Did ground potential damage my computer's HDMI ports? - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #1 of 40 Old 11-29-2013, 04:36 PM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
The HDMI ports on my motherboard's integrated graphics and now on a Radeon 4350 card no longer work. I'm wondering if the HDMI ports on both units were damaged because of ground potential difference between the computer and the HDTV set.

I was originally running a Samsung HDTV set from the mobo's integrated HDMI port. That stopped working so I installed a Radeon 4350 card that I already had. The video from the 4350 worked for a few months and I went on vacation. When I returned from vacation, the 4350's HDMI video won't work either. I had not touched "any" cables when I came back from vacation.

Although the computer and HDTV set are both in the living room, they are on different circuit breakers. All of the TV stuff like cable DVR, DVD player and Magnavox DVD recorder are on the same circuit breaker as the TV set. The computer is on a different wall and it plus the router are on a different circuit breaker.

HERE'S MY SETUP:
- Homebuilt PC with an Asus P8H67-V motherboard running Win7.
- Have a Samsung 2253 monitor connected via VGA or DVI and either always work fine.
- Have integrated graphics on the motherboard's back HDMI port.
- HDMI cable from computer to TV set is a 30 foot RedMere HDMI cable.
- I also tried a 10 foot HDMI cable.

When the mobo's integrated HDMI stopped working, I installed the 4350 card which worked with the 30 ft RedMere cable. After vacation, the HDMI would not work so I tried the 10 ft HDMI cable and it won't work either. I tested the 10 ft HDMI cable using my laptop to the same TV set and the display is fine so I know that the 10 ft HDMI cable and the TV's HDMI input port are good.

SYMPTOMS:
1. When I connect the 10 ft HDMI cable from the TV to the integrated HDMI port, the PC appears to boot all the way into windows but there's no display on the computer monitor running VGA or DVI, nor on the TV set. If I disconnect the HDMI cable, then the display appears on the computer monitor. The computer monitor is connected to the motherboard's integrated VGA or DVI ports.

2. When I connect the 10 ft HDMI cable to the 4350 card, the display appears on the computer monitor and Win7 boots fine. The computer monitor is connected to the motherboard's integrated VGA or DVI ports. When I look at Device Manager, the monitor entry only shows one "Generic PNP" monitor. Before when the HDMI was working, it would show two "Generic PNP" monitors.

3. Win7 control panel > Displays only shows one monitor which makes sense since Dvc Mgr only shows one monitor.

4. With the HDMI cable disconnected from the computer, when I measure the a/c voltage between the HDMI cable ground (the metal part that plugs in) to the computer's ground, there is 23 volts a/c. There is 1 volt dc.

5. I disconnected all cables from the HDTV set and ran an a/c extension cord to the same power strip that the computer is plugged into. The HDMI to the TV set still won't work.

CONCLUSION:
I think the a/c ground potential difference blew the HDMI ports on both my motherboard and the 4350 card. The TV HDMI port works with my laptop so I know the TV set side is OK.

WHICH REPLACEMENT GRAPHICS CARD SHOULD I BUY?
I want to buy a graphics card so I can view video from the computer on the HDTV set. This time I plan to run a #12 wire and connect it to the computer ground and the TV set ground to hopefully prevent another HDMI blowout. I don't do any gaming or 3D. Would a 5450 card be a good choice? It seems to be about the cheapest card that can do 1080p video to the HDTV set and also run my computer monitor. Does the 5450 card have 1650 x 1080 resolution for my computer monitor?

Any other ideas or suggestions to prevent blowing out more HDMI ports?
Sky
Skylark is offline  
Sponsored Links
Advertisement
 
post #2 of 40 Old 11-29-2013, 06:13 PM
Senior Member
 
ajkrishock's Avatar
 
Join Date: Nov 2008
Posts: 251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 17
I'm no electrician, but it seems unlikely to me that poor grounding could be the cause of such a problem. You can check by using tools such as this one, but my feeling is that if you had any problems with that circuit, you'd probably see other effects, too. I used to test HDMI ports for a living, and I know first hand how fragile they are. They generally don't stand up to a lot of insertions & removals before the electrical connections become intermittent.

Check your outlets, by all means, but I suspect your problem lies elsewhere.. like maybe windows updates or some other recent software change. Maybe even a DRM issue?
ajkrishock is offline  
post #3 of 40 Old 11-29-2013, 07:59 PM
 
cybrsage's Avatar
 
Join Date: May 2007
Location: Harrisburg, PA
Posts: 8,074
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 147
The difference in ground between your two outlets will be extremely low. The ground on both outlets runs to the same grounding connector panel in the breaker box. It is far more likely you have a bad motherboard or power supply, sending too much power (or too little) to the video card.
cybrsage is offline  
post #4 of 40 Old 11-29-2013, 08:57 PM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by ajkrishock View Post

I'm no electrician, but it seems unlikely to me that poor grounding could be the cause of such a problem. You can check by using tools such as this one, but my feeling is that if you had any problems with that circuit, you'd probably see other effects, too. I used to test HDMI ports for a living, and I know first hand how fragile they are. They generally don't stand up to a lot of insertions & removals before the electrical connections become intermittent.

Check your outlets, by all means, but I suspect your problem lies elsewhere.. like maybe windows updates or some other recent software change. Maybe even a DRM issue?

I already had an outlet tester so I just checked the a/c outlets involved. All are wired correctly.
Thanks,
Skylark
Skylark is offline  
post #5 of 40 Old 11-29-2013, 09:10 PM
Advanced Member
 
jbcain's Avatar
 
Join Date: Jul 2010
Posts: 868
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 63
This isn't a difference of potential issue.
jbcain is offline  
post #6 of 40 Old 11-29-2013, 09:37 PM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by cybrsage View Post

The difference in ground between your two outlets will be extremely low. The ground on both outlets runs to the same grounding connector panel in the breaker box. It is far more likely you have a bad motherboard or power supply, sending too much power (or too little) to the video card.

Hi cybrsage,

I've been doing some research on HDMI connectors and found the following webpages, (among others), that are of interest:

http://superuser.com/questions/421067/is-it-really-necessary-to-unplug-devices-from-the-wall-before-connecting-hdmi

http://www.hdcabling.co.za/Best_Practises_HDMI_Installation_Guidelines_and_Recommendations.php

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=28&t=26282

Evidently USB connectors are designed so Vcc and Gnd make connections first to prevent potential difference problems from damaging the hardware, but HDMI connectors appear to have all pins even so any pin could touch first.

I think I might have screwed up and blown the HDMI port on my laptop today. (It was working yesterday when I used it for testing.) I had the a/c charger plugged into the computer power strip with the battery removed and connected the HDMI cable to the TV set. Now the laptop's HDMI doesn't work anymore either. I tested the laptop's HDMI on a different TV and it doesn't work. I'm doing a backup restore to the laptop now to get a known working Win8 OS when the laptop's HDMI was known working. If the laptop's HDMI still doesn't work, then I know it got blown too.

Am learning a lot about how fragile HDMI ports really are, the hard way,
Skylark
Skylark is offline  
post #7 of 40 Old 11-29-2013, 09:40 PM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by jbcain View Post

This isn't a difference of potential issue.

That's a pretty definitive statement. If not, would appreciate insight as to how I can get all of the HDMI ports working again.

Skylark
Skylark is offline  
post #8 of 40 Old 11-29-2013, 09:46 PM
Advanced Member
 
jbcain's Avatar
 
Join Date: Jul 2010
Posts: 868
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 63
Here's an easy test, if you have a real volt meter... Check and log voltage of outlet computer uses. Then, check and log outlet that tv uses. Now, test power leg to power leg on each outlet to each other. Post results
jbcain is offline  
post #9 of 40 Old 11-29-2013, 11:46 PM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by jbcain View Post

Here's an easy test, if you have a real volt meter... Check and log voltage of outlet computer uses. Then, check and log outlet that tv uses. Now, test power leg to power leg on each outlet to each other. Post results

Used a Fluke digital volt meter.

Computer outlet = 120.7 volts a/c
TV outlet = 120.8 volts a/c
Power leg to power leg = 0.2 volts a/c.

But with the HDMI cable plugged into the TV but not into the computer, when I check the HDMI cable shield to computer chassis, there is 23 volts a/c. The power supplies are probably using floating grounds that are isolated from the a/c input power grounds.

Skylark
Skylark is offline  
post #10 of 40 Old 11-30-2013, 05:00 AM
Advanced Member
 
jbcain's Avatar
 
Join Date: Jul 2010
Posts: 868
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 63
On that last test, what is it conversely?
jbcain is offline  
post #11 of 40 Old 11-30-2013, 11:39 AM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by jbcain View Post

On that last test, what is it conversely?

Don't know what you mean. Please clarify.

Thanks,
Skylark
Skylark is offline  
post #12 of 40 Old 11-30-2013, 11:59 AM
AVS Addicted Member
 
Mfusick's Avatar
 
Join Date: Aug 2002
Location: Western MA
Posts: 20,987
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 593
You should double check that the HDMI isn't running a resolution the TV can't handle. I would manually set the display to output 1280x720p and test again.

I am guessing your ports are ok but the HDMI sync is not.

-


"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
Mfusick is online now  
post #13 of 40 Old 11-30-2013, 03:28 PM
Advanced Member
 
ajhieb's Avatar
 
Join Date: Jul 2009
Posts: 946
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 77 Post(s)
Liked: 234
Floating grounds or not, you should not see 23V a/c between any two pieces of equipment. I'd double check the potential between your TV's HDMI shield and ground and see if that's where your problem is (I'm inclined to think so as the TV is the common component with all of your troubles)

I doubt it is a configuration/resolution problem as Device Manager should show the display connected even if it is running an incompatible resolution.

You might try checking the voltages on the other HDMI ports on your TV. It could just be a bad port, but I'd be very leary of plugging any more devices into that 23V HDMI port.

If I had a signature, this is where it would be.
ajhieb is online now  
post #14 of 40 Old 11-30-2013, 03:37 PM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by Mfusick View Post

You should double check that the HDMI isn't running a resolution the TV can't handle. I would manually set the display to output 1280x720p and test again.

I am guessing your ports are ok but the HDMI sync is not.

MORE NEW INFO:

Before when the HDMI was working (either the integrated motherboard or the 4350 card), when I looked at Dvc Mgr > Monitors, I used to see two monitors. One was the computer monitor attached to the VGA or DVI port and the other was the Samsung HDTV set. This allowed the second monitor to appear in the window to select cloned or extended displays. Now, only the computer monitor shows up in Dvc Mgr > Monitors which results in only one monitor showing up in the screen to select cloned or extended displays.

So I re-installed the AMD driver and Catalyst for the 4350 card. The 4350's HDMI still doesn't work. Before the Catalyst icon would show up in Win7's notifications area but it does not show up now. I also looked in Control Panel and the Catalyst option is not in there either. It appears that the 4350 card has gone bad so even the Catalyst driver cannot find it.

Note that I'm running the computer monitor off the motherboard's integrated VGA or DVI ports which is why the monitor works.

If the 4350 card has indeed gone bad, it explains why the HDMI was working before I went on vacation but not after I returned from vacation without me touching any cables or anything. All I did was power the PC up and use it.

So my conclusion now is:
1. The motherboard's HDMI port differential driver is blown so it won't work.
2. The 4350's HDMI port doesn't work because the 4350 went bad.

I ordered a used HD4650 card from the amazon warehouse for $27.25. It's eligible for the full amazon 30 day return if the "used" card has problems so I'm brave enough to try a "used" card.

Thanks for the help (as always),
Skylark
Skylark is offline  
post #15 of 40 Old 11-30-2013, 05:16 PM
Advanced Member
 
ajhieb's Avatar
 
Join Date: Jul 2009
Posts: 946
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 77 Post(s)
Liked: 234
Quote:
Originally Posted by Skylark View Post


So my conclusion now is:
1. The motherboard's HDMI port differential driver is blown so it won't work.
2. The 4350's HDMI port doesn't work because the 4350 went bad.

I ordered a used HD4650 card from the amazon warehouse for $27.25. It's eligible for the full amazon 30 day return if the "used" card has problems so I'm brave enough to try a "used" card.

Thanks for the help (as always),
Skylark

Since it appears the TV has killed 2 Integrated HDMI ports (on your motherboard, and laptop) why would you assume that the HD4350 died of its own accord after being plugged in to the same TV?

It would appear that you're 0 'fer 3 on plugging devices into that TV. Why would you risk a 4th (even if it is used) when all signs point to a defective HDMI port on your TV?

If I had a signature, this is where it would be.
ajhieb is online now  
post #16 of 40 Old 11-30-2013, 06:49 PM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by ajhieb View Post

Since it appears the TV has killed 2 Integrated HDMI ports (on your motherboard, and laptop) why would you assume that the HD4350 died of its own accord after being plugged in to the same TV?

It would appear that you're 0 'fer 3 on plugging devices into that TV. Why would you risk a 4th (even if it is used) when all signs point to a defective HDMI port on your TV?

This is a long, detailed post meant for anyone who has the time to read it and wants to try to figure it out.

I restored the SSD in my laptop but the HDMI port still wouldn't work with the TV set. I was using two 10 foot HDMI cables while testing. As a last resort I tried a 6 foot HDMI cable. The laptop's HDMI port displayed on the TV set!!! So the laptop's HDMI port isn't toast after all. I tried a 10 ft HDMI cable again and it worked. Go figure.

Here's what I don't understand. Maybe the sleuths on this forum can figure it out:

TOWER PC RUNNING WIN7:
1. PC's integrated HDMI port initially worked with a monoprice 50 ft HDMI cable to the TV set.
2. After about a year?, the 50 ft HDMI cable stopped working.
3. Replaced it with a 30 ft RedMere HDMI cable from monoprice and it worked.
4. After maybe 6 months (not sure exactly), the 30 ft RedMere cable stopped working.
5. Tried a 10 foot HDMI cable since it barely reached from computer to TV across the living room floor.
6. It wouldn't work.
7. Pronounced the integrated HDMI port dead.
8. Installed the used HD4350 card that I already had.
9. It worked with the 30 ft RedMere cable to the TV for maybe 6 months.
10. Went on a 10 day vacation.
11. Upon return, the 4350 HDMI via the 30 ft RedMere HDMI cable wouldn't work.
12. Tried a 10 ft HDMI cable to the 4350 but still no work.
13. Reinstalled the Gigabyte driver for the 4350 but still no work.
14. Installed the latest AMD driver for the HD4350 from the AMD site and it won't work.
15. Tried a 6 ft HDMI cable to the TV. Still no work.
16. In steps 13 and 14, the Catalyst software icon does not show in Win7's notification area. Nor does the Catalyst show in Control Panel. This leads me to believe that the HD4350 card died.
17. Throughout steps 11 to 14, Device Mgr > Monitors only show one "Generic Pnp" monitor which is the computer monitor on the integrated VGA or DVI ports. When the HDMI was working, Device Mgr > Monitors used to show two "Generic Pnp" monitors.


LAPTOP:
Background info: Laptop worked for many years using 6 ft or 10 ft HDMI cables (which ever happened to be handy) to the HDTV in the living room (same TV that the tower PC uses). This was only very occasional use of maybe a day or two, every 2-3 months or so.

The following started when the Tower PC HDMI stopped working in step-11 above.
a. Tested TV's HDMI port using my laptop via a 10 ft HDMI cable. It worked fine.
b. The next day, I wanted to watch a movie on the TV so tried the laptop and it wouldn't work via the HDMI to the TV.
c. Tried the second 10 ft HDMI cable and it wouldn't work either.
d. Restored the laptop's SSD to a known working backup.
e. Laptop still no display via 10 ft HDMI cable to TV.
f. Last resort tried a 6 ft HDMI cable. Laptop displayed on TV.
g. Tried the 10 ft HDMI cable again. Now it displayed on the TV also. Go figure.

Sorry for the long details. If you waded through the details and your detective work figured out whats happening, please post.

From my perspective now, it seems that things worked with long HDMI cables but gradually deteriorated to where shorter HDMI cables are needed to work. This is true for both the tower PC and the laptop. No clue why.

Thanks for reading,
Skylark
Skylark is offline  
post #17 of 40 Old 11-30-2013, 07:02 PM
Advanced Member
 
ajhieb's Avatar
 
Join Date: Jul 2009
Posts: 946
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 77 Post(s)
Liked: 234
I haven't seen anything you've psoted that would indicate it is a driver/configuration/resolution issue.

You have an electrical problem, be it within the TV or elsewhere. You should not under any circumstances I'm aware of see a 23V A/C difference between your TV's HDMI ground/shield and anything. The most obvious conclusion is that the HDMI port on your TV is bad.

Try reproducing your original test between the shielding of your HDMI port on your TV (where you measured 23V A/C) and test between something grounded on the same circuit as the TV. If you see that same 23V difference, then you have a defective HDMI port, and it will most likely continue to kill devices plugged into it.

As far as your laptop goes and the differences in HDMI cables, my first thought would be that it has less to do with the length of the cable, and more to do with the robustness of the shielding and its ability to deliver enough current to overdrive whatever is connected to it.

But regardless of that, you shouldn't be measuring 23V A/C on that HDMI port.

If I had a signature, this is where it would be.
ajhieb is online now  
post #18 of 40 Old 11-30-2013, 07:09 PM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by ajhieb View Post

Since it appears the TV has killed 2 Integrated HDMI ports (on your motherboard, and laptop) why would you assume that the HD4350 died of its own accord after being plugged in to the same TV?

It would appear that you're 0 'fer 3 on plugging devices into that TV. Why would you risk a 4th (even if it is used) when all signs point to a defective HDMI port on your TV?

The laptop works with that HDMI-2 port. This tells me that that port works.

I left the following part out to avoid additional confusion since my posts are lengthy enough as it is:
I have another signal path that I use. The tower PC normally connects to the TV set via a Monoprice 4x2 switch/splitter. The configuration is:

NORMAL USE:
(TowerPC).....30' HDMI Cable....(input-4 of the 4x2 switch --- Output-A) .....6' HDMI cable.....(HDMI-1 of TV set).

WHEN TESTING:
(TowerPC)......10' HDMI Cable......(HDMI-2 of TV set)

The 4x2 switch has inputs as:
1. Cable DVR
2. DVD player
3. Magnavox DVDR
4. Computer

The TV set's HDMI-1 port works fine with everything except the Computer, so I know it is working.
The TV set's HDMI-2 port works fine with the laptop so I know it is working.

Skylark
Skylark is offline  
post #19 of 40 Old 11-30-2013, 07:18 PM
Advanced Member
 
ajhieb's Avatar
 
Join Date: Jul 2009
Posts: 946
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 77 Post(s)
Liked: 234
Of all of the things you've said thus far in this and all of the other threads about your HDMI ports not working (I see this has been a long time in the works) the only thing you've observed that can be a cause is the 23V on the TV's HDMI port. Everything else you've listed is a an incidental detail, or a symptom but the only potential cause is the 23V. that is enough to damage driver circuitry. Unless you turn up another potential cause I can't fathom why you would fail to fallow up on the one thing you've discovered that could actually be the root of your problems.

To be clear, I'm not saying that the HDMI port on your TV isn't working I know you've managed to get it to work (at least for short periods of time) I'm saying it isn't working properly and a port that isn't working properly has the potential to cause all of the symptoms you've listed.

If I had a signature, this is where it would be.
ajhieb is online now  
post #20 of 40 Old 11-30-2013, 08:12 PM
Senior Member
 
ajkrishock's Avatar
 
Join Date: Nov 2008
Posts: 251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 17
Is it possible to make that 23 volt measurement someplace else that has a similar setup (a friend/relative)? It's be useful to know what that voltage is supposed to be on a known good system.
ajkrishock is offline  
post #21 of 40 Old 11-30-2013, 08:21 PM
Advanced Member
 
ajhieb's Avatar
 
Join Date: Jul 2009
Posts: 946
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 77 Post(s)
Liked: 234
Quote:
Originally Posted by ajkrishock View Post

Is it possible to make that 23 volt measurement someplace else that has a similar setup (a friend/relative)? It's be useful to know what that voltage is supposed to be on a known good system.

I am an electrical engineer. 0V is the answer to your question. That's why I keep insisting that the port on the TV is defective. Unless he was measuring something besides the shielding on the HDMI cable (as originally indicated) then it should be 0V.

If I had a signature, this is where it would be.
ajhieb is online now  
post #22 of 40 Old 11-30-2013, 08:30 PM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by ajhieb View Post

Of all of the things you've said thus far in this and all of the other threads about your HDMI ports not working (I see this has been a long time in the works) the only thing you've observed that can be a cause is the 23V on the TV's HDMI port. Everything else you've listed is a an incidental detail, or a symptom but the only potential cause is the 23V. that is enough to damage driver circuitry. Unless you turn up another potential cause I can't fathom why you would fail to fallow up on the one thing you've discovered that could actually be the root of your problems.

Please note that in my original post under "WHICH REPLACEMENT GRAPHICS CARD SHOULD I BUY?" I said:

"I want to buy a graphics card so I can view video from the computer on the HDTV set. This time I plan to run a #12 wire and connect it to the computer ground and the TV set ground to hopefully prevent another HDMI blowout. ".

So I thought that I would be addressing the thing that could be the root of my problems. Is my plan flawed?

Thanks,
Skylark
Skylark is offline  
post #23 of 40 Old 11-30-2013, 08:56 PM
Advanced Member
 
ajhieb's Avatar
 
Join Date: Jul 2009
Posts: 946
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 77 Post(s)
Liked: 234
Quote:
Originally Posted by Skylark View Post

Please note that in my original post under "WHICH REPLACEMENT GRAPHICS CARD SHOULD I BUY?" I said:

"I want to buy a graphics card so I can view video from the computer on the HDTV set. This time I plan to run a #12 wire and connect it to the computer ground and the TV set ground to hopefully prevent another HDMI blowout. ".

So I thought that I would be addressing the thing that could be the root of my problems. Is my plan flawed?

Thanks,
Skylark

if the problem is a difference in ground potentials between your different household circuits, running a wire between them might mask the problem, as far as your HDMI issues are concerned, but would in all likelihood cause other problems (like fires) since it means that something is pretty dreadfully wrong in your home wiring.

What's much more likely is the HDMI port on your TV is defective, in which case, bridging the grounds won't do anything to fix your HDMI issues. Again, you can test this by measuring between whatever ground you choose and your TV's HDMI port shielding. If you're getting a consistent 23V A/C on it then the problem is your TV, and it won't go away until you get the TV repaired.

Keeping in mind you identified a problem between the HDMI ground on your TV and (what is assumed to be) the household ground on your PC. (as the chassis should be grounded to household ground/earth)

It seems like you're assuming that the HDMI ground is at the same potential as household ground/earth on your other household circuit, as you've proposed bridging the grounds between the two household circuits, but you haven't yet established that the HDMI ground on your TV is at the same potential as the household ground. You've just assumed it as and are proceeding (with possibly dangerous plans) based on that assumption. Measure the difference between the HDMI port and your household ground and see if you're still getting the 23V. If you are, then your household wiring is probably fine, and it's your TV. If it is 0V then you've got some more hunting to do, but I still would keep plugging video cards into it until you've definitively figured out what the problem is.

Sorry if I'm coming off as a bit of a prick, but this conversation is getting more and more alarming as you get closer to starting fires.

If I had a signature, this is where it would be.
ajhieb is online now  
post #24 of 40 Old 11-30-2013, 09:13 PM
Advanced Member
 
jbcain's Avatar
 
Join Date: Jul 2010
Posts: 868
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 63
we already established it's not a difference of potential in the home wiring with our 3 tests.

we also established that those two circuits are on the same hot leg in the breaker box, because outlet to outlet showed 0v and not 220(240). this also tells us that those circuits share the same grounding bar in the panel for that hot leg bank.

one more test for the OP to disprove his theory.

take your fluke, put it on the ringer setting, pyramid of bars, also called a continuity check.

put one fluke leg in the neutral of the tv socket and the other in the computer socket neutral.

now do the same with the ground prong of the outlets.

if it rings, they clearly go to the same place and the wiring in the house is a-ok.
ajhieb likes this.
jbcain is offline  
post #25 of 40 Old 12-01-2013, 01:29 AM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by Mfusick View Post

You should double check that the HDMI isn't running a resolution the TV can't handle. I would manually set the display to output 1280x720p and test again.

I am guessing your ports are ok but the HDMI sync is not.

Been thinking about your suggestions regarding running a resolution the TV can't handle.

How does Windows detect monitors and show them in Device Manager > Monitors? Doesn't that occur before using any resolution that the TV can't handle?

For instance take my Dell Studio 1537 laptop. It just uses the Win8 monitor drivers.
When I was not able to get a display on the TV set using a 10 ft HDMI cable, Dvc Mgr > Monitors always only showed one "Generic PnP Monitor" entry which is the laptop's screen. When I use the 6 ft HDMI cable and the HDMI to the TV works, Dvc Mgr > Monitors shows two "Generic PnP Monitor" entries.

From what I've read, in the HDMI EDID handshake process, the TV tells Win8 what it is and what it can do. I think this is what puts the "Generic PnP Monitor" entry in Dvc Mgr > Monitors. Without this entry in Dvc Mgr, the TV can never appear as a second monitor.

Is my understanding correct?
Thanks,
Skylark
Skylark is offline  
post #26 of 40 Old 12-01-2013, 12:12 PM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by jbcain View Post

we already established it's not a difference of potential in the home wiring with our 3 tests.

we also established that those two circuits are on the same hot leg in the breaker box, because outlet to outlet showed 0v and not 220(240). this also tells us that those circuits share the same grounding bar in the panel for that hot leg bank.

one more test for the OP to disprove his theory.

take your fluke, put it on the ringer setting, pyramid of bars, also called a continuity check.

put one fluke leg in the neutral of the tv socket and the other in the computer socket neutral.

now do the same with the ground prong of the outlets.

if it rings, they clearly go to the same place and the wiring in the house is a-ok.

Frankly, I was a bit leery about using the continuity checker on my Fluke DVM to check a/c neutral to a/c neutral for fear of burning it out. But after convincing myself that the voltage difference from neutral to neutral of the different a/c outlets is only 0.1 volts, I went ahead and did the test.

The Fluke rings when checking neutral of the TV a/c outlet to the neutral of the computer a/c outlet.
It also rings when checking the ground prong of the TV a/c outlet to the ground prong of the computer a/c outlet.

So I guess this proves that the house wiring is a-ok.

Skylark
Skylark is offline  
post #27 of 40 Old 12-01-2013, 12:33 PM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by ajhieb View Post

if the problem is a difference in ground potentials between your different household circuits, running a wire between them might mask the problem, as far as your HDMI issues are concerned, but would in all likelihood cause other problems (like fires) since it means that something is pretty dreadfully wrong in your home wiring.

What's much more likely is the HDMI port on your TV is defective, in which case, bridging the grounds won't do anything to fix your HDMI issues. Again, you can test this by measuring between whatever ground you choose and your TV's HDMI port shielding. If you're getting a consistent 23V A/C on it then the problem is your TV, and it won't go away until you get the TV repaired.

Keeping in mind you identified a problem between the HDMI ground on your TV and (what is assumed to be) the household ground on your PC. (as the chassis should be grounded to household ground/earth)

It seems like you're assuming that the HDMI ground is at the same potential as household ground/earth on your other household circuit, as you've proposed bridging the grounds between the two household circuits, but you haven't yet established that the HDMI ground on your TV is at the same potential as the household ground. You've just assumed it as and are proceeding (with possibly dangerous plans) based on that assumption. Measure the difference between the HDMI port and your household ground and see if you're still getting the 23V. If you are, then your household wiring is probably fine, and it's your TV. If it is 0V then you've got some more hunting to do, but I still would keep plugging video cards into it until you've definitively figured out what the problem is.

Sorry if I'm coming off as a bit of a prick, but this conversation is getting more and more alarming as you get closer to starting fires.

I connected one end of a HDMI cable to the computer and measured the potential difference between the shield of the free end of the HDMI cable to the HDMI shield on:

1. The living room TV = 32 volts a/c.
2. The dining room TV = 32 volts a/c.

Before it was 23 volts a/c. Today it's 32 volts a/c.

The living room TV and dining room TV are back-to-back and share the same a/c outlet in the living room. That one dual outlet also powers the cable DVR, DVD player, Magnavox DVDR and the 4x2 HDMI switch. So it makes sense that the potential difference between the computer's HDMI shield is the same to all HDMI devices that I just listed, since all of those devices are connected together via their HDMI shields.

Both TV sets have worked with everything for years. It is only the computer HDMI that has the problem. So I'm convinced that it is not a problem in the HDMI port on the living room TV set.

Regarding connecting a #12 wire from the computer chassis (same as the HDMI shield ground) to the shield ground of all the devices I listed above, I can't see how that could possibly cause a fire. We're talking about chassis ground that humans touch and have no chance of being electrocuted. How in the world could connecting them together cause a fire?

Skylark
Skylark is offline  
post #28 of 40 Old 12-01-2013, 03:41 PM
 
cybrsage's Avatar
 
Join Date: May 2007
Location: Harrisburg, PA
Posts: 8,074
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 147
HDMI should only carry 5VDC, if I remember correctly. There should not be any AC involved at all. Seems like you might have a problem with the HDMI switch, since it is a common component to all your devices.
cybrsage is offline  
post #29 of 40 Old 12-01-2013, 05:34 PM - Thread Starter
Advanced Member
 
Skylark's Avatar
 
Join Date: Aug 2004
Posts: 772
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 15
Quote:
Originally Posted by cybrsage View Post

HDMI should only carry 5VDC, if I remember correctly. There should not be any AC involved at all. Seems like you might have a problem with the HDMI switch, since it is a common component to all your devices.

During testing, I disconnected the HDMI cable from the 4x2 switch from the living room HDTV set. The only cables connected to the TV set were 1) the a/c power cable and 2) the HDMI cable to the computer.

I also carried the 32" HDTV set from the dining room to the computer and it has the exact same symptoms as the living room HDTV set, with nothing else connected to the 32" TV set.

Thanks for the suggestion,
Skylark
Skylark is offline  
post #30 of 40 Old 12-01-2013, 05:41 PM
Advanced Member
 
jbcain's Avatar
 
Join Date: Jul 2010
Posts: 868
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 63
Quote:
Originally Posted by Skylark View Post

During testing, I disconnected the HDMI cable from the 4x2 switch from the living room HDTV set. The only cables connected to the TV set were 1) the a/c power cable and 2) the HDMI cable to the computer.

I also carried the 32" HDTV set from the dining room to the computer and it has the exact same symptoms as the living room HDTV set, with nothing else connected to the 32" TV set.

Thanks for the suggestion,
Skylark

How are you measuring voltage on the hdmi cable, physically speaking?

Turn the fluke to dcv and see what it says.

Pin 18 is said to be able to carry 15v or so.
jbcain is offline  
Reply Home Theater Computers

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off