Installing DCC sound in a Bachmann 44-tonner

Started by JusticeCity, May 26, 2017, 02:32:38 PM

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JusticeCity

So I take on the next challenge,

https://youtu.be/8xzYvk9i3c4

and how it is going to be done, (you shoukd be able to view it niw.)

https://youtu.be/oY0NurBtD78

JusticeCity

You should be able to view part 2 now. Sorry about that but I firgot to make it public)

JusticeCity

I got the LokSound Select Micro V4.0 73844 decoder and a second small speaker. It was not cheap, all things said and done the decoder and parts are around $200 CDN.

It is cheaper to buy a new Bachmann 44 tonner with DCC already installed. However, I just wanted to see if I could do it and add my touches to it.

Here is the next video.

https://youtu.be/cXr2yDRbspk

JusticeCity

So I have learned a lot doing, or attempting to do, this conversion. However, I am going up! I blew the sound part of the ESU LokSound Select Micro V4 decoder (73844) by attempting to get the ESU 15 x 11 mm cell phone speaker to work. It overheated the decoder to the point where the shrink wrap melted then it just shut itself down. I cut off the speaker, turned down the master volume to 0 and ran the engine for a few minutes. The decoder board was too hot and then shut itself off again.

So I am considering this a learning lesson and closing down this failed project.

https://youtu.be/2-OM9J6mUGs

Time to go drown my sorrows.

Marty

tct855

#4
Marty,
           I want to take the time to show you some pics of some very difficult engines I rebuilt with Dcc sound some years ago that still run today on the F&SM rr.  I wanted to give up, but just couldn't let myself get away with that.

I rebuilt the Atlas S-1 4 times till I got it right.  I rebuilt the Bachmann 44 Tonner twice till I got it right.  I rebuilt the 45 tonner once then got it right.  Each time I knew it could be done, but kept having unforeseen  problems arrive which meant a total rebuild.

I stuck with it and finally won.  I would suggest to put only one 4Ω speaker in the cab, loose the light board and use a shorter cap lower in the frame.  You might find it works.  That's what I did.  Hope this helps Big M.  Thanx Thom...

JusticeCity

Thom,

Thanks for the pep talk.p and great pics.

The sound part or thr card is toast! I disconnected the cell speaker and connected another 4ohm speaker and zip nothing no sound. l can't afford the a new decoder ($150) and a better speaker at this time.

What I've done is to take the plastic off the decoder, cut a mica insulator such that the main chip sticks through it. I added some thermo gel and pressed the decoder directly to the frame and taped it in place. The frame acts as a heatsink and the decoder runs cooler.

I had not installed the capacitor yet and debating whether I should the recommended 25v cap or the shorter 16v one. Normally the voltages are overrated by 2-3 times. However, the blue line voltage is low enough that the 16v should be enough. Any thoughts?

I will add head and rear lights then weather/detail and then see what happens later. I think I will post video(s) when I get that part done. Maybe a new decoder will show up for Fathers day.

tct855

Marty,
            I know some of the decoder manufacturers will repair a damaged decoder for a small fee usually a 60% or more off charge.  Just fill out their repair form and mail in with the decoder.  When it returns you'll have a brand new decoder.  You'll need to check with Loksound to see what their repair policy is. Just an FYI.  Also, can't remember.  Did you wire the twin motors in series or parallel?  I did mine in parallel.  I think? ha. Can't remember, Getting old I guess.  T...

JusticeCity

Thom, my motors were in parallel.

I will inquire about the warranty, but expect including shipping, etc it may not be worth it.

Wife says it's time to focus on getting some of the repairs and painting done around the house. She has agreed to give me a few more days on the loco, but that's it. Boy do I feel whipped!

(Just found local train store has 20% off for Father's day. Hmmm, maybe if I do some of the work before than. I sucks being on a pension.)

tct855

M~,
      I totally understand on all points!  Now having said that, three things to explain to momma:

1) Don't care what anybody's argument is, but in my opinion this hobby is as expensive and time consuming as any or most other hobbies out there to do well! 
2) As far as engine building goes.  This is probably the most expensive & time consuming and most difficult and most rewarding art of the hobby.  If it were easy, all the modelers would be doing it!
3) You can always build engines for others to make that extra cash! You're good enough to!  However having said that.  N-O-B-O-D-Y can return your time spent on solving their problems.

I find if you give momma a soft kiss on the cheek & a smile- tell her you are the man! and she is the Whoa-man! but say it in latin. It sounds more noble... There's always rock collecting.  ;D

7thStreetShops

"There is always rock collecting".... I love it! Rock collecting is a lot of hard work. I use to do it - in Colorado where there are some 500 plus minerals to collect, most of them requiring DIGGING!

Collect Stamps! Once you get over paying outrageous amounts of fiat (paper money, no more valuable than the gov'ments good word that it is really worth a buck) cash for other, even smaller bits of paper, you can bore yourself to tears slipping them into those obstreperous plastic sleeves and looking at them! Yawn... But with NO sweat!

To all who may be interested - Ohms Law; Voltage over Amperage times Resistance. Two motors in parallel means (roughly) 1/2 total actual impedance (resistance) as opposed to the impedance of each individual motor. Motors in series means twice the total impedance over that of either individual motor. This is perfect in theory but pratice is rarely perfect.

Personal practical observations; the reality is that the impedance of two motors manufactured at the same time by the same mnf'r. to the same specifications are NOT likely to be equal and sometimes substantially different. You can observe this by noting how, when two motors wired together, you will see one motor start before the other motor. I've not noted "scientifically" but assume that it is VERY rare (next to impossible in fact) for both motors to start at exactly the same time. The motor that starts first requires less voltage therefore its resistance is lower and it draws higher current (which could briefly tax the entire circuit beyond its capacity but more likely will further inhibit the second motor). This fact does not matter if the motors are in parallel or in series -  it is simply physics. (You can break the laws of National Security but you CANNOT break the laws of physics.)

Speakers present a similar situation tho the differences are much smaller. However the trick to speakers is to present the required (4 ohms in this case) to the output of the decoder's sound amplifier. If the decoder is overheating it means the load demand on the provided potential is in excess of that supplied. This is easy enough to prove (we use to do this as kids) get a 1 farad polarized capacitor (something on the order of 1" in diameter), charge it to its designed capacity (x number of volts) and then place 1/4 watt, 1000 ohm resistors across its terminals - be sure to wear eye protection! So if you put two 4 ohm speakers in parallel you now have a 2 ohm load across the amplifier. Two ohms is 1/2 the required load. Less resistance MORE amperage at the same level of potential. Very bad... (conversely more resistance, more voltage - also bad!)

It is my expectation that something about the install of the 44 tonner was in violation of the decoders provided potential. It is always good to have a volt / ohm meter on the bench - and USE it! When I install I do not leave it simply to theory to determine the external components, especially resistors (the metallic colored band is important but is NOT to be completely relied upon - a resistor can be substantially off of its rated value). I measure voltage drops and calculate the real values against the actual provided potential. A speakers rating (4, or 8, or multiples thereof, ohms) is more difficult to determine but the variations are much smaller - within tolerances.

More importantly to speakers is that they are place with care that their polarities are properly aligned. In parallel the positive side of one speaker must be connected to the positive side of the other. In series the positive side of one speaker must be connected to the negative side of the other. If you violated any of these things you get exactly what's to be expected - a fried sound amplifier. The only other explanation might be somehow a short to the track voltage which will instantly destroy the amplifier. That doesn't sound like the case here especially on a plastic model (I don't do plastic DCC installs) - but one never knows. Has the motor been physically (entirely) isolated from the frame?

A bit of info about isolation. There is NO ROOM to be lazy about isolating motors for DCC. I WILL NOT install any decoder in a model that has an uninsulated motor - WILL not. The mnf'r tells you to isolate the motor. But modelers, being human, try to get away with the rational that; "well it's a can motor so the armature is automatically isolated. And besides I tested the motor shaft (armature) to both terminals to see if there was any resistance short of infinity (open) and found that it was good."

Riiiiight.... WRONG!

That is simply the static test. Did you do the dynamic test? A motor can leak voltage that will only show up when the motor is running! (Momma didn't tell you about that, did he?) As little as two volts from the track to the decoder WILL destroy it. Ask me how I know. Test the motor by applying power to its terminals and then look for voltage drop between each terminal and the can of the motor. If there is the slightest reading, that motor will fry your decoder if not isolated.

So you test it and you find it has no leaks - la, la, la-la, laH... that is no guarantee. Oh, its good today. But tomorrow that may very well change because any motor, at any time, can develop a leak! I've found even the vaunted Falhaber can have this failing. Falhabers are nothing less than the wrong motor for the job as MR motive power. The Fablehabers (those mystical beasts akin to Unicorns!) are not designed for long term continuous running (so stop wasting your hard earned money on them).

My policy is ISOLATE EVERY MOTOR. Waste no time; do the job right and save the grief!

JusticeCity

Good refresher of my university Electronics degree. The issue was the speaker terminal touched the live track shorting things out. Decoder is rated at .7A so steady state is fine. I ran it for ten minutes with heatsink and all is right with the physical world. I set cv54 =0 and pressed f1 which re-set the BEMF values and it runs like a charm.

JusticeCity

Sometimes reality is a cool thing.

The performance of the loco is as I would have expected - reasonable. Here is a quick video to see what I mean.

https://youtu.be/ellwUNqmO_A

JusticeCity

#12
Ok, time to get into some painting and detailing until my SMD LEDs come from China.

https://youtu.be/ixnfscUCqgc


tct855

M~,
         Nice video!  I like the new color paint. I'm curious how you'll solve the window mystery.  T...

JusticeCity


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