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adding decoder to old BB loco

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  • Member since
    March 2023
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adding decoder to old BB loco
Posted by John Gray on Friday, December 22, 2023 11:47 PM

all my BB locos are now going to get decoders, they are wired as 5-wire style (DC)

I have a light board and an 8-pin decoder, what wires do I need to move and or fix?

my original wiring is done this way + wires are soldered to the truck engineer's side frame and the - wires to the other side frame, LED lighting is directional. athearn DCC-friendly motors, no sound. Well, that is about all for now.

Merry Christmas and a happy newyears 

John

 

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Posted by basementdweller on Saturday, December 23, 2023 2:25 PM

Hi John, it has been some time since I have hardwired a Athearn BB loco. First things first make sure the loco is a solid and decent running loco with DC, DCC will not improve any poor running loco.

The motor needs to be isolated from the frame, remove it and place tape over the contact strip in the bottom of the frame, swap the copper motor clips so the clip with the two prongs is on top of the motor and not eating into the tape. While you have those motor contact strips off solder you orange and grey decoder wires directly to them. Go easy removing the contacts as springs and brushes are under them and they will fly away forever.

Solder red and black pick up wires to each side of the truck frame with additional wires between each truck for 8 wheel pick up. 
Remove the bonfire in the cab bulb and wire in an LED behind the headlights, get creative with using a straw or heat shrink to hold LED in place. 
I use to try and place the decoder under the DB blister as there is limited room inside these locos. 
Good luck.

There is a decoder available that hooks into this loco without soldering but in my opinion it's not worth the additional cost. 

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Posted by John Gray on Saturday, December 23, 2023 2:54 PM

Thank you this helps very much

John

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Posted by mbinsewi on Sunday, December 24, 2023 9:23 AM

Basementdweller does a nice job of explaining the basics of the process Yes

The decoder harness that was simple no solder install on Athearns in no longer availiable.  I didn't like them any way, they didn't provide good solid contacts.

There are a zillion YouTubes on doing this as well.

A big percentage of my locos are refurbished and dcc hardwired Athearns.

Good luck!

Mike.

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Posted by MisterBeasley on Sunday, December 24, 2023 1:40 PM

Don't forget the couplers.

I've also put decoders into old BB engines for my layout.  I used the traditional Kadees.  This can present a problem depending on how the couplers are mounted.  I make sure they are mounted in plastic Kadee draft gear boxes, which insulate the coupler shafts from the engine frame so the couplers never receive rail power.  In some installations that use the frame as part of the circuit, if the couplers are hot you have to watch which way the locomotives are pointed in a consist to prevent shorts.

It takes an iron man to play with a toy iron horse. 

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Posted by John Gray on Monday, December 25, 2023 12:10 AM

the hot wires go to the trucks and the frames are used for grounding 

Thanks for all the info now on to tomorrow's food and family.

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Posted by jjdamnit on Monday, December 25, 2023 3:07 PM

Hello All,

John Gray
(T)he hot wires go to the trucks and the frames are used for grounding

Yes!

A word of caution:

DO NOT USE THE FRAME AS AN ELECTRICAL CONDUIT (PATH)!!!

If you do not isolate the trucks and motor from the frame you will fry the decoder.

To completely isolate the trucks and motor from the frame you will need to remove them to perform this surgery.

basementdweller
...swap the copper motor clips so the clip with the two prongs is on top of the motor and not eating into the tape.

To swap the top and bottom motor clips you will need to cut the long top clip at the point where it clips onto the motor and use this as the bottom clip.

basementdweller
Go easy removing the contacts as springs and brushes are under them and they will fly away forever.

When I am converting an Athearn BB to DCC I go so far as to paint the well in the frame, under the motor, with "Liquid Electrical Tape" available online or at your local or big box hardware store.

If you are a "Suspenders & Belt" kind of person you can also add Kapton® tape to the bottom motor clip.

Athearn BB truck towers have an upside-down "L" bracket that contacts to the long upper motor clip.

I cut off the inverted "L" bracket flush with the sides of the trucks.

On the opposite side of the trucks, there is a bracket that contacts the frame.

This contact needs to be cut off at the same point you cut the other bracket.

Now the trucks and motor are completely electrically isolated from the frame.

basementdweller
While you have those motor contact strips off solder you the orange and grey decoder wires directly to them.

The Red (Right Wheel Pickup) and Black (Left Wheel Pickup) wires need to be soldered directly to the metal sides of the trucks; where you cut off the contact brackets.

basementdweller
...wire in an LED behind the headlights, get creative with using a straw or heat shrink to hold (the) LED(s) in place.

When converting to LEDs you will need a resistor on one leg of the LED.

I get my LEDs from MoreLEDs.com.

They include the correct resistors with every order along with handy printed instructions for both DC and DCC installations.

MisterBeasley
I used the traditional Kadees. This can present a problem depending on how the couplers are mounted. I make sure they are mounted in plastic Kadee draft gear boxes, which insulate the coupler shafts from the engine frame so the couplers never receive rail power.

More great advice on further isolating the frame to avoid frying a decoder!

I also go so far as using the non-conductive Kadee Nylon 2-56 (#256) screws, cut to length, to attach the gearboxes.

Keep the questions coming and let us know how you are progressing.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by wjstix on Monday, December 25, 2023 4:07 PM

John Gray
I have a light board and an 8-pin decoder

Note that if it came with a lightboard attached, some early ones with the lightboard did not have the motor isolated from the frame, so you still have to do that. If it doesn't have a lightboard, you can add it, or get an 8 to 9 pin harness and just do it that way. If you use LEDs, you'll need to add a resistor in that case.

Stix
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Posted by jjdamnit on Monday, December 25, 2023 4:19 PM

Hello All,

wjstix
Note that if it came with a lightboard attached, some early ones with the lightboard did not have the motor isolated from the frame, so you still have to do that.

Your observations are spot on!

I believe you are referring to "DCC Ready" a very confusing term.

No Athearn BB was ever "DCC Ready."

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by John Gray on Tuesday, December 26, 2023 12:39 AM

Ok, everybody, the BB engines are good old BB engines. The light board I bought has an 8-pin receptacle for the decode and is plugged in now.  The LEDs have resistors, the frames are isolated from rail power, and all of the after for the mentioned wiring is done but the engine motor power wiring.M1 M2 on the board.

all this is so hard to convey but with all your guy's help I can finally get at least one working properly 

thank you 

John

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Posted by jjdamnit on Tuesday, December 26, 2023 4:26 PM

Hello All,

John Gray
(A)ll this is so hard to convey but with all your guy's help I can finally get at least one working properly.

That's great!

The first conversion is typically the hardest and most time-consuming.

Since you've got the first one "under your belt" the rest should become easier as you go.

I've gone back to past conversions- -with the new knowledge I've gained through experience- -and redone work to improve previous work.

Now that I've jinxed you...

If you run into any "head scratchers" please make a separate post so the new issue doesn't become buried in the old post.

Congratulations again and as always...

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by wjstix on Wednesday, December 27, 2023 9:15 AM

John Gray
The LEDs have resistors, the frames are isolated from rail power, and all of the after for the mentioned wiring is done but the engine motor power wiring.M1 M2 on the board.

If you're using a lightboard, you probably don't need to add resistors; that's kinda the original reason for lightboards pre-DCC. Using a regular 9-pin harness is probably the easiest way to convert a BB engine, and there's a lot of info in books on DCC and online showing step by step how to do it.

For engine headlights I like to use Evans Designs LEDs that come pre-wired with a resistors so you can use it with any power source up to I think 15 volts AC or DC without needing to add anything.

Stix
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Posted by John Gray on Wednesday, December 27, 2023 2:10 PM

thanks everybody for this help Ill let you all know how it comes out.

John

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Posted by John Gray on Wednesday, January 17, 2024 2:02 PM

once you cut the engineer side bracket side off how do you hook up the truck to the frame? ( it does have the locator pinhole?) I know stupid question. But if you don't cut the bracket off can you put a thin shim there to do the isolation factor?

John

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Posted by jjdamnit on Wednesday, January 17, 2024 5:44 PM

Hello All,

Yes, a shim of thin styrene can be used to insulate the bracket (bolster).

However, if the shim wears through and the "live" bolster conducts with the frame bad things happen quickly!

Another option would be to make the bolster out of thicker styrene and use "Thick " or "Gel" type CA (Super Glue to carefully adhere it to the trucks, being careful to not get any CA on the gears. 

What I've done when making this conversion is carefully cut the top of the bracket off and file it even with the plastic on the truck creating a gap between the two metal pieces.

Then I use two-part epoxy to reattach the bolster.

An advantage to using the thicker 2-part epoxy is that you can control where it goes and once dry, it provides some insulation between the two parts.

Then you solder the wheel pickup wires to the metal sides of the truck.

As Albert Einstein was credited with the quote...

"Once you open a 'can of worms' the only way to get all the worms back in is to use a bigger can."

Many of these conversions or "upgrades" require a "bigger can".

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by Geared Steam on Thursday, January 18, 2024 2:08 PM

"The true sign of intelligence is not knowledge but imagination."-Albert Einstein

http://gearedsteam.blogspot.com/

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Posted by John Gray on Thursday, January 18, 2024 8:42 PM

what I did was cut off the bracket and file the little metal piece to fit I used CA, but it came off, and now I have wasted trucks . I'm going to use shims from my computer building stuff very thin but made out of hard fiber. The next set will be as you said epoxy oh ya , already bought some two-part thick.

John

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Posted by John Gray on Thursday, January 18, 2024 8:44 PM

I talked with Larry Puckett email he is so good with dcc

thanks 

John

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Posted by Polarys425 on Friday, January 19, 2024 5:54 PM

Can you elaborate on how using the frame as a negative electrial path will fry a decoder? Seems like the frame would just be a "wire" from the truck pad and one could simply run wire from the frame to the decoder. In theory anyway.

Thanks,

Kevin

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Posted by jjdamnit on Thursday, January 25, 2024 1:41 PM

Hello All,

Polarys425
Can you elaborate on how using the frame as a negative electrical path will fry a decoder?

The Proto 2000 BL2 locomotive I'm dealing with does not have a plastic tank cover.

The metal frame is just painted black.

If the frame shorts out on the track power by derailing it can fry the decoder and possibly damage the DCC components if they are not protected by a circuit breaker.

This can also happen if the couplers are metal and not isolated from the frame when using the frame as an electrical path.

When the trip pin shorts against the rail it can fry the decoder.

The best practice is to completely isolate the motor from the frame and use wires from the wheel pickups to the motor.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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