UPDATED - Why would this happen? Non-response to Legacy signal

Sounds like an antenna issue on the loco. Send it back if its under warranty. Happened to me with my mohawk, exact same symptoms. The antenna wasnt isolated from the body.

Are both units powered ?

@Richie C. posted:

Are both units powered ?

Yes. I haven't tested this one with the other A unit on the track but I have with a Legacy B unit and the same thing happens.

I have a nasty feeling that this is an RCMC board issue rather than just a track signal problem - but I'll be happy if someone more expert tells me that's wrong.

I explained the initial symptoms in my original post. The other engine in this A-A set answers Legacy commands with no problem - but it doesn't have sound and that is now another issue with the lead engine.

Basically the quilling horn doesn't work correctly - it will sound briefly but otherwise stops instead of going on as long as the slider is held down. I have tried doing the ground plane test of holding one hand flat over the engine and if I do so it will respond to startup commands. However, I have noticed that intermittently the headlight flickers after this. If I have the body shell on but take off the hatch that covers the switches, the engine will usually catch the Legacy signal on start up but won't hold it through normal running.

If it was not for the horn and the fact that two other Legacy engines of the same vintage as this set have no command issues on the same track I'd think that this must be a ground plane issue or a problem with my old reliable 990 base and CAB2. Some while back I got a new base antenna of a kind @gunrunnerjohn mentioned but hooking that up to the base makes no difference to this engine.

I don't know of any way to test the Legacy signal strength or boost it so I am slightly in the dark - but my instinct is it's a board failure, which is a complete PITA.

If the only difference in responding to Cab2 commands is that it will with the shell off and won't with the shell on, I'm not sure how it could be a board issue.

Seems like more of a signal/antenna/pinched wiring issue.

What happens if you just lay the shell on the engine, but don't screw it down ?

@Richie C. posted:

If the only difference in responding to Cab2 commands is that it will with the shell off and won't with the shell on, I'm not sure how it could be a board issue.

Seems like more of a signal/antenna/pinched wiring issue.

What happens if you just lay the shell on the engine, but don't screw it down ?

Without the shell screwed down it will not start up in conventional and will answer the Legacy startup command, but the quilling horn will not work properly after that. No other Legacy engine on the same track has these symptoms, which is what makes me think this is specific to this one, i.e. the board.

However, I really don't know enough about these Legacy boards despite the fine diagrams by @Bruk and my current but uninformed thinking is that the radio receiver part of it may have failed.