11-30-2019, 12:09 PM
(This post was last modified: 11-30-2019, 05:50 PM by pfeerick.
Edit Reason: mod edit: reply ran into quote
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Anyway as I started to use it after two months. It\'s was a situation without positive issue. I wouldn't be able to RMA it anyway. If I had schematics and part specifications, or only part specification, I could try to repair it. But in this case...
(11-30-2019, 10:15 AM)Nikolay_Po Wrote:(11-30-2019, 12:43 AM)diskers Wrote: PS. From the beginning this device made a slight buzzling sound when powered and up.
The buzzing is the sigh of problems in DC/DC voltage converter. Either defective or inappropriate (saturating) inductor or faulty feedback compensation circuitry. Possible causes of that in my opinion are (decreasing probability):
- Physical damage to DC/DC converter components, ferrite inductor or ceramic capacitor. Most probably the board was accidentally dropped and struck the floor while handling.
- Component damage at an assembly factory, while mounting and soldering.
- Incorrect values/part numbers of components (design mistake) or assembly mistake at a factory.
Usually, operating at a hundreds of kHz or at MHz frequencies DC supply components of PCB rarely producing an acoustic (hearable) noise with normal design. Mine boards still working without of a noise. Now with @diskers case it is evident that the noise from working SBC PCB is a sign of future failure (IMHO).