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Yamaha amp fried?

 

Anonymous
 
was listening to a burned cd when it started cutting in out, went to check the cd and could smell the amp burning smell. Took off the cover and noticed it was coming from a box inside with copper band around it and a bunch of wires going to it. It's a Yamaha AX700u, if anyone can give me an idea what this component is, how much to fix, how easy to fix, or if it's even worth it.
Much appreciated for any help!
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 3594
Registered: May-04


That is the power transformer. At this point, the amp either works or not. The power transformer is the single largest portion of the cost of any amplifier.
 

Anonymous
 
any idea as to how much it will cost, and how easy it is to fix?
thanks
 

KenO
Unregistered guest
Sorry I can't help, but do you know how many watts per channel this amp is?
 

afarah
Unregistered guest
Power transformers are very hardy and are well protected from overheating via a thermal fuse. If it is really fried, then its probably due to a short circuit on the output terminals which means you may have a faulty power section in your amp. The bridge rectifier is a good suspect. If you don't have a techie friend to take a look for you, just call up the authorised service center and describe the symptoms. They should be able to guage the extent of the damage and give you a quote.
 

Unregistered guest
I have amp that cuts out when I turn up the volume. I have since discovered that I have 4 Ohms speakers and an amp that is rated at 8 ohms. Is there a solution? Can I add another set of speakers in Series and make this work?
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 4155
Registered: May-04


Adding another pair of speakers may make the situation worse rather than better. Speakers are not simply 8 or 4 Ohms; their actual electrical impedance swing (or curve) can vary tremendously and dip and rise across a very wide range of impedance. Even a simple 8 Ohm speaker can change drastically in the impedance it shows an amplifier as you can see in this link:

http://stereophile.com/loudspeakerreviews/1204psb/index4.html

Adding a load resistor will help the impedance situation but may harm the sound quality. The best suggestion would be to replace the amp or speakers with something appropriate to the situation.




 

afarah
Unregistered guest
Hi Nimaz. You can safely add another pair of speaker in SERIES bringing the total speaker impedance to 8ohms per channel.

However, most amps will be able to handle down to 4ohm speaker loads. If yours is tripping its probably b'cos its not able to supply enough current to the 4 ohm speakers at high volumes. You might want to check your speaker impedance with a multimeter just to be sure that the voice coil has not degraded.
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 4211
Registered: May-04


"You might want to check your speaker impedance with a multimeter just to be sure that the voice coil has not degraded."

HUH? What exactly does that mean?




 

Silver Member
Username: Nuck

Parkhill, Ontario Canada

Post Number: 109
Registered: Dec-04
hehe it hasnt degraded to nil, I presume.
 

Silver Member
Username: Eramsey

South carolina United States

Post Number: 231
Registered: Feb-05
What are you talking about running another set of speakers wired in series?! This will put an even greater stress on the amp,especially if the two sets of speakers have wildly different phase shifts and impedence swings. Let it be known speakers are not a fixed impedence purely resistive load. You also cannot wire two sets of speakers to the same terminals. This will fry your speaker outputs. Now, granted you can do this to a certain extent with car audio but not with home audio.
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