Katzhagen - Archive - March 2008

Sound for the V200 - or: "444 days - an exercise in patience""



Christmas 2006

After this train had finished its first "silent runnings", a sound module for the V200 loco appeared to be a must. In January 2007 my model train dealer signaled that Dietz was planning on such a module - also usable in my analogue environment.

Years ago I had purchased a demo CD from this manufacturer which contained sample sounds of various locos. The sounds were not really convincing and so I never bought a Dietz sound module before. But at that time (early in 2007) there was no alternative and the V200 module was said to be available soon. I ordered ... and had to check off 444 days on the calendar between purchasing the loco and getting hold of the sound module.

So the term "soon" turned out to be relative. The sound module itself was available in the end of spring 2007 - if memory serves me correctlty - when I was told that I would need an additional power storage board for playing the standing sounds. This one was said to be available "soon"...


Time is relativ...


... if you are waiting for something
Weeks passed by, months as well. For a change in autumn there were rumours that there was some problem with the supply of a particular electronic part for the power storage board. Then, early in December, breaking news: The power storage board was announced to be delivered "soon". I looked forward to putting my hands on the loco over Christmas. You are given three guesses now what was not delivered. This was the point when I nearly abandoned hope for a good end of the story.
But early in February 2008 the long desired but meanwhile unexpected change occured: A package from the model train dealer arrived and it indeed contained both the sound and power storage boards.

The first hurdle was cleared

Attention now had to be payed to the V200's missing starting delay circuit, which in analogue operations would allow standing sounds as well as an illumination when the loco stands still. As luck had it, such a circuit board from the V51 was offered on ebay... - and of course it took the seller nearly three weeks to mail the parcel. Given the case history, I didn't wonder about that.

Time to descend to the workshop

On February, 29th, it finally happened - I had all the parts needed for mounting the sound. Had I ? No, I hadn't !! I still had to get hold of a reed-switch which is required to have the sound trigger magnets actuate the sounds of both the whistle and the horn. A call was placed in Nuremberg and the friendly folks promised to send a reed-switch the next day.

Per aspera ad astra...

Despite the missing reed-switch I started to work on the project the next morning - and was presented with a bad joke: The speaker delivered along with the sound module was 7mm too big for the place it was meant to be resident. Well, a nuisance, but a minor challenge at most.


What an exercise in patience... well, off we go now...

A preliminary test of the module prior to its mounting revealed some less desirable facts. A useful sound was impossible to produce on the module's first startup - the Lehmann/Massoth-modules behave differently. The module began to play the startup sounds but aborted the procedure after a couple of seconds and started over again ... and again and again. As the slips (the term manual were a wording too friendly) accompaning the product did not mention such a behaviour, I had to investigate a bit on my own. Result: Decrease the volume and use a power source more effective than the LGB 1A-transformer. Then the sound does work - at least for the moment. The reason why the module refuses operations when the volume control is turned to its maximum remains the manufacturer's secret.


Removed housing


First tests - and where do I mount which parts ?

Based upon the criticism regarding Lehmann's sound modules posted on several forums, I had expected a significantly different or even a better sound quality - an obviously baseless expectation.



The operating noises sound a bit indistinct under test conditions and there is no engine shutdown sound (as opposed to LGB's V51). Sound off, done. This was no improvement compared to demo CD mentioned above. Exceedingly positive to mention are the whistle's and the horn's sound.

Next surprise: The starting sound wasn't played any longer. Supplying power to the beast resulted in the sound of an already running engine immediately. The attempt to "read the programmer's mind" resulted in the finding that there had to be a "significant" difference between the track and the motor voltage before the loco starts moving... And right - disconnecting the motor from the module and supplying voltage to the module then resulted in a reappearing starting sound. The additional board from the V51 was expected to solve this problem... Hints regarding this behaviour in the accompaning slips of paper ? No such luck.

Control of motors and lights

Considerations to use only the board from the V51 for these purposes were deprecated due to the fact that controlling the V200's lights was not easy to implement with this board. Therefore this board was integrated to just control the motors:

Both of the motors were disconnected from the original V200 DCC interface board and connected to the corresponding output terminals on the V51 board. The motor outputs of the V200 board were connected to the V51 board's track input terminals. As a result the starting delay now worked and the red tail lights came up while the loco stood still. Unfortunately, the head lights remained dark. The LEDs used for the head lights apparently are blue or UV-LEDs with a photoluminescent material which need a voltage of approx. 4V to light up... A further reduction of the voltage supplied to the motors by inserting suitable diodes into the leads helped to have also the head lights come up while the loco stands still.

A brief analysis of the operating mode switch revealed that switch position "3" is just used to provide power (taken from the in left rail in direction of travel) to a single pin on the V200's DCC interface board. The sound module was connected to this pin so that it can be switched on and off using the loco's operating mode switch.




      Lord of the cords

Mounting the parts

Three 2mm-drillings were applied to the second metal weight to mount the V51 board. This way the metal weight was a heat sink for the transistors, too. Afterwards the above described wiring was implemented. A home for the sound module and its power storage was found in the loco's housing - mounted upside down. This required a seperate mounting of the power storage board as its connector didn't appear to be suitable for a permanent "upside down operation". A flat cable with a suitable plug was used to reestablish the connection between both of the boards.
One of the sound module's track connection cables was soldered to the pin of one of the motor blocks corresponding to the right rail, the other one to pin "3" of the operating mode switch. The module's motor connection cables were soldered to the motor pins of the same motor block. Some minor modifications were applied to the metal weights as well as to the housing's screw joints in order to fit the speaker into its intended place. Finally, a cover frame was made for the speaker to prevent undesired emergence of sound - which had a really positive influence on the sound's quality !



Mounted and wired components - just the reed-switch is missing. Inside the housing fltr: Sound module, engine compartment illumination, operating mode switch. On the chassis: V200 DCC interface board, speaker terminals, V51 motor control

Last act

After the reed-switch (used to trigger the whistle and the horn) had been delivered, its housing had to be modified in order to fit beneath the loco's drives. The mounting arms and the cover were removed.

Reed-switch board and partially modified housing parts

The drive unit had to be opened for installing the cable

The drive unit was opened to look for possibilities regarding the cables installation. Since there is plenty of space, the flat cable can be led through it, after applying a drilling in both the drive's bottom and top covers.

The cable escaping the drive unit

Mounted board with cover

A bit of the board's housing height had to be abraded so that it fitted under the drive unit. Mounting was accomplished with a cyanoacrylate adhesive.

Existing structures were used for installing the reed-switch cable

SIL multipoint connector converted into a plug-and-socket connector

The place where the reed-switch cable emerges the drive unit was chosen near the unit's original terminals so that the chassi's existing structure could be used to lead the cable into the loco's interior. A plug-and-socket connector was inserted into this cable to keep the unit dismountable.

Summary

The Dietz sound module's operation in analogue mode does not really compare to the modules from Lehmann/Massoth, which is due to the different power supply designs. The root cause for this is that the Dietz module works best at at least 10V - but it also works fine below this value if the terms of operations and parameters are adjusted to the design of the module's construction and software. The power storage module for playing the standing sounds works flawlessly if one does not expect to be presented with a starting sound after pausing operations for some time, say days or weeks. In my ears, the sound itself is neither better nor poorer than that from Lehmann or Massoth respectively. Instead of a manual there only is a collection of slips for non-techies.

Now the loco hums marvelously and magically invokes a smile on its owner's face when the din starts.
The installation's minor challenges already are forgotten.


February 2008 | Archive "Current Affairs" | April 2008