Making a Stealth analog BLI AC6000

[u18b]

I have two BLI AC6000s.

I got one pretty cheap with a blown sound decoder (not the faulty one).  They won’t replace- and that’s OK.  I didn’t expect them to.

The point of this thread is this:  I have a blown decoder and BLI wants $130 for a new one.

So, I now have several options.
1.  Pay BLI $130 for a stock Paragon 4 decoder.
2.  Install an ESU Loksound 5 micro ($120)
3.  Install a plain non-sound decoder (about 30-45 bucks)
4.  Make this loco analog (free!).

I’m opting for free.  And I can always go back an add an ESU later if I change my mind.   I guess making this analog will make this a “stealth” unit.

(And this is not the first time I’ve done something like this.  I bought a used first run Athearn Challenger.  Man, the sound was wonderful.  Loved it.    Then the decoder fried one day because of all the issues that run had.   So I hot-wired the plugs for a Digitrax decoder.  )

I pulled the shell off the ac6000 and removed the BLI decoder.  The wires that go to the LED in the cab broke – which made me very happy since I really hate the light in the cab.  I pulled the plug out of the nose circuit board and tossed aside.



I then went through my parts bin.  Through the years, I’ve saved most of the light boards I pulled out of locomotives when I converted them to DCC.   I found a very old Atlas board labeled 645-X001.  I think it had only diodes for directional lighting and old incandescent bulbs. 

I removed the bulbs and diodes because all I wanted was the board.




You can look at the chassis and get an idea of the wiring harness.   There are two plugs- one at each end.  I’m going to eventually remove them.

Here is how my ac6000 is wired (not sure if your color coding will differ).  I identified the wires by simply tracing them to their component origins.


Rear plug has:
yellow and orange speaker wires
black and gray track wires
red, black, and brown LED wires in the middle.  The red is rear LED positive, the brown is rear LED negative, and the black LED wire runs up front.

Here is the rear plug




The front plug has:
blue and yellow to the motor
black and gray track wires
black, red, black, and brown LED wires in the middle.

[u18b]

No need to cut off the plugs.   You can simply pull the wires sideways and they come free from the plug.  I started with the yellow and orange speaker wires.



The LED wires were pulled aside for now.  All I cared about right now was the black and gray pickup wires and the blue and yellow motor wires.   I just want to get the loco running.

I pulled all the wires out of the rear JST plug. 
I then only pulled to two outer wires on each side of the front JST plug.  These are the gray and black track wires and the blue and yellow motor wires.

By leaving the LED wires in tact, this allowed me to examine them better in a moment.
I removed the screw low at the frame behind the front circuit board.  This allowed the front LED board to come loose.





The plugs are all removed and all wires free.


Since I am not currently running sound in this loco, I pulled the fuel tank off and then tucked the orange and yellow speaker wires into the fuel tank.

I wanted to secure the board with the stock screws, so I measured and cut notches in the old Atlas circuit board.  Short end is to the front.





I covered the rear metal frame with Kapton tape in the rear of the board.



I then mounted the new circuit board with the stock screws.

I soldered the gray wires to the left side of the board.
And the black wires to the right side of the board.
I then  soldered the blue motor wire to the left side and the yellow motor to the right (to match the typical direction of most analog locos).

I tucked the excess wires away and took it for a test run.  It ran perfectly and quietly.

[u18b]

Now I can turn my attention to LEDs.

The rear is easy.
I soldered a 1.5k SMD resistor in the gap and the LED wires as follows.  The red wire goes to the plus trace (on the left gray side) and the brown wire goes to the resistor.

[u18b]

The front is a bit more complicated because there are a lot more LEDs to deal with.

The back of the front LED board is labeled.
The long black wire u top is for the cab light which I removed- so I don’t need it.

The rest in order from top:
Brown is front headlight
middle black is ditchlights
Red is positive.
Lower black is ground.






I am not an electron head.  I’m slightly OK at following traces and figuring out what’s happening- but this one was tough and confusing.  I didn’t think I could add decoder wires and make this work.



So I made my own double sided board cutting traces with a motor tool.  The big upper LED is the headlight.   
The upper to the sides are the number boards.    The two bottom are the ditch lights.

I tried to do this so that- while analog for right now with all lights coming on together- I still have the option of going DCC later. 

So all LEDs have the same positiove common connection (eventually the blue DCC wire).



It had to be the same size to fit in the loco chassis and the light cover.



On each of the negative pads of that board, I drilled a small hole and soldered .014” brass wire on both sides.   This got electricity to the back side of the board.

From those brass wire jumpers (now trimmed off) I added resistors.  Each LED has its own resistor (as @peteski is always reminding me is good practice).

Now, one negative wire will solder in the middle to feed all LEDs.  In the future, if I go DCC, I’ll need to separate the lower two for ditch light control.  The main CSX nose headlight and the number boards may be lit together.



Test run- and it works. 
This light board was the most time consuming part of this project.

[u18b]

I used blue and white DCC colors for the wires to keep them straight.
The LED board is mounted in place with its screw.




Polarity could be decided by trial and error (you have a 50/50 chance of getting it correct on first try.).

But the Atlas board have little plus and minus marks up by where the headlight was.  So I soldered the blue wire to the right side and the white wire to the left side.



Test run- and all works.

I now have a stealth BLI AC6000.
All lights light up and are directionally controlled- like most analog locos.

And if I ever decide to spend an extra $120, I can install a LokSound decoder fairly easily.

But for now, free is nice.

[peteski]

Problem with BLI decoders is that they do not adhere to the DCC standard.  Unlike other DCC decoders which use positive (blue) common for all the function outputs, BLI uses common ground. So converting a BLI loco to standard DCC requires reversing polarity of all the LEDs (or making your own PC board). 

As for the polarity of SMD LEDs, like most other LEDs out there, the cathode (negative side) has some sort of markiing. Usually on both the top and bottom of the package.  On the top there might be tiny spot of paint, and on the bottom is usually an arrow or a T-shaped marking where the arrow points to the negative side.

And as far as the track pickup goes, if the right rail is positive, and left rail negative, loco should run forward.

Couple of suggestions for using white LEDs:
1. they can be easily damaged by reverse voltage (even as low as 5-12V).  A protection diode shoudl be wired wither with series with the LEDs, or paralell reverse (after the resistor).  It will protect the LEDs from excessive reverse damage.

2. The LEDs in the opposite travel direction (rear) will likely be flickering (due to the reverse polarity BEMF generated by the rotating motor armature during brief losses of contact with the track.  Installing a small capacitor in parallel with the LEDs will prevent the flicker.  If you look at typical Kato DC light board, you will see those capacitors installed on it.

[mu26aeh]

I got one with a burned decoder, some heat damage to the long hood.  I asked about any replacement shells.  They responded with yes, we have one and for the price of $56 it can be shipped to your door.  Needless to say I still have the heat damage shell.  I don't mind paying but that's a little steep in my mind.  So instead for free, I might just be modeling that door panel being open

[u18b]

Any of you guys have a second run AC6000 and can take a photo of a stock chassis.   Mark wants to add it to his website.

I informed him that I discovered BLI changed motors.   The second run motor is the one you see in my photos above- black open sided like a Kato or Atlas motor.
The first run used closed motor that was silver.

I noticed the new motor is quieter.

Bottom line, with my blown decoder, I don't have a photo of the stock configuration.   I had already tossed it.

So let me know if you can take a good photo for Spookshow to update the BLI page.

Second run is in the 3000 series in the crystal box.
Third run is 6000 series.
First run is 3000 series in mammoth cardboard box.

[LarryN]

I am modifying a BLI AC6000 chassis also, but to serve as the running gear for a U50C. I used silicon casting putty from Micromark to make impressions of truck side frames from my UP Turbine. I then made castings with JB Weld. They came out OK. I just cemented the side frames onto the  ones on the AC6000, after thinning off the original detail as much as I could. Some time back, I purchased a U50C from Shapeways (I do not think he is making them anymore).
I too intend to  run it in analog fashion. It is a good chassis.

Larry N