by Dave Chaney

General:

Regardless of the guides, manuals, tips, suggestions, experts or whatever,
troubleshooting can occasionally degenerate into a vast chasm of darkness and confusion.

Invariably the information necessary for solving the problem is lost to antiquity, the dog or just general confusion.

The first and foremost rule of trouble shooting is WHAT happened ? or What did you DO (what changed) just before the problem struck?

Once the guilty have been identified and punished then one can move on to solving the problem.

It would be impossible to cover all the areas that have, can or may cause problems. We will try to give you a general guide to identifying and resolving problems with DCC.

You should have a plan and a wiring diagram of the layout.

You will also need a log for the locomotives which should include the decoder installed, both addresses, any special programming and other information about the locomotive.

You will also need a similar log for any devices that require programming or special configurations such as the DS-54, BDL-16,etc.

As John Palmer indicated in 'The Big Book of DCC', the manufactures spare no expense to write manuals so it would help to at least know where you put them.

You can never have enough information to use in trouble shooting:

What happened?

When did it happen?

Where did it happen?

What was the last change made to the layout?

Who found the problem?

Who worked on it last?

What were you doing?

Who told you to do that?

Why didn’t you ask?

Your mother?

Do you have any idea how much this is going to cost?

And so on!

The system manual and the Big Book of DCC have glossaries that will help with understanding the terms and equipment of DCC.

Tools:

There are basic items, tools, which you will need for trouble shooting.

First: A good VOM ( volt, ohm, milliamp meter ), also called a multimeter, is indispensable in measuring voltage and resistance. Most any of the inexpensive meters will do.

Second: A United States 25 cent piece, or similar size coin, sometimes called a quarter. Hence, the quarter test!

Third: The manuals mentioned above.

Fourth: Patience.

Fifth: Small hand tools, the same ones that you used to get yourself in this predicament in the first place.

Sixth: The LT-1 which is included with the starter sets.

The Layout

The most common problems on the layout that will impact your DCC system are shorts. If you find that you cannot get Track Status to come up, the beeps from the booster were lost in the general confusion, then disconnect one of the Rails from the booster and the problem should be apparent.

The quarter test is the BEST diagnostic tool that you have! With the DCC system up, with Track Status ON, using a quarter, short the layout every six feet or so and the booster should shut down and beep.

If the booster does not beep and shut down, then you have a wiring problem that must be addressed. Your system manual covers this in the Track Wiring Considerations section.

Gaps, as in rail gaps, are NOT permanent! They will close up,due to temperature and humidity changes, and cause all kinds of misery.

Locomotives and cars sitting on turnouts and gaps have caused more gray hair than kids.

Polarity mismatches between power districts are usually cleared by swapping Rail A with Rail B on one of the boosters.

Track, turnouts, crossovers, wheel sets, etc., must be checked with a Standard gage. The NMRA has a gage for each scale.

A quick way to identify track problems is to run an analog locomotive around the layout. Any problem that the locomotive has is most likely caused by the track

Command Station / Booster

Input voltage:

The input voltage to the Command Station / Booster can be either AC or DC. The booster has a full wave filtered bridge inside to handle the AC or DC with ripples.

Both the system manual and the Caution label on the bottom of the booster indicate the proper voltage/current requirements.

Measure the input voltage at the Power In terminals on the booster. To measure the system current draw place an ampmeter of the proper rating in series with one of the leads from the power transformer to the booster.

Basic input voltage is 12 to 24 volts. The minimum current input is 5 amps.

Low input voltage ( and low current ) will result in unpredictable locomotive performance and should be one of the first areas checked if using a power pack from a DC layout.

Output voltage:

Track voltage (output from the booster to the rail ) is measured as follows:

With the system on and with Track Status on, select the analog address,00, and set to speed 00.

With a multimeter set to the 20 volt DC scale measure from Rail A to ground ( the toggle switches on the booster are grounded ), then from Rail B to ground.

With the Scale switch set to N scale the readings should be about 6.2 volts DC, for each rail. Total track voltage is the sum of the two, or about 12.4 volts DC.

At the HO setting the rail voltage should be 7.5 volts DC each.

At the G/O setting it should be 10 volts DC each.

The difference between the rail voltages should not exceed 0.2 volts. Satisfactory operation will still occur if the difference is as much as 0.5 volts DC.

Track voltage maybe adjusted using the yellow trim pot inside the booster located between the LocoNet B port and the Scale switch.

This maybe used to balance the track voltage between booster power districts.

The DCS-100, and the DCS-50, Programming Track, PROG A and PROG B, is NOT powered.

You cannot run locomotives on the program track. After programming transfer the locomotive back to the layout to run.

In general, trouble shooting with the Command Station / Booster begins with the indicator LEDs and the beeps.

Get familiar with what the various indicator LEDs represent and what the series of diagnostic beeps means. The system manual has a listing of each and their meaning.

A soft ticking from a DB-100 is an indication that the DB-100 is no longer talking to a command station.

Shorts- rail:

The booster will react to a rail short by beeping and shutting down, Track Status indicator will go OFF.

When the short clears the booster will beep and Track Status will come ON.

IF the booster can NOT “see” the short it will not shut down but will pump current into

the problem until something smokes.

The Quarter test is essential in testing track wiring such that no matter where the short occurs the booster will “see” it and shut down.

Shorts-other:

A short on LocoNet will bring down the network and the system will cease to run trains.

The LT-1 maybe used to test for LocoNet problems both in the cables and in the LocoNet devices.

A short internal to the booster may cause the Track Status LED indicator to go solid Red or Green and may also trip the power supply circuit breaker or fuse.

Command Station / Booster OPTION SWITCHS

The Option Switches, OPSW, allow the booster to be configured to suit individual layout parameters.

BUT the OPSWs can also be set to disable the booster, which can lead to much hair pulling.

The OPSWs usually get set incorrectly when the system is new and the resident button pusher is at work.

The system manual contains a list of the OPSWs, their function and the default settings.

For example, if OPSW#01 is closed, the booster and LocoNet go dead. So always check the OPSWs if there is a problem.

When the registers fill up the throttle will display FF when trying to SELect an address.

To clear all the registers in the DB-150 and the DCS-100 you must close OPSW#39.

( Closing OPSW#39 clears all the registers. To clear selected registers please see your system manual.)

Close OPSW#39 as follows:

Set the Booster Mode Switch to OP, the center position.

On the throttle , push MODE one time. The display will show either SW 001=c or 001=t.

Using the right knob dial up, clockwise, to switch 39. Close OPSW#39 by pushing the Right Reverse Arrow button, marked c.

Immediately return the Mode switch on the booster to RUN.

The registers will clear and you can begin SELecting locomotives again.

Please see the Zephyr manual for the proper option switch and how to close.

LOCONET

LocoNet is the communication network for the DCC layout.

Trouble on LocoNet means trouble on the entire system.

LocoNet because of the wiring configuration is very robust and will tolerate a lot of problems. Even so, it is very important that trouble be identified and resolved.

The LT-1 is furnished with each system to allow testing of LocoNet cables and the LocoNet devices, such as the UP-3.

When testing with the LT-1 remember that a throttle has to be plugged into LocoNet for all four of the LEDs on the LT-1 to light.

A good LocoNet device or cable will show all four of the LEDs on the LT-1 at the same brightness.

A short LocoNet cable, two to three inches, with one of the plugs reversed is handy to have for testing devices with the LT-1.

LocoNet wires:

1. White 5 – 7 VDC

2. Black Ground All voltages DC.

3. Red 10 – 15 VDC Measure between the pin or wire and

4. Green 10 – 15 VDC case ground.

5. Yellow Ground Wires 3. and 4. (RED and Green) are

6. Blue 5 – 7 VDC. connected in each throttle.

The Universal Panels, UP-3, UR-90, and the UR-91 are the primary fascia mount LocoNet devices.

The LocoNet ports on the front are intended for throttles while the ports on the back are for linking LocoNet to other devices and are DIFFERENT from the front ports! So use the front ports for throttles only.

A not so common problem can occur when one of the pins in the LocoNet port is crossed over another. Look inside each port to be sure that the pins are lined up in their respective slots.

Throttles

The throttle is the primary input device for the DCC system. The throttle plugs into LocoNet which permits it to communicate with all the devices active on LocoNet.

The throttles have multiple configuration options that can be set by the user. See the section in the system manual that talks about Configuration Options.

The DT-100, 300 and 400 throttles, when plugged into an active LocoNet, have a “wake up” period that can last as long as 16, or more, seconds.

If the display shows IDLE:

The throttle has a good battery and/or is not in an active LocoNet.

Or

LocoNet is Off Line, the booster may have been switched to SLEEP.

Does the throttle beep and LCD light up when a battery is first installed?

No: Is the battery dead?

The CPU may be out of its socket.

One of the wires from the PCB to the case may be broken.

Illegible characters or blank display: The CPU may be out of its socket.

Skipping or erratic numbers while turning a knob: Bad encoder.

Does the throttle beep and display light up when plugged into LocoNet without a battery?

No: Bad connector or port.

Internal problems.

LocoNet trouble.

Radio:

The DT-100R and DT-300R are the radio throttles, the transmitters.

The UR-91 is the combination radio and Infrared receiver.

The UR-90 is the Infrared receiver.

A typical radio problem is that the locomotive does not respond when the radio throttle is tetherless. This can be either a throttle problem or a receiver problem. Plug the throttle into the UR-91 and try again. Be sure that the throttle is configured for radio operation.

Status Editing

Status codes are assigned by the system to each locomotive address that is active or being Selected.

IT IS ALMOST NEVER NECESSARY TO CHANGE THE STATUS OF A LOCOMOTIVE ADDRESS!

Please spend at least a moment to look at the Section in your system manual on Status Edit. It will save you a lot of heartache.