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Has anyone using the chuff generator had it change chuff rate after an engine not being used for a while?  I installed it in my 606 TMCC J and it has been working great @4 chuffs per. Tonight I put it on after about a year of sitting unpowered and it was at 2 and there seemed to be some sporadic chuffs as well. I took off the shell and checked that the sensor was still secure and the tach strip was good. Both seemed fine. Before I reprogram it for 4 chuffs again I thought I’d inquire if this is something I need to be aware of in the future.

Maybe @gunrunnerjohn will chime in. It’s a great product so I suspect it’s a simple reprogramming but thought I’d ask.

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While it shouldn't lose it's settings, it's hard to say what happened.  I'd clearly reprogram it first and see if that fixes it.  I have had one other person contact me with a similar story.  The calibration is stored in the uP FLASH, and should be there until changed.

It it's forgotten it's calibration, it could be an issue with the microprocessor parts, though they're normally really reliable.  I'd also check the wiring to make sure there's not a suspect connection.  For instance, losing it's ground can cause issues with the board.

@BobbyD posted:

I had one installed and now there are no chuffs. How would it be reprogrammed? Dreading shipping it back.

Follow the instructions, install the jumper, rotate the flywheel (probably manually), remove the jumper.

AKA- the same way you originally "programmed" the chuff rate during the install.


Put another way, it's either lost the programming, or it's no longer functioning. Again, the way to sort that out is go back, get the original install instructions, and follow the steps for setting the rate. If it never blinks the LED- then it's probably not working/sensing/powered and you have to sort out which one.

Last edited by Vernon Barry

Well I got to look at this today.  Double checked the sensor distance, reprogrammed.  Took a few tries but I had 4 good chuffs per revolution.  Put the shell on and came back after dinner to one chuff ever couple revolutions.  I'll pull the shell tomorrow to see if I did something putting the shell on.  After that I may have to call in an expert.

I have the same issue. I can program for 4 chuffs, assemble the engine, set it on the track, start out slow w/ 4 chuffs. Then, as i increase the speed it changes to 3 chuffs, then to 2 , then to 1. If I stop, and wait a few seconds and start out slow, back to 4 chuffs, Then it repeats.
Totally scratching my head. I have even changed the chuff generator. Going to look at the tach tape next time I open the boiler.
I'll see if I can get a video of it.

Last edited by Jayhawk500

Look at the tach spacing and the mounting of the C-G.  Obviously, this is not normal operation!  It sounds like it's not able to read the tape at faster speeds.  When the spacing is adjusted properly with a good clean tape, it can keep up with the motor RPM at 8,000 RPM, so clearly something is amiss.  It can probably keep up faster, I just never tested beyond that motor speed.

FWIW, my was working great, she’ll off at slow and high speed chuff. Once it sat and the shell was on it was 1 chuff maybe 2 revolutions. I’m going to pull the shell again, probably next weekend , and check for the cold solder joints and maybe a loose wire. My tach spacing is pretty tight. I adjusted and confirmed yesterday when it was working before the shell went on.

I’m confident I’ll get it figured out. I just have little to no time during the week.  Besides I hear customer service is pretty good with the product.

Last edited by MartyE

Here's the video I promised. Listen to the audio, watch the chuffs of the smoke and watch the side rods for the timing.  You'll hear a chuff skip and the # of chuffs changes at that point. Notice when I slow down I lose the audio until I fully stop, then it comes back when I start up again. This is the second generator set at 7 mm or .040. The only thing I didn't do was change the tach tape when I replaced the generator. But I did blacken the stripes with a marker.

My Chessie Steam Special has no issues. 4 Chuffs/revolution, looks and sounds great.

Last edited by Jayhawk500

Well I must say I am stumped.  Re-checked all the connections, re-verified the sensor placement.  Had various scenarios all happening once I had it calibrated for 4 cpr.  It seemed fine at low speeds but when advancing speed it was apparent that it was missing chuffs randomly and high balling the chuff generator was completely missing chuffs.  After powering down and returning after a coffee break the chuff rate would be almost 1 per 2 revolutions roughly.  I am beginning to suspect I have a failure but I am open to suggestions as I have left it open on my roller base so I can try things.

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