Talking T Gauge

tmanni · Joined: 17 Nov 2008 Posts: 9 Location: Germany

Hello guys,

one of my t-gauge end cars LED doesn't work anymore.

Does anybody know what type of LED are build in and where can I get a

new one or equivalent type?

Thanks for helping

tmanni

David K Smith · Posted: Thu Nov 20, 2008 4:56 pm Post subject:

Interesting. In normal operation, the middle cars are the powered ones. The powered cars have no headlights.

If you are referring to one of the end cars, which are non-powered but lit, I'd recommend popping off the shell and checking the connections to the lighting unit.
_________________
—David

http://www.t-gauge.net/
http://1-450.blogspot.com/

tmanni · Joined: 17 Nov 2008 Posts: 9 Location: Germany

Thanks for quick reply, David.

Of course the end cars!

I have checked the contacts. It doesnt help. Think the LED is burn out.

tmanni

David K Smith · Posted: Thu Nov 20, 2008 9:54 pm Post subject:

First, are both LEDs not working? I'd be really surprised if the failure was due to burnout if both the yellow and the red LEDs were dead, unless the unit was subjected to a major spike in voltage. So, if they're both dead and you can definitely rule out a power spike, then you'll need to look for another cause.

The LEDs are surface-mount type (SMD), probably 0603s. Performing the replacement is certainly feasible, but a big enough PITA to probably not be worth it, unless you are skilled at--and enjoy--making micro-soldering connections.

Removing the LED module from the car first requires removing the two contact strips, tipping the module away from its plastic nest, and wriggling it up and out.

The module is very small (3 x 4.5 mm) with the two LEDs mounted side-by-side on one side of the double-sided PC board, and a resistor mounted on the other. The SMD LED solder connections are all painted with black paint, so that would have to be cleaned off first. Then the polarity of the LED would need to be determined before a replacement can be attached.

Hope this information is helpful.
_________________
—David

http://www.t-gauge.net/
http://1-450.blogspot.com/

Chris333 · Joined: 25 Sep 2008 Posts: 74

I just popped my unpowered car on the rails for the first time just to see the lights. Can't believe how small they are and that they work.

David K Smith · Posted: Thu Nov 20, 2008 10:37 pm Post subject:

tmanni · Joined: 17 Nov 2008 Posts: 9 Location: Germany

Only one LED doesn't work.
Cars had never been overvoltage. But I tried sometimes using a PWM-Controller.
I don't think that PWM can destroy the LEDs??
I am using PWM-Controller for all my locos from Z-Gauge to T-Gauge.
Never had any problems therewith.
What ever the cause is, the LED is definitely dead.
I removed carefully the LED out of its casing and made a visual check by a magnifying glass. Nothing to see(expected).
Put 4,5 V on its contacts, no light.

So I am looking for a new LED.

Will inform you, if I find a replacement for the LED.

Your advices were very helpful, thanks.

tmanni

B 67 · Posted: Fri Nov 21, 2008 1:22 pm Post subject:

Did the LED stop working after you tried the PWM controller? As has been mentioned elsewhere, PWM uses short bursts of the full voltage intermittently to run motors at lower speeds. In the case of Z gauge, that's 8-9 volts - double what T gauge is designed for. So that may be your answer as to why the LED doesn't work.
_________________
Darren,
Stratford,
Australia.

tmanni · Joined: 17 Nov 2008 Posts: 9 Location: Germany

Darren,

I am not shure, when the LED no longer glows.

I was very carefully when I have used my PWM-controller.
This controller has a potentiometer and I trimmed it on 4,5 V for using on tgauge.

I think the LED was defect at delivery time and I didn't notice it.
Bad luck for my in this case.

Anyhow, I like my T-Gauge furthermore.

tmanni

David K Smith · Posted: Fri Nov 21, 2008 2:39 pm Post subject:

Chris333 · Joined: 25 Sep 2008 Posts: 74

Tmanni,

Can you tell us more about the PWM controller you are using?

I've been trying to order the parts to build one, but I'm an idiot when it comes to electronics... So far I am using a Zthek controller:
http://www.zthek.com/id64.htm
But I'm powering it with a 5 volt power supply. It says "pulse" so I should find something else.

I also tried to build this:
http://www.easterngeek.com/2008/06/simple-and-dirty-pulse-width-modulation.html
But as far as I can tell it doesn't work...

David K Smith · Posted: Fri Nov 21, 2008 7:19 pm Post subject:

"Pulse" is a very tricky word.

In more traditional use, as applied to commercial "power packs" like MRCs, the pulses are short spikes of relatively high voltage (much higher than the DC voltage). These can be harmful to some modern motors, like coreless motors. It would be very harmful to T Gauge products.

"Pulse" in the PWM form is not harmful assuming the maximum supply to the throttle is no more than the maximum of the motor. The pulses do not exceed the maximum DC sopply. They work by varying the length of the pulses to control motor speed, rather than just plain voltage.

So, PWM throttles shoud be fine for T assuming the maximum supply voltage is not exceeded. That said, I don't know what ZTkek throttles are; I thought they were PWM, but the only way to be sure is to scope it. (You can always contact ZTkek.)

BTW, I believe Eishindo uses 4.5 V because that is a convenient battery multiple (3 X 1.5). I suspect the motor maximum is closer to 5 VDC, which is the voltage present in many electronic devices where the motors are often used.
_________________
—David

http://www.t-gauge.net/
http://1-450.blogspot.com/

Chris333 · Joined: 25 Sep 2008 Posts: 74

With the Zthek throttle I don't get the same results as Armand did with his circuit. I can make the cars run very slow, but they shake like crazy! and while running at a realistic speed the cars jerk around and and seem to slow and speed up. Ultimately I want them to run just like Armand did so I ordered the parts to built his circuit, I'm not confident though that I will be able to do it...

The trains will not run on one single battery (1.5V) and with 2 (3V) they run too fast.

Tmanni,
If you want I can send you the 2 LED boards from my cars, I won't need them.

David K Smith · Posted: Fri Nov 21, 2008 8:27 pm Post subject:

Chris333 · Joined: 25 Sep 2008 Posts: 74

Another thing I just tried now. Running at 2volts my regular MRC 2500 pack runs these trains smoother than the Zthek controller at the same voltage. Perhaps the Zthek is made specifically for Marklin locos.