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RS uncorrected errors

I had a problem with my Tivo re-setting and freezing etc.. The engineer called and replaced it with another Tivo box which he set up but that had bad problems where diagnostics showed very low signal strength - often as low as 3% or even 0% but very variable) and picture break up etc...

Eventually we received a brand new Tivo box which we've had about 3 weeks.

This seemed OK at first but still occasionally had problems. For instance sometimes looking at diagnostics the signal strength of Tuner 1 and you had no measurement at all (just a hyphen instead of a % measurement i.e. I do NOT mean 0%) although the others were both at 100%. I think it was Tuner 1 each time but I wouldn't swear to it. If you recorded 3 programmes simultaneously then 2 would be ok but one would be a blank screen (presumably the Tuner with no recorded signal strength). Switching off the box, removing power, then re-starting (power-cycling) cured this each time (only happened maybe 3 times in the first week and hasn't been seen in the next two weeks.

However we get occasional picture break up and this time I looked closer at the diagnostics which reveals variable results on 'RS Uncorrected' (RS-Corrected errors are usually 0). A typical situation would be where Tuner 0 would have 0 RS-U (uncorrected) errors while Tuner 1 might have thousands of RS-U clocking up and Tuner 2 might have a maybe a few hundred uncorrected errors. Power-cycling and this may alter the distribution where maybe all three tuners have RS-U errors or sometimes T-0 and T-2 have zero RS-U.

Now having said all this the box seems to behave mostly OK, even though there are a lot of RS-U errors...although very occasionally you get break up on a recorded picture. The characteristic of this the last time was a regular break up, every 17 seconds.

Now I do recall this regular break-up behaviour on our original Tivo box on certain channels every now and again but the box overall gave good service for many years (about 8 years iirc) and only very rarely caused this problem.

So my question is, is there anything I can do to isolate this occasional fault without sending another box back? I don't want to do that unless the fault becomes too bad to put up with. At the moment it's not too bad but if I can eradicate the occasional faults then that'd be great.

For example is it worth playing with an attenuator in line with the Tivo box (Router seems ok)....or maybe before the splitter? The splitter itself has 2 outputs, one marked 4dB the other 3.6dB. Swapping these has little effect as you'd imagine with only 0.4dB difference.

How can I check that the signal level isn't swamping the tuners or that the matching of the co-ax is OK (reflections causing problems?

Seems to me a modest 3dB attenuator on all 3 ports of the splitter might achieve a better match with less reflections and also prevent swamping the tuners but I don't know if this is pointless or not. The AGC seems to be running at around 77 to 80% but I'm not sure if this means that the gain is nearly running out of range to give the tuners 100% signal strength.


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