# Wiring Diagram



## flyernut (Oct 31, 2010)

I need a simple, easy to follow wiring diagram for a 377, not the usual ones a person would fine in a manual, etc..I have one that's causing me fits, and I believe the wiring is messed up.


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## T-Man (May 16, 2008)

I worked on one in 2013, a diesel with sound caused by a vibrator. A pair 377/378 this was the non motor side.


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## Firewood (Nov 5, 2015)

The Portlines site diagrams are pretty good. 377 here: http://www.portlines.com/images/WIRING DIAGRAMS - 377 DIESEL.jpg


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## flyernut (Oct 31, 2010)

Firewood said:


> The Portlines site diagrams are pretty good. 377 here: http://www.portlines.com/images/WIRING DIAGRAMS - 377 DIESEL.jpg


Thanks, but I already have that one. I was thinking maybe something color-keyed to the same Gilbert colored wiring.


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## Sagas (Dec 13, 2013)

What I've attached is for 4713. It is not color coded but has a more detailed wiring diagram and should work for the 377 as well.


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## mopac (Feb 24, 2011)

Sagas, link is not working for me.


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## Sagas (Dec 13, 2013)

Just edited it so try now. J.B.


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## flyernut (Oct 31, 2010)

Thanks all for the replies....I HATE DIESELS!!!...I am truly baffled on this one!!!!! This will be my very first engine in 30 years I could not repair!! Did I mention I hate Flyer diesels???This one is going to go to a higher power than me.. I'll have to get the customer's ok for me to take to the"professional" shop.This particular engine belongs to a guy who I have worked on 4 of his steam engines, and he loves them. He asked me about diesels and I told him I would look at it...I hate diesels...I thought it would be a easy fix as the field had several laps of broken wires in it, and I put in a NOS field. NOTHING!! E-unit cycles 100%, both lights work, (377), new top fingers, polished drum, brushes are like new, armature cleaned and polished and centered,actually a great chassis....I've cut wiring, added wiring, returned to original, checked continuity, I've got at least 12 hours into this engine, and I'm no farther with it than the day I got it in the mail. It must be something simple/stupid. I've walked away from it several times to no avail..Brushes are in contact with the drum,all insulating bushings are intact, wiring is correct.. I've told the gentleman no charge for the hours I have into it, just the cost of the field.


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## T-Man (May 16, 2008)

My first question is: DId the motor ever run? After cleaning, I bench test the motor. Just to get life out of it. You replaced the field but did the armature check out.? You may have fixed half the problem. If the motor was just placed on the frame it complicates everything. Insulators, insulators insulators. Are the insulators all there? Intermittent working is normally a short. I would check the axles too. They have insulators.. See if traction tires were added. I cannot remember if they are both insulated.

Back to the armature, they are held in on both ends by a plate and screw. Does the armature spin? Is it too tight?
These are just some thoughts.


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## flyernut (Oct 31, 2010)

Have to talk to the customer, does he want it to go to my "specialist" or does he want it back?..I'm done..I knew I shouldn't have taken it in, but I've repaired these quite a few times in the past, both single and dual motor.


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## flyernut (Oct 31, 2010)

T-Man said:


> My first question is: DId the motor ever run? After cleaning, I bench test the motor. Just to get life out of it. You replaced the field but did the armature check out.? You may have fixed half the problem. If the motor was just placed on the frame it complicates everything. Insulators, insulators insulators. Are the insulators all there? Intermittent working is normally a short. I would check the axles too. They have insulators.. See if traction tires were added. I cannot remember if they are both insulated.
> 
> Back to the armature, they are held in on both ends by a plate and screw. Does the armature spin? Is it too tight?
> These are just some thoughts.


Armature is free, clean.. Power to the brushes, power to the field. the only thing left is the armature..Now where to find the correct one??? Are they interchangeable?? The armature I need is a XA12AO62. Secondly, how do I check the armature for any shorts, etc?? Electricity is not my forte, easy to understand terms would be helpful.


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## T-Man (May 16, 2008)

The three plates that contact the brushes are connected. Check with the meter on ohms you should not get 0 between any two plates.
Now EACH plate is isolated from the shaft. So with the meter from one plate to the shaft should read 0 and be the same for the other two plates. The plates are connected so if one is short they will all read as a short. I check each anyway.

These armatures are all the same for the diesels with worm gears in each side. The design is the same as my 71 dual motor diesel.

Piece # 13 has to be in perfectly since it holds the field around the armature. The side srcews go all the way in to be flush. I remember that it was a small challenge to get it right.


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## mopac (Feb 24, 2011)

flyernut, it would be best to try another armature. Chuck says they are all the same. I am sure you remember the armature trouble I had with my 282. It tested great with my meter. Well, it wasn't. Tried another armature and that took care of my problem. It is now my best running and fastest engine. Not sure armatures go bad that often but they cause the dickens when they do. My 282's problem was why I joined this forum. I was hoping to find someone that could help me. I did not get any help that worked but the guys sure suggested things to try. My 282 was running
slow and motor getting extremely hot. Good luck.


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## AFGP9 (Apr 8, 2015)

Flyernut the crazy problems you are having with that 377 is exactly why I got rid of all of my PA's. As I said not long ago, some ran well some didn't run at all well no matter what I did. Sold all of them and swore to never buy any more. Steamers only, thank you. However, I do have both versions of the UP 372's, 2 370's, link and a kc versions. Those all run fine. I have another 372 that has been in a box in pieces because I encountered much the same things as you have with that 377. Tried just about everything as you have to get it to run. I finally flat just gave up. That was 5 years ago. After reading the comments from T-Man I might go at it again even though what he mentions I pretty much did. I must have missed something. The 370 motor and plate arrangement sounds similar to the PA's and that brings back nightmares. Especially those side screws T-Man mentioned. 

Kenny


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## flyernut (Oct 31, 2010)

My customer says to just keep it, use it for parts, but are all the parts good??My wife says she can't believe I'm going to give up on it, she has never seen me do that before,lol..I'll try another armature, that's the only thing that I haven't replaced...But where do I find one???


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## Sagas (Dec 13, 2013)

The attached instructions below has values to test for field and armature and may be of some help or not. Alignment of the the field and armature is no fun either. On one it took me about two > three hours playing with the adjustment screws. Another thing to look at are the thrust pads (look like little black squares at each end of the armature chassis). If they are too worn or missing it can cause the armature to move too much laterally within the field. I agree they are a PITA to work on but when set up can run like a scared rabbit. J.B.

*What's important?*
_*
(a) The total thickness of the stacked plates (laminations) of the field should match the total thickness of the armature's stacked plates. If not, you have a mismatched motor, and it will not run well, and may overheat.

(b) The resistance readings of both the field and armature should not only be correct, but should be very similar.
How do you measure the resistance? - You'll need an ohmmeter or multimeter....

Armatures: 
The armature's copper commutator face is divided into three segments. Touch the two ohmmeter probes to any two of the segments to get a resistance reading. Repeat this for each of the other two combinations of two segments. All three resistance readings should be within 0.1 ohms of each other.... anything greater than that indicates a problem with the armature. Moreover, the actual readings should be within 0.2 ohms of the resistance readings listed below.

Fields: 
Disconnect the field connections from other wiring in the engine. Touch the two ohmmeter probes to the two bare ends of the field winding. Variation from the expected resistance should be no more than 0.3 to 0.5 ohms.*_


_*PRODUCTION YEARS*_​​_*ARMATURE*_​_*RESISTANCE*_​_*DESCRIPTION*_​​_*FIELD*_​_*RESISTANCE*_​_*DESCRIPTION*_​_*1950 - 1951*_​​_*XA11445*_​_*2.2 - 2.4 ohms*_​_*Stacked plates total 18/32" wide. Gaps are skewed (diagonal). Fits PA12C197
diesel chassis.*_​​_*XA11461*_​_*2.5 - 2.7 ohms*_​_*Stacked plates range from 16/32" to 18/32" wide. Plates are riveted together. Brass strip above them.*_​_*1952 - Early 1955*_​​_*XA12A062*_​_*1.9 - 2.0 ohms, or
2.3 - 2.4 ohms*_​_*Stacked plates total 22/32" wide. Gaps are skewed (diagonal). Fits PA12B065
diesel chassis.*_​​_*XA12A064*_​_*1.8 - 2.0 ohms*_​_*Stacked plates range from 19/32" to 20/32" wide. Plates are riveted together. Brass strip above them.*_​_*Late 1955 - 1957*_​​_*XA14B873*_​_*1.9 - 2.0 ohms*_​_*Stacked plates total 17/32" or 23/32" wide. Gaps are skewed (diagonal). Fits PA12B065
diesel chassis.*_​​_*XA13A036*_​_*1.8 - 2.0 ohms*_​_*Stacked plates are 21/32" wide. Plates are riveted together. No brass strip. *_​_*1958 - on *_​​_*XA14B873*_​_*1.9 - 2.0 ohms*_​_*Stacked plates total 17/32" or 23/32" wide. Gaps are linear.
Fits PA12B065 diesel chassis.*_​​_*XA13A036*_​_*1.8 - 2.0 ohms*_​_*Stacked plates are 21/32" wide. Plates are riveted together. No brass strip. *_​


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## alaft61ri (Oct 11, 2019)

When i bought mine year or 2 it ran ok so this was my first diesel clean replaced finger took armatures out cleaned put it back. well set on track ran it It went forward then reverse. Make a long story short the armatures i had them in wrong i had to flip them and its been running good since.
Al


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## flyernut (Oct 31, 2010)

I've found NOS armature for $29.95, and/or a used, guaranteed one for $35...To rewind a armature it's $69.95.


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