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Tandy 1000 RL Troubleshooting Guide

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Tandy 1000 RL with CM-11 monitor (Plasticboob)
A Tandy 1000 RL (photo: Plasticboob, CC BY-SA 3.0).

Fault finding on the Tandy 1000 RL and Tandy 1000 RL-HD draws on owners' repair reports, the Tandy 1000 FAQ and Tandy's 1995 parts list. Tandy's service manual for the RL could not be obtained, so there are no published test points; the checks below are the ones owners have used.[1]

Quick reference

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Symptom Likely cause Section
Wailing tone and burning smell at switch-on Shorted tantalum capacitor Tone or smoke
No power Supply, fuse or a short on the main board Tone or smoke
Stops at the memory count, or will not boot after a setup change EEPROM settings Will not boot
Floppy drive spins but will not read Drive, cable or controller Floppy drives
XT-IDE card BIOS does not load Address clash with the Tandy ROM Hard disks
DeskMate locks up with the mouse Early BIOS Mouse
Serial MIDI or other serial device runs slowly Clash with an added serial card Serial ports

Tone, smoke or no power

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One RL gave a wailing tone that died away, then a smell of burning, at its first switch-on. The cause was a shorted surface-mount tantalum capacitor, C98, which had burnt.[2] keenerb's checks for an RL that will not power up, or has done this:[2]

  1. Unplug the supply from the main board and check the board's +12 V and +5 V pins for shorts to ground.
  2. Measure the supply's outputs with it unplugged from the main board.
  3. Remove the riser board that carries the volume and joystick connectors; it can fail on its own.
  4. Disconnect the floppy drive. A non-Tandy drive on the RL's floppy cable shorts +12 V to ground.
  5. Check fuse F1, near the back of the board.
  6. Check the surface-mount tantalums for shorts.

The full tantalum procedure and the supply data are on Tandy 1000 RL Capacitor Replacement Guide. One owner's supply board cracked when the power switch was pressed too hard.[3]

Will not boot

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  • Stops at the memory count with no beep code: the FAQ says the EEPROM settings are badly corrupted. Disconnect the hard disk, remove the expansion card, remove the EEPROM (U18) and try again; once the machine boots, restore the defaults with the setup program.[4][1]
  • Removing the clock cell does not reset the settings, because they are held in the EEPROM.[5]
  • "Boot disk failure" after disabling the floppy controller in SETUPRL /A: one owner could not boot from any device until he fitted a floppy controller card, after which the machine booted from its hard disk.[5]
  • Asks for drive A: when it should boot from ROM: check the boot device in the setup program.[6]

Floppy drives

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An RL/HD owner whose drives spun but would not read was advised to test the drive in another machine first, then check continuity from the floppy header to the controller, since a failed passive part between them may be the fault and the controller may be fine.[5] The controller is soldered to the board, and an added floppy controller will not take over while the built-in one is enabled.[5] Replacement drives must be Tandy-style drives that take power through the data cable, or the cable must be modified.[7]

Hard disks

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  • The RL/HD's drive is XT IDE and will not work on an AT IDE controller.[5]
  • XT-IDE card BIOS not loading: one owner disabled the built-in hard disk with SETUPRL /A and found the card only worked at D800h; another padded the XT-IDE ROM image with 16 KB of FFh bytes before the BIOS.[5]
  • A 40 MB drive that shows only 20 MB: the FAQ reports this on the RL, although its author's own 40 MB drive worked.[8]

Mouse

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The mouse port needs a special driver such as CuteMouse and may need enabling in the setup program; if it is enabled but dead, disable it, restart, enable it and restart again.[9] The FAQ lists BIOS 02.00.01 as the fix for DeskMate lock-ups caused by a mouse driver bug.[10]

Serial ports

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One RL/HD owner found MIDI playback through the built-in serial port slowed to less than half speed after fitting an I/O card with its own serial ports. Disabling the card's serial ports, or moving them to COM3 or sharing IRQ 4, cured it.[5]

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References

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  1. ↑ 1.0 1.1 Tandy National Parts, bill of materials 250-1450 "Tandy 1000 R L", January 1995, 25-1450.txt, TVDog's Tandy 1000 archive (retrieved 2026-10-21). Lists service manual 25-1450.
  2. ↑ 2.0 2.1 "Tandy 1000 RL tone of death", Vintage Computer Federation forum, February 2021, thread. Posts by falter, daver2, keenerb and compaqportableplus, 14-20 February 2021.
  3. ↑ "Building a Tandy 1000 RL\RLX power supply", Vintage Computer Federation forum, May-August 2012, thread. Post by Compgeke, 15 May 2012.
  4. ↑ Jeff Hayes, "Tandy 1000-series FAQ", version 2.52, 25 October 2005, TVDog's Tandy 1000 archive (retrieved 2026-10-21). Sections II.K.8 and III.F.2.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 "Help with Tandy 1000 RL/HD", Vintage Computer Federation forum, March 2023 to March 2024, thread. Posts by Scottmm78, Deleted member 33842, SteveHere, indyjoenz, dr.zeissler and Cloudschatze.
  6. ↑ "Tandy 1000TL drive A critical error on startup", Vintage Computer Federation forum, November 2020, thread. Post by Trixter, 10 November 2020.
  7. ↑ Hayes, "Tandy 1000-series FAQ" (2005), sections II.C.2 and II.C.5.
  8. ↑ Hayes, "Tandy 1000-series FAQ" (2005), section II.D.1.
  9. ↑ Hayes, "Tandy 1000-series FAQ" (2005), section II.G.5.
  10. ↑ Hayes, "Tandy 1000-series FAQ" (2005), section III.E.2.


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