Atari Lynx II LCD & Backlight Mod

The Lynx II's cold-cathode backlight tube in its reflector, with the diffuser and LCD removed. The three-pin plug goes to the main board

The Atari Lynx II lights its LCD with a cold-cathode fluorescent tube, like the original Lynx and the Sega Game Gear. It can take an LED backlight that keeps the original panel, or a complete replacement LCD kit from McWill or BennVenn. The kits are compared on Atari Lynx LCD & Backlight Mod. The notes below cover fitting them in the Lynx II.

The original backlight circuit

Atari's Lynx II schematic drives the tube from the high-voltage transformer T1, switched by the 2SD965 transistors Q13 and Q14 and fed from +5 V through the 68 µH inductor L17. The tube's two ends go through 100 °C-marked fuses F1 and F2 to the three-pin connector JP5. The backlight button on the membrane toggles a 74HC74 (U11), whose BACKLIGHT OFF output stops the inverter. The same transformer supplies the +20 V LCD rail at TP12 through D5, D6 and C23.

The tube and its reflector sit behind the LCD in the screen assembly, which is held to the front case by four screws.

LED backlight

The Atari Lynx Vault describes a Sega Game Gear LED backlight kit, sold by Hand Held Legend, that fits the Lynx and keeps the original screen; it reports double the battery life and a cooler console with the LED fitted.

BennVenn IPS kit

K-Retro's description of the BennVenn IPS kit for the Lynx II:

• It connects with a ribbon cable and normally needs no soldering. A mounting bracket that reuses the original screen screws, and an optional bezel mask to hide the metal edge of the panel, come with the kit.
• Scanline switching and VGA output need two soldered wires: one to the SCANLINE pad on the kit's board and one to the fourth pin under the cartridge connector, which is the backlight button line.
• A Lynx II with the early C104129-001 board needs an extra soldered wire and a cut trace on the ribbon cable.
• A zener on the kit's board protects it if the Lynx's own MOSFET or zener fails, and gives the Lynx some limited protection. It is sold as an option. K-Retro still advises replacing the Lynx's MOSFET and zener (see Atari Lynx II Troubleshooting Guide).

The Atari Lynx Vault adds that the BennVenn brightness controls work the opposite way to the original screen, and that the kit's install time on a Lynx II is about fifteen minutes.

McWill kit

Igor Kromin fitted a revision 2.0 McWill kit to a Lynx II in 2017 and recorded the steps that the single-sheet instructions left unclear:

1. Remove the parts of the backlight high-voltage circuit listed in the instructions. The transformer T1 was the hardest part to remove, and he could not save it.
2. Solder GND and VCC wires to the board. Reconnect the button ribbon so the Lynx can be switched on, and measure the supply. His measured 4.84 V; the instructions set an upper limit of 5.45 V, above which the Lynx's power circuit needs repair first.
3. Wire the kit's backlight-button lead to pin 2 of U11. U11 is a small surface-mount chip, so he soldered a spare capacitor lead into the via on the trace from pin 2 and attached the wire to that.
4. Without the VGA connector fitted, link the kit's MENU pad to GND.
5. Connect the kit to either the RES or the TPR pin on the Lynx board. The kit's "jumper" is the pair of pads marked LNX on its chip side: closed for TPR, open for RES. The instructions tie the choice to whether the board is a C104129-001. His was not, so he used RES and left the pads open.
6. Connect the remaining nine signal wires between the two boards. Cut the ribbon generously; his was only just long enough.

At every switch-on the McWill panel shows coloured noise for a moment before the picture appears. Orange-Phantom's measurements show a McWill-modified Lynx II drawing current with the console switched off, enough to flatten a set of rechargeable cells in about four days.

Related pages

• Atari Lynx II
• Atari Lynx II General Maintenance
• Atari Lynx II Troubleshooting Guide
• Atari Lynx LCD & Backlight Mod