Last month I published CABLE 82, a recreation of the 1982 cable community bulletin board channel that runs on a Raspberry Pi and an old CRT. That post covered the software and the shape of the hardware. Then a reader with a Pi 3 B+ hit “localhost refused to connect,” we went back and forth in the comments, and I realized I had never written down the whole build. I will take you from a blank SD card to a glowing tube.

The TV is a Magnavox portable from Facebook Marketplace, a Perfect View from August 1987, the kind with a handle on top, a rod antenna, and a 12V jack so you could watch it in the car.

The Pi is a 3 Model B+, the same board the reader had.

The false start: the original 2012 Pi

My first instinct was to do this on the least capable Pi in the house: the original Model B, board marked “(c)2011.12”, with the 4GB “Debian 6 for Linux” card it came with. Raspberry Pi OS still supports it, which is remarkable for a 2012 computer, and Node.js 20 installs from apt. The server half of CABLE 82 would run fine.

The TV half would not. The original Pi’s chip is ARMv6, and no current browser runs on it. Raspberry Pi dropped Chromium for ARMv6 in 2023; on the current OS it prints “This hardware doesn’t support NEON SIMD extensions” and quits. Firefox is built for ARMv7 and dies the same way. The one engine left is WebKit, with no JavaScript JIT, on a 700MHz core. I looked at that path for a while… and decided the tutorial should be about the channel, not about heroics.

What you need

• Raspberry Pi 3 Model B+ (or any Pi 2 or newer; a Pi 4 is a fine choice too).
• 16GB or larger microSD card. Mine is a SanDisk Ultra PLUS 16GB.
• Micro-USB power supply, 5V at 2.5A. The 3 B+ is the last micro-USB Pi.
• A network connection. Ethernet is simplest for the first boot; the 3 B+ also has Wi-Fi.
• 4:3 CRT with a coax antenna input. Almost every tube TV has one, which is why this is the path that works for everybody. Mine has nothing else: one F connector marked EXT ANT and a switch to pick it over the built-in rod antenna.
• HDMI-to-RF modulator, the little box that turns HDMI into channel 3 or 4 on the antenna input, plus a short coax cable. Mine is an “HDM61” unit; the same design is sold under a dozen brand names.
• Another computer to flash the card and to SSH into the Pi (needs to be on the same network as the Raspberry Pi).

Step 1: Put the OS on the card

Which image, and why

Raspberry Pi OS (64-bit), the desktop edition. It is the image Raspberry Pi’s own kiosk tutorial tells you to use, and there are two practical reasons to follow that advice on a 3 B+:

1. Chromium is the browser that will show the channel, and the 64-bit build is the one that has been solid on Pi 3 boards (the 32-bit build had a will-not-start bug on the Pi 3 as recently as this summer).
2. Node.js 22 from NodeSource is 64-bit only now; their installer refuses 32-bit outright.

The image is a 1.3GB download and takes about 6GB on the card, so 16GB leaves plenty of room.

Flash it with Raspberry Pi Imager

Raspberry Pi Imager is the right tool here, and not balenaEtcher or dd, because it can bake the hostname, your user, and SSH into the card before the Pi ever boots. That is what makes the headless setup work. Install it from raspberrypi.com/software, put the card in your computer, and walk the steps down the left side.

Device: Raspberry Pi 3. This filters the OS list to images that run on the 3 family (A+, B, B+, and Compute Module 3).

OS: Raspberry Pi OS (64-bit). The top entry, marked Recommended. Not the 32-bit one and not the “Legacy” one; Legacy is the older Bookworm release.

Storage: the SD card. Imager hides your system drives by default, so the only thing in the list should be the card. Mine shows up as a 14.8GB “Generic MassStorageClass USB Device” because it is in a USB reader; a 16GB card really is about 14.8GB once you count the way computers count.

Customisation. This is the part Etcher cannot do, and the reason the Pi will come up on the network with no screen attached.

• Hostname: cable82. That gives you cable82.local later, so you never have to go looking for an IP address.
• Localisation: your time zone and keyboard layout. The clock on the channel runs off the Pi’s time zone, so get this right.
• User: a username and password you will remember. You will type them into SSH in a few minutes.
• Wi-Fi: your network name and password. I set it even though the Pi would be on Ethernet for the build; it means the finished TV can live anywhere in the house.
• Remote access: enable SSH, password authentication. I also left Raspberry Pi Connect on, which gives you a browser-based remote shell to the Pi from anywhere, handy for a TV that lives in a corner.

Then Write. Imager asks once more whether it can erase the card, downloads the image, writes it, and verifies it. The write was the slow part: this card takes data at about 10MB/s, so the 6GB image plus verification took about fifteen minutes.

First boot

Imager ejects the card when it is done. Card into the Pi, Ethernet in, power in. The green light flickers for a while: the first boot resizes the filesystem to fill the card, generates SSH keys, and runs a one-time setup pass. Mine answered on the network in well under two minutes. Then from your computer:

ssh yourname@cable82.local

(If .local does not resolve on your machine, your router’s device list will show a cable82 with an IP address; SSH to that instead.)

Three things to check while you are in:

head -2 /etc/os-release
free -m
df -h /

Mine came back Debian 13 (trixie), 905MB of memory with about 570MB available, and a 15GB root partition with 8.4GB free after the 6GB image. The Pi had been up eight minutes by the time I got around to asking. Then bring the image current:

sudo apt update && sudo apt full-upgrade -y

(sudo asks for your password; recent Raspberry Pi OS releases turned off passwordless sudo by default.)

The Pi is on the network, current, and answering SSH.

Step 2: Node.js

CABLE 82 is a Node.js app with no dependencies, so Node is the only thing to install. It needs Node 18 or newer, and a fresh Raspberry Pi OS has none at all:

$ node -v
bash: node: command not found

That line, by the way, is almost certainly what was behind the reader’s “localhost refused to connect.” No Node, no server, nothing listening, and the browser reports it as a refused connection.

Two ways to get Node on a 64-bit Pi. The quick one is the distro’s own package, sudo apt install nodejs, which gives you Node 20. I went with NodeSource for Node 22, the current long-term-support line, and it is two commands:

curl -fsSL https://deb.nodesource.com/setup_22.x | sudo -E bash -
sudo apt-get install -y nodejs
node -v

Mine printed v22.23.2. (NodeSource only builds for 64-bit now; if you flashed the 32-bit image, use the apt route.)

Step 3: CABLE 82 on the air

With Node in place, the channel itself is next. Clone it and start it:

cd ~
git clone https://github.com/nothans/cable-82
cd cable-82
node server.js

It prints every address it answers on:

CABLE 82 broadcasting
  http://localhost:1982   (a browser on this machine)
  http://192.168.68.93:1982   (a browser on another device on your network)
Control room: http://localhost:1982/config

Read that second line carefully, because it is the other half of the reader’s problem. localhost means “this machine.” Typed into a browser on your laptop, it asks the laptop for a channel it does not have. The 192.168.x.x address is the Pi as seen from everywhere else on your network, and that is the one to open from the laptop. I did, and the channel was there: blue screen, the clock, the crawl.

The first run also writes a config.json next to the server, which is where everything you change in the control room ends up. Open http://192.168.68.93:1982/config from the laptop and make it yours: channel name, your messages, your feeds, your town for the weather. Save, and the channel picks it up within about twenty seconds.

Make it a service

Ctrl-C the server and hand it to systemd so it runs at boot and restarts if it ever dies. Create /etc/systemd/system/cable82.service:

[Unit]
Description=CABLE 82
After=network-online.target

[Service]
ExecStart=/usr/bin/node /home/cable82/cable-82/server.js
Restart=always
User=cable82

[Install]
WantedBy=multi-user.target

Both cable82s are my username; use yours (whoami tells you, and which node confirms the path on the ExecStart line). Then:

sudo systemctl enable --now cable82
systemctl status cable82

active (running) with the broadcasting lines in its log, and sudo journalctl -u cable82 -f is where to look if anything is ever wrong. The server sits at about 46MB of memory.

Step 4: Chromium in kiosk mode

The desktop image already logs in automatically and starts a Wayland session (the compositor is called labwc; the old LXDE desktop from earlier Pi OS releases is gone). Chromium 151 is preinstalled. All we have to do is tell the session to open Chromium full screen on the channel at login.

The file for that is ~/.config/labwc/autostart. Create it with these lines:

# CABLE 82 kiosk: wait for the channel server, then put Chromium on it full screen.
until curl -s -o /dev/null http://localhost:1982; do sleep 1; done
/usr/bin/lwrespawn /usr/bin/chromium http://localhost:1982   --kiosk --noerrdialogs --disable-infobars --no-first-run --no-memcheck   --disable-lcd-text --autoplay-policy=no-user-gesture-required   --enable-features=OverlayScrollbar --password-store=basic --start-maximized &

A few of those deserve a word:

• The until curl loop waits for the server to answer before launching the browser. Without it, Chromium can win the race at boot and show “localhost refused to connect” on the TV, and nothing ever tells it to try again.
• lwrespawn is a Raspberry Pi helper that restarts a program if it dies, so a crash brings the channel back instead of leaving a blank desktop.
• --no-memcheck stops Chromium from popping a low-memory warning over the channel on a 1GB board.
• --autoplay-policy=no-user-gesture-required lets the background music start without anyone clicking.
• --disable-lcd-text turns off subpixel font smoothing so the chunky text stays crisp white instead of going pink at the edges.
• --password-store=basic keeps the desktop keyring from asking for a password at login.

Then turn off screen blanking, or the TV goes dark after ten minutes:

sudo raspi-config nonint do_blanking 1

(Or interactively: sudo raspi-config > Display Options > Screen Blanking > No.)

If you are here from the original post: the chromium-browser --kiosk line and the /etc/xdg/lxsession/LXDE-pi/autostart file in that post were for the previous Pi OS release. On Trixie the binary is chromium and the file is the labwc one above.

Reboot. About a minute later Chromium was running full screen on the channel. I could tell from the laptop before the TV was even connected:

$ pgrep -a chromium | head -1
1407 /usr/lib/chromium/chromium ... --kiosk ... http://localhost:1982

Check the power supply while you are here

This section wasn’t what I expected. My first run was off a phone charger…

$ vcgencmd get_throttled
throttled=0xd0005
$ vcgencmd measure_clock arm
frequency(48)=600064000

Any bit set in get_throttled is a complaint; 0x5 means under-voltage and throttling right now, and the clock line shows a 1.4GHz Pi running at 600MHz. It worked, in the sense that the channel was on, but at less than half speed. With a proper 5V 2.5A supply the under-voltage bits cleared and the clock came back up. If you only run one check from this whole post on an existing Pi, run that one.

(On a 3 B+ you may still see 0x80008 with a 1.2GHz clock: that is the board’s own soft temperature limit at 60C, normal with Chromium running, and nothing to do with power.)

Step 5: The CRT

Note on photos of the TV… it turns out to be surprisingly hard to get a good photo of the screen. My phone didn’t capture it well. Also, the screen had a giant smudge backed into the acrylic covering the TV. I had to use Novus 2 polish to clean up the smudge and scratches. I assure you that it looks better in person…

The Magnavox has exactly one way in: an F connector marked EXT ANT.

So the path is HDMI out of the Pi into a small HDMI-to-RF modulator, coax from the modulator into the TV, and the TV tuned to channel 3. The box is the size of a cassette tape, takes USB power, has a CH3/CH4 switch, and its spec sheet says everything you need to know: NTSC out, 480p to 1080p in, sound on the 4.5MHz carrier (that means mono, the way 1982 did it).

Plug it all in and the channel was on the tube.

Send it a 4:3 picture

The box scales whatever it gets to fill the 4:3 tube. CABLE 82 draws a 4:3 stage, so if the Pi sends a widescreen mode, the stage gets squashed. The Pi has to output 640×480. On current Raspberry Pi OS the old hdmi_group and hdmi_mode lines in config.txt are dead; the kernel takes its orders from cmdline.txt, and the desktop then picks its own mode on top of that. So it takes two small files.

Append to the end of the single long line in /boot/firmware/cmdline.txt:

video=HDMI-A-1:640x480@60D vc4.force_hotplug=1

The D forces the output on even when nothing answers, and force_hotplug keeps it on if the modulator never raises the hotplug pin (mine does not). Then pin the desktop to the same mode in ~/.config/kanshi/config:

profile crt {
  output HDMI-A-1 mode 640x480 position 0,0
}

Without that second file, the desktop on my Pi happily chose 1024×768 on top of the kernel’s 640×480.

Give it an EDID, so there is sound

The first picture had no audio, and the reason is a good one: cheap modulators send no EDID, the little data block a screen uses to introduce itself. No EDID means the Pi does not know the “screen” can hear, and it refuses to send HDMI audio at all. So I made it one. The CABLE 82 repo now ships a 256-byte EDID that describes a 640×480 4:3 screen with stereo audio (edid/cable82-640x480-audio.bin, with the script that generates it). Hand it to the kernel:

sudo mkdir -p /lib/firmware/edid
sudo cp ~/cable-82/edid/cable82-640x480-audio.bin /lib/firmware/edid/cable82.bin

and add one more parameter to that same cmdline.txt line:

drm.edid_firmware=HDMI-A-1:edid/cable82.bin

Reboot. wpctl status now lists an HDMI sink next to the headphone jack; make it the default and give it some level (WirePlumber remembers):

wpctl status                       # find the "(HDMI)" sink's number
wpctl set-default <number>
wpctl set-volume <number> 0.8

The channel’s music came out of the Magnavox’s speaker on the next page turn.

Hide the cursor

A mouse pointer sat in the middle of the picture with no mouse attached. The HDMI CEC input counts as a pointer device, so the desktop draws one. The fix is a labwc keybinding that hides it, pressed automatically after boot. Copy /etc/xdg/labwc/rc.xml to ~/.config/labwc/rc.xml, add inside <keyboard>:

<keybind key="A-W-h"><action name="HideCursor"/></keybind>

then sudo apt install wtype and add to the end of ~/.config/labwc/autostart:

(sleep 10; wtype -M alt -M logo -P h -p h -m logo -m alt) &

The detour: composite

Before the HDMI modulator arrived I tried the other way in: the Pi’s 3.5mm AV jack, a 4-pole cable to yellow/red/white, and an old composite-to-RF adapter. On a Pi 3 that means sudo raspi-config nonint do_composite 0, which turns HDMI off; on every Pi before the 5 it is one or the other. The Wayland desktop also does not trust the composite connector until it is told the mode, so video=Composite-1:720x480@60ie,tv_mode=NTSC goes on the cmdline.txt line too.

Step 6: Make it readable

With everything working, the verdict on a 9-inch 1987 tube over RF: the big clock and the crawl read fine, the small text was marginal, and the red and blue pages were worse than the cyan one. That is NTSC. It smears saturated color, it clips pure white (broadcast engineers kept white at 90% for a reason), and the hard drop shadow under every character turned into ringing.

So I added a CRT set of settings in the control room for much older TVs…

• CRT mode swaps in a softer palette (less saturated backgrounds, 90% white) and drops the drop shadow.
• Text size enlarges the body text, kicker, crawl, and the small header lines, from 1 to 1.5x. I run 1.25 on this set; the big clock stays as it is.
• Overscan safe margin was already there; raise it if the TV crops the edges.

Turning text size up found one more thing: at 640×480 the weather card no longer fit and its HI/LO line slid under the crawl.

So pages now fit themselves: if the content would overflow, the weather card gives up its sunrise/sunset line first, then shrinks just enough, and a long fact does the same.

All of that is in the repo as of this post.

What changed because of this build

Three things fed straight back into the project:

• The original post now carries a dated update: the kiosk command is chromium in ~/.config/labwc/autostart on current Raspberry Pi OS, and the power supply got the mention it earned.
• The repo README was rewritten from this build, step by step as tested, with a Troubleshooting section keyed to the exact errors from the comment thread.
• CABLE 82 itself gained CRT mode, the text size setting, the fit-to-page behavior, and the shipped EDID, because a real 1987 tube demanded all four.

That is the part I did not expect when a reader said “localhost refused to connect”: the failure report turned into the best test pass the project ever had!

A channel of your own

The Magnavox sits there now, tuned to channel 3, being a channel. The clock, the bake-sale energy, the crawl, the beautiful-music bed coming out of a mono speaker that was built when the music was new. It is a thirty-nine-year-old TV showing a channel that stopped existing before the TV was built, fed by a computer the size of a deck of cards, and the whole thing works because somebody left a comment saying it did not.

So: if you build one and it refuses to connect, say so. That is how this channel gets better, and it is very 1982 of you. Thanks.