[mythtv-users] HDPVR intermittent failure

Sun Jun 28 16:45:36 UTC 2020

On Sat, Jun 27, 2020 at 7:51 PM glen <glenb at glenb.net> wrote:

> On Sat, 2020-06-27 at 18:46 -0700, DryHeat122 . wrote:
>
> On Mon, May 11, 2020 at 12:59 PM DryHeat122 . <dryheat122 at gmail.com>
> wrote:
>
> On Mon, May 11, 2020 at 2:41 AM Stephen Worthington <
> stephen_agent at jsw.gen.nz> wrote:
>
> On Sun, 10 May 2020 20:20:30 -0700, you wrote:
>
> >On Sun, May 10, 2020, 7:58 PM Greg <gregl at nycap.rr.com> wrote:
>
> >Ok thanks I will investigate that.  But it's been working fine with the
> >current power source for like a year now, and others on this list use it
> >too.
>
> USB cables often fit badly into the sockets.  If so, the connection
> generally gets worse over time as you get dirt or oxidisation on the
> contacts.  So badly fitting cables will degrade with time.  The result
> is that the voltage drop across the cable will increase markedly.  And
> they can be too thin - the amount of copper in the wires is too little
> and that causes high resistance and a big voltage drop across the
> length of the cable.  Some (most?) USB cables are designed only for
> data transmission, or to run very low power devices.  For a high power
> device, you need a better (thicker) cable.  The high power devices do
> a negotiation with device supplying the power and request high power
> mode.  If the cable is not capable of high power, that negotiation is
> not supposed to work and the device should either only work in low
> power mode or it should turn itself off.  But USB cable makers often
> make cables not capable of high power transmission that will allow the
> high power mode negotiation to succeed.  So even though the device
> supplying the power is sending high current, the voltage drop in the
> cable means that at the other end, the voltage can be below the level
> required for proper operation or to fully charge the device's battery.
>
> I have had two notably bad experiences with USB cables.  One was a USB
> DVB-T tuner, and it was very like your experience - it would go for a
> number of days just fine, then suddenly stop.  If I unplugged it and
> plugged it in again, it would usually work again.  When I finally
> investigated properly, I found the cable was just a little loose in
> the PC's socket.  I replaced the cable with one that fit more tightly
> and the tuner was much more reliable.  It still occasionally caused
> trouble, but only when I had bumped the cables (or in one case, after
> we had a small earthquake).  So because of that and because I needed
> more DVB-T tuners, I finally replaced all my DVB-T tuners with an 8
> tuner PCIe card.
>
> The second bad experience was my Samsung Galaxy Tab S2 tablet.  Its
> USB charging cable was supplied with it by Samsung, so I assumed it
> was a good one.  But right from the start, the tablet took a long time
> to charge, and the time gradually got longer and longer and the
> battery life on one charge was getting less and less.  And then I
> started to have to jiggle the cable in the socket to get it to charge
> at all.  I actually called the Samsung help line about this, and they
> said it sounds like a bad cable.  So I bought a expensive (NZ$30)
> Pudney & Lee charging cable, which was a fair bit longer than the old
> Samsung cable, but fit very tightly at both ends and was significantly
> thicker - it has more copper in the wires in the cable.  Then suddenly
> the battery charging times were what was specified for the tablet,
> rather than three times as long.  And over a number of charging
> cycles, the battery life came back again.  So the original Samsung
> supplied cable was clearly bad from the start - it is probably less
> than the specification required to charge the tablet properly as it is
> too thin and has too much voltage drop even when the plugs fit
> properly.  So definitely NZ$30 well spent.  But I am surprised that a
> reputable company like Samsung would supply a bad cable with an
> expensive top-of-the-line product like my tablet.  But they did - so
> now I always suspect any USB cable I get and keep an eye on how well
> it is working.
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>
> Thanks for all the suggestions.  I will investigate all of them.
> Something I do not see in here is an opinion that some software problem
> could have evolved.  I was kind of thinking of that as a possibility given
> that it worked fine for so long then seems to be degrading.  OTOH I never
> thought of the possibility that the USB connection could be degrading.  I'm
> going to try Greg's connector, assuming I can get parts during the
> Apocalypse.  Also, his link specifies Radio Shack parts.  What's Radio
> Shack?!? ;-)
>
>
> Well folks this is getting frustrating.  I addressed a possible
> ventilation issue.  I also unplugged the power cord I had from the Myth box
> USB and connected it to an old iPad charger rated at 5V/2A.  No help.  It
> wouldn't record anything, no matter how much rebooting and power-cycling.
> So I concluded the HDPVR was hosed and got a new one (more accurately, a
> replacement circuit board for it).  Powered it with the same wall wart.
> Recorded great for a day.  Just turned it on and I have failed recordings
> and it won't respond when I try to manually play a channel.  Reboot, and it
> works fine, same pattern as before.
>
> I finally got a molex connector and am still going to try what Greg
> suggested, but I really don't think it's a power issue.  Apply makes good
> electronics and that wart has the same specs as the power supply that comes
> with the HDPVR.  The HDPCR isn't overheating.  It's not the HDPVR itself.
> That only leaves the software on the myth box.  Anyone have ideas how to
> troubleshoot that?
>
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>
> have you tried a conf file in /etc/modprobe.d setting this option:
>
>
> options ir-kbd-i2c enable_hdpvr=1
>
>
> No.  does ir-kbd stand for infrared keyboard?  I don't have one of those.
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