MTH lighted Christmas tree car

I can only guess the Zcontroller in the corner is how you are powering? What power brick or version is that?

Second part is, MTH has not posted a parts diagram of that specific car, however I know that some used switching mode regulators, and others used linear regulators.

Example switching regulator

VS

Linear style regulator

One theory is that a chopped AC power waveform might interact with the switch mode style supply.

The LEDS are simply powered by 6V and then strands or the light strings are current limited with a resistor.

I would say return it, but given demand and supply- hopefully the dealer can exchange for you.

Remember, this whole "repair" and warranty is more like refund and you end up car or train less. There is no MTH factory service center, there is no warehouse with spare cars. That means it really matters who the dealer is, are they a service center, did they stock parts and do this level of repair?

Also, the linear regulator style, they mount using the tab of the 7806 regulator, and the wiring and plugging and unplugging can rip and tear the traces of the single sided PCB causing a number of issues. I've seen plenty of failures, and again, it's mechanical failure then causing electrical failure.

I have not seen a switchmode version of the regulator fail yet, but not all cars use them and so just have not had one cross the repair bench.

I am using a MTH Z750 controller and brick.  So can I assume the lights should stay on at the higher voltages?  I purchased it yesterday from English’s Model RR in Montoursville PA,  a good shop but they don't work on electronic stuff.  Its a 90 min drive, I was going to have them test it but I didn't.  They actually have one on their layout display, working properly.   I will try another transformer before I call them.

Ok, just hooked up a Lionel PW 1033 transformer and the lights stayed on from 5-15 volts, no problems!  I had known about the sine wave differences but never experienced it before with any MTH equipment .  Thanks so much to Vernon for all the detailed info.  Fortunately, I don't have to go the ‘Return’ route.

@pennsydave posted:

I just purchased this brand new car, 30-76821, and the lights go on about 6 volts but at 11 volts they go off.   They will not relight until I go below 6 volts again.  Now this is fine for conventional running but not for command where you need the higher voltages.  See video and note voltage meter .

30-76821 Is this normal since they are leds or should I return it?  I am planning to only run it in conventional initially. There is no info in the instruction. The on off switch underneath works fine

Return it, defective board. Just had same thing  with Xmas box car

Didyou try a different transformer?  Solved my problem!