• The forum software that supports hummy.tv has been upgraded to XenForo 2.1!

    This upgrade brings a number of improvements including the ability to bookmark posts to come back to later. Please bear with us as we continue to tweak things and open a new thread for any questions, issues or suggestions in Site/Forum Issues.

Initial black screen/error at switch on

Foo

New Member
When I switch on my T2 from stanby on all channels I get the error message "No programmes are currently being broadcast on this channel" with a black screen and no audio. This continues for about 5 minutes then I gradually get a pixellated picture and audio then normal service a few minutes later. Recordings are also blank at the start in the same way. I have tried powering off and on, updating the offical firmware, reseting and installing the custom firmware. I did a disk repair using the custom firmware but the issue is still there. I am thinking a damaged hard disk, or any other ideas?
 

Trev

The Dumb One
If it's doing it on live TV, then it's unlikely to be the HDD. But to make absolutely sure, open the box and disconnect the HDD. The box should boot up normally and you should get live TV (but obviously no recordings)
 

MymsMan

Ad detector
It sounds to me to be more likely to be tuner related to me.
Have you tried a retune?
What is the signal strength/quality shown on the box setting menu?
Do you have any problems watching TV directly without using the Humax?
Does it affect all channels equally or worse on some?
 

Black Hole

May contain traces of nut
It's just a crap signal. Menu >> Settings >> System >> Signal Detection will soon tell you what's what.
 

Trev

The Dumb One
Recordings are also blank at the start in the same way.
Is this for a recording that has been made (since the problem started), from 'switch on' or on all recordings, including ones that start off OK when the box has 'warmed up'? If otherwise-OK recordings only show the fault immediately after switch on, it sounds unlikely to be a 'warming up', tuner.
Having said that, I haven't got a better idea.
 

Black Hole

May contain traces of nut
It could very well be a thermal related tuner fault.
It could... but it could also just be that the signal is marginal and slight sensitivity variations before the box warms up (if you like) pushes it over the edge. The strength and quality figures for a mux that shows this effect, monitored as soon as possible after start-up, should be informative... "OK" would be a quality figure of 100% at all times, anything less requires investigating. Note that if strength is 100%, you are probably maxing out and overloading the tuner rather than too weak a signal.
 
OP
F

Foo

New Member
If it's doing it on live TV, then it's unlikely to be the HDD. But to make absolutely sure, open the box and disconnect the HDD. The box should boot up normally and you should get live TV (but obviously no recordings)
Will try later if I can find a screwdriver
 
OP
F

Foo

New Member
It sounds to me to be more likely to be tuner related to me.
Have you tried a retune?
What is the signal strength/quality shown on the box setting menu?
Do you have any problems watching TV directly without using the Humax?
Does it affect all channels equally or worse on some?
1 Yes
2 strength 72 to 83 quality 100
3 No
4 equally
 
OP
F

Foo

New Member
Is this for a recording that has been made (since the problem started), from 'switch on' or on all recordings, including ones that start off OK when the box has 'warmed up'? If otherwise-OK recordings only show the fault immediately after switch on, it sounds unlikely to be a 'warming up', tuner.
Having said that, I haven't got a better idea.
Old recordings are fine just ones made since the fault developed.
 

Trev

The Dumb One
But are the 'faulty' recordings made immediately on switch on, or after the box has been fully up for a while?
I.E. Does it record OK once the 'warming up' period is over, but not record OK during the 'warming up' time.
 
OP
F

Foo

New Member
But are the 'faulty' recordings made immediately on switch on, or after the box has been fully up for a while?
I.E. Does it record OK once the 'warming up' period is over, but not record OK during the 'warming up' time.
Perfect once warm up is over (about 10 minutes) but damaged during this 10 minute start up window. So if I left the box on all the times recordings would be ok but timed recordings are the problem because the machine is cold starting.
 

MymsMan

Ad detector
Perfect once warm up is over (about 10 minutes) but damaged during this 10 minute start up window. So if I left the box on all the times recordings would be ok but timed recordings are the problem because the machine is cold starting.
So leave the box permanently on
There are many discussions on the advantages of 24x7 running, though a daily time switch restart is useful to protect against hangs (especially while away from home)

Do you use Accurate Recording? With AR the box should switch itself on over 10 minutes ahead of the scheduled recording start so I would have expected it to have 'warmed up' sufficiently before starting to actually record.
 

Trev

The Dumb One
O that's a couple of work arounds. But it would be nice to find out what's causing the problem. From what OP has said, my money is it not being the HDD, but I would still try the disconnect trick to prove it.
 

MymsMan

Ad detector
All very odd. If the signal reports okay, then we're down to the decoder (within the SoC).
Since there are two tuners and, I assume, decoders in the Humax it would be interesting to start two recordings just after power on and see if the problem affects both recordings
 

Black Hole

May contain traces of nut
Since there are two tuners and, I assume, decoders in the Humax
Hmm. I'm into "best guesses" here, but the output of each tuner is a data stream containing multiple services (each of which is a container for multiple individual data streams... so the tuner output is a "super-container" maybe?). Each super-stream has to come into the SoC separately and demuxed into services separately, and then up to three services selected and passed on for further processing (all of this going on in hardware).

However, at that point the service streams are M2TS - ready for dumping to disk for recording or TSR. No further decoding is required until presentation (output by HDMI or SCART/Phono).

So no, I think there is only one decoder (ie module which decodes the M2TS into separate PCM video and audio streams).

Recordings are also blank at the start in the same way.
It appears the data is therefore faulty before it gets to the disk, and therefore before it gets to a decoder. Therefore my statement
then we're down to the decoder (within the SoC)
was a bit lax. What I meant was "somewhere within the datapath after the signal extraction and before the HDMI output".

As the signal detection reports OK (even during the fault symptoms), there's clearly a physical fault - and as the fault ceases to manifest after a "warm up" period the most likely explanation is that it is in some way related to heat and the work-around (for the time being) is not to let it cool down. But that is only a work-around, and it could cease to be effective at any time.

Can we pin this fault down any further, and is there any point? I believe so (this is how I used to earn my living in the development labs, but I had access to circuit diagrams!).

The signal strength figure has to come from the tuner front-end, so there has to be a live feed of that value from the tuner module to the SoC. Is that an analogue voltage on a wire (one for each tuner), or a response to a query on a data bus such as I²C or JTAG? I don't know, but the tuners have to be sent commands for tuning, so my guess is that would be done by serial bus, and status is probably reported the same way. The quality figure is a measure of how much error correction is going on after the demodulator. Where is the error correction? It could be in the SoC, but my guess is that the tuner modules also do this and are therefore also the source of the quality stats.

The typical heat-related fault is an intermittent circuit break which opens when the parts expand or contract. If I can pin this fault down to a PCB pad, it might be possible to repair by resoldering a pin. It seems to me the only hope of this is if the fault is on the input to the SoC from one tuner only, in which case we should see differences in performance between the two tuners (and the fault could be in the tuner itself). Otherwise the fault is within the SoC, and therefore irreparable.

Things to test (for more data):
  • Individual tuner tests available from the hidden menu - see Things Every... (click) section 9.
  • Record two programmes (from different muxes) at the same time.
If the individual tuner tests show no difference between the tuners, or the fault manifests on both simultaneous recordings despite them coming from separate multiplexes, I think we're stuffed.

Meanwhile, I strongly advise not subjecting the unit to physical shock. If the problem is something come adrift, shock could make it better... or permanent.
 
Last edited:
Top