Noise on Rigol DM858

[felipesevilhano]

Hello everyone at EEVblog

Firstly, I'm sorry for the English, I'm Brazilian and I'm using a translator.

I recently purchased a Rigol DM858 from an authorized Rigol dealer. The equipment is working properly, but I noticed a high-pitched noise coming from the power connector.
I have already exchanged the equipment for another of the same type and the same behavior occurs.

Just be connected to the power supply and the noise appears (Even in standby).

If the environment is silent this ends up bothering me and I need to unplug it.

I am attaching an audio I recorded.

Model: DM858
Hardware Version: 01.01
Software Version: 00.01.00.00.20
System Version: 1.5.3

Does anyone have any idea what it could be?

Thanks!

[Kean]

I can only just hear it with headphone and max volume.  An FFT on the audio shows a peak at about 8800Hz.

I don't know the design, but that is kind of a low frequency for a modern buck converter.
Maybe a capacitor is vibrating due to piezoelectric effect, or power supply noise coupling into a speaker/buzzer.

[felipesevilhano]

Hello, thanks for your help.

I measured it with my cell phone and it really seems to be an 8.8Khz noise.

I opened the equipment and identified that the sound seems to be coming from this DC-DC converter.

I found a video on YouTube about a German who had the same problem. I believe it may be a problematic batch 

[KPbICKA]

Just be connected to the power supply and the noise appears (Even in standby).

I have same problem with new Rigol DM858

[hp3310a]

I measured it with my cell phone and it really seems to be an 8.8Khz noise.

I opened the equipment and identified that the sound seems to be coming from this DC-DC converter.

I recently had the same kind of problem with a different device type (electronic load) and it turned out to be caused by ceramic capacitors that surround a DC- voltage converter. It operates at 10kHz and so the capacitors can emit extremely annoying noise at audible frequencies. Replacing the capacitors (https://www.eevblog.com/forum/testgear/brand-new-et5410-emits-high-pitch-noise/msg5821403/#msg5821403) with electrolytics fixed the problem almost completely.