Want to Replace DCC Guts of HO Scale Atlas B30-7

[peteski]

Hi Dave.

Just so you'll know: my understanding is that the AS-MB2 board comes with a separate KA4 keep alive (that is, the keep alive is not on the board, but plugs into the board).  If you are planning on using the keep alive, the KA4's dimensions are 13.25mm square by 11.5mm thick.

One of the circuit boards that you're going to keep has some hefty-looking caps on it; I wonder if these are keep-alive caps, and if they could be used in place of the KA4?

John C.

QSI usually has a 1000-2000uF of electrolytic caps. Good enough for some stay-alive, but not a true keep-alive (like KA4 which will keep the motor running for more than a second).
I have been trying to keep my terminology standardized.  Any circuit rated up to few  thousands of micro Farads which will keep the decoder powered for about a second or less is "stay-alive". Any Super Cap circuit where the capacitance is in hundreds of thousands of micro Farads which will keep the model running for a second or more is "keep-alive" to me.

[davefoxx]

According to TCS:

The Keep-Alive™ (KA) devices are used to supply power to decoders during times of power interruption due to dirty track or problematic track work.

KA4 will power an HO-Scale locomotive with headlights on for approximately 6 to 20 seconds (depending on the locomotive and the efficiency of the motor).

Wow!  I'm certain that's light years beyond whatever capacitor is on the QSI board.

DFF

[peteski]

According to TCS:

Wow!  I'm certain that's light years beyond whatever capacitor is on the QSI board.

DFF

Exactly - I  was just trying to clarify the terminology.

[k27463]

@k27463,

Boy do I appreciate the knowledge around here.  Thanks to everyone for your help.  I apologize for my ineptitude at what probably is basic electronics.  Thank you for your patience.

DFF

I only know this stuff cause I mostly do HO 

I did install Tsunami 2 in a Kato FEF last night...

[davefoxx]

Bummer!  I received the package in the mail today with the motherboard and decoder.  Unfortunately, the dealer shipped a TCS B-MB7 instead of the AS-MB2-NC, and that motherboard is waaaaaaaay too wide to fit under the hood of even an HO scale locomotive.  I believe it's for a Bachmann steamer, so it goes into a tender.

This was going to be this weekend's project, so utter disappointment abounds.

DFF

[davefoxx]

Well, with the order screw-up, as mentioned in my last post, this is far as I can go on this project now.    I removed the factory QSI decoder and installed a piece of black 0.080" styrene to fit in its place.  The styrene will give me a solid flat place to installed the TCS motherboard.  As for wiring, here's what I have figured out (from left to right):

1) From what I believe are red and black wires (with the heat shrink tubing) is the wiring for the headlights (low nose) and numberboards (above the cab);
2) A pair of black wires (front truck wires);
3) Another set of red and black wires (motor wires);
4) A third set of red and black wires (speakers, clearly wired in series); and
5) Another pair of black wires (rear truck wires).



What is missing is the wiring for the rear headlight, which had been cut off of the QSI decoder.  Here's the circuit board that was installed over the rear truck, for those of you who were curious as to whether the blue things were a keep-alive.  Experts?



I want to cut off the unnecessary parts and salvage the LED and circuit board, because that will place the rear light in the proper location.
 


Thanks,
DFF

[drbnc]

Unsolder the blue capacitors from the board.  Then remove the blue and black wires from the left side of the board in your first pic.  The remaining black wire is the LED cathode ( - ), the red wire goes thru the resistor, that is the LED anode ( + ).  If your decoder already handles LEDs without needing additional resistors, just  run the + lead to the other LED pad.

[davefoxx]

@drbnc,

Awesome.  Exactly the information I needed.  Thank you!

DFF

[davefoxx]

I removed the components from the circuit board and moved the red wire over to the LED lead, since the motherboard is supposed to have the proper resistors for LED use:



The circuit board and rear LED have been reinstalled into the locomotive.  This puts the LED back where it belongs.  Just need the motherboard.



DFF

[k27463]

I removed the components from the circuit board and moved the red wire over to the LED lead, since the motherboard is supposed to have the proper resistors for LED use:


The circuit board and rear LED have been reinstalled into the locomotive.  This puts the LED back where it belongs.  Just need the motherboard.

DFF

*sniff* They grow up so fast.


Looks like you're on the right track

[davefoxx]

Bingo!  Success!!!  Thank you to each and every one of you who contributed to this thread.  As you can see, the motherboard is wired up (except for the Keep Alive), and the locomotive is running beautifully.  It sounds 100% better, despite keeping the factory speakers.  I can always update those later, if need be, but the sound is so much better that I'm satisfied for now.



Shell on (it fits!) with front (nose) headlights and numberboards (over the cab) on:



Shell on and rear headlights and numberboards on:



The only problem that I had was that I had a 50% chance of wiring the motor wires to the correct pads.  Of course, I got them backwards, because the wires were not colored according to the NMRA specs.  No biggie.  I adjusted the necessary CVs to reverse the direction and the headlights.

Oh, and I plan to mount the Keep Alive by double stick tape to the circuit board that the rear headlight is mounted to.  It will tuck in nicely under the LED and over the rear truck.  I also need to build the Sergent Engineering couplers for this locomotive.  But, since I have to be to work in less than 3-1/2 hours and I haven't gone to bed, that should probably wait. 

DFF

[peteski]

Looks (and I'm sure sounds) great!

The only problem that I had was that I had a 50% chance of wiring the motor wires to the correct pads.  Of course, I got them backwards, because the wires were not colored according to the NMRA specs.  No biggie.  I adjusted the necessary CVs to reverse the direction and the headlights.

I always find it confusing when people say they did this.
If you just flipped the direction bit in CV29 then the motor and headlight would have flipped direction (CV 29 is not just for the motor but for the entire decoder ot "locomotive").  This would be done in this type of locomotive if the railroad ran them long-hood-forward, or if the entire decoder (not just motor) was installed backwards.

Or did you flip the direction bit in CV29, *AND* then also reassigned and flipped the F0F and F0R (both headlight outputs).  If you did that then it seems to me much less complicated (and possibly problematic in the future) to just flip and re-solder the 2 motor leads. 

[davefoxx]

I did change CV29 to get the locomotive going in the correct direction.  But, I had to also correct the headlights, which was done with a mere three or four mouse clicks in the Function Mapping with the LokProgrammer.  That's a ton easier and quicker than resoldering the motor leads and resetting CV29.  Not to mention the risk of me screwing something up with a soldering iron.

I've actually never had this happen before.  For example, on an Athearn Southern Ry. GP38-2, I adjusted CV29 to make the long hood forward, and the headlights changed simultaneously and didn't require the extra step.  I believe that locomotive has Tsunami onboard, though.

DFF

[davefoxx]

Here's where the KA4 (Keep-Alive) was placed.  Under the rear headlight in the long hood.  Double-stick tape helps it stay in place and makes for a nice fit.  The truck does not bind with the KA4, and the headlight is just as visible.



Calling this project done.  Just needs couplers, and it's good.

DFF

[davefoxx]

Here you go!  A video to compare the old QSI to the new ESU decoder.  B30-7 No. 5515 is the QSI unit.  No. 5502 is the new ESU unit.  Much better!

The QSI unit is first in the video followed by the ESU unit.

/>
DFF