Thayer's Quest Virtual Library - Images and information on the major components

Thayer's Quest - Owners Manual (37 pages)
Thayer's Quest - Schematics (7 pages)
Thayer's Quest - Electrohome NTSC Decoder Specifications and Pinouts (4 pages)
Thayer's Quest - Wells-Gardner NTSC Decoder Pinouts
Thayer's Quest - DIP Switch Settings

Thayer's Quest - ROM Images
Thayer's Quest - ROM Images (alternate)
Thayer's Quest Laserdisc Player Conversion ROM - Made in 2021, this ROM replaces the command set to use the Pioneer LD-V8000/4000/2000 series players.  (new control cable needed)
Thayer's Quest Uncensored ROM - Made in 2000, this ROM removes the restrictions that censor keyboard entries for the player's name.

Compatible Laserdisc Players - Pioneer PR-7820, Pioneer LD-V1000

Pioneer PR-7820 - Service Manual (168 pages)
Pioneer PR-7820 - General Adjustment Procedures (20 pages)
Pioneer PR-7820 - Programming Reference Guide (30 pages)
Pioneer PR-7820 - Users Guide to Programming (13 pages)
Pioneer PR-7820 - DVA System Manual (68 pages)
Pioneer LD-V1000 - Operating Instructions (7 pages)
Pioneer LD-V1000 - Interface Guide (24 pages)
Pioneer LD-V1000 - Service Manual (81 pages)
Pioneer LD-V1000 - Provisional Service Manual (27 pages)
Pioneer LD-V1000 - Cleaning the Optics (3 pages)
Pioneer LD-V1000 - Changing the Laser Tube (3 pages)

Standard LD-V1000 Firmware - The LD-V1000 players that were used in the game Badlands contain firmware that was modified by Konami.
Download the standard Pioneer LD-V1000 EPROM image.

Laserdisc Player Upgrades - The original laserdisc player models are not natively compatible with any other model for a direct substitution.  The following upgrade solutions have been created:

Conversion ROM - Download the Thayer's Quest Laserdisc Player Conversion ROM.  This 2021 modification (at U33 on the main PCB) replaces the command set to use the later model Pioneer LD-V8000/4000/2000 series laserdisc players.  The accompanying documentation details the construction of the required control cable.  Additional documentation for the later series of players can be found in the Pioneer Laserdisc Player Guide.

Conversion Cards - Various products have been developed over the years to allow replacement/upgrade of the laserdisc player.

Dexter is the newest product.  Unlike the other products below which convert to a newer laserdisc player model, no player or disc is needed with Dexter.  The Dexter board is a drop-in replacement which poses as a laserdisc player and plays the video for the game digitally, from a custom file format.  Dexter accepts the original commands from the PCB through the original interface cable.  Dexter has been going in and out of production multiple times, per demand, via pre-order process only.

LaserCon is a laserdisc player conversion card that allows the game to use newer supported Pioneer players.  LaserCon is no longer in production; however, the above conversion ROM, made subsequently by the same developer, achieves the same function.

The LaserAce conversion card allows the game to use a variety of different Pioneer and Sony laserdisc players.  LaserAce is no longer in production.

Kit Information - Thayer's Quest was released as a conversion kit only.  The Dragon's Lair wiring harness, laserdisc interface ribbon cable, and score display interface ribbon cable plug directly into the Thayer's Quest main logic board.

Keyboard Emulator - "TQKey" is a program that allows you to use a standard computer keyboard in place of the original Thayer's Quest keyboard.  Check out the Thayer's Quest Keyboard Emulator page.

Player's Name Censorship - The voice synthesis of Thayer's Quest speaks the player's name after it is typed on the keyboard, but the ROM contains a list of bad words that will be rejected if typed.  The Thayer's Quest Uncensored ROM made in 2000 disables the bad word check and accepts and speaks anything the player types.

Volume Control Wiring Error - Cinematronics made an error in the construction of apparently all Dragon's Lair and Space Ace main wiring harnesses used by Thayer's Quest.  Two pins are reversed in the connector for the volume controls, shorting the right audio channel to ground and creating noise in the system.  For the fix, see the Dragon's Lair / Space Ace Operator Convenience Panel Pinout.

Monitor Swap - If the monitor in your Dragon's Lair, Space Ace, or Thayer's Quest is not up to your liking, you can replace it with a 19" TV.  The Monitor to TV Swap page will show you everything you need to know.

LD-V1000 Boot Switch - A simple inexpensive way to build a switch that issues a play command to the LD-V1000 or LD-V1001.  See the LD-V1000 Boot Switch page.