100% Signal, No Lock

[nocturnalcodehack]

I moved my combination front/backend to a new location in the house I also added a separate frontend PC and configured both for connectivity. Since then, I have the problem with only SOME channels getting 100% signal and no lock after 3000 ms. The system worked fine before it was moved. Here's what I've tried on MythTV v.29, running on Ubuntu 18.08 LTS. Intel i3, 8GB RAM

1. Removed, the cable line to the Hauppague Quad tuner, from the booster -- another post here suggested too much signal can cause 100% signal, no lock. Tuner card is now direct to antenna -- No change, some channels (mostly HD channels) do not Lock..

2. Upgraded Linux 5.3 kernel to 5.4 -- thinking LinuxTV drivers could be the problem - No change.

3. Re-scanned from the backed - No change.

4. Ran w_scan. It showed ok for all frequencies that carry my OTA channels.

I've run out of ideas as the system worked fine before it was moved. Thoughts appreciated.

[wmorrison]

So you ran the antenna direct to the tuner, no amplification at all? None integrated into the antenna either? Antenna still in the same location?

So you're getting 100% signal, I assume just on some channels? Are they close/strong? Are other weaker/farther channels that work showing less than 100% (which is fine?)

When you moved the machine, what changed for the coax? Longer coax, shorter coax? Multiple coax joined together?

[nocturnalcodehack]

Responses:

Yes, unit is on a splitter directly in-front of the booster amp:: IN: Antenna, OUT1: MythTV backend/frontend, OUT2: Winegard HDA-200 Distribution Amplifier feeding an 8x splitter for all other TV's. Signal to MythTV is not amplified, still getting 100% signal on these channels with no lock. Antenna is not moved, still in the attic.

Yes, some channels get a variety of signal levels: 87 that still lock, 78 that still lock. They are usually Sub-channels (-2, -3, -4) located on the same tower, 15 miles away, as the -1 channel, likely with less transmitter power.

Yes, Completely different single, direct RG-6 cable, 20 ft longer than upstairs. I'm wondering:

a. Did I 'fry' my tuner card with too much signal?

b. Should I format the hard drive and re-install everything? (upgrade to v30 at the same time)

[wmorrison]

I would test running the antenna straight to only your MythTV box, eliminating all splitters. If possible with a single unbroken run of coax.

If that works, the problem may be reflections within the "maze" of splitters/coax. Especially if the layout changed when you moved the machine.

[nocturnalcodehack]

I may have found the problem--that is, it is working now... I put the tuner card back on the main splitter and did a re-scan. But before I did the scan, I DELETED all existing channels (and behind the scenes, I assume their associated transport records). After the scan, all channels worked again. I had previously ran an update/insert scan. I wonder if that 'messed up' the virtual channel to ATSC channel or pid mapping. I will delete all channels before re-scan every time in the future.

[kmdewaal]

It is great that this fixes your problem but also a bit surprising. Rescanning and updating should be fixed in the forthcoming version 31. Note that deleting all channels does not delete the transport stream multiplexes and that is, with pre-v31 mythtv, sometimes needed when the allocation of channels over multiplexes (also known as repack) has changed.
Deleting the multiplexes can be done on a one-by-one basis in the Transport Editor of mythtv-setup.