Intermittent missed chuff on a MTH 30-1784-1 New York Central 4-6-4 Imperial Empire State Express Steam Engine w/Proto-Sound 3.0

Just topping this - I have to call today for an RMA, and hoping to get an easy self service fix today.

First question, does the speed vary as it runs, or is it smoothly running and dropping chuffs?  If the speed varies, it's likely the tach reader.  If speed is constant, I'd start by loading the sound and chain files again.

Thanks GRJ - speed is constant, I'll reload the sound and chain files and see it that resolves the issue.  Otta be able to get that closed out today before time runs out on the return.

I would check the gap of the tach reader.  Not sure an intermittent miss read would result in a visible change in speed.  Maybe, just not sure.  G

True George, easy to check and probably less work.

I've had a couple of PS3 steamers do this. It's a problem with the tender connection at the wireless drawbar. My missed chuffs were mostly occurring when rounding a curve.  One I fixed it by opening the tender and swapping the 6 pin wire connector from the tender board to the post connector where the drawbar connects. I cut the zip tie on that wire connection and left it off to give the swivel on the tender a little more free motion. Another had a bad solder on the wireless drawbar.

Everything else worked great on these two engines except missing the occasional chuff sound (when the chuff missed the smoke unit also didn't puff).

On a test stand I tried the longer tether and had no issues.  So I put the short tether back on.  Tomorrow evening I'll run it round the Christmas layout and see what happens.

Thanks for the input.

I'm having trouble with the signals in the drawbar seeing how a conductor here could only affect the chuff.  It would seem any interruption would affect a lot more than the chuff.

GRJ,

Here is my report to MTH Support (Does this help your thinking?):

All,

After ~4 hours of running in the test stand - half with the short tether and half  with the long tether, and not being able to replicate the behaviors, it occurred on my layout.

Note the performance on the test stand, as well as the consistency of speed on the layout indicated that the dropped chuff is not related to the tach reader.  I should see variation in locomotive speed over ground coincident with the dropped chuff if it was tach related.  Especially in the instanced where I have multiple dropped chuffs in sequence.  This of course assumes that the duration of the dropped chuff interval is long enough to counter the tendency for the flywheel to maintain speed/momentum.

For reference I have attached a SCARM file to document the layout.  From that SCARM file your can see that my ruling curve is R31 and the most common curve is R36 and I have R54 and R72 in play. My switches are Lionel 6-14-62s ( their R36 equivalent).

The locomotive repeated the drop chuffs on my R31, R36 and intermittently on the R54 radius curves.  It does not reliably operated as advertised on curves tighter that R36 even with the longer tether.

Please advise as to next steps.

Thank you

You've eliminated some variables:

Fine on test stand. That means everything is fine in a straight line.

Problems on layout = curves are probably causing some issue. That would point to the drawbar connection.

I bet the drawbar connector on either the locomotive or tender side doesn't have enough slack. That is probably causing either side to lose connection and then come back. Pop the shells off the locomotive and tender to make sure the wire harness has enough slack to move with the drawbar. I bet that solves the issue.

Below is a video of an RK PS3 engine with the same symptoms as the OP.  This one I fixed by switching around the 6 wire connection tether inside of the tender. I also cut the zip tie that bundled that wire harness to allow the more free motion at the swivel joint where the draw bar connects under the tender.

Real tempted to push for a return RMA and a refund.  I have confirmed that out of the box it has this issue from 031 to 054 and thru my Ross double crossover.

Open tender, adjust wire harness. Done. No need to mail it off for a repair .

Sorry Lou, willing to do a whole lot to make a second hand engine hum, but brand new from a store in a box, a whole lot less willing to do the grunt work.  And besides as soon as I open up the body and start moving things around - there is an excuse to say I voided the warrantee. 

By all means if you don't feel comfortable working on the locomotive send it in for repair.

I don't care about warranties and have been know to void them .

How to void the warranty on your brand new Legacy steam locomotive in one step, swap the motor. | O Gauge Railroading On Line Forum (ogaugerr.com)

@H1000 posted:

I've had a couple of PS3 steamers do this. It's a problem with the tender connection at the wireless drawbar. My missed chuffs were mostly occurring when rounding a curve.  One I fixed it by opening the tender and swapping the 6 pin wire connector from the tender board to the post connector where the drawbar connects. I cut the zip tie on that wire connection and left it off to give the swivel on the tender a little more free motion. Another had a bad solder on the wireless drawbar.

Everything else worked great on these two engines except missing the occasional chuff sound (when the chuff missed the smoke unit also didn't puff).

We saw this occasionally at MTH.  Repeated connecting/disconnecting of the drawbar enlarges connections inside the 6-pin harness.  Swapping end for end sometimes fixes it because the harness connection in the board doesn’t move.  I used to disassemble the harness wire by wire and tighten the  “clamp” that grips the pins on the drawbar.

Interesting that it would only result in dropped chuffs and no other symptoms.  I wouldn't have expected that, nice to know.

GRJ,

Yeah - if I had a timing strobe I would have used it be able to watch the driver wheels to see if I could detect any change in the rotational speed of the wheel. but I don't have anything on hand to make more precise observations.  With just my eyes, I could not perceive any change. As I told the MTH Tech in my e-mail, a tach misread could be causing the missed chuff, and momentum obscuring the speed variance.

Jon G,

Keep in mind, this is brand new out of the box, never run.  Drawbars have been connected to the tender less than 10 times, to the engine less than 4 times.  I hope the material is spec'd out to exceed my usage to date.  I also took great care to insure that bar was aligned to the connector and that pressure on both attachment and disattachment in-line and avoided torque on the fitting as much as possible.  Granted there was some - didn't build a fixture but I believe I am somewhat precise with my hands and not particularly hamhanded.