Amp Shutting Down, need help

I like to go for the simplest answer as the best one so my thinking right now is the breaker itself is defective.
08-23-12: Atmasphere

Ralph,

I agree....

I would think both toroidal transformers would have to be the first items powered up on the amp along with the DC power supplies long before that last click is heard.....
I mean the active sequence start up circuity needs DC power to go through its functions. I have no idea what that last click, relay is doing....

I also believe the soft start circuitry of the amp is doing a good job smoothing out the current as the two toroids and DC caps of the power supplies are charging. In fact, because of the 20 sec time frame for start up, both toroids may not even be powering up at the same time.

I was surprised by the voltage load test readings Sailcappy measured at the end of the 50' 16/3 cord with the amp connected.

No load 118V and through the whole active start up sequence the voltage only dropped 3 volts!
Granted the impedance of the 50' cord would limit inrush current..... I still would have thought the VD would have been more than 3 volts.

I mean we are talking about a 7 channel power amp rated at 250 watts @8 ohms each channel.

I think I would call Cary and ask them what it would cost to change out the switch breaker to just a switch and add an accessible fuse holder and fuse on the rear panel and replace the cheap magnetic breaker.

I believe I counted 6 fuses in the amp already.... What's one more.....

A look inside the Cary 7.250 Amplifier.

08-23-12: Jea48 “I would think both toroidal transformers would have to be the first items powered up on the amp along with the DC power supplies long before that last click is heard.....
I mean the active sequence start up circuitry needs DC power to go through its functions. I have no idea what that last click, relay is doing....“

I would speculate that the standby circuit is merely a passive or solid state design (no transformer) to minimize idle/standby current - fed after the magnetic breaker, which then feeds the delayed progressive interlock power-up circuits, which then controls the toroid’s power relays where any “soft start” circuitry might be interfaced, or something along those lines.

“I was surprised by the voltage load test readings Sailcappy measured at the end of the 50' 16/3 cord with the amp connected. No load 118V and through the whole active start up sequence the voltage only dropped 3 volts! Granted the impedance of the 50' cord would limit inrush current..... I still would have thought the VD would have been more than 3 volts. I mean we are talking about a 7 channel power amp rated at 250 watts @8 ohms each channel.”

I would have expected a larger dip as well unless it *was* slightly larger, but the refresh-rate of the meter was too slow in conjunction with a very short soft-start period (milliseconds). Granted, all outputs were unloaded, but the size those two toroid’s KVA rating would commend a substantial inrush without a soft-start. Orrrrrr, I'm betting because the mag-breaker tripped before the meter read the actual larger voltage drop.

Which now gets to Ralph’s speculation regarding the mag-breaker’s condition. If we knew what the typical (unloaded) inrush current was after the 20 second delay, within an ideal supplied AC scenario, we would have a better idea how close we’re getting to a *healthy* breaker’s 15 amp trip threshold vs. sailcappy’s suspect breaker.

Frank

Orrrrrr, I'm betting because the mag-breaker tripped before the meter read the actual larger voltage drop.
08-23-12: Metro04

Hi Frank,

The magnetic breaker doesn't trip when the 50' 16/3 cord is used.

Which now gets to Ralph’s speculation regarding the mag-breaker’s condition. If we knew what the typical (unloaded) inrush current was after the 20 second delay, within an ideal supplied AC scenario, we would have a better idea how close we’re getting to a *healthy* breaker’s 15 amp trip threshold vs. sailcappy’s suspect breaker.
08-23-12: Metro04

Agree.....

I asked Sailcappy in an earlier post, I believe, if his friend had a clamp on amprobe to check the current draw of the amp through its start up cycle.... The meter would need to be a true RMS.

His friend would need do a little surgery on an old short power cord carefully cutting away the outer jacket exposing the 3 insulated conductors inside about 6" to 8" or so.

For the test.

The Cary amp plugs into the short power cord.
Clamp the Amprobe around the exposed insulated hot conductor.
Set the Amprobe so it will lock onto the highest reading.
Plug the short power cord into the wall outlet.
Fire up the cary amp.
The Amprobe will lock onto the highest ampere reading just at the point the magnetic breaker trips.
.

"Hi Frank, The magnetic breaker doesn't trip when the 50' 16/3 cord is used."

Uhhhh, yeeeaaah.... I was just seeing if you were paying attention. LOL!

Seems I get these A.D.D. attacks more frequently ever since upping my Cialis treatment from a PEZ dispenser, to one of those cranial-sported gravity drip-feeder apparatuses. The T.V. adds make it look so harmless.

The fact that a co-worker walked in on me wearing a L'il Bo Peep outfit, while typing, may have affected my train of thought as well. No excuses... Just sayin'

Frank

Uhhhh, yeeeaaah.... I was just seeing if you were paying attention. LOL!
08-23-12: Metro04

LOL....
.
Jim