Decoder Tester

DCCWiki, a community DCC encyclopedia.


A Decoder Tester is a device used to check a decoder for proper operation, prior to installation or for troubleshooting a decoder.

Some are designed to test a sound decoder.

Another use is to program a decoder prior to installation. This can be done on the workbench instead of on a layout. The tester receives DCC signals from the Track or the Track connections on the booster.

Commercial Decoder Testers

ESU 51900 Decoder Test Stand

The ESU Decoder Tester is designed to handle a number of different decoders, both sound and non-sound. It can also test Marklin decoders.

It is meant to work with your command station or a LokProgrammer from ESU. All connection points are labelled.


Five pole motor to correctly load the decoder motor outputs. Many decoders will not work if the motor load is not present.
LED indicators for functions.
Multiple DCC connection points.
Speaker with impedance selection, Off,100, or 160 Ohms, as some decoders use high impedance speakers.



The ESU Decoder Tester has connections for the following decoder interfaces:

  1. 21 Pin MTC Connector
  2. Terminal Block
  3. NEM 651 / NMRA 6 pin DCC
  4. NEM 652 / NMRA 8 pin connector
  5. PluX22 connector (This may be missing from earlier versions)
  6. Next18 (May not be present).

LED Indicators

  1. Headlight
  2. Taillight
  3. Auxiliary 1 to 4

ESU 53900

Scheduled for release in the third quarter of 2016, it will have the NEM 651/652, MTC21, PluX22, Next18 as well a connections for a wired decoder. It will also have a coreless motor, LED monitors, with a speaker and extension port.

The 53901 will be an extension for the LokSound XL v4.0/LokSound L v4.0 decoders.

Digitrax LT1

The LT1 is included with all Digitrax Starter Sets. It consists of a harness with 6 conductor Telco type wire and a male plug, a tester with a female 6 conductor jack and a protection resistor.

The LT1 can be used to test LocoNet cables, as well as mobile decoders.

The LT1 uses RailSync power to check the cables. Do not leave it connected as it can destabilize your LocoNet. Cable verification is done by plugging the cable into the tester, and the other end to a Universal Panel (UP-x) to connect it to the LocoNet for power. The four LEDs should light.

As the LT1 is not a LocoNet device, it should not be left connected during normal operations.

Loy's / Urlich Decoder Tester

The Loy's Toys/Urlich Models Decoder Tester includes clips to quickly connect decoder wires to an NMRA socket to test decoders with an NMRA plug. LEDs are used to indicate speed, direction, and function status. This device is assembled and ready to use - not a kit.