Loud Noises
It’s hard to find good quality toys for kids. Most stuff is so junky, so I was happy to find that this Lionel “North Pole Central” train was not a total hunk of junk. It’s really well-designed, cute, and detailed. I got it so that it could choo choo whimsically around our Christmas tree, but it has a big problem: it’s loud. It makes these constant steam engine noises, and when my kids push the buttons on the remote, it makes a surprisingly loud bell, whistle, or conductor announcement. All this noise was really messing up the Christmas vibes. Time to take this thing apart and see how to quiet it down.
Really nice little train. Pity it is so loud and annoying.
First challenge: screw maze. So many screws. Which ones should I take out? ALL OF THEM! Now I know which ones not to take out.
Learn from my mistakes. Don’t forget that little hidden one underneath the hinged front wheels.
Once inside, you can see that there is a single PCB and a mess of wiring harnesses headed out to the battery pack, power switch, speaker, lights, and motor. There’s also a fun little wire whip antenna for the remote control (which I was surprised to find has FCC approval).
The PCB and wiring harness guts of the engine. There’s a surprising amount of stuff going on in here.
The back of the speaker. Looks like they put a little strain relief glue on here. Someone at Lionel cares about things. That’s nice.
My first idea wasn’t great. I just stuffed a bunch of cotton balls behind the speaker. I guess that quieted it down a little bit. But it distorted the sound in an unpleasant way. Let’s solve screw maze again and open this thing back up.
New plan: there’s a JST connector with silkscreen that says SPK. I bet that stands for “speaker.” Yep, the wires go straight to the speaker. Increasing the series resistance on the speaker should quiet it down quite a bit.
Receptacle for speaker plug. Note “SPK” in silkscreen. Also, only V1.2 on that PCB revision. Nice job, guys. We usually don’t get it right until at least V1.3.
I cut the wire on the right-hand side if you are holding the PCB in the orientation where “SPK” is right-side-up. But honestly it probably doesn’t matter which wire you cut.
The cut speaker wire. I stripped the insulation and tinned the wires. Tinning the wires always makes life easier when it comes time to solder something to them.
I tried holding a 100 Ohm resistor in series with the wire, and sure enough it had quieted way down. A bit too much, in fact. I didn’t have any resistors handy less than 100 Ohm, so I just put two in parallel to get 50 Ohms. That sounds great!
Two 100 Ohm resistors soldered in parallel. No 50 Ohm resistor laying around? No problem. Thanks, harmonic addition.
Resistors soldered in series with the wire. Don’t forget to slip the heat shrink on there first. I still forget about 75% of the time.
Now just reassemble all those screws and enjoy your toy train at a pleasant volume!
Just some heat shrink to clean it all up. It’s oddly satisfying to watch it shrink around the messy blob of resistors and solder I just made.
Yes, this is a silly little hack. Nothing Earth-shattering here. But my kids were impressed. My three-year-old even remarked, “Daddy, you are so powerful.” This tiny hack might not get any love from Hacker News, but it sure did warm my heart (and soothe my ears and nerves).
