1800T says signal too weak, but TV says it's fine

BarFly

BarFly

New Member
Strange problem here. HDR-1800T connected to a Panasonic Viera TV. TV aerial socket is connected to the Humax, so it's receiving its signal via the Humax box. On some Freeview HD channels the Humax is saying that the signal is too weak, and the picture and sound drop out frequently, however the TV shows these same channels without problem. Channels affected are all on the COM7 multiplex (Freeview 106-110, 113). Measuring the signal strength on the Humax gives about 65%, while the TV says it's 98%. Tried an (automatic) re-tune of the Humax, but no change.

Does this imply a fault in the Humax, or is there something else I should try?
 
Hypothesis: The HDMI interface between the Humax and the TV is creating interference which knocks out the aerial signal to the Humax's tuner, but while you are using the TV tuner, the HDMI interface is inactive and not producing interference. To prove or disprove: temporarily disconnect the HDMI cable and use the SCART/Phono to connect the TV. If the hypothesis is proven, you need one or several of the following:
  • a better TV aerial cable;
  • a screened HDMI cable;
  • better separation between HDMI and aerial cables;
  • change the Humax's output to 1080i instead of 1080p (there will be no significant loss in quality).
BarFly said:
Measuring the signal strength on the Humax gives about 65%, while the TV says it's 98%.
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Meaningless. Without detailed specifications, you have no idea whether "100%" represents the same signal level on both units.
 
Black Hole said:
Hypothesis: The HDMI interface between the Humax and the TV is creating interference which knocks out the aerial signal to the Humax's tuner, but while you are using the TV tuner, the HDMI interface is inactive and not producing interference. To prove or disprove: temporarily disconnect the HDMI cable and use the SCART/Phono to connect the TV.
Click to expand...

Interesting suggestion, but alas, connecting by SCART made no difference (apart from a poorer picture quality on those channels which work).

Might a manual re-tune help? I haven't looked at that yet.
 
Thanks, Martin. It says Channel 32, but I can't figure out from digitaluk which transmitter that implies. I'm supposed to get signal from Craigkelly. Blackhill is twice as far away. There is a closer transmitter which retransmits the signal from BlackHill, but it's low power and down in a valley.
 
Try THIS web page on for size and scroll down a long way. Com7 is on CH 33 from there. Com7 is on CH32 from Blackhill. So the Hummy might just 'lock on' to Blackhill CH 32 before it gets to Craigkelly on CH33.
Sounds like you need a touch of the old manual tune.
 
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Trev said:
Try THIS web page on for size and scroll down a long way. Com7 is on CH 33 from there. Com7 is on CH32 from Blackhill. So the Hummy might just 'lock on' to Blackhill CH 32 before it gets to Craigkelly on CH33.
Sounds like you need a touch of the old manual tune.
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Most likely. I haven't used the latest HDR-1800T software but I can conform that all the previous HDR-1800T/2000T versions locked on to the lowest mux number apart from muxes BBC A and D3&4 for which the region selection would override.
 
Luke said:
I haven't used the latest HDR-1800T software but I can conform that all the previous HDR-1800T/2000T versions locked on to the lowest mux number ...
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As far as I can tell, that still applies. So Trev is probably right and you are getting COM7 from the wrong transmitter on your Humax. Follow Trev, Luke & Martin's suggestions and do a manual retune. I would even go as far as to say never trust automatic tuning. Do your research and find out the one transmitter and frequencies you need and manually tune them all.
 
OK, chaps, thanks for your help. Before I got this sorted out, something more serious went wrong. The Humax started to green-screen immediately after startup. I would get about 10 seconds of TV picture before it died completely. Turning off and on again made no difference, so I pulled the power and left it overnight. In the morning, it started up OK and showed TV, but could not access its hard drive. (Media button did nothing, Menu>System>Data Storage was greyed out. I could connect by ftp, but only the empty root directory was visible.) As a last resort I set it to do a software update. It sat for a long time displaying "Searching for software", then went back to the TV picture, without any acknowledgement of success or failure. After another re-start however, everything worked! The TV channels which didn't work before now do, and I can see the HD again.

Is it possible that I have been suffering from corrupted system software all along?
 
Probably not. The total system reset may well have retuned and picked up the right mux this time.
 
BarFly said:
In the morning, it started up OK and showed TV, but could not access its hard drive. (Media button did nothing, Menu>System>Data Storage was greyed out.
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Could you post the output from the Webif >Diagnostics>Hard Drive
As a last resort I set it to do a software update. It sat for a long time displaying "Searching for software", then went back to the TV picture, without any acknowledgement of success or failure. After another re-start however, everything worked!
Click to expand...
I assume you set it to do an OTA software update? This will do nothing as no software updates are currently being transmitted.
Is it possible that I have been suffering from corrupted system software all along?
Click to expand...
I doubt it.
 
Not sure quite what you mean by "Webif >Diagnostics>Hard Drive"? If I choose Settings>System>Data Storage>Internal Hard Drive, I get the following:

Available Size 226.8 GB
Used Size 55.7 GB
Reserved Size 57.5 GB
Total Size 320.0 GB

If I choose Settings>System>Data Storage>HDD test, I get (after a while):

No defects are found.

Yes, it was an OTA software update, and that might explain why it gave up without any further messages.
 
BarFly said:
Not sure quite what you mean by "Webif >Diagnostics>Hard Drive"?
Click to expand...
Martin has forgotten he's not talking about an HDR-FOX with custom firmware. It would be a mistake to assume a poster had CF installed, even if we were talking about HDR-FOX not HDR-1800T. In your case, the only remedies for a malfunctioning HDD would be reformatting internally, removal and analysis externally, or replacement.

In as much as you seem to be up and running again, I suggest you take no further action at present.
 
I had the same issue but with weak signal on BBC 4 on my Panasonic TV. At the suggestion of a friend in the biz I got hold of a One For All aerial distributor (other brands are available) and gave a feed to each device (1800T, TV and old Sony HDD machine), so each has it's own interrupted aerial feed rather than looped thru other machines. Solved the problem of alleged weak signal.
 
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Black Hole said:
Hypothesis: The HDMI interface between the Humax and the TV is creating interference which knocks out the aerial signal to the Humax's tuner, but while you are using the TV tuner, the HDMI interface is inactive and not producing interference. To prove or disprove: temporarily disconnect the HDMI cable and use the SCART/Phono to connect the TV. If the hypothesis is proven, you need one or several of the following:
  • a better TV aerial cable;
  • a screened HDMI cable;
  • better separation between HDMI and aerial cables;
  • change the Humax's output to 1080i instead of 1080p (there will be no significant loss in quality).

Meaningless. Without detailed specifications, you have no idea whether "100%" represents the same signal level on both units.
Click to expand...

Thank you for this! On the recent transmitter changes, I lost COM7 as it moved to Ch55 in London. There's nothing wrong with my aerial (as TV receives CH55 fine through same aerial connected via HDR-2000T) and the Hummy itself gets COM8 fine on Ch56.

I had retuned multiple times, manual retuned in Ch55, flashed firmware, factory reset, nothing worked. After reading this, I changed from 1080p to 1080i and now I have COM7 back! Physics is weird.
 
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