Investigating the HDMI "Green Screen After a Few Seconds" Problem

Black Hole

May contain traces of nut
There have been a couple of reports of video on HDMI being OK for a couple of seconds after start-up and then going green-screen, eg:

My HDR is one of the first "horizontal" hardware builds. It has worked absolutely fine with my 2011 Samsung UE40D6530 TV from the time I got them.

Earlier this week I upgraded (slightly) my amp to a Yamaha rx-v387 whereupon no matter what I did the HDR gave me a green screen after about 2 seconds after a good picture/sound, which i researched thoroughly on this and other forums.

I changed firmware, Humax and Custom, and loaders, swapped cables, messed with all combinations of CEC on and off etc.

Anyway, eventually I plugged the HDR into the Yamaha port HDMI 4 which is the only one that supports HDCP 2.2, and it works fine, the other 3 HDMI ports fail to green screen.

Our old Humax started showing a fault where a second or so after booting up it switches to displaying a blank green screen. It's been tested with different HDMI inputs on the TV, for example swapping with the DVD player. The inputs work OK with the DVD, Also tested with a different TV set. I was all set assuming this is a fault with the Humax, however today I tried a replacement (second hand of course) and it shows the exact same fault. From a cold start it displays the initial logo then displays a menu for a second or so before going blank green.

Any ideas? I'm finding it hard to believe two units with the same fault, unless it is possibly a known problem.

I am currently investigating an HDR-FOX with exactly the same problem, although it was not reported to have this problem previously (on a different TV).

From boot: the Humax splash screen is displayed, then the screen goes black, then there is live TV+sound for maybe one or two seconds, then the picture and sound drop out and the screen displays solid green. Analogue outputs work fine (RCA; I haven't tested SCART but there is no reason to suppose SCART wouldn't work). If I have analogue and HDMI connected at the same time, the analogue output is interrupted periodically with the "The programme cannot be viewed..." on-screen message** (this happens when there is both analogue and digital outputs in use, to prevent HDCP* being bypassed) – so clearly the unit thinks there is an HDMI link.

* HDCP: see Glossary

1622395543750.jpeg

Changing the VFORMAT resulted in the screen going black for a fraction of a second and then back to green (the VFORMAT can be operated blind: the first press displays the current setting, and a second press while the current setting would be on-screen changes the setting). This suggests HDMI output stops while the video format is changed, and that the green screen is actually being generated by the HDR-FOX as video output.

A coincident factor is the loader version. This "problem" HDR-FOX has loader a7.31. The same TV (LG 32LD690) works fine on the same input with the same HDMI cable with an HD-FOX which reports loader L7.27. Another HDR-FOX (again working correctly) reports a7.33. My other HDR-FOXes (on other TVs) are either a7.30 or a7.33.

The next thing was to try the "problem" HDR with a different TV. I switched in a Samsung UE32H5000, and what do you know: it's fine on that.

What I want to do now is find out whether this is repeatable: do all HDR-FOXes with a7.31 loader fail to work with the LG 'LD690 TV chassis?

I know "we" have all the loader versions in captivity, so if the relevant personnel would care to contact me by PM with details of how I can install different versions of loader, I will be grateful (and it will help extend the knowledge pool).

It is also possible different HDR- or HD-FOXes have slightly different versions of HDMI chip, which might require tweaks to the firmware to accommodate. If I get inconsistent results from loader versions, minor differences in hardware might be the culprit.

What this does not explain is how a unit can go from "working" to "not working" spontaneously, or how two units can go faulty simultaneously, unless there was some other factor which has not been accounted for (firmware update, firmware update on the TV, different TV). I propose that, if there is a burst of good video (including the splash screen) and not no video at all, the basic HDMI output hardware is working and the later loss of video is something to do with the firmware (and not necessarily at the HDR-FOX end).
 
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MartinLiddle

Super Moderator
Staff member
I know "we" have all the loader versions in captivity, so if the relevant personnel would care to contact me by PM with details of how I can install different versions of loader, I will be grateful (and it will help extend the knowledge pool).
Loader 7.31 is available from http://hpkg.tv/rpc/cfwget.html?file=loader.a731.hdf You rename it and install it as a normal firmware update. I think 7.30, 7.33 and 7.34 are also available; just make the obvious change to the URL.
 

bottletop

Active Member
I have a HDR with the green screen HDMI issue - but only one TV to test it on!
It was my first HDR and was working fine for a while. The green screen issue started as an intermittant fault and gradually got worse. It shows up during start up and also when switching to it from another source when all devices were warmed up (eg from HDMI-2 (Bluray) to HDMI-1 (Humax HDR). There is often a flash of the loader screen before it settles onto the bright green display. Sometimes it'll be green from the start. Other HDRs and other devices work fine with this TV using any HDMI socket and/or cable.

Things that worked to skirt around the issue
  • acquire another HDR FOX T2
  • use scart instead of HDMI output (loss of quality, may not see the Humax loader start screen well)
  • use composite yellow, red, white phono instead of HDMI output (loss of quality, may not see the Humax loader start screen well)

Things that made no difference to the green screen issue
  • replacing the HDR loader to a7.30, a7.31, a7.33 or a7.34.
  • leaving the HDR powered off overnight to cool down
  • leaving the HDR powered off for a few days to cool down
  • using other HDMI sockets on the TV
  • using other HDMI cables
  • cycling through the V-FORMAT options
  • unplugging hard drive power cable
  • changing the order the TV and/or HDR are powered on
  • using a cheap Ebay 1 input to 2 output HDMI splitter advertised as having HDCP stripper function
  • cleaning HDR HDMI socket with toothpick and alcohol
  • powering up without the aerial cable

Things that might make a difference to the green screen issue
  • I didn't have/try a HDMI matrix thingy that is occasionally mentioned in the forum
  • another TV or monitor that has HDMI input (changing TV worked for some people)

What appears on the TV HDMI during green screen HDR start up (ie faulty HDR)
  • Humax loader screen - dark screen, Humax logo with the boot loader version on bottom left
  • as the dark screen fades, occasionally there is a brief split second flash of the green screen
  • Blank screen for up to 5 seconds while the hard drive starts to spin up
  • Then it tries to show live broadcast channel signal for 1-2 seconds
  • bright green screen shows instead of broadcast channel (note menu navigation also shows green screen)
  • note if aerial cable is not plugged in, you obviously won't see the broadcast channel, but the everything else will be as above
What should appear on the TV HDMI during normal HDR start up (ie a normal working HDR)
  • first three things are same as above paragraph (the loader boot up screen)
  • Then it shows live broadcast channel signal (and stays on that channel)
Note regarding firmware update
  • SCART output is a garbled mess - can't see firmware update progress
  • HDMI output is fine! (ie 4:3 ratio, clear text etc and shows firmware update progress)
  • @BH mentioned this is due to this sequence being pre-HDCP

Edits
1 Format text for clarity.
2 Add details of V-FORMAT.
3 Add What appears on the TV HDMI during green screen HDR start up.
4 Add Note regarding firmware update.
5 My TV is an old Sony Bravia LCD circa 2010.
6 Add What appears on the TV HDMI during normal HDR start up.
 
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OP
Black Hole

Black Hole

May contain traces of nut
I like your post edit, great improvement.

There is often a flash of the loader screen before it settles onto the bright green display. Sometimes it'll be green from the start.
I am convinced this is not the same HDMI issue. The symptom I have observed, and appears to be reported in the other posts quoted in Post 1, does not just "flash" the splash screen – it shows the full duration of the splash screen and goes on to show a second or two of live video before going to green screen. This suggests a systematic deterministic process is at work, rather than something being "broken".

It would be interesting to know whether your example also demonstrates the HDCP pop-up message, or the switching artefacts on operation of VFORMAT.
 
OP
Black Hole

Black Hole

May contain traces of nut
Oh dear! Well, that's a blow:

I have installed loader a7.33 on the troublesome HDR-FOX and it has made no difference. WTF?
 

bottletop

Active Member
..
I am convinced this is not the same HDMI issue. The symptom I have observed, and appears to be reported in the other posts quoted in Post 1, does not just "flash" the splash screen – it shows the full duration of the splash screen and goes on to show a second or two of live video before going to green screen. This suggests a systematic deterministic process is at work, rather than something being "broken".
..
I have seen a HDCP pop-up message, although I can't say for sure if it was the exact same one. From memory it appeared gradually so it may have been in line with the increasing failure / green screen issue. But the phrasing does look very familiar.
 

bottletop

Active Member
Oh dear! Well, that's a blow:

I have installed loader a7.33 on the troublesome HDR-FOX and it has made no difference. WTF?
Look on the bright side, only another 2-3 to go. But these loader installs are quick, a minute or so compared to the 3-5 minutes for the standard firmware update.
 
OP
Black Hole

Black Hole

May contain traces of nut
Later maybe. I'm wondering about the HDCP blacklist now – anybody know much about that? Is it actually a thing?
 

EEPhil

Number 28
I know nothing! But a quick search suggests that it is a thing. The fact that the FOX-T2 has been hacked (custom firmware) would make it a candidate for the blacklist. But why now? And has everybody’s FOX-T2 got the same problem? If not, why not? (rhetorical!)
 

BMAX

Member
I convinced myself that it was a timing issue caused by component ageing as, in my case the problem first showed up some years ago with a Sony Bravia TV, and got progressively worse over some months. When the Bravia was replaced by a Panasonic, the green screen went away. However, some years later, the problem has resurfaced very occasionally. It remains to be seen whether it gets gradually worse as before.
For info the Loader is 7.31. I didn't try changing it as others had reported no improvement.
 

/df

Well-Known Member
... I'm wondering about the HDCP blacklist now – anybody know much about that? Is it actually a thing?
Not so much for 10 years, at least with HDMI 1.x.

As the sage authors of the Wikipedia article note,
http://en.wikipedia.org/wiki/High-bandwidth_Digital_Content_Protection said:
Edward Felten wrote "the main practical effect of HDCP has been to create one more way in which your electronics could fail to work properly with your TV," and concluded in the aftermath of the master key fiasco that HDCP has been "less a security system than a tool for shaping the consumer electronics market."

That "timing issue" would be a candidate for being fixed by a matrix switch.
 

BMAX

Member
I did try a switch that was lying around to no effect, but it was probably not a suitable type.
 

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MartinLiddle

Super Moderator
Staff member
I have installed loader a7.33 on the troublesome HDR-FOX and it has made no difference. WTF?
I am not surprised; when this problem first surfaced there were a couple of reports suggesting changing the loader helped but since then all the reports I have seen say no improvement from changing the loader.
 
OP
Black Hole

Black Hole

May contain traces of nut
The reason I find this so perplexing is because the HDMI is clearly basically working. it "feels like" a firmware problem, so it ought to be solvable in firmware and repeatable with the same combination of firmware under the same circumstances.
 

bottletop

Active Member
The reason I find this so perplexing is because the HDMI is clearly basically working. it "feels like" a firmware problem, so it ought to be solvable in firmware and repeatable with the same combination of firmware under the same circumstances.
I'll have to agree.
HDMI seems to work during the loader sequence, but fails after a normal boot, usually just after it tries to show the current live broadcast TV channel.
I've added to my post#4 (note 4) https://hummy.tv/forum/threads/inve...after-a-few-seconds-problem.10218/post-155508
The troubled HDR green screen unit displays fine during firmware update!
 

/df

Well-Known Member
Does this mean that it's somehow failing (or perhaps failing to fail) to interpret some copy-protect signal in the broadcast stream?
 

bottletop

Active Member
Does this mean that it's somehow failing (or perhaps failing to fail) to interpret some copy-protect signal in the broadcast stream?
I did consider that, but no. The green screen occurs even when the aerial lead is unplugged and/or there are no channels scanned & stored. It's just that it occurs at a particular point during the boot process. When the fault was intermittent, I occasionally saw the green screen when switching HDMI sources on the TV remote while the Humax was playing back something.
On my troublesome HDR the only time I see a non green screen on HDMI is during the initial boot process before the drive spins up. I've also tried disconnecting power to the drive but same results.
 
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