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B&O HO EM1 wiring schematic and harness pin call out

Started by Chazz53, January 22, 2019, 09:54:04 AM

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Chazz53

I recently purchased a used (and damaged) B&O EM1.
The four wire harness connector was gone, and I ordered a universal 4 wire harness.
So far so good. Identified the motor's positive and negative connections, but have reached a mental stumbling block with other factors.
I am converting the factory decoder to a TSC Wow package. Now I have discovered that the tender trucks have complications, in that wheelsets were removed and installed haphazardly.
Some are reversed, I suspect.
So here are my questions:
Are both tender trucks supposed to pick up track voltage from the same rail, or are they staggered? If staggered, which rail does each truck pick up from?
And where do the tender truck leads connect on the Wow-Bac-3 #1902? I have the following link open but confusion exists...
https://tcsdcc.com/installation/ho-scale/bachmann-2-8-8-4-em1-steam/wsk-bac-3

Thanks in advance!
Charlie

rich1998

#1
Welcome.
The below link should show you. You can see the insulators for the wheels.
Front truck, left rail.
Rear truck, right rail.
Jonathan is the resident expert for this loco and he should be around soon to verify. I think he has two. He has posted photos here in the past.
There are other diagrams for this loco in the Information page. Look in the Parts page also if you need parts. Not many but you can call the Parts department.

https://www.bachmanntrains.com/home-usa/dwg/dwgs/HO_2-8-8-4_(4).pdf

Rich

Chazz53

Ah! Thanks Rich!
I see the details on the tender wheels, now.  Never thought of checking the parts breakdown.  ::)

Will still need some direction on the rest of the wiring, but probably won't get to it until later this evening.


rich1998

I have some Bachmann steamers.
The two pin connector is for driver pickup from the loco.
Wrong polarity, when you plug in the tender you get a short.
I replaced connectors on a loco once.
The four pin, two leads are for the motor and two leads for the headlight which you might know by now. I do not remember which ones but a ohmmeter will help you figure that out. I am sure you know LED's are polarity sensitive and you cannot read them with an ohmmeter.
When Jonathan shows up, he will help you.
Good luck.

Rich

Chazz53

Thanks, you've given great info. Now I can continue the install of the decoder.

rich1998

#5
Just in case, a nine volt battery and a 1k resistor will show which leads are used for the LED headlight. No idea of your DCC experience.
No idea where Bachmann hides the two inductors and capacitors they put in locos now. They do hide them in the loco sometimes. The caps affect slow speed when using BEMF with quality decoders.
I suspect it is on a PC board in the rear of the loco but it might not be an issue. Jonathan would know.
I know the motor resistance will be under a hundred ohms. Been a long time since I measured a motor.
Everything should be fairly easy.

Rich

Chazz53

I got the tender straightened out as far as the trucks are concerned. Also have the 2 wire  harness to the driver wheels connected to the corresponding truck leads, and stopped there for tonight.
Took a 20 year hiatus from my model railroading, but followed from a distance at times. New to DCC for thr most part.

rich1998

Progress. Sounds good so far.
What is your DCC system?
I use to use the NCE Power Cab. It can easily be expanded but I never did. I only ran three sound locos at home. I would take the cab to the club where we had the five amp Power pro

Rich

Chazz53

I am dabbling with an original Digitrax Zephyr. About 16-18 years ago,I bought it from my cousin who was a Digitrax dealer. I had dismantled my basement layout, and moved into a small apartment with only enough room for a 4x6' oval. Basically, just used it in the DC mode for a couple of months and packed it away.
Over the years I bought a loco now and then, and a few decoders, mostly Digitrax, until recently, when I decided to build a new layout, and equip some with sound. Have a number of P2k GP9's/18's, Stewart F units, Bachmann F units, and added to the brass collection of B&O steam with this Bachmann EM1.
I should be able to stay pretty busy when i retire!

rich1998

Well that sounds good. Still a decent system.
I retired in 2006. I turn 78 in April. Eyes and shaky hands at times I cannot model anymore but had a lot of fun.
Ride bicycle on rail trails in my area in good weather and watch train forums. Former station in my little city is now a bagel shop.
I can ride thirty miles a day, trails and roads. Manhan Rail trail connects to two other rail trails. Off topic.
Cheers.

Rich

Chazz53

Wow, thirty miles?! My hat is off to you! And thanks for the valuable help!

Regards,
Charlie