[mythtv-users] Hauppauge NovaT-500 I2C read errors

Alex Butcher mythlist at assursys.co.uk
Fri Feb 25 09:09:20 UTC 2011

On Fri, 25 Feb 2011, Gary Dawes wrote:

> About the middle to the end of January I started getting the "classic" i2C
> read errors on the card.
> I did have an hardware problem, which resulted in a swap of the graphics
> card for a Nvidia Geforce 210. There were no other hardware issues, and the
> OS was not reinstalled or reconfigured in any way.
> I have been though the Mythtv and LinuxTV wikis and various mailing lists
> and followed the standard steps for fixing this issue.
> 1. ensured that the LNA is on, USB autosuspend and RC poling are off - my
> /etc/modprobe.s/options.conf is below
> options dvb_usb_dib0700 force_lna_activation=1
> options usbcore autosuspend=-1
> options dvb-usb disable_rc_polling=1

Good, good. I'm pretty sure that the USB autosuspend is important for
Nova-T-500 stability, that the LNA is usually important (dependent on signal
strength) and the RC polling is an old bug, but doesn't hurt if you're not
using the 500's RC. :-)

> 2. I have tried various combinations of having setting long tuning delays on
> each card together or individually, and having no delays on either or both
> tuners.

Yeah, I think that's bogus. I've put mine back to defaults.

> 3. I have tried the various combinations of active EIT, on each card
> individually, together, and off ( I use the XMLTV radio times grabber so do
> not rely on EIT for data)

As far as I can see, Mythbackend should stop EIT scanning shortly before a
recording is scheduled, so this /shouldn't/ make any difference. Doesn't
hurt, though.

> 4 . I have flattened the cards, video sources, and channels in the db, and
> recreated from a full scan.

Shouldn't hurt, providing the scan process works properly.

> 5. I have verified that the signal strength and quality is good. The main TV
> is an hitachi 42" with an extremely picky tuner, and that is working great -
> I have also ran the Mythbox with the antenna feed straight into the Nova-T
> card, by passing any signal amps etc.


> 6. I have tried with the number of simultaneous recordings set to 1 and 2 on
> each and both tuners.

Shouldn't matter.

> When the tuners work as they should the picture and signal are rock solid
> and stable.
> Does anyone have any suggestions on what to try next? Sod the WAF, this is
> starting to make me lose faith with Myth.....

1) The Nova-T-500 apparently has a hardware bug which means it only works
properly after a cold boot. So shutdown, power off for a bit, then power on
again and boot. Try to remember this in 6 months time...

2) Since filling in the NULL/auto settings in my database, my MythTV box has
behaved perfectly, and a dev on #mythtv-users gave a guarded confirmation
that that probably wasn't coincidence.

> I have seen suggestions about replacing the NULL entries in the database
> with manually entered ones, but have not managed to identify what settings
> need changing and what to.

Go to <http://www.ukfree.tv/transmitters.php> and find your transmitter.

Look at the dtv_multiplex table. The rules I used were:

guard_interval should be 1/32, bandwidth should be 8.

If a multiplex is QAM64, set lp_code_rate to 1/2, modulation and
constellation to qam_64, hp_code_rate to 2/3.

If a multiplex is QAM16, set lp_code_rate to 3/4, modulation and
constellation to qam_16, hp_code_rate to 3/4.

If a multiplex is using 8k, set transmission_mode to 8. If it's 2k, it
should be 2.

These could well be wrong, but they seem to be good enough for me, my Nova-T
and Nova-T-500 and the UK Mendip transmitter. Corrections welcome.

> I then came across a post from Michael Dean, who stated that manually
> inserting into the DB is a bad thing, and the recommendation in that post
> was to delete all and start again.

It's not ideal, but it hasn't done my MythTV system any harm; quite the
reverse in fact! Probably best to stop the frontend(s) and backend first,

> Could it be that the card is getting to the end of a useful life, and simply
> needs replacing?

I'd be surprised. I don't think it even has any electrolytic capacitors.

> Gaz


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