Lights pulsing on rolling stock

Generally that is due to current fluctuations, generally on the low voltage side. Do you have an accessory operating at that same interval (Oil derrick comes to mind, but there are many) or another train running?

This could also be a totally outside influence.  An appliance that's trying to start a motor and failing can cause a whole circuit, or even the panel to have fluctuating voltage.  I've seen this effect in my whole house when the well pump failed and was trying to start and failing.  It was causing a voltage fluctuation with everything in the house.

Hey guys, thanks for the thoughts and advice!

Since I'm starting fresh, nothing--NOTHING--else is hooked up. No accessories, nothing. There aren't any appliances nearby, either. I'm going to take the TIU out of the equation to see what happens then, just out of curiosity. I'll keep y'all posted. Thanks again!

Rafi

I had a house main shut off that did that to all my outlets in the house as well as the train room. I replaced the main and it went away.

If you connect an incandescent bulb lamp to the same wall-socket does it pulsate in unison?

If you (as an experiment) connect the Z-4000 fixed 14V Accessory AC output to the track do still get the pulsing?

Memory is fuzzy but I seem to recall some discussion about slow pulsing on the Z-4000 main outputs.  It might have been at light loads, only at higher voltages, or just my imagination .

Firstly, I'd like to reaffirm my love for this forum. You guys are incredibly generous in offering thoughts and ideas. I guess we all share that appreciation when we post our questions and get these great replies, but I'm just humbled time and time again, so thank you.

Update...

-I tried with TWO different Z-4000s and had the same experience.
-I removed the TIU from the chain and had the same experience.
-I removed the TIU and Terminal Block from the chain (Z-4000 directly connected to the track segment conventionally) and had the same experience.
-I plugged an incandescent light into the same power outlet as the Z-4000 and DID NOT observe the same behavior while the track was powered on or off.
-I connected the track to the Z-4000 fixed 14V AC output and DID NOT observe the same behavior (however the passenger car lights were dimmer, understandably). 

So I think this points to the main outputs of the Z-4000, and I was able to replicate it between two separate Z-4000s. I wonder if this is normal behavior? It's so interesting... I would have thought with all of the rivet counters in our hobby that someone would have complained long ago about this phenomenon, but I can't seem to find any mention of it on the forum. I have a Lionel PowerHouse in storage that I may dig out just to confirm it's a Z-4000 main output issue, but that's certainly the way it's looking.

So odd!!

If nothing else, it's easier to live with knowing that I've tried every possibly permutation, and I have you guys to thank for those suggestions.

Thanks again, guys. I'm still all ears if anyone has any other ideas.

Rafi

I too tried the forum's "Advanced Search" using combinations of terms like Z4K Z4000 Z-4000 pulsing pulsating toggling etc. without luck.  But using Google, first try came up with these 2 OGR threads! 

https://ogrforum.com/...age-pulse-under-load

https://ogrforum.com/...sing-building-lights

There were more threads but these two (from 2013 and 2016) match my recollections of earlier discussions.   So this is a known behavior that depends on the Volts and Amp operating conditions. 

Hopefully one of the MTH repair techs can chime in if there is a "fix", only affected units built in some time span, or whatever...  

I remember something about this, but I searched my service bulletins and came up dry, so I don't know if there's a fix for it.

Normal operation. Seems to be in present when DCS boards are cycling. Mostly noticed when 42 lighted subway cars are parked in the yard. Both Z4000 handles are at 17v. When moving the right to 18v, it seems to lesson a bit. 

Incandescents are also pulling Amps as well as 14 Volts.  Depending on how many are on at the same time, they may not be getting enough amperage...  But, generally pulsating is caused by a wires touching each other or touching metal somewhere along the lines.. Not enough to completely short out the system, but enough to cause intermittent pulsing...  Check all your lighted cars for clean connections.  Check all track wiring.... for same...  Report what you find'...🧐

I think the consensus is that it's the Z-4000 voltage variation quirk.  Given that MTH is closing and they already announced the demise of the Z-4000, I suspect it's the way it is.

Just to close the loop here--it was unequivocally the Z-4000 quirk at issue here. The workaround? All you have to do is ever so slightly throttle each Z-4000 lever back so it rests JUST before the maximum throw. If you do that, the self-correction that folks talked about in the other posts doesn't rear its head. It's that self-correction that's manifesting itself as the pulse in incandescent lights. The reduction in power, from what I've observed, is inconsequential and unnoticeable. 

As Clouseau would say, "Mystery Sol-Ved!"

Thanks guys!

Rafi