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Repair guides and support for your Sanyo TV.

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Sanyo FW42D25T HDTV says "weak or no signal detected"

This TV used to display channels just fine. Now all of sudden it won’t display ANY. So I re-did the auto-scan and re-detected 46 channels. None display. All produce the "weak or no signal detected". I hit reset twice which auto-scanned and again found 46 channels. Still: "weak or no signal detected" for all. I took the cable that normally runs from the antenna to my HD-HomeRun device on my PC. I know this cable works because my PC displays live TV just fine ON THIS TV. So the Sanyo TV has video, it can display a TV signal that is received via a third party device and sent along to it via HDMI. But when I switch the INPUT from HDMI to TV it cannot or will not interpret and display a TV signal that it receives via its own ANTENNA jack. It can DETECT the channels, just not display them.

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My tv won't scan any channels and when pick channels it's not many could it be my antenna

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Do need a new antenna

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hi @billbaldwin ,

Sounds like there may be a problem with the tuner circuit or signal amplifier circuit in the TV, unless there are multiple antenna outlets via a splitter arrangement in the premises and not just the one antenna output connection. Then it may be in the antenna leads somewhere, if the PC was hooked up to another outlet.

Unfortunately the user manual doesn’t show an option to check the actual signal level for each channel which can usually be done in most digital TV as this would help to to know if the problem is in the TV or maybe perhaps is in the antenna or antenna lead/connections. Usually most show signal strength and also signal quality which is just as important in the reception of the signal.

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Hey, thanks for the reply! Your diagnosis sounds probable. I know it's not a splitter problem. I did have it set up with a splitter--one cable going to the PC, one to the TV. And the PC half got great signal and showed nice clear HD on all channels. So the first thing I did was switch the cables to see if that made a difference. Nope. Then I sent the whole signal to the TV via the cable that had been going into the splitter. Not even a glimmer. Zero display on the TV.

It's not a big deal. I almost always watch TV via the PC and that works fine. It's just sometimes I like to watch TV while the PC reboots, and now I can't do that. :-)

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@billbaldwin

Is there an option in the PC to check the TV signal level?

It's strange that the TV detects a weak signal when connected via the splitter but not when directly connected to the antenna.

Just verifying that the TV is set to receive from an antenna and not a cable connection?

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@jayeff No, no, the TV detects a weak signal regardless. It finds 46 channels and can display none of them.

Yep, all those channels are found via the antenna connection, not cable. I hit the MENU button and select the CHANNEL menu. The Air/Cable selector is set to Air. When I Autoscan for channels, it detects all the same channels that I can detect and display with no trouble from the same antenna connected to my HD HomeRun device and from there to my PC and from there via HDMI to this same TV. So the TV knows the channels are there. But when I select a channel to display, it tells me the signal is weak or non-existent. I never get a weak picture, just no picture at all. It's peculiar.

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@billbaldwin

Pity you haven't got an indoor antenna that you can connect to and check ;-).

It may be something as simple as a faulty co-ax connector in the TV.

The problem then is if it is, that that it is mounted in the sealed tuner which is mounted on the mainboard which makes it difficult to check but they can be repaired (if you're very careful)

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@Ronald Spikes

Has it worked OK before?

Is the antenna pointed in the same direction as all the other TV antennas in your neighbourhood i.e. has it maybe swung around so that it is not getting the strongest signal possible from the TV broadcast transmitters? Antennas need to be pointed directly towards the relevant TV broadcast transmitter to ensure that they get the strongest possible signal. If off line the signal is weaker and problems can then occur.

Can you try connecting a different antenna (indoor?) or if possible, connecting the TV to an existing known working antenna? This is just to prove whether the problem is in the TV or the antenna or the antenna cable - faulty connection somewhere, in your premises.

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