Coil Whine on Marantz Melody M-CR412

[karthiks1_ht]

Recently purchased used Marantz Melody M-CR412, it has an audible high pitched whine when listening in a closed environment, however it is tolerable in an open room. Sound does not affect speaker output. While listening to song, the coil whine increases and becomes unpleasant.

When checked, sound originates from SMPS section, suspected from transformer. Attached image of transformer.

Has anyone faced similar noise and any solution to dampen the sound?

Solutions attempted so far to no improvements:

1. Different AC power outlet in my home and checked it at friends location.
2. Attempted isolating and powered with home UPS.
3. Kept isolation pad under four legs of amplifier.

 

[mbhangui]

Recently purchased used Marantz Melody M-CR412, it has an audible high pitched whine when listening in a closed environment, however it is tolerable in an open room. Sound does not affect speaker output. While listening to song, the coil whine increases and becomes unpleasant.

When checked, sound originates from SMPS section, suspected from transformer. Attached image of transformer.

Has anyone faced similar noise and any solution to dampen the sound?

Solutions attempted so far to no improvements:

1. Different AC power outlet in my home and checked it at friends location.
2. Attempted isolating and powered with home UPS.
3. Kept isolation pad under four legs of amplifier.

Can you post the photo of the entire SMPS board if possible. There could be many reasons for this high frequency whine

1. Failing electrolytic capacitor (a capacitor that is developed a high ESR). Replacing the electrolytic cap could solve this issue
2. Some components are susceptible to vibration (especially any transformer or inductor coils). Usually manufacturers put some kind of glue to prevent vibration. Varnish is applied to transformers to prevent the iron core from vibrating, etc. Check all places where components have some kind of glue applied between the component and the PCB.
3. Aging or heat can cause the electrical characteristics of components (capacitors, resistors, semiconductors) to drift, causing the SMPS to operate at a frequency that becomes audible (often in the 10kHz - 20kHz range). Again the reason for this drift could be one ore more of the electrolytic capacitors failing.
4. Sometimes ears are sensitive to this whine. e.g.I can hear this wine in all SMPS. Do all members in your household hear this whine?

 

[karthiks1_ht]

Can you post the photo of the entire SMPS board if possible. There could be many reasons for this high frequency whine

1. Failing electrolytic capacitor (a capacitor that is developed a high ESR). Replacing the electrolytic cap could solve this issue
2. Some components are susceptible to vibration (especially any transformer or inductor coils). Usually manufacturers put some kind of glue to prevent vibration. Varnish is applied to transformers to prevent the iron core from vibrating, etc. Check all places where components have some kind of glue applied between the component and the PCB.
3. Aging or heat can cause the electrical characteristics of components (capacitors, resistors, semiconductors) to drift, causing the SMPS to operate at a frequency that becomes audible (often in the 10kHz - 20kHz range). Again the reason for this drift could be one ore more of the electrolytic capacitors failing.
4. Sometimes ears are sensitive to this whine. e.g.I can hear this wine in all SMPS. Do all members in your household hear this whine?

Thanks for getting back. Yes, my wife could also hear the whine. The metal cover over the smps section is very difficult to open. I am afrarid will break the fm/usb pcb placed over it. But will try to find image from internet if possible and will share.

For the glue check, when checked everything was tightly sitting and there was not a loose component I could find.

 

[karthiks1_ht]

Can you post the photo of the entire SMPS board if possible. There could be many reasons for this high frequency whine

1. Failing electrolytic capacitor (a capacitor that is developed a high ESR). Replacing the electrolytic cap could solve this issue
2. Some components are susceptible to vibration (especially any transformer or inductor coils). Usually manufacturers put some kind of glue to prevent vibration. Varnish is applied to transformers to prevent the iron core from vibrating, etc. Check all places where components have some kind of glue applied between the component and the PCB.
3. Aging or heat can cause the electrical characteristics of components (capacitors, resistors, semiconductors) to drift, causing the SMPS to operate at a frequency that becomes audible (often in the 10kHz - 20kHz range). Again the reason for this drift could be one ore more of the electrolytic capacitors failing.
4. Sometimes ears are sensitive to this whine. e.g.I can hear this wine in all SMPS. Do all members in your household hear this whine?

Photo taken from service manual

 

[mbhangui]

Photo taken from service manual

Some 15 electrolytic caps and 6 transfomers/inductor coils. Also I see one flyback convertor IC 25x. This IC is just 1 volt (265 volts) below the threshold of Adani standard voltage (264 volts) being supplied to households. So if the unit has been used without voltage stabilizer it is possible that the IC operating frequency has changed. But nothing here is expensive (including the IC). In this forum I have read post about some expert guy from Royapettah who repairs. You can search this forum and get the contact and try your luck. In reality there is nothing in the board that is expensive to replace. See if you can return the unit back unless you have got a very good discount