A lay person here trying to understand TV signal electronics and how to solve a problem. I have no desire to get rid of a 1993 GE Portable TV. It displays an awesome color picture and has a built-in alarm system with snooze on whatever station I select. I normally wake up to local news and weather. It also has a built-in AM/FM radio. There is no equivalent mini flat screen available with these features. Sometimes older is better. So, my problem is that my cable provider (Spectrum) will no longer support a modem with a coax output I need for this TV. Converter purchased for HDMI to coax does not work. Error message is “not tunable”. Should I somehow resort to using an antenna? Please help!
I’m sorry, I’m not finding any information on what type of antenna or converter to solve this issue. I would recommend you contact a local TV repair to see if they can provide some assistance.
1 Like
Any TV repair shop I contact will not offer any advice related to an old tube type TV.
Ordered and attempted following without Success:
HDMI RF Modulator Coax Converter VHF Demodulator HD Digital Video Input Adapter for Roku Fire Stick VCR DVD Laptop PC PS4 PS5 Xbox Set-top Cable Box to F Type Female Antenna ANT Output Coaxial NTSC TV - Walmart.com.
Under consideration:
https://www.amazon.com/dp/B0856VTG4W/?coliid=I3JN87U0W9YSVB&colid=3J8A4J2LA2VX8&ref_=list_c_wl_lv_ov_lig_dp_it&th=1
Attached here is information on back of GE Portable TV for possible reference. TV is “Cable ready” with one coax input on back and no other kind of connection for a signal. Remote controller for TV has menu that comes up that will accomplish automatic set up of channels.
It appears this is the adaptor you got:
https://www.amazon.com/SDS-Converter-Digital-Adapter-Antenna/dp/B0BJT8HSMK/
That adaptor should work as long as the HDMI signal does NOT have copy protection (HDCP).
There is the catch, as far as I know all modern cable TV tuner boxes have only HDMI with HDCP so that you can’t record the video using the analog loophole created by this adaptor.
If you plugged an older 720P DVD player into the HDMI side, and the convertor is not defective, you should be able to see the DVD video on the analog TV.
3 Likes
? - Not seeking to see a DVD video, but rather all the channels I normally get on cable. Not a problem until the modem upgrade to HDMI output only. Modern day technology should not render old TVs nonfunctional.
@PaulHutch is probably right about this. If you want to verify that it’s not an issue with your cable modem rather than this converter device, have you tried connecting it to a TV with HDMI inputs? If not, there’s a remote chance that it’s your modem rather than the HDMI-to-coax converter. If so, it may need to have some configuration set-up done.
Also, make sure that your TV is tuned to the appropriate channel. Typically, the output signal from devices like older cable boxes and such used either channel 3 or 4, so I would expect the same for this device.
Finally, in case you haven’t already done so, make sure that the converter is sending out the proper signal. According to the documentation I read, it can output multiple formats, which make it compatible with the old analog video signals from various places around the world. Press the “SYS” button until it sends out NTSC-M, which is the North American standard for analog video.
If the problem turns out to be copy protection then the only solution is to cancel the cable TV subscription and switch to broadcast TV from an antenna connected to a digital tuner (ATSC).
With broadcast TV there is no HDCP copy protection so the signal is allowed to be converted to analog for watching on old TVs.
1 Like
New modem works fine hooked up to another TV with an HDMI input. SYS button pushed multiple times on both channels 3 & 4 with no result. Sometimes get an error message that says, “not tunable”.
Looking at info on what I believe is the same product on Amazon, they do have a few instructions and reviews which might help. The main one I noticed is that they recommend a specific sequence for connecting and powering the converter.
Specifically, they specify that you should connect the RF cable to your TV and the converter box first, then connect power to the converter, and after that, connect the HDMI cable between your source (cable box in your case) and the converter box. According to the documentation, the LED indicator should turn from RED to GREEN when it detects the HDMI signal.
Other things to consider is that you may have a bad cable (either the RF cable or the HDMI cable), the box could be defective, or it can’t decode a copy protected signal, as Paul suggests. Obviously, trying different cables could help to eliminate the cable issues.
Regarding your alternate solution of going with over-the-air broadcast, depending on how close you live to broadcast towers, that may be a good option. Where I live, one needs a very good external antenna to reliably pick up any broadcast signals, but if you live within 20 to 30 miles, then an indoor antenna would probably suffice.
However, if you choose to go with over-the-air broadcast, keep in mind that your old TV will also need a digital TV broadcast decoder between the antenna cable and your TV, as all broadcasts are now digital. Your TV’s tuner will not be able to decode it without that device.
2 Likes
Ah, the good old days!
This set requires either an analog RF signal or a composite video signal. The RF signal (analog) is no longer broadcast and you will not likely find a ‘box’ to convert the Spectrum signal to RF or composite. A composite signal is what the early home computers and video games used. Today the RF signal carries a ‘digital’ signal on an analog radio wave.
I would have to agree with others here and go for the antenna. You would need a converter box, but I bet you can still find them on eBay. What people used to call ‘rabbit ears’ is not an antenna per se, but a simple magnetic pick-up and may work if you live near a tower broadcasting the digital signal you wish to view. A proper antenna would need to be a combination VHF/UHF and should be high enough and pointed in the direction of the tower. If you’re lucky enough, it may even work in the attic of your house. Don’t fall for the ‘you need a digital antenna’, nonsense, no such thing exists since radio waves are analog; only the information on that signal is digital and the antenna doesn’t care.
These are ‘proper’ antennas: Channel Master
I do not have cable or Internet TV at all, I watch over the air with an antenna and it works if you’re in the right area.
Good luck!
2 Likes
OK, I have been calling what is not a ‘modem’, but rather a 'cable box; upgraded to HDMI only without a coax output for my old TV. Sorry for my terminology confusion. Understand this problem can commonly exist for old gaming screen monitors as well. Finally, after numerous attempts that included a reboot process, I actually succeeded obtaining a signal that showed up on my old TV through the special converter. The next problem turned out to be that the new cable box is issued with a power save feature turned on that after 4 hours of no use turns the cable box off. This does not work for a built- in TV alarm feature since I sleep more than 4 hours. Also, the setting menu to reset this feature to power on always could not be viewed on my old TV. The solution was to verify the needed setting on another current day model TV with a like cable box and trade boxes. Thankful I do not have to go the antenna route to obtain a signal. I think all is well now and I can continue my old school TV wake up routine. Thanks to all here who have tried to help with suggestions. Prior help on another problem restoring a drive-in movie speaker was very helpful and I really do appreciate this forum where communication and advice comes from knowledgeable electricians.
1 Like
Glad you are up and running! You know, you could have saved the trouble of switching cable boxes by just setting your alarm for every three hours or so and keeping the box active. Don’t know why you didn’t just do that. 
The truth is that sometimes I am up every three hours without an alarm!