NP F3B electrocoupler buzzes, won’t stay shut, and gets hot. RESOLVED

#1 need the actual product number of the engine in question.

#2 this generally indicates a shorted electrocoupler and that is very bad and needs solved before you keep attempting to power this engine.

It's buzzing because the coil is activated. Stop using it till you find the short. Check inside the unit and check the wire connections on the truck.

Here is end flap:

Parts breakdown time so we know what we are looking at https://www.lionelsupport.com/...90-C-FREIGHT-6-18133

So that dummy is using an LCRX https://www.lionelsupport.com/...NITS-LTS-CPLR-STROBELCRX wiring diagram https://ogrforum.com/...wiring%20diagram.pdf

One wire of the coupler is tied to frame ground, and the other to the LCRX outputs. This would tend to indicate that either that second wire is shorted to 3rd rail power or the TRIAC output on the LCRX has failed stuck on. I guess it is also possible someone could miswire it and put to the wrong output or misprogram the LCRX?

You might also read this related topic https://ogrforum.com/topic/tmcc-f-3-problem

Also note the 2 different versions of the LCRX board picture from @Hotbox

Just to make sure, your power source for your track is AC right?

This is one of those never ever run on DC boards because it needs the zero crossing of the AC power to turn off.

Also, it's possible someone did the same thing here

@PaperTRW posted:

While it's better than nothing, it's the wrong version of the board and also the wrong wiring configuration.

Glad to hear the light has been fixed.

Your other problem is where you've hooked-up your ElectroCoupler -- the wiring between the two versions of the LCRX is NOT the same. For your unit, hook one coupler wire to Pin D. Connect the other wire to Ground (or Pin K).

Here's the rundown for the nine stick-pins on your board:

C - Front Coupler
D - Rear Coupler
E - Front Light/Cab Light depending on wire jumper
F - Rear Light/Strobe Light depending on wire jumper
B - Open for Front & Rear Directional Lighting/Jumper to Pin L for Cab/Strobe Light functionality
J - Center Rail pick-up
N - Program-Run Switch
L - Program-Run Switch/Jumper to Pin B for Cab/Strobe Light Functionality
K - Ground

Unfortunately, the Lionel listing on their website is wrong, as the 610-8124-110 is the earlier version of the board. The correct board for your Milwaukee B unit is 691-PCB1-00E, but those aren't currently available from them. (And that might explain why they list the earlier board, as they have those in stock.)

TRW

Again, in theory, per Lionel Parts, this unit might be using the older pin style only connector board.

It's possible someone wired up the electrocoupler incorrectly to a light output and that is why it is constantly buzzing activated.

Take some pictures of what you have going on inside that loco, specifically the LCRX board and wiring connections with detailed pictures.

Don’t see any gross abnormalities. Inside looks pristine.

Picture that matters

So from @PaperTRW

The rundown for the nine stick-pins on your board:

C - Front Coupler
D - Rear Coupler
E - Front Light/Cab Light depending on wire jumper
F - Rear Light/Strobe Light depending on wire jumper
B - Open for Front & Rear Directional Lighting/Jumper to Pin L for Cab/Strobe Light functionality
J - Center Rail pick-up
N - Program-Run Switch
L - Program-Run Switch/Jumper to Pin B for Cab/Strobe Light Functionality
K - Ground

Specifically the Brown wire plugged over pin D.

Unplug that wire from the board and power the car. If the coupler does not fire, then the board has a bad output TRIAC.

You can either just leave the uncoupler unplugged , replace the LCRX board, or if someone is skilled with soldering, replace the TRIAC.

In theory, it's Q2 which is most likely a https://www.sparkfun.com/datas.../General/MAC97-D.PDF

However, it should be noted I do not have this exact board on hand and I'm going off of a more recent and different LCRX0398 board that had separate connectors sockets for the electrocoupler outputs. Given the 4 TRIACs in a row, it's still a fairly good guess.

Brown wire removed from D; coupler does not fire; replaced, and coupler buzzes. Where would I get the triad you have referenced above? Thank you Vernon for all the help.

https://www.google.com/search?...-b-1-d&q=mac97ac

Mark,

I have the triacs and can likely fix your LCRX board, if needed.

TRW

Follow up: LCRX replacement Board available and received from Lionel. They shipped quickly. It was a simple plug and play install, and electrocoupler problem solved. My thanks to all who added their thoughts to this thread.

@Mark V. Spadaro posted:

Follow up: LCRX replacement Board available and received from Lionel. They shipped quickly. It was a simple plug and play install, and electrocoupler problem solved. My thanks to all who added their thoughts to this thread.

Thanks for the update!

Replacing the triac on that LCRX will give you a spare board.

Thx GRJ, but that’s not in my wheelhouse. I have the board if anyone is interested. Just pay whatever the shipping cost is.