yamaha cx-2 powers but non functioning

Maybe someone can ease my mind or send me into a mourning state but heres what happened last night. Let me start by saying that this exact thing happened two months ago, only difference is new preamp and speakers this time. I attempted to change my rca cables for my tuner into the tuner inputs on my yamaha cx-2 last night. When I unplugged the cables from the aux inputs and tried to put them on the tuner inputs on the preamp there was a loud buzz. The preamp did not work but it did power on. I removed the preamp and put my kyocera r-611 into the loop as a preamp using the pre-outs. It worked but my alon 1 speakers sounded funny. I determined that the tweeters stopped working but the mids and woofers both worked. Two months ago the same thing happened and my nad 1000 stopped working and my large advent tweeters died. The woofers still worked. It was like deja-vu all over again but with more expensive components. I brought amp to be tested and a quick test showed no problem so u assumed it was the preamp that caused the problem. So I bought a new preamp (yamaha cx-2) and alon 1 speakers. Hooked up to my amp and for a week ran perfectly. Last night I went to change rca cables without turning amp off and poof....does anyone off the top of thier head know what this could be caused by? And whether the yamaha is toast? Ive located replacement tweeters for my alons but im not sure about the yamaha? It powers on but not functions work...the tweeters were only drivers affected not mids or woofers.

Thanks

Scott

You should NEVER hot swap cables or speaker wires. What you heard was 60 Hz hum caused by momentarily touching an un-grounded signal wire to the jack. You blew the tweeters when you did that. Next time shut it down first.
You may have damaged the preamp, but check to make sure you didn't push one of the tape monitor buttons or something. If the tape monitor is on, you will get no output from anything except the tape input, and if you don't have anything connected to the tape inputs you'll get nothing.

The tape monitor is not on. Is this type of damage extensive, or an easy fix for a good tech? I know it would have to be looked at, but what is typical for this type of incident? would a fuse have possibly saved the preamp for serious damage? I know its speculation, but Im trying to decide whether its worth having it put on a bench..Thanks


scott

Yamaha Pre

No fuse issue. Most fuses are in power supplies or output stages. Un plug the Yammie from your power soure actually pull the plug.them wait a few minutes and energize the amp,pre-amp. See if this helps your situation,if not you very may have damaged your Pre-amp. Yes and a good tech can repair but you may be able to pick up a new pre-amp cheaper of Craig's list.

What exactly does unplugging, as opposed to simply turning off then on with power switch accomplish? I never actually tried that...

And I understand the 60hz hum killing the tweeters but would that also kill the preamp?

Unplugging the powre cord and plugging it back in usually resets the microprocessor. You should wait 5 minutes before plugging it back in to allow time for the power supply caps to discharge. The 60Hz hum didn't damage the amp, more likely static discharge, although it's possible there are mosfets on the output that you blew from the large ungrounded signal, or ESD. The likely scenario is you put the microprocessor into an undefined state or damaged it by ESD. A reset might fix it, but if not it will need service. If the processor is blown it's expensive. If you blew the muting mosfets on the output it is a cheap repair. Impossible to tell without looking at it on the bench.

Im dropping it off tonight at a repair shop tonight...if its going to be more than a couple hundred to fix I guess ill have a new door stop...I really liked this preamp...bummer

Thanks again for your advice

It shouldn't be more than $200 to repair. Sometimes the processor is expensive, sometimes reasonable. NAD charges around $25 for a processor, for example, but they kill you with shipping, probably because it has to ship from China. I think I paid $40 including shipping last time I ordered one. This is what I dislike about the new digital receivers and preamps. Lots of special semiconductors that are easily damaged by ESD or a line surge. If you had an analog preamp with knobs and switches it would not have been damaged by what you did.

This still doesn't make sense to me...the amplifier was connected to the preamp. ..the turntable, cd player, & tuner were connected to the preamp. The speakers connected to the amp. I had tuner connected to auxillary input instead of dedicated tuner input s. I decide to connect tuner to the dedicated inputs so I pull interconnects out of auxilllary and as im plugging them in theres a buzz...volume was fairly low....doesnt power go from pre to the amp? And how did electricity travel to the speakers? Could there be an undetected amp issue?

Hey...it works....you were right about the reset...wow..I am one happy camper..thank you..I would have just brought it to the shop ...

Scott

honestabe316 said:

Hey...it works....you were right about the reset...wow..I am one happy camper..thank you..I would have just brought it to the shop ...

Scott

Click to expand...

Glad I could help. Now, no more hot swapping cables! This does seem to prove it was an ESD hit. To prevent such things happening in the future always touch ground with one hand (the chassis) when plugging and unplugging cables. You were lucky this time. AV components are not as robust as the old stuff.

Will do for sure..thank you

Scott