RF Out from STB - Good Picture, Barely Any Sound

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RakiuraJohn

4 posts

Wannabe Geek

#171685 27-Apr-2015 20:44

I have a Sat Dish (ex-Sky) connected to a Freeview Set Top Box (DTVS 1-B), connected to our lounge TV's Video 1 Input Terminals – which set-up works fine.

Wishing to use my existing Freeview STB to run a second TV (Toshiba LCD 20V300A) in our bedroom (I am aware I will still need to change channels via the STB) , I connected a 14 metre run of 75 Ohm Coax cable from the STB's “RF Out” to the bedroom TV's "Antenna Terminal". I flicked through numerous Channels on the TV but couldn't find any signal so I then ran a Channel Scan on the TV and picked up a perfect Picture but hardly any Sound (just discernible despite TV's volume being turned to maximum). To eliminate the bedroom TV and the long Coax as possible culprits, I connected the STB's “RF Out” to the lounge TV's Antenna Terminal using a different Coax interconnect, again couldn't find anything so ran a Scan, – but exactly the same result (good Picture, barely any sound).

I wonder if I have mistakenly tuned the TVs into a UHF channel, whereas I should simply be getting a signal direct from the existing Channels already tuned into the STB. What do I need to do, either to the TV or to the STB, for the TV to get onto the RF source from the STB?

Your help would be appreciated.
Regards
John

RunningMan

8953 posts

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#1292523 27-Apr-2015 20:51

Does the STB have a volume control that bypasses the line out to the first TV?

Failing that, faulty STB perhaps.

B1GGLZ

1961 posts

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#1292638 27-Apr-2015 22:17

Turn up the volume on the STB using the Vol buttons on the remote. I always set vol on the STB to max and leave it there. Vol is then controlled by my amp remote.

RakiuraJohn

4 posts

Wannabe Geek

#1292656 27-Apr-2015 23:14

Thanks for replies.
STB doesn't seem to have ability to set different volumes for different lines out.
I have volume on both STB and TV set to max just get that "barely discernible" TV audio (which sound is accompanied by background hum because the volume controls are set so high). I'm not running the audio through any amplifier.
I can now confirm that I haven't tuned into a UHF signal as I previously suspected - I must be getting the signal via the STB "RF Out". I know this because the Channels appearing on the TV change as I change the STB Channels. So the problem seems to be purely a sound issue. The TV Settings on the STB state: "RF Mode = Pal-1; RF Channel = 38". The Specs for the bedroom TV state: "Special RF signal: NTSC 4.43 color system 5.5/6.0/6.5 MHz sound system. PAL 60 Hz color system 5.5/6.0/6.5 MHz sound system".
Not sure if these settings have any bearing on the matter?

Apsattv

2388 posts

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#1292691 28-Apr-2015 06:39

Try setting the output to a lower UHF channel, other modulator setting should be PAL B/G if listed

richms

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#1292695 28-Apr-2015 07:18

If the box is outputing PAL-I (not 1) then just set the TV's to Pal-I or 6 MHz when tuning in and you should get sound. There is a different offset for the audio carriers between the systems which is why you have no sound.

Richard rich.ms

trig42

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#1292742 28-Apr-2015 09:38

richms: If the box is outputing PAL-I (not 1) then just set the TV's to Pal-I or 6 MHz when tuning in and you should get sound. There is a different offset for the audio carriers between the systems which is why you have no sound.

Yes, what he said. You do not want it tuning to NTSC, you will get the picture, but no sound (other systems, you may get sound, but a picture missing colours, or looping rounds and round like it's vertical/horizontal sync is out).

Apsattv

2388 posts

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#1293232 29-Apr-2015 02:29

The screenshots in the manual show the modulator setup. Image shows it must be set to PAL B/G. PAL I or PAL 1 or whatever is the wrong setting output for New Zealand.

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richms

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#1293280 29-Apr-2015 08:22

Apsattv: The screenshots in the manual show the modulator setup. Image shows it must be set to PAL B/G. PAL I or PAL 1 or whatever is the wrong setting output for New Zealand.

The right setting is whatever you have the TV set to, so long as you dont choose M since that doesnt have enought bandwidth for pal. Its not like you have to match over the air broadcasts since there are none anymore.

Chosing one of the systems with a bit more video bandwidth should in theory give a slightly better picture, and pal I has 500kHz more bandwidth.

Richard rich.ms

RakiuraJohn

4 posts

Wannabe Geek

#1293401 29-Apr-2015 10:58

Okay, I found the RF Modulator setting under "TV Settings" on the STB and have changed this to "PAL B/G". But I can't find where to check/change these settings on the Toshiba TV (Model 20V300A). Perhaps I have to get into an "advanced" menu, often only available to technicians. Any ideas on how to access such a menu on this model?

richms

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#1293402 29-Apr-2015 11:01

If it was tuned into analog broadcasts when they were a thing then it will already be set to it.

Some tvs do it as a per channel setting, others when you tune each channel in.

Richard rich.ms

JimmyH

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#1293869 29-Apr-2015 20:54

For what it's worth, consider running a different cable. Of all the options you could have chosen, an RF cable will give the worst possible picture quality.

Even composite AV (the yellow-red-white connectors) will give a much better picture. If, as it appears from your post, you are already using these for your main TV then there are relatively inexpensive AV cables with piggyback plugs, and alternately little splitter plugs, that will let you use this output for both TVs.

In order of best picture quality, try for:
- HDMI; then
- Component, then
- AV; and only of none of those can be managed
- RF.

Most STBs have either HDMI and/or component as options. Try these first, at least for the primary TV in the lounge, before attempting AV or RF.

Apsattv

2388 posts

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#1293967 30-Apr-2015 01:56

RakiuraJohn: Okay, I found the RF Modulator setting under "TV Settings" on the STB and have changed this to "PAL B/G". But I can't find where to check/change these settings on the Toshiba TV (Model 20V300A). Perhaps I have to get into an "advanced" menu, often only available to technicians. Any ideas on how to access such a menu on this model?

Just delete the channel then retune. Then store it

RakiuraJohn

4 posts

Wannabe Geek

#1299277 6-May-2015 17:10

FWIW I contacted the STB's NZ technical dept and explained the poor sound issue. They immediately sent me a replacement STB from which the TV OUT (i.e. RF Out) sends perfect picture and sound to the Bedroom TV. I suspect they tweaked the RF Out on my replacement unit to achieve this result. Unfortunately, this resulted in a new hum coming thru the sound when watching the Lounge TV (which was connected to the STB via composite - so presumably the hum was due to RF interference coming thru the unshielded composite cables). I resolved the issue by plugging a $9 Splitter into the STB's RF Out and running both TV's via the STB's RF feed. Now have great picture and sound on both TVs. (I appreciate the comments about RF being the least desirable mode of connection, but in my case the quality of the TVs involved is not high so the result is more than adequate).
Thanks for you help. Cheers