Lionel C&O George Washington F-19 will not chuff

The chuff switch should be grounding pin-17, that's the first thing to check.  If it is indeed toggling pin-17 of the R2LC, top suspect would be the R2LC.  FWIW, "a few ohms" doesn't sound right, you should read zero ohms across the switch when activated.

Thanks John.  The switch reads 2.1 ohms to be precise.  Checked a new cherry switch and exact same 2.1 ohms.  Switch looks good.  Do you have a schematic or show me the orientation of the pins on the R2LC for 17?

Thanks,

Greg

Greg,

Try this:

Originally from here, courtesy @gunrunnerjohn:

   https://ogrforum.com/...6#151773314486472756

Mike

Thanks for the schematic.  Checked pin 17 to AC ground.  I get 5 volts all of the time whether chuff switch is switched or not.  However, I do get the ohm change from the chuff switch (2 or infinite).  Sounds like this is leading me to the R2LC?  Do you folks agree?

Thanks, Greg

Greg, I always try a new R2LC first. It’s the easiest thing to do. Just remember to set a new engine ID #. If it is the R2LC perhaps GRJ can tell you what electronic part can be replaced on the board if possible.

@Steam Loco Greg posted:

Thanks for the schematic.  Checked pin 17 to AC ground.  I get 5 volts all of the time whether chuff switch is switched or not.  However, I do get the ohm change from the chuff switch (2 or infinite).  Sounds like this is leading me to the R2LC?  Do you folks agree?

Thanks, Greg

Actually, that screams out that the chuff is never getting to the R2LC, check the wiring between the chuff switch and the R2LC, that's where your problem is.

John/Rod, thanks for the feedback.  John, in the second pic above I have checked continuity from the pins on the cherry switch to the connector you see with 2 blue wires and 2 white wires.  The white wires are the cherry switch.  If you see the print on the motherboard below the chuff and ground of the connector corresponds to where the white wires are in the molex connector.  I tested with the R2LC board plugged into the mother board and powered up the engine.  I checked voltage (backside of the board on the solder connections) between pin 17 (chuff) and pins 3/4 - ground and got 5 volts.  Not sure which wiring to check on the chuff circuit since I checked it prior.  Could it be a bad motherboard or R2LC?  I know I am missing something you are suggesting, pardon me on the brain fart.

Thanks, Greg

The chuff switch has two leads.  One is frame ground, the other should connect to pin-17 of the R2LC.  Determine which is ground, and then measure continuity from the other lead to pin-17 of the R2LC.  If you don't have a connection there, start following wires, that's your problem.

Thanks John!  Will let you know what I find.

John, believe it or not.  I think it is the motherboard.  if you look at the 5 pin connector the chuff wire corresponds to the motherboard pin that says "chuff", "ground",.....  I checked resistance between this pin (ie chuff pin where the 5 pin connector plugs in) and the corresponding pin 17 that the R2LC would plug into and no continuity (infinite resistance).  I checked it with the other pins and no continuity anywhere.  Must be a cold solder joint or a trace issue.  Surprised to see this.  Will have to get a motherboard it appears.

Take the motherboard out, it should be easy to trace & repair the broken trace.  I can't imagine this will be hard to fix.

Here's a pinout for your motherboard from Rod's excellent Motherboard document.  The two pins on the top of J8 are the chuff switch, one of those should go to ground, the other to pin 17 of the R2LC connector.  If they don't, it should be easy to fix.

Found the culprit and fixed now.  It was the motherboard.   Never saw this before.  Almost looks like solder joint rubbed off.  Purchased a new one for $12 from service and repaired the engine and all works well now.  Just wanted to follow up that it was fixed.  Thanks for all the help.

Greg

Glad you got it working Greg. Enjoy

I have a more basic question - how to open up the engine.  The smoke unit has stopped working and I want to get inside to check things out.  The manual points to the locations of 4 body screws which I removed but things still seemed solidly bolted together.  Any advice on how to get this engine opened up would be great! 

Mike

@DC Mike posted:

I have a more basic question - how to open up the engine.  The smoke unit has stopped working and I want to get inside to check things out.  The manual points to the locations of 4 body screws which I removed but things still seemed solidly bolted together.  Any advice on how to get this engine opened up would be great!

Here's a link to the instructions: https://ogrforum.com/...19#83368077923567919

Apparently, you have to do some wiggling and jiggling.