.
The Power Button performs no function when the amplifier is power off with the rear Master Power Switch.

When the rear panel master switch is powered on the model 7.25 is in standby mode. Pressing the Power Button when the rear panel mater panel switch is powered on will activate the power amplifier"..... And so on....

NOTE.
"When the status of the model 7.25 changes relay checks may be audible. This is normal operation."

I suggest you reread the owners manual again.
Section on, "Controls and Displays".

9. The breaker only trips after I take the unit out of standby mode and put it into “Active Mode”.
Sailcappy

Immediately after?

The 50' 16/3 power cord is limiting inrush current flow through the magnetic breaker.

.

Sailcappy, thanks for the additional info. A few things are not clear to me, though, which are along the lines of some of the questions Jim had.

1)If the extension cord is not being used, am I correct in understanding that the breaker on the amp trips 20 seconds after the amp is switched from standby to on/active (the rear power switch/breaker having been turned on previously)?

2)And when the extension cord is being used, will the amp play music during those 20 seconds, or does it really become active only after the 20 seconds have elapsed?

3)And as Jim asked, when the extension cord is being used do you hear the click of a relay at the 20 second point?

Regards,
-- Al