Lionel U28CG Lights Flickering

If you mean they flicker as the engine moves, that's some what normal, If it's when the engine is still, then I would clean the pickup rollers and my track. Actually, you might clean them anyway. I use a damp rag with isopropanol. 

I have that exact loco and the lights do not flicker. Sounds like you have dirty track or dirty rollers as cjack suggested. 

Dave

This condition exists with the locomotive sitting stationary. 

Are the lighting circuits powered directly from track voltage or is there a regulated power supply on one of the boards that provides the voltage?

Loose wire could be the issue. Take the shell off and check for loose wires

Dave

If you are in command mode (TMCC) and the lights are flickering, it generally means the engine is receiving a weak signal. Have you tried moving it to a different place on your layout?

A weak signal can also be caused by dirty and/or oxidized metal rollers. You might want to take a pencil eraser to the rollers.

This is the same place I program all my Legacy and TMCC engines (several) so we can rule out the location.   Cleaned rollers and track with no change.  Sounds like I need to look under the cab.  

I haven't pulled the cab just yet.    New information.  The flicker of the lights and the buzz from the speaker seem very in sync.  As I raise track voltage the flicker frequency and speaker buzz increases and vice versa.  I turned the RS switch to off and the problem persists.  Could both symptoms be caused by a failing Railsounds Power Supply Board?

When I pull the cab, can I simply remove the RS Power Supply board and then check to see if the flicker stops?  OK just to remove that board and leave the RS Board still installed?  Just don't want to damage any good boards.   

The flickering lights have nothing to do with either of the sound boards.  The lights are driven directly from the R2LC, I'd try swapping that out first.

I have not removed the cab yet.  I have bad memories from years ago on a Chessie U30C and taking the cab off and on was a pain especially compared to Dash's and SD-70ACes.  I do have a another piece of data for this problem.  The light flickering stops when the engine is in motion.  Forward or backwards and the lights stay on.  However, I noticed when going forward the reverse light would sometime turn on.  Does that sound like the RL2C or maybe something with the spring loaded contact block for the light circuits?  

Steims posted:

This is the same place I program all my Legacy and TMCC engines (several) so we can rule out the location.   Cleaned rollers and track with no change.  Sounds like I need to look under the cab.  

That's not necessarily true, some engines are more finicky than others. A short video clip of your issue might help. And Marty has to love you included the item number, always a great start!

I attached a quick vid to show the flicker. 

That sure looks like a bad signal reception. Try placing your hand over the engine first and the turn on the power.

I just received a Lionel CA-4 caboose and set it on the track and its led lights flickered also.  Turns out it's only this certain block section on the layout.  Just so happens I have a Lionel Cell Tower powered on that same section.  When I disconnect the tower the  caboose flickering stops. 

The root cause appears to be the CW-80 that powers this block.  When I power the same 2 items in another block no flicker.  

Sounds like problem solved, ditch the CW-80.