HDMI Power Down before Connect/Disconnect? - AVS Forum
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post #1 of 10 Old 02-09-2010, 07:35 PM - Thread Starter
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I read somewhere (sorry to be so vague) that it is very important to power down the equipment at both ends before connecting or disconnecting HDMI cables. It sounded as though one might be risking damage to the equipment. Being a cautious sort (and having fried a few laptop motherboards over cable issues), and being aware that people who say "Heck, I do it all the time" may just be lucky, I have always followed this advice. But I'm wondering: Is it really necessary? Is there a problem with the HDMI design or spec or something? Are certain brands of equipment more susceptible to damage?

Thanks!
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post #2 of 10 Old 02-09-2010, 07:40 PM
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it is very important to power down before connecting/disconnecting ANY cables, not just hdmi...

safety first... you may very well hot-swap cables many times without running into a problem... however, if (when?) you do run into a problem, it's going to be a very bad day...

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post #3 of 10 Old 02-09-2010, 11:14 PM
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HDMI is designed to be hot swapped. I hot swap cables all the time at work and have never run into an issue. Occassionally you might get a bad sync at the display (the image won't come up or will be garbage). You either unplug and replug the HDMI cable or you can toggle the power on the display and it should come up all sync'ed up.

That said, it sure wouldn't hurt to power down before reconfiguring cables - I just don't have the patience.
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post #4 of 10 Old 02-10-2010, 02:25 AM
 
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I've always seen it recommended that everything be powered down. However even powered off, HDMI ports are usually still active and communicating, so truly dead swap means unplugging the gear from the wall.

Because I'm lazy, I will usually just hot swap no problem. However, doing this is far more apt to cause glitches which will require power cycling everything or fully unplugging everything.

So I would recommend just as a good idea to power stuff off.

Because while you're not likely(to my knowledge) to hurt anything hot swapping, let me put it this way: whenever I have tested HDMI devices for reliability (in other words try to make them fail in as many different ways as possible) one of the best ways to glitch something out is to plug and unplug things repeatedly while everything is powered up. So it is good practice to avoid doing that unless, like me, you're impatient and you have a million other things to do.

So IMO, a good idea to power everything down, but not really because of a fear of damaging stuff. So I encourage your caution anyway.
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post #5 of 10 Old 02-10-2010, 05:47 AM
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true on the hdmi hot-swap that both fod and chris point out... i should have clarified... my bad...

while the hdmi connection itself is "ok" to hot-swap (recognizing that it may cause some issues that will require power cycling anyway), there are a bunch of other cables connected to the back of your equipment as well... not all of those are so "friendly" to a hot-swap (or grounding, or so on)... and although you may only be intending to pull the hdmi cable out of the port, it's also quite easy sometimes to move/release other cables while doing so... the law of "unintended consequences" sneaks in every now and then...

i guess it's ingrained habit on my part, which is why i responded the way i did... when mr. electron is involved, i tend to turn things off/remove power before working on them... i shocked myself enough when i was young and foolish... unlike now, when i'm old and foolish...

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post #6 of 10 Old 02-10-2010, 11:00 AM
 
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Quote:


i guess it's ingrained habit on my part,

which is always a good thing. It's a good habit to have.

That does require patience though, which is probably even more important a habit to acquire!

I'm still working on that one...
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post #7 of 10 Old 02-10-2010, 12:25 PM
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lol... if you figure out how to acquire the "patience habit", fill me in too... definitely not my strong suit either...

i learn best by pain... whenever i'm tempted to do something with electricity and leave it on/connected, memories of being zapped come back... not to mention the few times that i let the magic smoke out of stuff...

kinda like with garden rakes... i had to step on one with the tines up and whack myself in the head with the handle before i learned to always make sure to put it tines down...

- chris

 

my build thread - updated 8-20-12 - new seating installed and projector isolation solution

 

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post #8 of 10 Old 02-14-2010, 10:55 PM - Thread Starter
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Hey, thanks to everyone who replied. It sounds like the consensus is pretty much where I've been: probably okay to hot swap, but it might cause some problems (or rarely, total disasters!). I think I'll keep turning things off.

Thanks again!
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post #9 of 10 Old 02-15-2010, 12:00 AM
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Now you just have to worry about static discharge, whether hot-swapping or not. I think this is a more common cause of damage than hot-swapping itself. It is really hard to protect against transients due to static discharge without affecting the operating parameters adversely because the protective circuitry adds capacitance, and even a little is potentially detrimental to the signal at the rates HDMI operates.
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post #10 of 10 Old 04-09-2012, 01:45 PM
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Quote:
Originally Posted by drum365 View Post

I read somewhere (sorry to be so vague) that it is very important to power down the equipment at both ends before connecting or disconnecting HDMI cables. It sounded as though one might be risking damage to the equipment.

Here's an example... see the link on the hdcable.co.uk web site (sorry, can't post URL due to anti-spam) for downloading the product manual for a 4x4 HDMI matrix switch from HD Cable Ltd, in which you will find repeated dire warnings, including the following:
WARNING!
DO NOT HOT-PLUG HDMI CABLES. ALWAYS FULLY POWER OFF THE MATRIX UNIT BEFORE CONNECTING AND RECONNECTING HDMI CABLES.
FAILURE TO DO THIS WILL RESULT IN CRITICAL DAMAGE TO THE MATRIX THAT IS NOT COVERED UNDER WARRANTY.

I must confess it has put me off purchasing it, even though it's a nice unit and HDMI 1.4 compliant.
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