Digital TV Converter Reverse Engineering

Back when broadcast television was first switching over from analog to digital most people needed to get a converter box to watch DTV broadcasts. Remember that abomination that was “HD-Ready”? Those TVs could display an HD signal, but didn’t actually have a digital tuner in them. Nowadays all TVs come with one, so [Craig] found his old converter box was just gathering dust. So he cracked it open and reverse engineered how the DTV hardware works.

The hardware includes a Thompson TV tuner, IR receiver for the remote control, and the supporting components for an LGDT1111 SoC. This is an LG chip and after a little searching [Craig] got his hands on a block diagram that gave him a starting place for his exploration. The maker of the converter box was also nice enough to include a pin header for the UART. It’s populated and even has the pins labeled on the silk screen. We wish all hardware producers could be so kind. He proceeds to pull all the information he can through the terminal. This includes a dump of the bootloader, readout of the IR codes, and much more.

15 thoughts on “Digital TV Converter Reverse Engineering

  1. The ‘converter box’es typically found for using DTV signals with old TVs that only have NTSC tuners (including the free ones subsidized by the government), typically only have SD (composite, sometimes svideo) output.

    If your display is HD ready, or are using a higher than NTSC resolution display, it would behoove you to snag a tuner capable of digital output to fully enjoy the high resolution and high bitrate signals being broadcast.

    Personally i dont see tunerless (HD-Ready) displays to be an ‘abomination’, we’ve all owned monitors capable of such resolution without TV tuners in them for ages. Many professional and commercial displays also lack tuners since those interested could always fall back on a separate or more specialized/featureful tuners.

  2. TV box firmware is simple except with RF and encoding/decoding algos which are usually DSP lib calls from chip vendor libs.. some you also cant dump..

    TV boxes are actually cool, I learned a lot abount satcom encryption during the 90s by reversing broadcom and siemens firmware in sat boxes..

  3. Doesn’t say anywhere what converter box that board came out of. Cool rundown of what he went through, though. It’s above my pay grade, but it was educational nonetheless…

    What I really would have liked to see back when I was using a converter box was a hardware method to decode the over the air digital audio into a digital (SPDIF, et al) format output. Not much point to that now, but so it goes.

    Cool read.

  4. The RCA DTA-800 CECB (Coupon Eligible Converter Box) has bare spots on its PCB for an S-Video jack and the few other components for that output.

    It has been figured out what components fill those empty spots.

    This model has a separate power supply board inside. The tuner board runs on 12 volts, which makes it crazy easy to adapt for vehicle use.

  5. @ Galane not only for car use but you can build a sort of ups for it by running from a battery and then using a power supply to charge the battery.

    no need to step up the power and then back down during a power outage witch can be wasteful even with modern ups that uses switching power supply instead of bulky transformer

  6. i found a labeled usb pin set inside a 20 dollar dvd player, and it turned out I could play movies off of a flash drive. After some searching I realised the same company sold a version that did that (for about 200 bucks more), along with an sd card port and a network connection. Sure enough, I found pins for all 3 in there.

  7. what we need is someone to re-enable the 508 and ?510(NO PVRCHARGE) ? until they make the swithch…. or if i could use those old recievers for coax.. prob need one of those dtv encoders and bypass the decoder … ie
    have they made the switch to mpeg 4 yet….. or what is a prog to view the changes done to an upgrade. …file, apply a patch.. tada..

    there is no hardware change they arent supporting updating the hardware because there is no pvr fee associated with it… as such you can get them for 20-40…. i have 3 and would hate to lay them to waste and just use them for hdds… but really hard to remarry the hdd and the box. I just wanted to change the box id# to an updated model and see what happens…. .. or my sonicview 360 dual dvr.. or atmega128 uses… can i prog them as smart cards? live debug??? I’m paying for dish and cant watch breaking bad

    1. If you can figure out where the RGB signals are at then it isn’t that complicated to wire in an analog converter. Lots of companies make single chip solutions for something like DVI to NTSC/PAL.

      It might even be possible to rewire your inputs for DVI, VGA, HDMI, or Component as outputs. Then you could use a plug and play HD digital to SD analog converter.

      If you can’t rewire the included ports you can always use a Dremel to make new holes to mount your own.

      Unless there is something extra special about the tuner, like tuning channels which are normally outside range, or something special about the software it sounds like a lot of work compared to the price of a DTV tuner these days. Even an adapter with DVR capabilities can be under $30.

  8. Thanks for this great article. It gives me hope for the following …

    I see that digital TV converter boxes with ATSC tuner and HDMI output are selling for around $30. And then set-top media center boxes with online streaming capabilities are selling separately for $50 to $100. I don’t see the reason for this dichotomy. I mean I thought that there will be at least A FEW media center boxes with ATSC tuner built-in. But rarely have I seen them. The only thing these $30 digital tuner boxes lack is networking (and the software). But fortunately they do have a USB port.

    So … theoretically at least, it should be possible to add both WiFi and a bit of extra storage (to carry extra software) using one of the USB dongles that contain both WiFi and some storage (Search for Xiaomi Mi Wifi USB dongle with 8gb storage). At that point, the hardware is ready. All you need now is proper software.

    I know it’s not easy to replace or extend the existing firmware on these boxes to add drivers for USB WiFi and the media center (Kodi?) features. I see custom firmware for almost every router out there. This seems to be the next frontier.

    Does anybody have thoughts/ideas/pointers on this?

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