During the process of evaluating the Bowser Tsunami-equipped PCC car, we were introduced to the MRC TECH 6 Sound Controller 2.0. According to the literature provided with the unit, "...the TECH 6 operates as a normal DC power pack. It is a sound controller that can operate all of the sounds in your locomotive if it contains a DCC sound decoder..." It has two modes of operation:

1. STANDARD (STD) DC for non sound equipped locomotives and,

2. DUAL for operating sound equipped locomotives.

The STANDARD (STD) DC Mode was operated first in the forward direction, using a Bachmann Peter Witt streetcar as a test vehicle and a Leader LBO-515B Dual Trace Oscilloscope.

The above represents the speed knob at the 50% mark. The bottom trace is zero volts and the upper trace is about 14 volts positive. One cycle of the square wave has a duration of approximately 45 micro seconds (0.000045 second). As the speed knob is varied the length of the positive pulse increases and the zero pulse decreases proportionately. This can be better illustrated in the next video clip.*

You should notice that at no time does the level of voltage increase, only the length of the positive pulse. The vehicle maintained a consistent slow speed with a pulse duration of 9 microseconds. The brightness of the lights is also a function of the pulse length.

The test vehicle was then changed to a decoder equipped Bachmann 70-ton diesel. The address of the decoder contained in the unit had not been changed from the factory setting of 03. The diesel ran smoothly with as short a pulse as 3 microseconds. The lamp brightness seemed to remain constant throughout the speed range.

In the DUAL Mode, the Peter Witt, which was not equipped with a decoder, would not run at all. The lights were on at full brightness but the motor just buzzed loudly. The 70-ton diesel functioned normally as it does on DCC. The instructions accompanying the unit provide the following guidance when operating a decoder-equipped loco in the DUAL mode.

"Whenever it does not respond, press the SHIFT key and then press 9,9. [Press 9 once and then 9 again]. This will reset your loco to factory default within 5 seconds. Note, if you plan to use a locomotive with a DCC system, you will need to reprogram the loco using the DCC system after it was used it the TECH 6."

We then tested this procedure using an Athearn Genesis HO scale PRR EMD FP-7a diesel locomotive, which had been readdressed to the cab number of 9833 on May 2010. The unit would not move until the above procedure was implemented. Once the procedure was finished, we had total control over all the sounds and the motor. We later checked the unit using our MacBook, DecoderPro 2.10 and a Digitrax PR3 and we found that the TECH 6 merely changed CV 29 from our preprogrammed value of 38 to 6 leaving CVs 17 and 18 intact. We readdressed the FP-7a back to 9833 and all was well.

Below is a trace of the DUAL mode wave form:

Our current equipment was incapable of analyzing this trace, however, it is similar to the trace obtained from our Digitrax Zephyr DCS50 DCC controller.

Surprisingly, for a unit which seems to have been designed for those who want nothing to do with DCC, the unit allows the operator to change CV values. Specifically, Button 2 can be used to set Start Voltage; Button 3 to set Acceleration Momentum; Button 4 for Deceleration Momentum and Button 5 for Top Voltage. These buttons correspond to CV's 2, 3, 4 and 5, respectively. The instructions indicate that other CVs can also be changed. We did not test that feature.

3. CONCLUSION:

1. In the STANDARD (STD) DC Mode, the TECH 6 produces a variable duration square wave pulse. this allows operation of non-decoder-equipped locomotives. In the DUAL Mode, the TECH 6 functions as a simple DCC system, capable of only operating decoder-equipped locomotives addressed as 03. Since it can not operate any other address, including 00, analog (i.e. non-decoder-equipped) locomotives cannot be operated. We did not test the advertised capability of the TECH 6 to change CV's.

2. This unit has been designed for modelers who have decided to NEVER embrace Digital Command Control. It will allow that type of modeler to enjoy all of the sound features of a decoder equipped loco. That modeler can take his loco to any model railroad club, allow them to change the address to run on their railroad and then the same modeler can change the address back to 03 in a simple procedure to allow operation on his/her home layout.

3. However, if there is even a slightest chance that the modeler would embrace DCC in the future, we would recommend that he or she invest in the Digitrax Zephyr Xtra. which has recently been upgraded with increased versatility and capability. Our club currently has four Digitrax Zephyrs, one Digitrax Zephyr Xtra, two Digitrax Super Chiefs and an NEC ProCab. All of these are used for testing and for operation at public appearances.