HP U28 Monitor No Longer Working as External on iMac 2021 M1

Question

HP U28 Monitor No Longer Working as External on iMac 2021 M1

Hi everyone,

This is now the second issue I've had trying to use an external monitor with my 2021 iMac M1, I'm hoping someone can help.

I connected a HP U28 monitor via USB C to my iMac 2021 M1, via one of the Thunderbolt ports. It worked instantly with no problems; I had it working for about a week.

The iMac now refuses to acknowledge the existence of the monitor in "Displays". I have tried everything I can think of:

Restarted and Shut Down/power on of the iMac;
Full system software update on the iMac (to Ventura, 13.0.1);
Tried the other Thunderbolt port on the iMac,
Turn the HP U28 monitor off and back on again,
Check the settings on the HP U28 (ensure it's expecting USB-C input, that it will power on automatically when the iMac sends a signal, etc).
Check for any drivers or updates on the HP website; none were available.
Extensive Google searches to try and locate others with the issue.

I have also gone in to 'System Information' and I noticed that the iMac is clearly detecting the HP U28 is connected - even though it won't acknowledge its existence in 'Displays'. Here's what I see in the System Information box:

USB3.1 Bus:

USB2.1 Hub:

Product ID: 0x0610

Vendor ID: 0x03f0 (Hewlett Packard)

Version: 69.21

Speed: Up to 480 Mb/s

Manufacturer: GenesysLogic

Location ID: 0x00100000 / 1

Current Available (mA): 500

Current Required (mA): 0

Extra Operating Current (mA): 0

I have to say I am traditionally a Windows user and simple things like this are just terrible on the Mac, in 2022 this should not be so unreliable and over complicated! If anyone in the community can help it would be much appreciated.

Many thanks for your time!

iMac 24″

Posted on Dec 9, 2022 9:53 AM

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Answer 1

Top-ranking reply

hcsitas

Level 6

13,142 points

Dec 9, 2022 10:07 AM in response to Edward Charnley

It’s shoddy engineering by HP - the monitor is clueless what’s connected and trying to charge the iMac 😁. Which the Mac won’t tolerate of course, at least not reliably over time.

Dell and other non-Apple USB C monitors are equally dumb! Best to avoid USB C for any and all non-Apple monitor video connections. Good luck!

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Answer 2

Dec 9, 2022 12:58 PM in response to hcsitas

Hi again,

I have researched this further and I think this is the correct adaptor to use: About the Apple USB-C Digital AV Multiport Adapter – Apple Support (UK) .

I was initially concerned that it does not specifically name the iMac M1 2021, the closest match is: "iMac (Retina 5K, 27-inch, 2017 and later), iMac (Retina 4K, 21.5-inch, 2017 and later)". However, after digging further on the Apple Store page (USB-C Digital AV Multiport Adapter - Apple (UK)) and expanding the 'Compatibility' tab near the bottom of the page, the iMac M1 2021 was listed.

The adaptor is very expensive however, so if anyone on the community does know for sure that this is what's needed to extend (not just mirror) an iMac M1 2021 to a secondary display which would connect via HDMI, replies would be much appreciated.

Many thanks!

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Answer 3

Dec 9, 2022 10:12 AM in response to hcsitas

Dear hcsitas,

Thank you very much for pointing me in the right direction here. Any idea why it worked fine for a week and now it won't work?

I would still like to use the HP U28 as the external monitor. Could you recommend a workaround here? It has HDMI and Displayport outputs (as well as USB C). Would there be, for example, an adaptor I could use for an HDMI or Displayport cable to connect in to one of the two Thunderbolt ports on the iMac?

Many thanks!

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Answer 4

hcsitas

Level 6

13,142 points

Dec 9, 2022 10:17 AM in response to Edward Charnley

There’ve been complaints of gradual degradation over time, including unresponsive Mac ports. So, the first order of business is to make sure your USB C port is still functioning fully and normally by connecting it to a hard drive or similar for instance.

As for adapters for HDMI/DP, these do exist but I’m not experienced in them. Hang around for @den.thed to respond, he knows this stuff like the back of his…dual monitors…

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Answer 5

Dec 9, 2022 10:21 AM in response to hcsitas

hcsitas wrote:

Hang around for @den.thed to respond, he knows this stuff like the back of his…dual monitors…

Ha ha :)

Ok, I will do (and thank you in advance @den.thed). I've just tested the USB C port and it appears to be working normally. I've also unplugged the HP U28 USB C cable, in part because it's not working but also to make sure it's not attempting to send any voltage any more.

Thanks very much again for taking the time to point me in the right direction here - very much appreciated.

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Answer 6

Dec 10, 2022 10:58 AM in response to hcsitas

Hi hcsitas, and for the benefit of anyone reading this thread in the future.

That solved it. I connected the external monitor (HP U28) via HDMI into the Apple USB-C Digital AV Multiport Adapter and instantly the iMac recognised it and began extending to it.

Thanks hcsitas for the steer away from using USB-C to USB-C as the connection path as this was clearly the issue. I marked your initial message as 'Best Answer' accordingly.

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Answer 7

hcsitas

Level 6

13,142 points

Dec 9, 2022 10:29 AM in response to Edward Charnley

😁😉👍

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Answer 8

hcsitas

Level 6

13,142 points

Dec 9, 2022 1:30 PM in response to Edward Charnley

Looks promising. If you buy it from Apple, you have a no questions refund window i.e. you can try it risk-free. So IMO, it’s worth going ahead without further ado.

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Answer 9

hcsitas

Level 6

13,142 points

Dec 10, 2022 11:00 AM in response to Edward Charnley

Happy to know & thanks for updating! All the best.

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HP U28 Monitor No Longer Working as External on iMac 2021 M1

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