I recently acquired a used Flyonel U33c (SP version, ca 2011 model) and I'm currently running it with conventional AC power. I've noticed that there are spots on my trackage (conventional Flyer) where the sound card cuts out and sometimes stays out (and yes, I've cleaned the track in those spots). I had a similar problem a while ago with my Flyonel Mikado, but that went away when I installed the 9v battery - which also had the benefit of playing the idling/shutdown sounds when track power is cutoff (always a crowd pleaser).
The U33c doesn't play an idling sound when power is removed, so my first assumption was that - like the Mike - installing a battery would solve both problems. The operator's manual - which I downloaded from Flyonel - has a figure showing access to the run/program and smoke switches (under the radiator cover) and the figure caption goes on to say "locomotive switch locations and battery installation". I don't see any room for a battery nor any snap-on leads for a 9v battery. There is something that looks like it might be a permanently installed rechargeable battery or capacitor system - but I can't tell without pulling the shell off the chassis - which I haven't done yet. Any advice or experience or both??
In the case of the Mike, the battery sits inside the tender, so it means pulling the tender shell off (a PITA) so maybe there is something similar lurking under the U33c hood??
- Rich