Another Vanderbilt tender and 4-6-0 question

[NevinW]

This weekend I am going to finally complete the mating of the Bachmann medium Vanderbilt Tender with a Tsunami sound system and connect it to the Bachmann Spectrum 4-6-0.  It will become Bullfrog Goldfield #12 when I am done.  I am well aware of the various wiring changes that must be made and figuring where I am going to put the speaker remains elusive but my question involves the front headlight.  On the 4-6-0 it looks like it is an LED but I am not sure.  The rear light in the Vanderbilt tender is a clearly a bulb.  What resistor should I put in to prevent burning out the the LED?  Do Tsunami's have any corrections built into them to correct for light voltage?

Bonus points for anyone who knows what the Bullfrog Goldfield RR is.   - Nevin

[jonathan]

Nevin,

The railroad of Bullfrog Goldfield Railroad Company, hereinafter called the carrier, is a single-track standard-gauge steam railroad lying just inside and about midway of the southwestern State line of Nevada. The main line extends from Beatty 78.95 miles in a general north-northwesterly direction to Goldfield. A branch line, 5.83 miles long, runs westward from Beatty to Rhyolite. The total road mileage owned is thus 84.78 miles. Yard tracks and sidings to an aggregate of 7.70 miles bring the total owned mileage to 92.48 miles. The carrier owns no terminal facilities, as such, but uses station and yard facilities at Beatty belonging to the Las Vegas & Tonopah Railroad Company.

Front headlights on newer models (possibly the 4-6-0) have LEDs.  Typically, the 1K ohm resistor rests inside the locomotive frame, but that is not always the case.  You will have to noodle out a way to test that.  I suggest a 9V battery with a 1K ohm resistor attached to the negative pole.  If the light is too dim, then there is already a resistor inside the locomotive.  There are other ways to check without having to disassemble the loco.

Tsunamis DO NOT have resistors, or the like, built into them, per se. If you go with LEDS, you will have to ensure there are resistors for them.  I think the Tsunamis push a constant 12V for the lights.  Can't remember for sure.

Can't help with the speaker.  I've never opened a medium Vandy.

Regards,

Jonathan

[Tom M.]

For the LED, depending on the brightness level you want to achieve, you will want to use a resistor with a value of 1K ohm to 2.2K ohm.  The lower the value the brighter it will be.  If you are using a standard Tsunami decoder, the lighting output is just a bit above 12 volts.  An LED will go "poof" in a matter of seconds at that voltage.

The resistor is generally placed on the (-) leg of the LED circuit.  For a headlight, that would be the white wire.  While you are going through all this effort, I suggest you convert the tender light over to an LED as well.  The LED will last a thousand times longer than a bulb and will not generate the heat that a bulb will.

Tom

[richg]

My factory purchased HO 4-6-0, DCC ready had 2570 ohms resistance for the LED. Much too high for any decoder. There have been complaints about the dim lighting with this loco. The LED is down inside the smokebox with a plastic light pipe up onto the headlight assembly. I have posted photos here of what the insides look like.
I would put in a 1k resistor.

The photos might be hard to find so here they are.



The white dot inside the smokebox is the light pipe.


You really don't want to open the loco.

Rich

[richg]

As was said, the Tsunami do not have built in resistors. The decoders come with instructions.
To date, there is one that has resistors but it is light board type for diesels.

Rich

[digitalgriffin]

For the LED, depending on the brightness level you want to achieve, you will want to use a resistor with a value of 1K ohm to 2.2K ohm.  The lower the value the brighter it will be.  If you are using a standard Tsunami decoder, the lighting output is just a bit above 12 volts.  An LED will go "poof" in a matter of seconds at that voltage.

The resistor is generally placed on the (-) leg of the LED circuit.  For a headlight, that would be the white wire.  While you are going through all this effort, I suggest you convert the tender light over to an LED as well.  The LED will last a thousand times longer than a bulb and will not generate the heat that a bulb will.

Tom

I'm a bit confused.  If it's a Spectrum, it should be DCC ready.  All you have to do is wire to the numbered pins (after you remove the dummy plug).

If you bypassed the DCC ready board that was preinstalled, then the tsunami directions say use a 680 Ohm resister which is safe for 20ma up to 14.25 VDCC.

[richg]

For the LED, depending on the brightness level you want to achieve, you will want to use a resistor with a value of 1K ohm to 2.2K ohm.  The lower the value the brighter it will be.  If you are using a standard Tsunami decoder, the lighting output is just a bit above 12 volts.  An LED will go "poof" in a matter of seconds at that voltage.

The resistor is generally placed on the (-) leg of the LED circuit.  For a headlight, that would be the white wire.  While you are going through all this effort, I suggest you convert the tender light over to an LED as well.  The LED will last a thousand times longer than a bulb and will not generate the heat that a bulb will.

Tom

I'm a bit confused.  If it's a Spectrum, it should be DCC ready.  All you have to do is wire to the numbered pins (after you remove the dummy plug).

If you bypassed the DCC ready board that was preinstalled, then the tsunami directions say use a 680 Ohm resister which is safe for 20ma up to 14.25 VDCC.
[/quote

There is nothing confusing.
My 4-6-0 was DCC ready. Below is part of what is used for the headlight on mine. I took the PC board out and traced the circuit.



Rich

[richg]

All the OP has to do is measure the actual resistance on whatever PC board that is being used. Modify as necessary or pull the PC board and hard wire, adding a resistor.
I have seen 680 ohms to 1k used.
Some users are buying super bright LED's and have to go higher than 1k but that is not the case here.
Anyone working at what I call the component level should have and know how to use a multimeter to achieve successful results.

Rich

[Tom M.]

When I work on any Bachmann Spectrum loco in my fleet, the first thing I do is remove the Bachmann PC board.  Depending on the loco, I often need the extra room to fit a speaker and enclosure along with either a TSU-750- or TSU-1000 decoder.  I then either hardware the decoder to the appropriate wires from the Bachmann harness, or wire in an 8-pin socket to the harness wiring.   I also replace the factory LEDs with 0602 SMD LEDs mounted in the actual headlight or tender light casting.  This eliminates the dim light condition associated with the light tube used in some locos and/or the overly orange light cast of the headlight in some of their locos.   The space gained by removing the factory PC board is also necessary if I want to add in a supplemental function only decoder to support additional features.  For example, in some locos I've added firebox flicker, a cab light, and classification lights on both the loco and tender.

Removing the board also ensures there are no conflicts between its components and those in the Tsunami.  I have found a 1K ohm resistor is good for the SMD LEDs.  They also work well with the factory LEDs if you want to reuse them.  While lesser values will work, I find the lights to be overly bright, almost like a laser.

Tom

[wjstix]

BTW you can switch the board out pretty easily. There are just two wires connected to the trucks of the tender. If you disconnect them, you can put the board from the first engine's tender into the new tender, replacing the one that's already there. That way you don't have to worry about rewiring the harness or other problems.

[NevinW]

Congrats to Jonathan for finding out what the BG RR was.  If you are not a big Death Valley railroad aficionado you are unlikely to model the BG.

I've got the Tsunami hard wired except for the lights.  The rear light will be a bulb but the front is an LED.  Before I hook up the white wire I should wired in a 1000 ohm resistor, correct?  -  Nevin