Buzzing sound in my speakers when I switch to the phono stage

Is that the right part number, MCS 10, and not MCS100?

The MCS systems use a basic sub which is matched to the satellites. There's very few controls other than level on the MCS100. So as long as the power light is illuminated the there's very little other than the volume control that could be set wrong on the sub. So what it comes down to is either

1. a blown fuse (no power at all at the sub);
2. a broken input (#1 cable, #2 sub input socket, #3 blown sub plate amp);
3. incorrect connection at the receiver end or the wrong settings

As a quick test, unplug the sub cab from the amplifier/receiver end. Switch on the sub and turn the volume down all the way. Briefly put your finger across to short the RCA/phono tip and ring. The sub should make a buzzing sound. You now know that the sub is working and the cable appears to be okay

Switch off the sub and reconnect the phono/RCA to the sub out socket on the receiver. You now know it is connected correctly.

Go in to the receiver's menu and check the speaker settings. Is subwoofer present? Yes/No

Are the satellites all set to Small? (they should be with this system)

Are you playing a 5.1 source in DD or DTS to ensure that the sub gets a signal? Play a BD or DVD.

On the speaker balances, is the sub channel set to 0dB?

As long as all the above is set as listed, then the only things stopping the sub working would then be insufficient volume at the sub's Vol control (so increase it), or an intermittent cable connection (wiggle the cable), or a broken subwoofer out signal at the receiver.

The Phono section has a very high level of amplification and so the audio input is very sensitive. So a possible faulty/loose grounding of the input can create a HUM which can be due to even a poor shielding of the input from stray AC factors. So you need to check for the these factors that can bring in the hum , you can confirm by isolating the phono circuit and working to the faulty stage.
Also it can be due to a faulty power supply - non filtering in DC- to the phono preamplifier.Finally faulty capacitors in power and feedback circuits can be a reason- check the negative feedback circuit which can be an op-amp with a feedback , check the capcitors here as a higher amplification can also be a reason.- check the preamp IC.

It may be too late given the date of this post, but the buzzing has nothing to do with the bulbs (usually, dimmers and lamp buzzing are a common problem which is why you probably got the suggestion), but in your case, you have radio-frequency interference from the dimming circuit leaking into the audio circuit. The best things you can do is either minimize the RFI, or separate the audio circuit away from the dimming circuit. Based on what you're saying about the PC input, it sounds like the main culprit is that specific audio wire going between the PC and the sound system - can it be run differently so that its further away from the dimmer/circuit. Are the PC and the dimmer on the same breaker? - If so, maybe noise is radiating from the dimmer into the PC through the power wiring - putting on different breakers could help.
One more note, the best dimmers, in terms of RFI performance, are reverse-phase control dimmers (usually designed for electronic-low-voltage... and be careful because they often get confused with magnetic low-voltage... and those will not help. Without going into too many specifics, the ELV dimmers have a much softer on/off/on/off dimming cycle when compared to standard incandescent dimmers (this is a circuitry thing with a much more complicated explanation), but as a result, they tend to have significantly fewer issues with RFI. They can be an expensive solution for simple problem solving, but the MIRELV-600 should do the trick (again, don't be fooled, the MIRLV-600 is the magnetic low-voltage product, and for what you're doing, won't help).

The reason for the hum is as follows:

1) The phono input on the receiver contains an additional stage of amplification required for typical turntables.
2) Pluggin in a unit that has a signal level too high will generate this hum.
3) Your turntable contains an pre-amp that allows it to work using an aux input (or tape input) as most receivers today no longer have phono inputs.
4) Grounding issues relate to the older types of turntables where there was NO pre-amp stage inside the turntable. In this case ,the signal levels were so low that stray noise would often get in the way of the signal. Proper grounding would elimiate this noise.

Hope this helps.

Dan

is the wire loose on either end? sometimes the electrical plugs can cause noise due to resistance, so trying different outlets might help too

You need a phono stage (phono amp) between the turntable and receiver to boost the lower signal from the turntable. If your receiver has phono inputs, use those as there will be a built-in phono stage.

This may be a power supply failure, and or a short in the output stage, and in the drivers for the output stage.

This is not a repair you can do at home unless you have a lot of experience in troubshooting and analysing problems in power amplifier equipment.


Jerry G.

in sound system you have different sound level start with phono level up to line level up to speaker level.-you will switch to phono when you connect phonograph and you will switch to line when you connect another audio source like dvd and video sound.

You may want to try putting an attenuater in the line with the RCA's to cut the input signal back just a little bit. So you are not driving the amp so hard with your preamp.