SKY HD HDMI Outputting too high voltage? Causing HDCP damage?

[byron_hinson]

Well I've run some voltage tests on the Sky HD box today since I started to get a HDCP error for the first time on my philips TV set, I thought this was unusual considering this set hasn't been mentioned much in regards to the current run of HDCP errors showing up on pioneer sets.

The tests I ran on other HDMI hardware show that the Sky HD box is putting out a much higher voltage (at least my box is) when compared to ANY other HDMI based hardware. This to me signals that it can/will/might! cause damage to HDMI connections...well it can to the HDCP bus and would be a good indication on why people are getting problems.

What I ask is that those who can no longer use Sky HD on their sets due to the HDCP error, see if you can run another connection to the HDMI port which doesn't use HDCP...if that displays then Sky HD is frying the HDCP on Tv's due to a high voltage. In which case, I recommend removing Sky HD from HDMI connetions until Sky can get it fixed...my guess would be that it won't be a over the air fix.

[MJG1985]

My understanding of the problem is that it is caused only by connecting live devices together.
I.e connect the units when they are powered-down. Then turn them on and things are okay.
HDMI does a 'hand-shake' with both bits of kit, a voltage is present to do this and having them on -can- 'fry' the chip.

[brendan_dj]

Originally Posted by byron_hinson

The tests I ran on other HDMI hardware show that the Sky HD box is putting out a much higher voltage (at least my box is) when compared to ANY other HDMI based hardware.

This is interesting!
How are you measuring the voltage? do you have actual figures?
Are you measuring the voltage on a certain conductor/pin on the HDMI connector?

I remember reading a discussion on here regarding significant and strong electrical sparking when the end of the cable touches the metal casing of something.

[Ultra2man]

Originally Posted by MJG1985

My understanding of the problem is that it is caused only by connecting live devices together.
I.e connect the units when they are powered-down. Then turn them on and things are okay.
HDMI does a 'hand-shake' with both bits of kit, a voltage is present to do this and having them on -can- 'fry' the chip.

Theer is one problem with the Sky HDMI output in that it does not power down completely when you put the box into standby.
I have an Octava switchbox connected between my HD box and my display and when I put the HD box into standby the LED on the switchbox still shows that it is getting some form of signal from the Sky HDMI output. The DVD player that I also have connected to the switchbox does not do this when in standby.

[HD-Dude]

I think the failure mechanism is this one:-
http://www.avforums.com/forums/showp...&postcount=202

I also think the HDCP chips are not "fried" as such, just need reprogramming (which is still a major job!).

Jim.

[midichlorian]

Got to hand it to you guys, if you're on to something I reckon Sky / Pio / Philips owe you more than a pint or two....

I await further info. with interest

[byron_hinson]

Originally Posted by brendan_dj

This is interesting!
How are you measuring the voltage? do you have actual figures?
Are you measuring the voltage on a certain conductor/pin on the HDMI connector?

I remember reading a discussion on here regarding significant and strong electrical sparking when the end of the cable touches the metal casing of something.

I'll post up some full results tomorrow when I get the chance, I did basic tests on a HD-DVD player, Samsung 950, Denon DVD Upscaling player and a test from a graphics card I'm reviewing which has HDMI on it....they were basic tests but the voltage on nearly all were identical apart from Sky HD, doesn't mean its the cause of the problem, but if its pushing a higher voltage to the TV then it can overload it and cause, at a guess, some damage to TV's that can't deal with that kind of surge.

HDMI is supposed to be a 1.0-volt as standard I believe (from work i did in a review a while ago), low voltage stops HDCP data from transmitting properly too, so that could be another reason for problems people are having if there is a voltage problem on the HDMI port on the Sky HD box, but I'm guessing the higher voltage that I'm showing can cause damage.

Its hard ground to cover as some HDMI cables differ in quality despite everyone saying its digital so quility doesn't change, but if the voltage is too low then it can cause signal problems.

I did a full test on the HDMI cable (showed higher than it should) and the two pins used for HDCP which showed slightly higher too (above the spec)

[byron_hinson]

Originally Posted by midichlorian

Got to hand it to you guys, if you're on to something I reckon Sky / Pio / Philips owe you more than a pint or two....

I await further info. with interest

If it fixes it I don't care too much, but I'm an amature when it comes to these things. Just hope that if the voltage is the cause of the problem, anyone with a damaged set gets compensated. But this is all hyperthetical at the moment.

[stevemac2006]

Does anyone know a switch box, like the octava or an amp with hdmi switching protect the screen. I'd be interested how many people with such devices have this problem (Yes I have a switch box)

[HD-Dude]

Originally Posted by stevemac2006

Does anyone know a switch box, like the octava or an amp with hdmi switching protect the screen. I'd be interested how many people with such devices have this problem (Yes I have a switch box)

I have not heard of any problems with HDCP faults occuring on TV's which are connected via HDMI to devices (including swith boxes and scalers) other than the Sky HD box directly. However, there are some devices (scalers, PJ's as well as TV's) which have failed when they are connected to the Sky HD box themselves directly.

I spoke to Pioneer who said that they were not concerned about signals to their plasmas from devices other than the Sky HD, including if you send component to an AV amp and then HDMI to the Pio media box.

I use a Denon AV switching amp with some quite sophisticated input buffering. I use HDMI directly from the Sky box to this amp and then HDMI monitor output to the Pio media box.

No trouble so far but then the HDCP protocol is not re-writable on the Denon amp.

Jim.

[spacecadet]

Originally Posted by byron_hinson

HDMI is supposed to be a 1.0-volt as standard I believe (from work i did in a review a while ago), low voltage stops HDCP data from transmitting properly too, so that could be another reason for problems people are having if there is a voltage problem on the HDMI port on the Sky HD box, but I'm guessing the higher voltage that I'm showing can cause damage.

Its hard ground to cover as some HDMI cables differ in quality despite everyone saying its digital so quility doesn't change, but if the voltage is too low then it can cause signal problems.

I did a full test on the HDMI cable (showed higher than it should) and the two pins used for HDCP which showed slightly higher too (above the spec)

Depends what you are measuring and how you are measuring it. At the very least you need more than just a voltmeter - more like a logic analyser - is that what you are using??

the I2C clock (SCL) and data (SDA) used for the HDCP handshake normally use 5V TTL levels that has a maximum rating of 5.5v in the I2C bus spec for standard mode devices that is used on HDMI

the TMDS signals that pass the video are DC coupled differential signals that require a 3.3v+/-5% termination supply voltage Avcc and 50 termination resistors Rt

The HDMI spec says the following:-

Single-ended high level output voltage, VH AVcc ±10mVolts
Single-ended low level output voltage, VL (AVcc – 600mVolts) ≤ VL ≤ (AVcc – 400mVolts)
Single-ended output swing voltage, Vswing 400mVolts ≤ Vswing ≤ 600mVolts
Single-ended standby (off) output voltage, VOFF AVcc ±10mVolts

Since the swing is differential on
the pair, the net signal on the pair has a swing twice that of the single-ended signal, or 2��Vswing.
The differential signal, swings between positive Vswing and negative Vswing.

This translates as a total swing of between 800mV and 1.2V

BTW, these signal must stil be OK on the failed Pioneer devices otherwise they would not work with non HDCP devices . What I am saying is you you cant just measure this stuff with a voltmeter - otherwise you will read just utter crap. You will also read crap if you measure an unconnected output without any load!! So do do this properley you need a sourc connected to a sink and to be able to breakout the signals somehow!!

Here is the HDMI pinout

PIN Signal Assignment PIN Signal Assignment
1 TMDS Data2+
2 TMDS Data2 Shield
3 TMDS Data2–
4 TMDS Data1+
5 TMDS Data1 Shield
6 TMDS Data1–
7 TMDS Data0+
8 TMDS Data0 Shield
9 TMDS Data0–
10 TMDS Clock+
11 TMDS Clock Shield
12 TMDS Clock–
13 CEC
14 Reserved (N.C. on device)
15 SCL 16 SDA
17 DDC/CEC Ground
18 +5V Power
19 Hot Plug Detect


Hot plug detect must not go beyond 5.3v

I have a copy of the 1.2 HDMI spec. PM me if anybody wants a copy.

[steve-p]

Originally Posted by stevemac2006

Does anyone know a switch box, like the octava or an amp with hdmi switching protect the screen. I'd be interested how many people with such devices have this problem (Yes I have a switch box)

Presumably it will, if the switch box is more robust than Pioneer TVs seem to be, and if it's a proper one and not just a mechanical switch.

[spacecadet]

Originally Posted by steve-p

Presumably it will, if the switch box is more robust than Pioneer TVs seem to be, and if it's a proper one and not just a mechanical switch.

Not necessarily - see this post.....

http://www.avforums.com/forums/showp...&postcount=487

[glimmerung]

Originally Posted by spacecadet

Depends what you are measuring and how you are measuring it. At the very least you need more than just a voltmeter - more like a logic analyser - is that what you are using??

the I2C clock (SCL) and data (SDA) used for the HDCP handshake normally use 5V TTL levels that has a maximum rating of 5.5v in the I2C bus spec for standard mode devices that is used on HDMI

the TMDS signals that pass the video are DC coupled differential signals that require a 3.3v+/-5% termination supply voltage Avcc and 50 termination resistors Rt

The HDMI spec says the following:-

Single-ended high level output voltage, VH AVcc ±10mVolts
Single-ended low level output voltage, VL (AVcc – 600mVolts) ≤ VL ≤ (AVcc – 400mVolts)
Single-ended output swing voltage, Vswing 400mVolts ≤ Vswing ≤ 600mVolts
Single-ended standby (off) output voltage, VOFF AVcc ±10mVolts

Since the swing is differential on
the pair, the net signal on the pair has a swing twice that of the single-ended signal, or 2��Vswing.
The differential signal, swings between positive Vswing and negative Vswing.

This translates as a total swing of between 800mV and 1.2V

BTW, these signal must stil be OK on the failed Pioneer devices otherwise they would not work with non HDCP devices . What I am saying is you you cant just measure this stuff with a voltmeter - otherwise you will read just utter crap. You will also read crap if you measure an unconnected output without any load!! So do do this properley you need a sourc connected to a sink and to be able to breakout the signals somehow!!

Here is the HDMI pinout

PIN Signal Assignment PIN Signal Assignment
1 TMDS Data2+
2 TMDS Data2 Shield
3 TMDS Data2–
4 TMDS Data1+
5 TMDS Data1 Shield
6 TMDS Data1–
7 TMDS Data0+
8 TMDS Data0 Shield
9 TMDS Data0–
10 TMDS Clock+
11 TMDS Clock Shield
12 TMDS Clock–
13 CEC
14 Reserved (N.C. on device)
15 SCL 16 SDA
17 DDC/CEC Ground
18 +5V Power
19 Hot Plug Detect


Hot plug detect must not go beyond 5.3v

I have a copy of the 1.2 HDMI spec. PM me if anybody wants a copy.

Interesting stuff.

How did you do the measuring Byron?

Does anyone else think that all this HDMI and HDCP stuff is unnecessarily complicated (due to the HDCP element) and was always likely to introduce problems? It's this bloody obsession with copy protection. Why doesn't the industry get over it. It costs them more money than a few pirates ever would.

[byron_hinson]

I just had a basic logic analyzer, I'm taking it into work tomorrow to use the Gologic one we have there that is far better and about 100x more expensive. I'm not home at the moment to run the tests again and I haven't had the call back from PR yet either.