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I have a LCD Monitor that has a 2.1mm Right Angle DC Power Plug which has gotten loose over time. It frequently comes off and I needed to tap it in, but now even that does not seem to work. I'm wondering if I can replace just the plug at the end. I'm looking at various plugs e.g.

Amazon - Philmore Right Angle DC Power Plug w/ 6' Cable - 2.1mm I.D. 5.5mm O.D. : TC210

This seems to be very similar to what I'm looking for, but I cannot figure out if it has grounding. The power adapter to my LCD Monitor is three pronged, implying grounding, but I cannot say if the actual plug has grounding just from looking at it. I can also see DC Power Jacks that have grounding e.g.

StackExchange - what is the name for this DC connector?

Which brings me to my question:

Are Coaxial DC Power Plugs with Grounding available?

If there are none, would there be any issue with using a non-grounded plug like the one mentioned earlier for my LCD Monitor.


Edit: Additional Information

I did not think this was necessary, but since it was raised in the expected answer I decided to add it here. I have two identical monitors (same brand and model number) which were purchased at the same time. One of them had a slightly defective power plug, but I did not complain about it because it worked for most part.

Now 5 years later, this plug does not work with either monitor. However, the plug of the other monitor can power up the first monitor just fine. Since the power jack on the first monitor has been worn out by twisting and turning this defective plug, it takes a small tap/twist for the working power plug to power up. (In it's original monitor it works on the first try.) So I'm certain the issue is with the power plug not on the monitor jack.

O.O.
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    what do you mean with "with grounding"? These connectors all, by design, have exactly two contacts. – Marcus Müller Jan 04 '18 at 16:00
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    This question does not make much sense. Why refer to number of prongs when talking about barrel jacks? If the connector has a number of prongs, it is not a barrel jack. If anything, please post a picture of the exact plug that you have. This will help in telling you more about what to search for when you look for a replacement. (NOTE: Shopping questions are considered off-topic on EE.SE) – MrGerber Jan 04 '18 at 16:07
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    grounding is not really a feature of these plugs per-se the power supply for the monitor may ground the outside shell of the plug or may not. but that happens inside the brick. – Jasen Слава Україні Jan 04 '18 at 19:13
  • Thank you @MarcusMüller and Jasen - This is what I was looking for. I suspected that these have only two contacts, but I just wanted to make sure my limited knowledge was not precluding other possibilities. No, this is not a shopping question. – O.O. Jan 04 '18 at 19:59
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    @O.O. - Thanks for the accept on my answer. I just wanted to comment on your update: "Since the power jack on the first monitor has been worn out by twisting and turning this defective plug, it takes a small tap/twist for the working power plug to power up [...] I'm certain the issue is with the power plug not on the monitor jack" That first part may point to a problem with that specific monitor jack too, since you say it requires a tap/twist even with a known-working plug. I just didn't want you to replace the plug and then be surprised if there is still a problem. Anyway, good luck! – SamGibson Jan 04 '18 at 20:20
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    @SamGibson - Thank you. I agree that the monitor jack is a bit damaged, but since it powers up with the other good plug, I think if I get a new plug it would work. The bad plug on the other hand does not work on the other good monitor, so I'm certain it is bad. Thanks again. – O.O. Jan 04 '18 at 22:00

1 Answers1

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The power adapter to my LCD Monitor is three pronged, implying grounding

Assuming you mean a three-pin (three-pronged) AC connector on the power adapter something like this:

DC power adapter showing 3-pin mains input connector

(Edited from this image on this web page)

... and not just a three-pin mains plug then yes, that suggests that the power adapter has a ground connection.

However that doesn't affect the type of DC power connector which is used - it just means that that the negative side of the DC output is probably ground-referenced.

Unfortunately, for this specific symptom that you stated:

It frequently comes off and I needed to tap it in, but now even that does not seem to work.

... the problem is usually that the "socket" in the device (in your case, that's inside the monitor) has become worn / damaged / broken away from the PCB etc. and the cause is not the "plug" on the end of the cable.

This picture of an "open frame" DC power jack (i.e. socket) makes it easier to see its flat spring (marked with the red arrow):

image of open frame DC power jack, showing flat spring

(Edited from this image on this web page)

That spring contacts the outer surface of the plug and pushes the inner surface of the plug onto the pin. Therefore it is the socket which provides the friction to keep the plug & socket "joined"; replacing the plug on the cable (as you suggest) is unlikely to help your problem, based on the "it frequently comes off" description you have given.

If you really want to replace the plug then, provided that the DC plug you have found has the same external and internal (i.e. pin) dimensions, and is visually similar (i.e. no non-standard notches, screw locks etc.) then that is what you need to know to get a replacement. See a list of possible sizes at the Wikipedia page for Coaxial power connectors.

It can be difficult to tell the difference visually between a 2.1mm pin and a 2.5mm pin, for example. However if you are sure that you require a 5.5mm x 2.1mm plug, then the plug + cable which you linked matches that description. The plugs are also available on their own. (If you have similar connectors on other power supplies, with known pin sizes, then you could "test fit" those to your monitor with the power off i.e. no mains connection to the "test" power supply, in order to try those known pin sizes. As Jasen suggested, a 2.5mm drill bit shank can also be used to differentiate between a 2.1mm and 2.5mm hole in a plug.)

SamGibson
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    the shank of a 2.5mm drill bit makes a handy tool to measuring these plugs. – Jasen Слава Україні Jan 04 '18 at 19:10
  • @Jasen - Good suggestion, I'll add that (with credit) into the answer. – SamGibson Jan 04 '18 at 19:22
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    Thank you @SamGibson and Jasen. Yes, I have a three pronged AC connector on the Power adapter. I also followed the toothpick method given at https://forum.digikey.com/t/measuring-power-supply-barrel-plug-id-2-1mm-vs-2-5mm/401 to determine I had a 2.1mm adapter. Thank you for confirming that it's just the negative terminal that is grounded. Thank you also for pointing out that the Jack may be defective. I don't think it is true in this case because I can power up the monitor with an identical power plug. So the jack and the monitor work. – O.O. Jan 04 '18 at 20:16