Lionel 8376 reverse board wiring diagram

If this is a Union Pacific Diesel, it's not supposed to have a double wound motor. It should have a 3 position E-unit.

If the motor is double-wound, you can run it from a 3-position e-unit (electronic or mechanical) by using only ONE of the two field windings.  Just tape off the un-insulated end of the other coil and leave it disconnected.

If the motor is single-wound, you can’t make it reverse with a pendulum-style 2-position e-unit.  You need a 3-position type to make it work.

The 8376 loco has the 40-0105-001 electronic reverse unit according to the service literature.

Larry

Here are some service docs

TrainLarry posted:

The 8376 loco has the 40-0105-001 electronic reverse unit according to the service literature.

I have this diesel, still new in box. I had no idea it was electronic, thought it was just like the Santa Fe version with the original E-unit.

The electronic units will eventually all fail, so it might be a good idea to replace it with the electro-mechanical 100-4 postwar type - just $32 at The Train Tender - and have a lifetime of reliability.

Thanks  to Rob, Carl , Larry, Ted. The correct # for the electronic E-unit is 40-0105-001 The engine #8376 UP A double wound single motor SD-40 mfg. 1983. My manuals show show both a  electronic or a mechanical  E units The electronic one i would like to see a wiring diagram since I have 3 in my parts cabinet.  And that is an original part. If I install a 100-004  E unit I would have to cut a hole in the frame. The wiring is not a problem. 

Hello, I also have the UP 8376 SD-40. I bought it used and have replaced the electronic e-unit. Rob, would it be possible for you to take a picture of the wiring on your unit for me? I have no idea what wires go where. I have replaced the brush plate, brushes and armature. Now I just need to melt some solder.

Thanks,

Joe

@Jhissong posted:

...would it be possible for you to take a picture of the wiring on your unit for me?

It's buried, and still new in the box, but I'm doing train stuff tonight so if I come across it I will look into it. Do the motors on these have a double wound field?

Yes, the green and red windings.

@Jhissong, if you post a picture of your board and motor(s) I can then draw on it to help you wire it out. You are using the 640-0105-001 reverse board, correct?

@Jhissong posted:

Yes, the green and red windings.

This should work then.

This is the original electronic e-unit. I had taken a picture prior to removing the board but lost it. The wires are all new. The green wires were originally brown but all of the other colors are the same as the originals. I know the white, blue and gray wires go to the lock out switch. I just don’t know which wires go to the brushes and field winding.

Thanks,

Joe

Thanks Rob,

I am just waiting on the new parts to arrive. I will post as soon as I get it back on the rails.

Hi Joe!

I too have a UP 8376 SD-40 with a failed 0105-001 electronic reverse board. I ordered an electronic e-unit from a vender on eBay, and I came to find does not work with a double wound field.

I'm wondering if you replaced the original board successfully. I'm also wondering if I can use my new electronic board by taping off ONE of the two field windings as Ted suggests.

@Don Winslow posted:

..wondering if I can use my new electronic board by taping off ONE of the two field windings as Ted suggests.

Yes, that will work.

I just purchased a Lionel 8376 that will only run in reverse and am planning to fix this only I know very little about motors and such. The 8376 I have does not "match" the wiring schematic Rob provided so I'm hoping to get some clarification on what I have. The schematic I provided is my best transposition of what is on my 8376. I know wiring photos can be problematic as well...following the leads and all. Is my 8376's motor wired correctly?

the field wire and the armature coils are wired together then the field wire is reversed in relation to the armature wire which makes the motor run in reverse this is because it's an AC motor. so, wire the armature n field like the brown wire. the electronic unit only reverses the green n red wires to make it run in reverse!

Alan

Most excellent tutorial Alan. I will have to read it slowly again (and again). I will give it a go none the less.

Update: But firstly, when it comes to electric motors I am a dunce. I have pulled the motor truck, separated all motor wires, and have had success running directly from the transformer in both forward and reverse. Now, I'm jumping the motor wires-lug-armature things to the board wires and replicating the prior "running only in reverse" with success but have yet to discover the wiring configuration which allows the transformer to switch forward/reverse. May sound crude but it is a motor break through moment for me...or at least perhaps on the cusp of such.

It looks like you might be missing an insulating washer for the solder tab where the red wire and one field wire are connected. This is not supposed to be a connection to chassis,ground, it is only a strain relief mount for the brittle field wire and must be insulated from the screw. Take this screw out and let the solder tab, with wires attached, hang free to test.

@ADCX Rob posted:

It looks like you might be missing an insulating washer for the solder tab where the red wire and one field wire are connected...

Just looked at this again, and it's hard to tell, but that 202-108 washer looks like it might be squeezed in with the other brushplate screw... circled in green.

Rob, thank you for digging into this. My findings thus far: Keeping the current wiring the same (see photos) with the exception of the red winding wire NOT grounded as you described, will produce an open circuit for which the motor does not run. However, removing those (red) wires/circuit from that brush plate screw lug and manually connecting a ground wire to that red winding, will run the motor (in reverse). Removing that ground wire from the same red winding wire and connecting the same ground wire to the green winding wire on the brush plate lug between the two brush holders, will run the motor (forward). I learned a ton more about simple motors. I'm satisfied now.

I'll wire the motor to run forward and assume there is some up-stream amiss with the board's switching of the two (red and yellow) circuits. The unit does have a 2-position "lockout" switch, but it seems to have no effect in either position. My take-away "news-to-me" is that power comes from that brown lead, through the armature plate to the other brush holder, then goes to both the red and green winding leads, and depending on which winding is grounded at its other end, the motor runs in one direction or the other direction. The board is controlling the grounding of the red and the green windings.

@TheLloyd posted:

...thank you for digging into this...

Just to be very clear, neither of those red or green windings should be grounded at all. One set of field winding leads, a red & a green, is properly connected to the one brush... so that means that each other end, one red & one green, must go straight to the reverse unit. The other brush must be grounded to chassis.

All the reverse unit does is select which field winding, red or green, is connected in series with the brushes. The brown wire is the common return to the reverse unit and usually wouldn't be needed, but the reverse unit must need it for feedback. It looks like, based on some messy soldering, that some wires have been switched around.

Thanks for the clarifications. I assumed that under a prior owner the factory wiring may have been changed up. For a novice like me, this just added to the confusion. However, and with your support, I do have a better understanding of how these motors run.

The voltage readings I got from the board leads follow: brown @ 12v (same as transformer setting) when meter grounding lead to frame) and @ 1v when meter grounding lead connected to red and yellow board wires (regardless of the lockout switch setting). So, I assumed the grounding directional circuits were faulty (open). Given your clarification I'm at loss to explain the current wiring scheme's results.

Currently, and I thought in acceptable for the time being, running condition, the brown wire is soldered to one brush holder and a set of green/red winding leads are soldered to the other brush holder. The red and yellow from the board are capped and tucked away (doing nothing). The other red from the winding is grounded on the brush plate screw. The other green from the winding remained untouched on the lug between the brush holders.

@TheLloyd posted:

red from the winding is grounded on the brush plate screw. The other green from the winding remained untouched on the lug between the brush holders.

That is not a ground connection! That is the red field wire strain relief lug and must be insulated from that screw in the same way that the green winding is on the insulated strain relief lug between the brush holders as you have observed. If it is grounded, it will only run in one direction.

Rob, Unfortunately there is something wrong with the board directional unit and the only way to run the motor is one direction with a hard ground to, say the brush plate screw.

Have you swapped the yellow & Red wires to confirm this?

Here are photos of the correct wiring, and also the insulating Nylon shoulder washer circled that MUST be in place for the motor to run in both directions.

Also. a more accurate wiring diagram reflecting the yellow wire.