All HDMI cables are not the same

I just put together a new mini-desktop with HDMI connecting the monitor. W orked great, except for some reason the monitor would not go into power sav e when commanded by the computer. Instead a box bounced around on the scre en saying there's no signal, going to sleep in 5 minutes.

It's not the worst thing I know, but I wanted to know why it did this. I d id some research, and while the general consensus was "I have no idea why i t does that, live with it", I found a forum post that claimed it was the HD MI cable itself. I have two TVs with HDMI cables each to a media player. One TV used the exact same cable, the other had a different, thicker cable. I stole the thicker one and guess what? Power save now works fine.

I can find HDMI pinouts easily enough, but nothing on how power save is com manded with HDMI. It seems to me the cheaper, thinner cables skimped by sk ipping a few connections. Unfortunately there's little info on any of this , but I have learned something:

Despite common wisdom, not all HDMI cables are the same. I just don't advi se you buy this:

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Even the cable that works cost me no more than a few bucks. The question n ow is, how to avoid buying the ones that aren't up to par?

Reply to
hondgm
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So why dont you just do a pin-to-pin connectivity check ?

Digital signals dont normally get 'lost' down a connection, regardless of whether the wire is 'ordinary' or 'magic'.

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Adrian Jansen           adrianjansen at internode dot on dot net 
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Adrian Jansen

I thought about doing a conductivity check, but then didn't have the ambition. However a conductivity check isn't possible when the cable is on Ebay or Newegg.

Reply to
hondgm

Good timing. I just dragged home a somewhat faster machine for myself. I'm in the computer repair biz, so this should be a no brainer. The machine has a video card with an HDMI output and my Flatron L246P also has a matching HDMI input. What could possibly go wrong?

Well, the L246P has a resolution of 1600x1200. Maximum vertical resolution for HDMI output on the video card is 1080 dots. Circles look like ellipses and there's no way to adjust the aspect ratio. So much for HDMI on a monitor that has too many dots. The HDMI specs go to a much higher resolution: but apparently the video card maker didn't read the spec.

So, I went back to the old 15 pin D-connector, and grumbled happily thereafter.

What HDMI mutation was printed on the various cables?

1.0, 1.1, 1.2, 1.3, 1.4, and now 2.0 ?? It shouldn't have any effect on the problem, but I'm curious.

There's nothing in the HDMI spec on screen blanking and power save. I skimmed the specs and found nothing: However, I did look at several (printed) schematics and found that power save mode is initiated by the lack of video signals or data depending on the input connector. In other words, it's up to the monitor to shut itself down when there's nothing to look at.

I haven't seen this effect before, but then I don't sell many HDMI cables. My best guess(tm) is that one wire from a differential data pair came loose or wasn't soldered. The intact wire is picking up hummmm and digital junk from the other wires in the bundle, which is what's keeping the display on. That should show up with an HDMI continuity tester:

Incidentally, I ran into another HDMI cable problem. I was setting up the lady friend's new Roku 3 player. I grabbed whatever HDMI cable was closest to the top of the pile from my office and used it to feed the big 50" TV. You can really see signal problems with a big TV and this one had a picture that looked terrible. What to do?

My normal troubleshooting method was to repair by substitution, starting with the easiest and cheapest. That's when I noticed the rather thin and ultra flexible HDMI cable. Going out to the car and digging for a much thicker and presumably better cable, I eventually found one. It worked and the picture quality was much improved.

Moral: If the cable looks inadequate, it probably is.

You can't. Just find a vendor that accepts returns. I buy most of my commodity stuff on eBay. Occasionally, I get something with a problem. I email the vendor and ask for an exchange for something that works. If it's really cheap, like commodity HDMI cables, they just send me a new one, and not ask for the return of the defective cable.

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Jeff Liebermann     jeffl@cruzio.com 
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Jeff Liebermann

Interestingly, I did notice that both HDMI cables said "HDMI" on one side o f each connector. However the problematic one had nothing on the other sid e. The one that worked said "v1.3". So, maybe having no version number is a bad sign. Luckily in this case, that cable is connected to a TV which d oesn't care about power save.

It's possible the bad HDMI cable had a wire off, however I can't help but t o think that the super-cheap ones are cheap because they tried saving every milli-penny possible. This could mean leaving out the wire for power save , but which one and how that's done, yeah that's the mystery. One other at tribute I noticed is the connector feels hollow, versus the better one with a connector that feels molded.

In any case, the suspect cable gives a perfect image on the 1920x1080 monit or, as well as on the TV when connected to a WD TV Live.

I just realized that the bad cable is one I got from Newegg for something l ike $1.50 shipped as some type of special. That's surprising because I usu ally assume Newegg sells decent stuff.

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Reply to
hondgm

The cable is suppose to have "HDMI 1.3" or something similar printed on the cable, not the connector. If you're trying to do ethernet, 3D, or 4K TV, you'll need HDMI 1.4 or 2.0. If your cable lacks a proper version number, it's probably 1.2 which lacks the provisions for automatic lip sync.

Hopefully, you mean the side of the cable, not the connector. Either way, just "v1.3" does not follow the HDMI spec for labeling the cable. However, that's the "old" spec. This is what you're suppose to see on the cable: I'll spare you my rant on what I think of such descriptive labels.

At $1.50/cable that's highly likely. I doubt that they were inspected or tested. At best, maybe sample tested. Caveat emptor and there's no way you're going to get uniform quality at that price.

There is no power save wire. The display looks at the data signals. If they're absent, the monitor turns off.

I don't believe that the connector packaging is the problem. More likely the soldering in insulation displacement connection inside the connector.

So much for my broken wire theory. Incidentally, I have several WD Live boxes, but don't use them. I switched to a Roku 2 XS. Much better and faster than the WD.

Newegg does better than most. What would have been interesting is if you had purchased several of these cables, and tested them all for screen blanking. If only one failed to function properly, it's obviously the cable. If they all failed, it might be a design or construction problem.

I noted from the above URL photo that this cable is one of the thin variety that gave me grief during the video quality problem on the lady friends TV. Are you sure that the picture is good (in 1080p) and that a thicker cable doesn't give a better picture? I couldn't see much difference on my 25" TV, but the quality difference was horribly obvious on a 50" TV in HD.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Jeff Liebermann

e:

Just looked at both cables. The junky one says "high speed HDMI cable" and the good one says "vw-1 HDMI cable" along with temperature and UL informat ion in both cases. No mention of version.

That doesn't explain how the one wire wouldn't convey the desire to go into power save. If I simply unplug the HDMI cable from the monitor, it doesn' t go into power save either. It does the same thing as with the "bad" cabl e: displays a message that there's no signal and it's going into power save in 5 minutes.

I use mine for playing files on my network drive as well as Netflix and You tube. That limits me to the WD, although it doesn't have the best designed firmware.

I do actually have another on a different TV. I'll have to try that one so metime.

The TV I swapped with was 19", and I have another one of those junky cables on a 32". What I can't understand is how the cable can cause bad image qu ality since it's a digital signal. Shouldn't it simply work or not?

Reply to
hondgm

Which means that you don't have a clue as to the capabilities of the cable or to which HDMI version it complies. Swell.

The VW-1 means it will pass a "vertical wire" flame test per UL 1581:

The complete markings on one of my HDMI cables from my pile is: "HIGH SPEED HDMI CABLE WITH ETHERNET E119932-T AWM STYLE 20276 80C 30V VW-1 COPARTNER".

An unbalanced pair of wires does not pickup any garbage from adjacent wires (common mode rejection). However, if you break a wire, it will act much like an antenna and pickup all kinds of crud.

Unplugging the entire cable unplug both wires in the pair. That's not a good test.

If that's true, then I would look for something wrong with the monitor, not the cable. Borrow another cable and try for 2 out 3 cables? If a 3rd cable does the same thing, then it's likely that the problem is NOT in the cable.

You won't see any difference on a 19" TV, which is probably limited to

720p. You should see a difference on the 32" in 1080p.

The cable has a limited frequency response depending on which HDMI mutation. Higher numbers mean more bandwidth. More bandwidth means better resolution. In my case, the picture detail was not very sharp. Note the range for frequencies for pixel clock rate, TMDS, and throughput for the different HDMI mutations.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Jeff Liebermann

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