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HDR FOX T2 - does the tuner fall over at low temperatures?

Discussion in 'HDR-FOX T2 Freeview Recorder' started by Watt Tyler, Dec 31, 2012.

  1. Watt Tyler

    Watt Tyler Member

    We've been away for a few days twice recently, and left the T2 to record some programmes while we were away. When we're not here, the house is unheated - except that the frost stat should turn the heating on to prevent the temperature falling below 10 degrees.

    On both occasions, some of the recordings have had the pictures broken up and discontinuities in the sound - like you get with insufficient signal - in some cases making them unwatchable. But it works ok when we're here, and the house is warm. The spec says it should work down to zero degrees. Are there any known temperature sentitivity issues? Is it likely to help if I leave it ON rather than on Standby when we're away in the winter, so that it keeps itself warm to some extent?

    TIA.

    WT
     
  2. Ezra Pound

    Ezra Pound Well-Known Member

    It's very unlikely that trouble with recordings are due to low temperature, even if the Humax was affected by low temperatures it would warm up quite quickly due to the hard disk and the rest of the electronics creating some 20Watts of heat
     
  3. Watt Tyler

    Watt Tyler Member

    Hmm. Any other ideas? Is it just coincidence that there's a problem with the signal when we're away?

    Another thought . . . The aerial signal to the Humax comes (along with other TVs and FM radios) via a Labgear distribution amplifier. Could that be playing up and degrading the signal when it gets cold?

    WT
     
  4. Black Hole

    Black Hole Felinos Guru

    Not very likely. There is no reason for the semiconductors to cease functioning at low temperatures, the low temp limit usually means it hasn't been tested beyond that. Mechanical devices might fail at low temperatures due to shrinkage and reduced clearances, electrical systems can fail if the low temperatures result in condensation forming - but that would have to be a chilled surface in contact with warmer air.
     
  5. Watt Tyler

    Watt Tyler Member

    OK, but SOMETHING is happening to the signal and/or Humax when we're away. Anyone got any theories as to what the root cause might be?

    WT
     
  6. socrates

    socrates Member

    Does it seem to be related just to temperature or perhaps also to humidity? ie might you have a bit of a condensation problem? This could be aggravated by positioning the box in a cold spot such as on/near a hard floor, window or outside wall. Have you scrolled through a recorded programme to see if it improves farther in, ie as the box warms up?

    It's not directly comparable I know but my car's cd player and sat nav can sometimes play up for a while on coldish but misty mornings until they have warmed up. On a much colder but dry day they will be ok from the start.
     
  7. Andy Hurley

    Andy Hurley Member

    Or maybe (on a similar theme) the aerial cabling is playing up in the cold. If some part of the cabling runs through the house and it has some moisture in it then maybe this condenses out as the house gets colder and causes reception problems.

    Realistically the only way to diagnose this is to do some tests while the house is cold, maybe on return from a holiday before turning up the heating.
     
  8. Sparks100

    Sparks100 New Member

    With the greatest respect for Ezra and Black Hole for their invaluable work, I offer some insight from my own Electronics experience. Personally, I would strongly suspect temperature as the culprit - both historic and the circumstantial evidence are strong indicators. Watt may be on the edge of decent reception, without knowing it (wikipedia "Cliff_effect") and as a result, a relatively small parametric change due to temperature could result in picture break-up. The performance of semiconductors is acutely temperature dependent, and whilst SNR does improve with falling temperatures, typically gain (amplification) does not, and I suspect that's the culprit here.

    It's true, Ezra, that given time the internally generated heat will warm up the unit - however if the tuner or LNA components are in the opposite corner of the box from the components generating significant heat (usually the PSU, then CPU/memory) then they may not warm up the problem areas in time (i.e. 30/40min maybe) to record the programs without breakup, so it could still be the PVR being cold. Permanently on in the cold may prove/disprove.

    As Black Hole states, the semiconductors still function at reduced temperature (they work better at low temps than at high ones), however their characteristics will change significantly and if no compensation has been designed in (unlikely in consumer grade volume electronics) then the circuit operation will be correspondingly affected. Realistically, you can expect consumer grade gear to work ok in the 20-40 degrees range, outside of that - good luck! e.g. I have a Ryobi battery charger that refuses to recognize the battery below 10 degrees - utterly useless for Winter work, it's just cheap/weak design. (To be fair, effective compensation can be a challenge, economically.)
    Condensation would only be an issue if the cold unit was taken into a warm (humid) room - but if the unit matches ambient, no condensation forms. Also, this performance change doesn't sound right for shrinkage/thermal movement, but it is possible if you had a dry joint.

    It's likely to be a combination of factors, maybe when cold, the broadcast signal is down a bit due to different propagation, the distribution amp and the PVR don't perform quite so well & the cumulative effect pushes the signal over the 'cliff'. Personally I suspect the Labgear amp; their low-end stuff is not the best (polite) and the Humax's design/build quality is likely to be significantly better, but only a rigorous testing will nail it down.
    If you want to test further Watt, say so & we can PM rather than clog the forum.
     
  9. MartinOnline

    MartinOnline Member

    An interesting discussion, to which I add my tuppence.

    I cannot speak about the HD or HD-FOX T2 yet as I bought my boxes in January and March, respectively, this year. However, for the Winters of 2009/10/11, when I went away for 2 weeks in the January with snow on the ground in Sheffield and my thermostat set to 10 degrees, both my 9200s worked perfectly. I have a set-top antenna feeding an amplifier in the loft. My house was built in late 2007 so I assume the cabling is good and well-protected by insulation in the cavity.

    On reading this thread my first thoughts were of cold draughts, water in cabling and condensation. Given the amount of rain lately, these seem likely contenders.

    Martin
     
  10. Ezra Pound

    Ezra Pound Well-Known Member

    Some interesting points, however there are quite a few areas inside the Humax that generate heat when the box is awake, the most significant of which is the hard disk, but also the PSU, CPU etc. as you say. It would be hard to see how any part of the box could avoid this heating. within 30-60 Minutes the hard disk heats to 55Deg C at which point the fan is turned on. If the OP does intend to do any more testing I would suggest installing the Custom Firmware (if not already installed), there can then be a permanent record of hard disk temperatures stored using the sysmon package
     
  11. Sparks100

    Sparks100 New Member

    Yes, the Humax would be bottom on my list of suspects. Contenders are: old/poorly aligned aerial (maybe in loft as opposed to ext.), old/damaged lossy coax, passive splitters (often hidden under lagging), lossy/incorrect coax terminations, crappy labgear dist. amp (and/or its power supply), maybe wet in coax (if ext.) but the majority of these potential problems would be largely consistent across temp. with the exception being anything that is active, i.e. semiconductors. Agreed, the fan would distribute the heat, but even so there's still a significant thermal mass to raise if the whole unit was very cold, and if the OP's programs were 30min then it still may not make it in time. Nice point about the firmware; I hadn't read up on sysmon, another useful bonus. As in any fault-finding exercise, the key to success is in reliable replication of the fault, and then systematic tests changing only one parameter at once. Tedious, but necessary.
     
  12. Sparks100

    Sparks100 New Member

    That's very promising. It may be that Watt is unlucky enough to have a bottom-of-the-spec (or even duff) unit, or more hopefully, some relatively minor and easily fixed problem within the signal path. I had hoped the Humax would have coped; as I remember it the 'nominal' domestic temperature range for consumer grade electronics to perform satisfactorily to is 0-60 degrees. However, compliance is very variable, usually strongly linked to cost. Since Humax is not a cheapo, I would expect it to work. The same may not be true, however, for the Humax YouView box, which is highly cost-sensitive, and customer specified. Just look at NTL/C&W's efforts at providing STBs; typically had the word "Kellogs" crossed out, and "Set top box" written over in crayon... nice'n'cheap, though.
     
  13. Black Hole

    Black Hole Felinos Guru

    I wouldn't be happy letting a house get that cold - even if I was away. I fancy it will prove to be something else.
     
  14. Watt Tyler

    Watt Tyler Member

    I don't think there's a condensation problem. The Humax is under the TV in a corner of a carpeted room - a long way from external walls or windows, and there's never any sign of condensation on the (double glazed) windows when we return home, having been away.

    I haven't personally scrolled right through the recordings - but SWMBO claims to have done so, and declared them unfit to watch - and watched them on iPlayer instead.

    WT
     
  15. Watt Tyler

    Watt Tyler Member

    Thanks for your very helpful replies. To deal with the points which you raise . . .
    The aerial is a decent multi-element (log periodic?) jobby which I installed on the chimney about 10 years ago and appears (from the ground) to be still in good condition and correctly aligned on Sutton Coldfield. The cable (again self installed) is decent quality low-loss co-ax (but not your fancy CT-100 stuff - if that's the right designation). The cable runs down the outside in a sheltered corner, then through the wall into an upstairs bedroom where the distgribution amp is located. There's only about one metre of the main downlead inside the house before it gets to the amp. If the problem were caused by the outside bit being wet, surely it wouldn't make any difference whether or not the house was occupied? There are no passive splitters - honest!

    I think that the distribution amp was made by Labgear - it's actually branded Wickes, and has 2 inputs (UHF and FM) and 6 outputs. It has an internal power supply and is always switched on. I've had it at least 25 years (maybe they made 'em better in those days?) and it's always given good service.

    I've had the Humax for about 18 months, and we were away for a similar amount of time last winter without any problems - it's only recently that this signal loss has occured. [I didn't buy it until after DSO because the digital signal wasn't reliable enough until they turned off an analog, turned the wick up, and moved the channels so that all muxes are within the scope of a Group-B aerial.] Ever since DSO, the signal has been fine - apart from one or two short periods of freak atmospheric conditions - despite being on the fringes of the SC reception area. However (as someone else has suggested) because we're on the fringe, it doesn't take all that much to upset it.

    I think that the first thing to do is probably to examine the plugs on both ends of the cable which runs from the amp to the Humax, and make sure that nothing's come loose. Even if it has, it would still need something else to tip it over the edge so that it stops working when the house is cold, but starts working again when it warms up!

    WT
     
  16. Andy Hurley

    Andy Hurley Member

    Given that more detailed description my money is on the amp as the culprit, although it is definitely worth looking for signs of corrosion on the input plugs to the amp to see if there could be moisture in the lead.

    I recently had to replace our distribution amp as we had started getting a lot of signal issues after 11 years without problems. At first I thought me must have an aerial problem but in an attempt to diagnose it I tried swapping out the amp for an old one I found kicking around in a drawer and it completely fixed the issue. Our amp is mounted on the wall of our (unheated) garage so it has always been subject to big temperature variations without issues but last Autumn it just seemed to give up. The new one is actually older, having been recovered from an installation I did for my mother-in-law about 8 years ago. Neither are designed for outdoor use but the location is dry so I never worried about that too much, maybe I should be more careful. On the other hand, 11 years service is not too bad so I won't be losing sleep over it.
     
  17. Watt Tyler

    Watt Tyler Member

    Not sure SWMBO would wear that! We always put the heating in 'holiday' mode, set to come on again BEFORE we get home!
     
  18. Andy Hurley

    Andy Hurley Member

    :)

    Well, I guess you need to explain that, if she wants to get working recordings again it is a necessary evil. Or, maybe you could arrange to come home a day or two earlier than her and don't forget to put on the thermals. If you can't reproduce the symptoms then you are reduced to making wild stabs in the dark.

    Seriously though, take a look at the connector going IN to the amp. If there is any sign of corrosion there then that would be a good place to start. If not then I would be very tempted to swap out the amp. After that there are just too many variables to make any useful diagnosis without chilling the house.
     
  19. antipodean

    antipodean Member

    Is the amp powered on while the house is in holiday mode ??? I did skip through the posts, but don't recall mention of this.

    If it is powered off while you are away it will be an attenuator rather than amplifier ...
     
  20. Watt Tyler

    Watt Tyler Member

    Yes, I think I did say earlier that the amp is on all the time - and this includes when we are away.

    WT