Did I wreck anything?

[sksfreund]

I accidentally unplugged the power cord from my Musical Fidelity A3.2cr preamp with the power still on. I heard a loud buzz for about 3 seconds that went away as the preamp lost power. I just want to know if I could have hurt anything. I have everything hooked up now, and nothing sounds like it is wrecked, but I just want to know for sure. Any help would be great.

[Mr Peabody]

I wouldn't think you hurt anything. It would be the same as any other power cutoff except with the unit on you probably heard the capacitors discharging. I get the same kind of sound when I forget and turn my power amp off first without turning off the preamp.

[sksfreund]

Is there a way I can check to make sure?

[Mr Peabody]

If it sounds alright, no difference noticed, I'd say it was fine and if everything is still functioning as normal. The only way I know for you to be positive other than that is to take it to a technician to be bench tested.

[hermanv]

An ON/OFF switch is a mechanical device that disconnects one or both leads from the AC power cord. In 99% of the cases it is exactly the same as pulling the power cord out of the wall.

[kexodusc]

Yeah, it's mega-doubtful you damaged anything just from unplugging the cord. I wouldn't make a habbit of it, but it shouldn't cause any problems.

[Geoffcin]

I accidentally unplugged the power cord from my Musical Fidelity A3.2cr preamp with the power still on. I heard a loud buzz for about 3 seconds that went away as the preamp lost power. I just want to know if I could have hurt anything. I have everything hooked up now, and nothing sounds like it is wrecked, but I just want to know for sure. Any help would be great.

I own a Musical Fidelity A3cr amp, and the power has been cut on it several times with no effect at all. Musical fidelity uses choke regulation on the power supply for the A3.x line, and that will cause an unusual sound when discharging. Nothing to worry about.

[sksfreund]

Ok, now my preamp is acting up. I had my dvd player hooked up to it through the aux 1 input and I started hearing a buzz sound out of the blue one day. It just "started". I unplugged the dvd player and the buzz is gone. No problem, but I want to know why it just "started" like that. Also, when I was trying to figure out what the buzz noise was, I unplugged my MMF 2.1 turntable interconnects and while I was doing that, I was getting a very loud popping sound from my speakers. That really concerned me. It seemed to only happen when I touched the black plug, and that plug did seem slightly "loose", but I don't know for sure. I unplugged it and plugged it back in a couple of times and the noise stopped, but not before making me think I had just blown my speakers. (yes, I even had the volume WAY down). Any thoughts?

[Resident Loser]

...didja' ever go to start your car and it won't...since you unplugged the dvd player(was it just the player OR the interconnects AND the player?)that pretty much rules out a problem with your pre, more or less(see below)...could be a failing cable, a problem with the player or it could have been there all along, but wasn't noticed until you "clued" into it.

You really shouldn't connect or disconnect anything with the power on, it's not good a practice...WAY down isn't off.

Intermittent problems are a technicians nightmare...without seeing a schematic I can't be sure, but there may be a terminal strip grounding problem in it's nascent stages...either that or your connectors may simply need a cleaning with an appropriate solution or the every-so-often pull-and-twist mechanical scrubbing(WITH THE POWER OFF!!!)...I've found the change of the seasons to cause some contacts to get cruddy...

jimHJJ(...good luck...)

[krzywica]

Turn the damn power off, thats why you hear popping!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Geoffcin]

Ok, now my preamp is acting up. I had my dvd player hooked up to it through the aux 1 input and I started hearing a buzz sound out of the blue one day. It just "started". I unplugged the dvd player and the buzz is gone. No problem, but I want to know why it just "started" like that. Also, when I was trying to figure out what the buzz noise was, I unplugged my MMF 2.1 turntable interconnects and while I was doing that, I was getting a very loud popping sound from my speakers. That really concerned me. It seemed to only happen when I touched the black plug, and that plug did seem slightly "loose", but I don't know for sure. I unplugged it and plugged it back in a couple of times and the noise stopped, but not before making me think I had just blown my speakers. (yes, I even had the volume WAY down). Any thoughts?

The cables are a good place to look for trouble. Your first problem seems to be the DVD players cables. NEVER undo a cable while the preamp and amp are on.

On your second problem; The phono section is the most sensitive input, and you could easily blow something if you play with that connection when it's active. Follow some simple common sense rules about plugging your components in and your probably never going to have a problem.

[Haoleb]

An ON/OFF switch is a mechanical device that disconnects one or both leads from the AC power cord. In 99% of the cases it is exactly the same as pulling the power cord out of the wall.


Not entirely true. In some cases yes. But especially with newer stuff this isint the case anymore. For example you can damage tv's by pulling the plug while they are turned on.

[hermanv]

Not entirely true. In some cases yes. But especially with newer stuff this isint the case anymore. For example you can damage tv's by pulling the plug while they are turned on.
So if the power company power fails your TV could be damaged? I certainly have not reviewed every manufactures schematic so I can not be absolutely sure, but this sounds like mysticism. Who would except liability for a failed TV designed to operate this way?

The "newer stuff" leaves the infra-red remote controlled receiver powered up when you operate the ON/OFF switch, that's all. Mechanically breaking a connection with an ON/OFF switch, with a circuit breaker or by unplugging the power cord has the same effect. Un-plugging the cord merely entails more contact bounce than a well designed switch does, otherwise it's identical to opening the flow of electricity with a mecahnical contact. If you take appart a modern wall switch you will usually find a blade that slides into and out of a female contact, pretty much the same thing as a male wall plug into a female wall socket. If your TV was plugged into an outlet controlled by a wall switch, it might blow up if you operate the switch?


Ok, now my preamp is acting up. I had my dvd player hooked up to it through the aux 1 input and I started hearing a buzz sound out of the blue one day. It just "started". I unplugged the dvd player and the buzz is gone. No problem, but I want to know why it just "started" like that.The RCA connectors used for interconnects are notoriously unreliable. They are ubiqutous, that's the only reason they're still around. Contact failure is quite common especially for the cheap tinned ones. That's one of the big reasons locking RCA's and gold plated RCA's exist.

When you unplug an RCA jack the ground lead (that's the outside ring) disconnects first. This leaves the center, signal carrying pin connected between two devices without a common ground. Lots of hum or popping sounds are pretty much guaranteed.

[sksfreund]

I consider myself semi-knowledgable on audio gear and I had no idea unplugging interconnects while the power was on was a bad idea. Thanks everyone for clueing me in. I still have one last question though. None of the before mentioned anomalies are happening anymore, but do you think I could have wrecked anything still? Everything sounds fine, but I am seriously paranoid about this whole situation, especially after being told that I could have been making the problem worse.

[hermanv]

99% of electronic failures are both immediate and catastrophic - that is to say it fails now and in an obvious manner. The odds of having created a latent failure (one that shows uplater) are very, very small.

Relax, enjoy your system.

[Florian]

Yeah dont worry about it. My Krell pre-amp doesnt even have a power switch !!! Its meant to run 24/7 ;-)

-Flo

[sksfreund]

Is it a lright to keep the MF A3.2 amp/preamp running 24/7?

[Geoffcin]

Is it a lright to keep the MF A3.2 amp/preamp running 24/7?

I keep my preamp on 24/7. It draws only 20 watts or so. I keep my amp on 24/7, and when I was using the A3cr I did also. No problem!

[mixadude]

I generally recommended turning off anything with electolytic capacitors in the power supply for about 10 minutes once a week or so. They'll last longer if they get cycled every so often. edit- other than that, always on is OK if it doesn't make too much heat, or use too much power ;)


As for plugging inputs when on, I do it all the time, I just make sure the channel im plugging into isn't selected, or the volume is all the way down, or muting is active, etc. The real danger is blowing a speaker, or making an embarrasing noise in front of everybody. On hi-fi gear, though, I definately power down before connecting or disconnecting speakers; amps don't like having their outputs shorted, even though the might say they have protection, I'd rather be safe than sorry.

And as for powering down by pulling the plug, I do it all the time to semis full of sound and video gear, but not the projectors or stuff that needs to cool for longer life.

[risabet]

if it's still working, it's undoubtedly fine.