I bought this Yamaha Receiver R-9 at a garage sale, it sounds great ( way better than my more recent Technics receiver) and has a lot of features. However, it produces a humming sound on one of the speakers, which is drowned by the music once it is played. The sound has peaks and valleys, kinda like a windy day. The unit is very dusty inside, should I blow some air in it or not? Thanks for the answers.
Most likely the main filter capacitors, and the decoupler capacigtors probably have to be changed in the power supply section. It is also possible that there are other components and capacitors in the set that have to be changed because of their age. This is common in these sets.
If you are not experienced in servicing electronic equipment, you should give the reciever out for proper service. There are also serious safety issues with servicing electronic equipment.
Jerry G. ======
As far as I recall, the power supply on these is common to all channels, thus if the hum is on one channel only, it is highly unlikely that it is being caused by the main smoothing caps. The first thing to establish is if the hum is affected by the setting of the volume control. If it is, then the problem will likely be a front-end grounding issue. Any power supply problem will normally not have the symptoms it's causing, affected by the volume setting, and will affect all channels equally.
Arfa
Agreed, but as I said, I seem to recall that this Yammy has a common power supply.
Arfa
>Arfa, what is a "Yammy"?
David
many high end audio amps have their own bridges and caps per channel, they may use the same xformer how ever.
-- Real Programmers Do things like this. http://webpages.charter.net/jamie_5
thanks for the answers, but what is a front end grounding issue? Excuse my ignorance, I am starting to pick up these old receivers for few dollars, and I am amazed by the sound quality ( I also have a small, old Sansui R-606 that sounds incredible), and I want to learn the basics. I think I have a new hobby.
On Sun, 21 May 2006 18:45:28 GMT, "David" put finger to keyboard and composed:
It's kinda like a Kwaka but with less horsepower.
- Franc Zabkar
-- Please remove one 'i' from my address when replying by email.
NOT the R-9 .... it has a single power supply for both channels and if it is bad then both channels would be affected. Look for loose grounds, leaky driver or preamp transistors, etc. Fortunately when servicing stereo equipment you have a fully redundant and duplicate channel for comparison tests and even temporary component swapping to verify problems. electricitym
It's 'trade speak' for a product from the Yamaha stable. Like calling a Panasonic a "Pan". Just lazy slang I guess. I was referring to the OP's question which referenced a specific Yamaha model
Arfa
Heg-zackerly !! That's just what I said. Thanks for the backup ...
Arfa
OK. 'Front end' is engineer speak for the input select / preamp / tone control etc stages of an amplifier, and is generally accepted as being any and all of the circuitry from the input sockets, as far as the volume control. After the volume control is usually taken to be 'output stage' or 'power amp', and the actual circuitry will include predriver, driver, and output stages.
If you connect a signal to an amplifier, with the ground disconnected, there's a good chance that the amp will produce a loud hum, which can be controlled by the volume setting. This tells you that the problem is 'front end' related. The results of bad ground connections internal to an amplifier can vary depending on the exact design and layout, but if, for instance, the ground pin of an input socket went dry jointed in the board, or sheared off - both common failures - you may well still get correct audio through the channel, due to the ground connection being intact on the other channel, but you may also get a degree of hum on the 'bad' channel, due to the ground following an abnormal path via the other channel.
If you have a hum which is not affected by the volume control, then this indicates that the problem is post the volume control, OR is power supply related. As noted by myself and electricitym, a power supply related problem will, in most cases, affect both channels, as a common power supply is typically used to supply both channels. The exception to this occurs in a few high-end amps, which employ separate power supplies for each amplifier. You can think of these amps really, as being two independant mono amps built on the same chassis, but with ganged controls. Your Yamaha employs a single common power supply, which is why I said that if you have hum on one channel only, the problem is *unlikely* to be power supply related. Hope this helps you to understand it a bit better. It's easy for those of us who work on the stuff all day, to forget that many people asking questions on here are either amateur, or just starting out.
Arfa
In one sense you are absolutely right. Jerry G. must have missed on that one. But, some of these receivers also used a split power supply. I cannot say for sure with his model.
--
JANA _____
As far as I recall, the power supply on these is common to all channels, thus if the hum is on one channel only, it is highly unlikely that it is being caused by the main smoothing caps. The first thing to establish is if the hum is affected by the setting of the volume control. If it is, then the problem will likely be a front-end grounding issue. Any power supply problem will normally not have the symptoms it's causing, affected by the volume setting, and will affect all channels equally.
Arfa
This confirms a separate set of filter caps for each side. The thing here, is that someone would have to know the specific model design, or have it opened on their service bench in order to even start making assumptions of what the fault may be.
--
JANA _____
many high end audio amps have their own bridges and caps per channel, they may use the same xformer how ever.
-- Real Programmers Do things like this.
Does it have a separate set of filter caps, and voltage regulators for each side???
--
JANA _____
Agreed, but as I said, I seem to recall that this Yammy has a common power supply.
Arfa
>What's a, "Kwaka"???
--
JANA _____
It's kinda like a Kwaka but with less horsepower.
- Franc Zabkar
-- Please remove one 'i' from my address when replying by email.
"Heg-zackerly !!"
I love your expressions! Do you have a list???
--
JANA _____
Heg-zackerly !! That's just what I said. Thanks for the backup ...
Arfa
I have worked on high end Crown amplifiers and others along that line. These are used in professional studio environments. They use a complete set of power supplies for each channel of audio. Some models only share the same power transformer, but the rest of the power supply is separate.
If you want to have some very good quality sound, that you cannot experience with any of the home audio gear, get in to collecting and building up a sound system using professional audio equipment. There is a big difference!
--
JANA _____
OK. 'Front end' is engineer speak for the input select / preamp / tone control etc stages of an amplifier, and is generally accepted as being any and all of the circuitry from the input sockets, as far as the volume control. After the volume control is usually taken to be 'output stage' or 'power amp', and the actual circuitry will include predriver, driver, and output stages.
If you connect a signal to an amplifier, with the ground disconnected, there's a good chance that the amp will produce a loud hum, which can be controlled by the volume setting. This tells you that the problem is 'front end' related. The results of bad ground connections internal to an amplifier can vary depending on the exact design and layout, but if, for instance, the ground pin of an input socket went dry jointed in the board, or sheared off - both common failures - you may well still get correct audio through the channel, due to the ground connection being intact on the other channel, but you may also get a degree of hum on the 'bad' channel, due to the ground following an abnormal path via the other channel.
If you have a hum which is not affected by the volume control, then this indicates that the problem is post the volume control, OR is power supply related. As noted by myself and electricitym, a power supply related problem will, in most cases, affect both channels, as a common power supply is typically used to supply both channels. The exception to this occurs in a few high-end amps, which employ separate power supplies for each amplifier. You can think of these amps really, as being two independant mono amps built on the same chassis, but with ganged controls. Your Yamaha employs a single common power supply, which is why I said that if you have hum on one channel only, the problem is *unlikely* to be power supply related. Hope this helps you to understand it a bit better. It's easy for those of us who work on the stuff all day, to forget that many people asking questions on here are either amateur, or just starting out.
Arfa
How exactly does this confirm a separate set of filter caps for each side ? Let me say again, as far as I recall, the Yamaha R9 has a single multi-rail power supply, which feeds everything. It's not a model that I've seen frequently, so I wasn't absolutely sure about this. However, electricitym confirmed in his post of the 22nd at 00:10 that this is the case. So, he does know the specific model, and made all of the same comments in his post, that I had : viz a single power supply feeding both channels, is unlikely to be the cause of hum on one channel only, and that front end ground issues are more likely to be the cause of the problem. I don't really think that either of us was making assumptions about what is wrong with the equipment. We were merely offering pointers to the probable fault areas, based on many years' experience of repairing this stuff commercially.
Also, I don't want to make big issue over it, but top posting does get confusing for people trying to follow the thread. It sometimes makes it difficult to follow just exactly which comment you are responding to. The common convention is to bottom post, which I accept also has its drawbacks, but if we all stick to the same convention, it makes it easier all round :-)
Glad you like my little words. It injects a bit of light-hearted humour, if nothing else. I'm surprised you haven't come across " Kwaka ". It's a fairly world-wide ( I think ) slang term for a Kawasaki motor cycle - hence Franc's comment about horsepower. d;~}
Arfa
Does it get hot?
How does your tweeter look?
The amp may be oscillating. Older yamaha's are slightly famous for that with certain speakers. The oscillation comes and goes, loading the amp to the limit without creating much audible sound. When the oscillation hits rail to rail the hum starts to be noticable. I did actually witness a tweeter dripping out of the box slowly...
-- - René
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