replacing power adapter with a grounded one

[Dispatrick]

my wifi modem uses a two prong power adapter that outputs 12V 1A. it's plugged into an outlet that is a three prong outlet, the standard outlet in any US home with a ground hole in it. Would it be safe to replace the current two prong power adapter with one that also has a ground prong on it as long as it is the exact output for the device? (12V 1A)

 

[mmckenna]

If all the following are true:
12 volts regulated
Capable of at least 1 amp
Polarity of the DC connector is the same as the original

Then, yes.

What's the end goal of this, though? Is the existing power supply failing? Are you looking for the grounded plug to help with RFI? Some other reason?

 

[Dispatrick]

looking to ground the device to reduce RFI.

 

[iMONITOR]

Not grounded, but it is a linear rather than a switching adapter, so it should be quiet.

AC-to-DC Regulated Linear Wall Adapter

12 Volts @ 1 Amp

Features:

• Manufacturer Part No.: RDU120100
• Output Connector: 2.10 x 5.50mm (ID x OD)
• Polarity: Center Positive
• Input (VAC @ Hz): 120 @ 60
• Size (H" x W" x D"): 3.20 x 2.30 x 2.00
• Case Color: Black
• Output Cord Length: 6'
• Weight (lbs.): 1.20
• Agency Approvals: UL / CUL

https://www.jameco.com/z/DDU120100H...ngle-Output-12-Volt-1-Amp-12-Watt_170245.html

 

[jonwienke]

looking to ground the device to reduce RFI.

Grounding a switching power supply will generally have little or no effect on RFI.

Shielding and strategically located capacitors and/or filter chokes are much more effective.

 

[mmckenna]

looking to ground the device to reduce RFI.

If the RFI is coming from the power supply, that may or may not work.

Safety grounds, like what the household ground system is designed for, will often just provide a path to ground for stray voltages and faults. It's not the best choice for RFI grounding, although it can do that.
It's entirely possible that the power supply, while having a grounding conductor, has zero shielding.
For RFI reduction, you want shielding and noise suppression components.

First, be sure you know where the RFI is coming from. Are you 100% sure it's coming from the power supply? Is it radiated from the power supply "through the air", or is it radiated through the power lines?

If you have a grounded power supply that meets the requirements of the device, then it won't hurt to try it, but simply adding a ground will not necessarily fix it.

 

[lmrtek]

Since the modem passed stringent FCC standards with the supplied power supply, i would stay with it.
Ferrite chokes are cheap and easy to add and are quite effective.