ERR Chuff problem

I'm not sure how the chuff is triggered in this loco but it sounds like the classic Micro Switch miss-adjustment or bad switch.  Or it could be it has a Hall Effect sensor if it uses that instead with the same issues.

Carl

I have to go with Carl, whatever is actually triggering the chuff is clearly not doing it's job.

I find it odd that it takes 30 minutes, that seems like an overheating issue to me.  I wouldn't expect a mechanical switch to need that kind of time before it overheats.  Since I don't have one to actually see how the whole system works, it's pretty hard to offer a concrete opinion on where the problem might lie.

I believe that 3rd Rail uses ERR electronics, so I'd start at the chuff input to the board and work back.  The chuff can be generated by triggering the Cruise Commander input or directly to the RailSounds board.

One thing comes to mind, the new single board ERR RailSounds Commander has a different input circuit than previous boards, and both of the chuff input pins must be totally isolated from frame ground.  If that's being used here, there might be an issue with whatever is driving that board.

Again, this is all speculation as we don't know how the chuffs are generated.  The fact that there is a 2-4 chuff switch suggests at least a bit of logic is involved.

It looks to me like there is a cam in the engine as I can see it when I had it upside down for lubrication.

Like I said, this is the 2nd engine that I've had, both AC9's that have done the same exact thing sound wise. I had a 3rd AC9, but it was damaged in shipping show how where it bent the frame so I could not run it continuously. It would not stay on the track. I have another YouTube video of that 1st engine and you can hear that it sounds great. The problem is I couldn't run it more than 5 minutes, but I'm guessing if I had, it would have had the same problem.

I think I'm going to get my 3rd Rail GS4 tender off the shelf and hook it to the AC9 and try to isolate the problem. The GS4 also has a cam, with a 2-4 chuff switch so it should work the same.

I told Scott Mann I was going to post this on here, so maybe he will chime in on exactly how the chuff is triggered.

I assume this is what is triggering the chuff? Along with whatever is inside? 

It would be useful to know more about the chuff generation.  I'm thinking maybe the 2/4 chuff switch selects a second microswitch with another set of lobes on the cam?

I think I'm going to get my 3rd Rail GS4 tender off the shelf and hook it to the AC9 and try to isolate the problem. The GS4 also has a cam, with a 2-4 chuff switch so it should work the same.

While you are at it you ought to hook up the GS4 to the AC9 tender.   

If you replace the RS boards and it fixes the problem for 30 more minutes I don't think it is the chuff switch.  The way you describe it, the RS boards stop functioning correctly after 30 minutes of running, and don't work again.  But a new board works fine until it is run for a while.  Scott should be able to explain how they are triggering chuff, either grounding the input to AC common, or using a 2 wire set up.  Or are they triggering some other effect simultaneously and that is causing a failure on the board.   G

OK Mars, it's gotta be the shoes!.... sorry, old Air Jordan commercial.

Whatever the problem is, I've isolated it to the AC9 engine itself. Not the tender with the electronics inside of it..so not the radio board, and not the sound board.

I ran my GS4 with the AC9 tender and it sounds fine. No pause, no skip, no random chuff all over the place. Normal 4 chuff or 2 chuff per revolution which ever way I put the switch. With the GS4 engine, you can hear definite "clicks" from the cam in the engine, I assume the chuff trigger.

When I run either AC9 3806 or 3810 with the GS4 tender, the chuff is all over the place. At slow speed you get the skip, and high speed sounds like a machine gun, just like the video I posted above. Also, I do NOT hear any clicks coming from the area of the cam. Maybe a different trigger, I don't know, but it's definitely not the same as the GS4.

So whatever it is in the AC9 that triggers the chuff is the problem. Loose cherry switch, bad cherry switch, micro switch... I don't know. But I do know it's definitely in the engine and not the tender or electronics in the tender.

Can that cam come loose from the drive axle? The randomness of the chuff makes me think the cam is spinning freely or not solid to the axle as it runs.

Ok, I agree with Carl and John now.  The cherry switch is the most likely culprit.  It can hang up and not open quickly which would give the machine gun chuff, and possibly miss closing if not adjusted right.

I guess a cam could come loose, but 3rd Rail would be better to say if they think that is possible, depending on if it is friction fit, or locked in place.  G

I am surprised Scott didn't suggest adjusting the cherry switches in the first place. He did when some were having the same problems with the GS-4s. It has to be a critical adjustment, especially in 4 chuff mode when you have 4 switch openings and closings per revolution and neither switch can be closed at the same time assuming circuitry has not been added like a one shot to control pulse width.

Its fiddley work and best done with with an ohmmeter across the chuff input while you turn the flywheel. Otherwise its trial and error if you try and make an adjustment and then set the engine on the track.

Pete

I had 3 different GN 08's sent to me and they had the 4 chuff per rev go out on them.  I got my money back as this is obviously a mfg defect.

Pete, I'm guessing switches for the two-chuff cam and the four-chuff cam are selected one at a time, so sync between the two is not an issue.