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Old 12-27-2013, 03:02 PM   #1
snorkelman
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Series 3 audio dropouts

Hi all,

I'm a new customer of TWC using dual cable cards on my Series 3 HD.

I've been troubled by audio dropouts from day one. I've read a number of threads that blame this on the Series 3's inability to handle a hot signal. Many of my channels read 100/36 db, and they definitely show huge numbers of uncorrected RS errors when this is the case.

Using the wisdom of the masses, I tried to fix this problem by dropping in some attenuation. This really did help quite a bit. My audio dropouts have nearly disappeared, but in order to make that problem go away, I sometimes drive the signal down low enough so that I lose channels completely, or get frequent pixelation errors.

I don't want to fight this problem forever, so I opened a case with Tivo support, suggesting that I would be happy to buy a new box without this problem if they were willing to transfer my lifetime service.

Of course, they were not willing to do so, and blamed the problem on TWC.

So I'm not sure what to do about all this. But it raises a number of questions.

1) Tivo support guy says "Whereas the signal does seem good (100 is a bit too high),". Is 100 really too high? Can a cable signal be too high, and if so, how does one actually verify this?

2) Tivo support guy says "those RS values should be as close to 0 as possible. With that type of feedback, it looks like there may be too much noise on the line". Yes, I know those values should be close to 0. Is this a symptom of the Tivo Series 3 HD problem with hot signals? How can I tell if there is actually noise on the line? Can TWC test this? Can I test it somehow?

3) Tivo support guy says "or quite possibly an issue with the CableCARD". I see basically the identical behavior on both Cable Cards. It doesn't seem likely that there is a problem with both cards. Any way to test this?

I don't mind sitting in the middle of a finger-pointing war between TWC and Tivo, if there is some way to drive it to conclusion. But I am afraid right now I don't have that possibility. If I get TWC to make a service call, I think they are just going to come out and say everything is good, and that my problems are all related to Tivo. If I do have a service call, I need to know what to do to get useful data out of it.

Has Tivo ever actually admitted that this problem exists? If not, is it a real problem, or just an urban legend?

One final note: Changing the settings for dolby output/PCM output has no effect on the problem.

- Mark
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Old 12-27-2013, 05:33 PM   #2
unitron
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Thanks to TiVo, the phrase Series 3 HD is ambiguous.

Do you have a TCD648250 or a TCD652160?
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Old 12-27-2013, 05:43 PM   #3
snorkelman
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Quote:
Originally Posted by unitron View Post
Thanks to TiVo, the phrase Series 3 HD is ambiguous.

Do you have a TCD648250 or a TCD652160?
Ah, this I did not know.

Based on the device ID: 648-0001-8028-AE2C Series3 HD 32hr

I'm assuming I have a TCD648250. Is that a fair guess? System Information doesn't seem to offer any more than "Series 3", so I'm guessing that the back panel must be the only place there is an actual model number.

- Mark
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Old 12-27-2013, 10:50 PM   #4
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The number following Device ID: is the TiVo Service Number for that particular piece of hardware.

Any other TiVo that looks exactly like it will also be a TCD648250 (or TCD648250B--I'm not sure if they ever released a non-"B" version or not), but all the others will each have their own unique TSN.

However, the first three numbers (at least) of all of them will be the same, 648.

If it were a TCD52160, then the TSN would start with 652.

There's a sticker on the back where the power cord plugs in, and both the model number and the TSN are on that sticker.

The TSN is how the TiVo servers keep track of your machine, and its account status), and if you have a lifetime subscription, it's tied to that TSN.

As for the signal strength, you can get attenuators that attach between the cable and the cable input and see if that helps, or for that matter you can get inline co-ax booster amps if the signal isn't strong enough.

However, there's something called "capacitor plague" (you can look it up on Wikipedia), and apparently all of the Series 2 platform models and Series 3 platform models of TiVos are potential victims.

(So are all sorts of other consumer electronics from the late '90s on, although it's gotten better in the past couple or 3 years).

But the chances of an S2 or S3 TiVo having a power supply that's not operating properly (although perhaps almost properly) is so high that you really need to eliminate the possibility as the first step of almost all troubleshooting on S2s and S3s.

A flaky power supply can cause all sorts of weird symptoms.

After you read the Wikipedia article, come back here and use the search function for the Series 3 forum and search for "capacitor" and that should bring up several threads where you can learn more.

The good news is the capacitors that might be bad can be replaced for about $10 in parts if you can do simple soldering.
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Old 12-28-2013, 09:50 AM   #5
snorkelman
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As for the signal strength, you can get attenuators that attach between the cable
As I said in my original post, I've already done that and it does correct the audio dropouts - however, to make the dropouts go away, the signal strength drops low enough to cause channel loss from time to time.

Although I'm sure that bad caps in the PS are always a possibility, it seems a bit of a stretch. All other functions in the box perform perfectly, and the only issue is the tuner on these specific hot channels. A flaky power supply seems like it would manifest itself in a few other ways.

That aside, my original questions are still open...

- Mark
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Old 12-28-2013, 04:34 PM   #6
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...

Although I'm sure that bad caps in the PS are always a possibility, it seems a bit of a stretch....

- Mark
With S2s and S3s, it's more like a high probability.

And until you know you have a PS that's 100%, no voltage sag or undercurrent conditions, even momentary, no ripple on the DC rails, no glitches or spikes getting through, you can't rely on the results of any other troubleshooting.
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