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Hello. As the title says, I have a K-Line Union Pacific Big Boy (3790-4015S) and it is not currently in the best shape. When I was much younger (14, I had the engine since I was a kid) and basically didn't know what I was doing , I decided to re-wick the smoke unit and the resistor and capacitor came loose and fell off the board. I am not any good at soldering (I also don't have a soldering iron) so I can't just simply solder new ones back on. I have misplaced those parts along with the funnel for the smoke fluid. I have also lost the (7?) screws that hold the body shell to the engine base. I am wondering where I may find any of these needle in a haystack parts. I found this (https://traindoctor.com/service/kline/kline.php), but don't know what to purchase. I read here (https://ogrforum.ogaugerr.com/topic/kline-smoke-unit) that the part number for the smoke unit is K3790-X008, but I'm not surprised it doesn't appear to be listed anymore. Does anyone know where I may find either a replacement smoke unit or the needed parts for the smoke unit. If I just need a new resistor and capacitor, which ones do I need. I have a friend that can maybe solder them for me. And does anyone also know what screws I need for the body? Also, I have of course learned to take better care of my trains and parts and not be so careless. Any help in getting this engine back up and running is appreciated. Thanks in advance.

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  • 1: Smoke unit board with missing resistor and capacitor
  • 2: Entire smoke unit for reference
Original Post

Its most likely a common 27 ohm wire wound resistor. Lionel has them. As for the cap you won't find it from Lionel or K-Line. There are hundreds that would work. Some electrolytic with at least a 15volt rating and small enough to fit. Capacitive value not all that critical. K-Line only offered a handful of engines with fan smoke. Someone would have to check theirs to determine an exact match.

Pete

@Norton posted:

I assume the smoke unit is driven off the R2LC, not track power. I didn't see a regulator on the board but if there is one the cap would only need to be around 6.3v.

Pete, the R2LC smoke output puts out half-wave track power in command mode and full-wave track power in conventional mode. Since there is a diode, it would all end up being half-wave. Half-wave 18VAC peaks at 12.7 volts, so the cap will charge up to the peaks. As I said, the Lionel smoke unit with the same arrangement has a 35V cap.  The cap comes BEFORE the regulator, so it sees the full voltage.  There is a regulator, it's missing as well. 

I've never seen any of these smoke units run the fan on unregulated power, that arrangement would put 11-12 VDC on the motor, that would make quick work of that motor!  I think we need to see better pictures.  If they are feeding this with some other source of power, I can't imagine what the diode and cap are doing there.  Here's a view of the bottom of a K-Line smoke unit, note the regulator.

 

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  • mceclip1
@jaketrainz posted:

And as far as a capacitor goes, I don’t know a whole lot about them. Should I measure the hole spacing to find the correct size one?

Measure the space between the leads and then the diameter available between the connectors to install the cap.  Find a 35V 100uf cap that fits, there should be tons of them.

Here's a suitable cap, pretty sure the lead spacing is .1".  Kemet ESH107M035AE3AA.  Pretty sure you'll also need the regulator if it's not there.  TI LM78L05ACZ/NOPB.

Pete, I found the picture on the web, I don't have one in hand or I'd have posted the picture sooner.

I'd burn up a motor for you, but I don't have any of them I want to sacrifice.  Have you ever heard one of the smoke fan motors running on higher voltage?  It's pretty loud, and I'm sure it won't last very long that way.

Not entirely sure why you're getting so worked up.

They're metric screws, 3mm and 6mm long if they right into the PCB, 8 or 9 mm long if they are holding a smoke funnel.

What’s the best place to source the screws? I have an assortment of random train screws, none of which fit. A google search for 3,6,8,or 9mm screws gives me wood screws and others that are far too big. Is there something more specific I should search? Also, what size screws for the body? Then I’ll have everything I need.

They're metric screws, 3mm and 6mm long if they right into the PCB, 8 or 9 mm long if they are holding a smoke funnel.

I ordered the specified screws and unfortunately they did not fit. I actually ordered 3 different sizes just in case and none of those fit either. I don't happen to have any of the original screws any more for reference. I called someone as Brasseur Electric Trains (traindoctor.com) and they did not know what the screws were either. I was told the service manuals were likely destroyed by Lionel! I still also need body screws. It was either 5 or 7 of them. If anyone out there happens to know what size screws I need for everything, please let me know. Thanks!

The body screws are very likely #6-32 size by about 1/2" long. Thats what K-Line used for most body mount screws that I have delt with.

Also the smoke unit body screws may be #4-40 but I wouldn't want to guarantee that. I have never worked on one of those smoke units.

If you take the body shell and the smoke unit to your local Ace hardware, Lowes, Home Depot whatever, you should be able to match up the sizes and then you will at least know what sizes you need.

Rod

Last edited by Rod Stewart

Go for 3/8" if it's just the PCB, 1/2" if it's also holding down a stack extension.  Also, sometimes it's useful to have longer screws.  I just worked on a Lionel Challenger, and half the smoke unit screws were stripped in the pot metal bowl!  Since it looked like it was never opened, I suspect it happened at the factory, runaway power tools.  I just used some longer 4-40 screws to engage the remaining threads and all was well. 

This is also why I use screwdrivers with a 1/2" handle for most of the work, makes it harder to get carried away and strip screws.  I've lost count of all the plastic shells I've repaired when people either strip the screws or twist the mounting posts off!  It's plastic people, you don't need 100 ft/lb of torque to put them back on!

Go for 3/8" if it's just the PCB, 1/2" if it's also holding down a stack extension.  Also, sometimes it's useful to have longer screws.  I just worked on a Lionel Challenger, and half the smoke unit screws were stripped in the pot metal bowl!  Since it looked like it was never opened, I suspect it happened at the factory, runaway power tools.  I just used some longer 4-40 screws to engage the remaining threads and all was well. 

This is also why I use screwdrivers with a 1/2" handle for most of the work, makes it harder to get carried away and strip screws.  I've lost count of all the plastic shells I've repaired when people either strip the screws or twist the mounting posts off!  It's plastic people, you don't need 100 ft/lb of torque to put them back on!

So I ordered what I believe to be a smoke funnel but it turns out it was just the small brass ring like thing at the hole if the smoke unit which I already have. I’m in need of the funnel that funneled the smoke and fluid to and from the dual stacks of the big boy to the single hole of the smoke unit. I’ve looked everywhere and can’t seem to find it. Is there a substitute that would work or does anyone know where I can find this piece. If I’ve learned anything from this repair, it’s don’t lose parts, especially K-Line parts, at just about any cost. I’m very close to having this engine fully functional once again and I’m looking forward to it. Any help is appreciated

You may have to break out the soldering iron and make one from brass tubing and brass sheet.

I think I found something that may work. Lionel’s American Flyer Big Boy uses a smoke funnel that looks nearly identical to the old one. I’ve even heard the A/F big boy used the same exact k-line tooling. I purchased the part directly from Lionel and I will see if it fits. Worst case scenario, I will make something

Ok, well I finally got everything in the mail and soldered everything together, added a new wick, added smoke fluid, screwed the unit together and plugged it in. Then turned the smoke switch on the engine to on. The fan sounds horrible, making a high pitch screeching noise, and when in neutral turns on and off every few seconds. I’m also getting either very little smoke, or no smoke at all. At this point, I’m done with trying to fix the existing smoke unit, and would rather cut my losses and add a new one. I’m looking at a Lionel unit (see picture) for $35 with a 3 pin connector that appears the closely match the K-Line unit. Is the 3 pin connector the same as the K-Line and can I simply just plug it in or is the pin out different?

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Jake, all you need is a motor, much cheaper than the smoke unit.  Also, the smoke unit turning on and off won't be fixed by a new smoke unit, that's a function of the R2LC.  Did you program it for a steamer with smoke?

In the course of normal operation, static electricity or an electrical “spike” can cause a loss of function. Following the procedure outlined below will restore functions.

STEP 1: Move switch on locomotive from run to program.
STEP 2: Turn on Command Base.
STEP 3: Place locomotive on track, then turn on power to track.
STEP 4: Press “ENG” then input locomotive ID ##. Press “SET”.
STEP 5: Press ”ENG” then input locomotive ID ## again.
STEP 6: Press AUX1, then input the reprogramming code 4
STEP 7: Turn off power to track, wait ten seconds.
STEP 8: Remove locomotive from track, move switch from program to run.
STEP 9: Place locomotive back on track. Turn power on to track.
STEP 10: Press “ENG” and ID#, then operate as normal.

Jake, all you need is a motor, much cheaper than the smoke unit.  Also, the smoke unit turning on and off won't be fixed by a new smoke unit, that's a function of the R2LC.  Did you program it for a steamer with smoke?

In the course of normal operation, static electricity or an electrical “spike” can cause a loss of function. Following the procedure outlined below will restore functions.

STEP 1: Move switch on locomotive from run to program.
STEP 2: Turn on Command Base.
STEP 3: Place locomotive on track, then turn on power to track.
STEP 4: Press “ENG” then input locomotive ID ##. Press “SET”.
STEP 5: Press ”ENG” then input locomotive ID ## again.
STEP 6: Press AUX1, then input the reprogramming code 4
STEP 7: Turn off power to track, wait ten seconds.
STEP 8: Remove locomotive from track, move switch from program to run.
STEP 9: Place locomotive back on track. Turn power on to track.
STEP 10: Press “ENG” and ID#, then operate as normal.

I don’t have a CAB-1 remote. I have a TMCC command base but use MTH’s DCS to operate my TMCC engines. Could I do that on the DCS remote?

Also, this was happening when I was running in conventional mode.

And finally, would the fan for that smoke unit I just showed work as a replacement?

Since he doesn't know what he really needs yet Don, it's premature to order anything.

Jake, the one thing that the DCS doesn't emulate is the SET button, there is no corresponding button for SET.  If you go to add a TMCC engine, it does send out a simulated SET for the TMCC ID change, but it doesn't know to do it for the locomotive type.

Find someone with TMCC or Legacy and get it programmed correctly.  You can get a smoke motor for a few bucks to fix the noisy motor.

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