I have finally got my Light Mikado running smoothly after having lots of stalling issues with dirty tender wheels. Now that I can crawl it along, I am hearing a speed-related noise from the loco that is best described as a knocking sound. The sound decoder is muted at this point, so it is apparently mechanical, rather than electronic. There are several knocks per driver revolution (maybe about 16, but it is hard to count them), and it happens in both directions though it is noticeably louder in reverse.
I am guessing that it is in the gearing somewhere, but have no idea what to do about it, if anything.
Any ideas on what can be causing this, and any remedies? I don't want to keep running it if there is a risk of doing damage.
Thanks,
Bob
Could be the gears, or something that is rubbing against the drive-train inside the boiler, like a lose wire. The only way to find out is to open up the loco and see what is going on.
Simon
My bet is the cam switch that synchronizes the cuff. it is located on the worm gear and is known to go bad.
I have two BLI Mikados, both required complete rebuilding to run smoothly.
Because I run DC, I removed the cam switch and all the DCC electronics.
Sheldon
OK, thanks Simon and Sheldon. I don't think I'm feeling brave enough to take the thing apart at the moment until I find some info on how to do it properly. A bit of research required I think....
The "cam switch" is a non-contact magnet and reed switch.
BLI_Chuff_detail by Edmund, on Flickr
R=reed sw. M= flywheel magnet
I've had the reed switches fail on a couple of occasions but I don't see where this would cause any extraneous knocking noise.
I have had the occasional plastic chip wind up jammed between the teeth of a gear on a few BLI diesels but so far (knock on wood emoji here) not on any steam.
The mikes and pacifics are easy to open but before you go that route you might want to remove the bottom axle cover. This will at least give you a chance to clean and inspect the main driver gear. If that doesn't cure the thump then you can remove the boiler and dig further.
Good Luck, Ed
Ed, I have two early BLI Mikes, and they are not like that.
I think they changed to that because of problems.
I have no photos, and the switches on mine are along gone because I removed the decoders for DC operation with no sound, but they were mechanical.
Reed switches used like that will almost surely fail at some pooint. They should have used a solid state sensor, but I think that's what MTH uses. If the magnet slips out of the flywheel, it could clip the edge of the PCB there. Since the bang is at multiples of the drive speed, it's got to be on the motor side of the gearing.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Someone needs to provide a clear 'comparative' picture of the setup that uses a 'cam' on the 'worm gear' in the supposed early version that was described. As that poster said he had actually removed this from a couple of examples we should presume it exists until proven otherwise; my one 'quibble' would be that if it were a switch physically operated by a cam it's a 'microswitch' rather than a sealed-envelope reed switch.
Presumably there's some kind of pulse-counting timer that can be set to 'chuff' after x number of pulses. A method antedating any Mike Wolf 'innovation' was to use an encoder wheel (which may have a great many slots, reflective panels, inscribed lines or codes, etc.) and then use the best count 'approximation' for gear reduction in use to generate the timing that 'in the old days' would be provided by something like a square nut 'in quarter' on one of the axles... relatively trivial, too, to take the absolute pulse frequency to get the 'road speed' and figure from that where the valve-gear reverse should be positioned, how the quality of the exhaust sound should change, etc.
In my opinion, it would be similarly trivial to gauge the output from the motor and modulate the sound system (and modeled valve gear) in proportion to load. Evidently Mr.Wolf's examiner(s) did not agree...
Several decoders are using BEMF to control dynamic exhaust sounds, both for diesel and steam locos. Soundtraxx might be the only one using it for diesels, but Soundtraxx, TCS, and, to a lesser quality result, BLI are using it on steam locos.
rrinker Several decoders are using BEMF to control dynamic exhaust sounds, both for diesel and steam locos.
Personally I think it's immoral just to speed up the chuffing noise, regardless of phase, as the engine speeds up. That's a toy train feature... not accurate modeling.
Bob, you might have to wait and go to a good hobby shop to get it done. Or contact BLI.
This source: https://hoseeker.net/broadwaylimited/bliblueline282lightmikado.jpg
Provides an exploded view of the boiler. I don't see anything unsual about it - seems like you need to remove a screw under the stack (with the loco on its back), and what seems to be two screws under the cab. You might have to remove the lead truck to access the front screw. Maybe Sheldon can let us know if there are any funny wires or parts to watch out for when removing the boiler.
I would recomment that you NOT take everything apart in one shot, that is, all visible screws. Removing just the boiler, without removing the plate that holds the drivers (part 84 on the diagram), is easy and will allow you to inspect the flywheel.
If you remove the plate that holds the drivers, don't remove anything else. Leave the boiler on. Just remove that plate to inspect the gears, with the loco on its back.
But I think that the theory about the synchro piece on the flywheel is a good one and worth inspecting. You don't need to remove the driver wheel cover plate for that, just the boiler.
Thanks, Simon. I don't think there are any "good hobby shops" here in UK that are accessible to me, especially for American models, but I shall have a go myself at some point.
Thanks for the link to the drawing - that may be different to mine? Blueline vs. Paragon2? Not sure. But I think there is an assembly drawing with my original box somewhere - all stacked away somewhere at the moment, but I'll dig it out and have a look.
Regards,
I have a blueline Mike, I would first look at the magnet inset into the flywheel.
I don't recall anthing spectalarly difficult about removing the boiler.
I do recall having to replace that dog-gone reed switch out though, and THAT is not fun...
Ricky W.
HO scale Proto-freelancer.
My Railroad rules:
1: It's my railroad, my rules.
2: It's for having fun and enjoyment.
3: Any objections, consult above rules.
Bob,
If you end up stuck you could speak to these guys. They're happy to do American. Parts though I expect you're on your own which doubtless will be BLI's response unless it's a very recent purchase.
You'll still need to ship it though unless you're in range.
https://www.dccsupplies.com/
Just for grins-- does Paragon 2 support CV 236?
At this point I think removing the upper boiler is a sensible step -- surely for Ed to have a detail pic of the flywheel and board he has successfully taken off a boiler shell and replaced it, and can at least suggest what to watch for with any wiring. The weight attaches through the 'bottom' half of the boiler, which stays with the frame structure, so it should be possible to reassemble the two trucks with the shell off and run the engine with a better sense of where the knocking is -- I think you lift up the back and rotate forward to clear the headlight assembly which is indicated as screwed to the front of the weight.
I think if there were major design change you'd see a 'separate' exploded-view diagram (as you do for the Paragon 3 T1s vs. the original) so I think removing the three indicated screws (the ones with the long orientation lines) should be 'conserved' for all versions. Note the components for the trailing-truck piece, which may have to come off to access the rear screws. I presume the different screw p/ns indicate different length; it's pretty easy to tell which of the three is the stack-end but be mindful of a difference.
The key here is that the knocking is more severe in reverse. This suggests to me that there is a magnet in the flywheel and it is slightly cocked or has moved and taken up that position, and a circuit board is now being hit, effectively, by a sharper 'engaging' angle to the flank rather than the face as the flywheel rotates. I would also look at the worm, and the teeth it drives; watch for play or for an area of damaged teeth. Whatever it is will become pretty clear when the physical drivetrain is exposed and the engine is run, either on the track or the bench.
If he then has to send it anywhere for service, some of the necessary disassembly will have been done...
Thanks to Overmod and to Flying Scotaman for your suggestions. I shall attempt to remove the boiler when I get some quiet time and take a look.
The model was bought new from BLI a couple of years ago (shipped from US) but has only recently had some track to run on, so I doubt it has done much more than an hour or so of running. I did lube the external moving parts but otherwise it is 'as supplied'.
OvermodJust for grins-- does Paragon 2 support CV 236?
Not sure I understand why you asked, but anyway, according to the manual it is the "Smoke unit heat level when moving". A tad academic as the Light Mike doesn't have a smoke unit due to size constraints.
FowlmereRROvermodJust for grins-- does Paragon 2 support CV 236? Not sure I understand why you asked, but anyway, according to the manual it is the "Smoke unit heat level when moving".
I said 'just for grins' because this won't be your 'issue' for a number of reasons even if your engine had this 'feature', among them that I understood you to have turned sound off entirely and not just disabled some of the 'tracks' the system plays, and the reported fact that the noise appears worse in reverse (which is not something I'd expect a rod knock to do, let alone a synthesized version of one).