Thunderbolt 3 Power Question

Hi guys, I’ve been using an HP USB-C to HDMI / Power Throughput / USB A adapter since I got my MBP 2017 and have used it over the years. One annoying thing it does is, if I have HDMI and my USB portable Seagate HDD for Time Machine plugged in, and I connect it to the Mac I hear the drive spinning but the monitor does not come on…

I have to disconnect and reconnect to varying degrees of success… but lately I figured if I plug in without the portable hard drive plugged into the adapter, the monitor comes straight on. I suspect this is just the limited power of USB-C and not Thunderbolt…

If I buy this dock, which uses full Thunderbolt 3 technology, will it be able to handle this properly without me needing to spare a thought?


Interestingly, when I had a 2018 MBP 13" 512GB 4port, it never had any issue with this regardless of what was connected… the monitor came on instantly… I miss that machine but I’m back on a 2017 base and it’s suitable for me :slight_smile:

I presume that you have had it working with both the monitor & HDD at the same time? If it was a power issue I’d think that connecting the second device would stop them both working and you’d never have both devices working together as there just wouldn’t be the power to do it.

I think something like this was discussed on MGG a while ago & (if I recall correctly) they concluded that the sequence devices are plugged in effects the way that it setups up the device / negotiates the protocols.

If a different adapter would dodge that issue… afraid I don’t know on that one.

I just did a bit of an experiment, I too have a 2017 MBP, I have a seagate USB HDD & a couple of monitors (although neither are connected with HDMI, ones USB-C to DisplayPort & ones mini DisplayPort to Displayport). All the devices are connected to a Caldigit TS3+.

Booted the MBP & logged in, then plugged in the TS3+ to the MBP, straight away both monitors came on and the HDD was mounted ok.

So as to whether a different adapter might work (given that HDMI is still a variable here), I’d say that’s definitely, possibly, a firm maybe! :wink:

Thanks for the replies guys. That’s a good point about power - it’d be showing a

See, what confuses me is that the very same HP adapter didn’t have the issue with the more expensive TB 2018 MBP, it worked flawlessly… Prior to me owning that higher spec MBP I had Apple replace the logic board on the original 2017 and still the same behaviour. Now on my 2019 purchased '17 model same thing.

I suspect a better quality proper discrete dock will solve the problem? After all, we’ve all had experience using HP kit before lol

I think the the USB chipsets have had some revisions each generation. I believe the 2018 model had an issue that didn’t allow it to work properly with the LG 5k2k monitor but other year’s MBPs were fine.

I’m not a big fan of HP stuff, had one of their printers many years ago, it was so many years ago that I don’t recall what what wrong with it however it was the last HP item I’ve ever bought.

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The Caldigit T3+ has its own power supply and the adapter that OP mentioned doesn’t seem to. I’m not sure if this is a fair comparison.

Would it be worth me buying one with its own power supply to ensure that power delivery doesn’t hold me back?

I would. I also have the Caldigit T3+ and have been happy with it. It’s nice to only have to plug one cord into the computer since the dock also powers the MacBook Pro.

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