I have a SD70M, vintage 2017 I think, and pulled it out of the box today to test on DC and open up for decoder & sound addition. This version still has bulb lighting and has a round cutout for a (thin) 28mm speaker. I am not planning to change the bulbs to LEDs nor make custom micro speaker enclosure, as for whatever reason I want this to be a simpler install.
The easy solution would be to buy the WOWSound kit of circuit boards & speaker, which can handle the 1.5v bulbs. But I prefer to use my typical LokSound Select as a plug-in, either the larger or the (smaller) micro. The Select has an 8-pin plug harness. If I use the plug-in approach, that can (I assume) utilize the existing Athearn circuit board ability for the 1.5v bulbs, keeping things easy (at least as long as the bulbs last).
You can see that the Athearn board has both an 8-pin plug, plus a 9-wire plug, the latter having a small circuit board attached. Do I just plug in the decoder 8-pin plug (and add the speaker)? Or do I need to remove the small circuit board from the 9-wire plug, like removing jumpers from some 8-pin locos? I don't understand what the circuit board on the 9-wire plug is about?? Does it stay in if adding a 8-pin decoder, and only come out if a decoder is added there?
I can wait for advice, as I have ordered the thin WOW 28mm speaker. Thanks for any clarification.
Genesis SD70M by Paul Ahrens, on Flickr
Paul
Modeling HO with a transition era UP bent
The 8 pin plug won't give you access to the extra lights, like the ditch lights. A Loksound Select Direct is the correct board repalcement form factor, but you have to add your own resistors to keep the light bulbs. Sorry, there are no shortcuts with those silly Athearn light bulbs, either repalce them with LEDs or add some resistors and hope they don;t burn out so yoou end up taking the thing apart every couple of years to replace the bulbs. FINALLY Athearn has decided to switch to LEDs like everyone else.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinkerA Loksound Select Direct is the correct board repalcement form factor, but you have to add your own resistors to keep the light bulbs. Sorry, there are no shortcuts with those silly Athearn light bulbs, either repalce them with LEDs or add some resistors and hope they don;t burn out so yoou end up taking the thing apart every couple of years to replace the bulbs.
Is there a specific resistor for each bulb if I decide not to go with the LEDs? The Select manual does not advise. The ditch lights look near impossible as they are not light tube types, are above the fromt deck, etc. So I want to try not going LED for now.
And, what is the funcion of the small board in the 9-wire connector?? If use the 8-pin, remove it (or not)?
Actually it does - the Select Direct manual lists how to hook up Athearn 1.5V bulbs and what resistors you should use (after bypassing the built in resistor for LEDs). Have to make sure you get the correct manual from the ESU site - the Select adn Select Direct are different.
The board in the 9 pin connector on the Athearn is the dummy plug that makes it operate on DC. If you plug in an 8 pin decoder, you need to remove that. If you plug in a 9 pin decoder, well, you have to remove it to plug in the decoder.
First, I'll report on status. I removed the 9-wire plug, loaded a Select 8-pin decoder with the SD70M file with LokProgrammer, and installed (sans speaker, enroute). The motor works, the dual headlights and rear lights work. Ditch lights do not (they did on DC). I can adjust the headlights intensity by turning off LED, keeping dimmable checked, and reducing brightness to 20 (vs 31 max) with the LokProgrammer. At least, I think the intensity is lowered (if I put in a low enough value it does not light). So, I presume I can limit voltage to the bulbs and perhaps help their life.
Having said that, I've decided to gut the Athearn boards for two reasons. First, it makes everything simpler, no guesswork. Ditch lights will be via an Aux function button, and applied (bulb) voltge can be limited via resistor choice and LokProgrammer adjustments perhaps atop that. The second reason is that I can have the neatest wiring tidiness with a LokSound Direct. The 3/4 amp motor spec will be enough (confirmed at stall).
Randy, thanks for all the input including pointing out the Select Direct "manual". My first Select was a Direct, but the 20 or so additional ones have been the 8-pin Select or Micro, where I cut off the connector and soldered the decoder directly. So if I ever saw the Direct "manual" I don't recall it. It seems to be only a 3-page Quick Start Guide but the resistor specifics indeed are there. A question on that. It says "Athearn: 2 - 1.5v bulbs 360 - 510 ohms (front or rear lights" and "Athearn" 1 - 1.5v bulb 680 - 1K ohm (acc. lights)". I need some clarity on that. My SD70M has pairs of bulbs for headlights and rear lights, with full length wires for each bulb. So, for instance, do the headlights need a single 360 - 510 resistor to a wire that then split to the two bulbs in parallel? And would a single ditch light (if wired to a separate AUx output) need a 680 - 1K? And would it be preferred to put a separate (680 - 1K) resistor on each headlight lead? You can see how I am confused, I hope.
Now to the subject of the ditch lights and the optimal approach...converting to LED. I will add a photo below. These look tough to add LEDs, as they are above the deck and somehow the bulb is in there. Not what I have seen before with below deck lights where a light tube or bulb from behind is easy to change from bulb to LED. Because of the difficulty (is there a relatively easy way?) of converting the ditch lights to LED, I'm inclined to keep them bulbs, therefore the same for headlight and rear light.
Genesis SD70M Ditch Lights by Paul Ahrens, on Flickr
More comments are most welcome and the assistance so far is quite helpful! This is more complex than I anticipated. I really enjoy the DCC/sound conversion projects, but realize this is an advertisement for buying with DCC & Sound installed (especially with LEDs).
I just did the same thing recently, actually. I picked up an ESU Select EMD 710 sound decoder. Is there an adapter to 9 pin that I can install to make the ditchlights work? I’m not trying to hijack the thread, sorry if I’m doing so.
I believe you can rewire the factory board so that F1 and F2 from the 9 pin connect to the ditch lights. If you don't need them to alternately flash, there's no need.
I assume that when Loksound says aux lights, they mean the smaller bulbs used for ditch lights, vs the slightly larger ones used for the headlights.
The ditchlight bulbs are the same bulbs used in the headlights. They are mounted vertically up through the walkway and the ditchlight casting is mounted over the bulb - a real pain to replace the bulbs.
As for the resistors on the bulbs (still not a great idea) - you should put a resistor on each bulb, not one resistor to pairs of bulbs. The reason being is that when (not if, when) one bulb burns out, the lower value resistor used on the two bulbs is not sufficient for one bulb when the other burns out - it will immediately be under-protected and burn out as well.
The factory board had votage regulators on the board to maintain the proper voltage. A resistor will maintain a calcualted voltage, but only as long as the input voltage remains contant. Any voltage spikes or fluctuations could oeasily overpower the resistor causing the bulbs to blow. Highly recommend to either use the factory board or use a voltage regulator instead of just a lone resistor. Check the bottom of the factory board, there should be four regulators on it - enough for headlights and ditch lights. You just have to take the green and violet wire from the decoder and solder it to the two AUX points on the board in order to utilze those two functions.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
I've ordered a LokSound Select Direct (which replaces the existing board) as that will make for an easy, not confusing (for me) installation. I will use that with the thin WOWSound 28mm speaker.
I understand that the ditch light bulbs can be removed and SMD LEDs inserted, but it looks risky as there are lots of small details around the pilot for me to damage. So I've decided to try the installed bulbs.
I tested an Athearn bulb I had from a GTEL conversion, using a 1K resistor and finding it barely on at 9.5v DC and ok up to 13v (I did not see how high it could handle). I will use the 1K resistor (one per bulb) and set the LokSound brightness well below the max 31 value and see how it goes.
I won't get that done for at least a week as I am awaiting parts. If an immediate bust, I will so report in due course. Thanks for all the input.
Just be careful what size resistors you use. If the bulbs are 15ma, using a 1K resistor means the resistor is going to dissipate just under 1/4 watt, so 1/2 watt resistors are probably a good idea. That's probably a good value though, a little high but that just means the bulbs will not get full power and should last a lot longer.
Thanks, Randy, for the attention which may prevent my blundering. I've typically used just 1/8W resistors on LEDs. I have 1/4W and 1/2W 1Ks on the way!
Yeah, 1K resistors on white LEDs ends up flowing less than 10ma of current, which translates into under .100 watt, so 1/8 watt is perfectly fine for LEDs. 15ma bulbs push it to .225 watts, just under 1/4 watt. 1/4 may work, but 1/2 would be better, if you have room - they will be a bit bigger.
With a quick wiki, I see that the resistor power rating is a value in watts that it can run indefinitely without degrading. I imagine that beyond that, the resistor life is affected, probably with a hyperbolic curve. That is, running at 110% of wattage can lessen its life from indefinite to something less, but it may last quite a long time, especially as some life tolerance may be built into the rating. But if run at 200% of rating, it would potentally have a relatively short life, and if run at 1,000% of rating, a very short life, and at 10,000% perhaps an instantaneously short life. So we want to use the proper rating, even if it takes up some marginal space (perhaps more of an issue in N scale than HO).
On another angle, I assume that the heat generation of different wattage rating resistors in a given lash-up of supply voltage and light source (bulb or LED) will give off the same (calculated) amount of heat. That is, the watts generated at the resistor are generated by the current through it, and its rating does not affect that. So in a circuit that calculates to a 1/4 watt resistor, either a 1/8, 1/4 or 1/2 watt resistor will generate that much heat to be dissipated (with detrimental effect for the 1/8 watt resistor). To accomplish that, I take it that the surface area of larger wattage resistors needs to be roughly proportionally larger.
Which makes me wonder, can we have a problem with a resistor getting hot enough to damage a plastic loco shell if in contact with it? Is there a case of a lighting circuit where the resistor needs to be a rather high wattage, enough to soften the loco shell? Or are all our cases of ~12DC lighting (LEDs, various voltage bulbs) a non-issue as the resistor wattage generation is low enough to not be a problem?
Which leads me to wonder, regarding potential shell damage, can using the wrong (too low an ohm rating) resistor cause enough current flow to generate enough heat at a (say, 16v) bulb to get it hot enough to cause damage to (if in contact with) the shell? An LED would burn out right away, I presume, and not cause damage.
Just curious to understand the whole picture.
Effectively, yes - a larger surface area can dissipate more heat, or, using a bigger resistor than necessary can result in the resistor body remaining cooler as the resistor would not be running near 100% of its capability.
Can they get hot enough to deform the shell? Or the light bulbs? Absolutely. That's why the little 1.5V bulbs are used - with DC it was never much of a problem because how many peole ran full throttle all the time? The old 112-16V bulbs were usually running at a fraction of their maximum voltage, and so didn;t get hot, but along comes DCC and, unless you are using dimming, the bulb is either on full power all the tiem, or off. Those big "fire int he cab" bulbs from old Blue Box locos - it's a goot thing they were pretty much in the middle of the cab, because at full power they would easily get hot enough to melt plastic. The 1.5V 15ma bulbs they use in the newer locos, even running at a full 1.5V, barely get warm, because they are relatively low current. Those old bulbs could be 50ma or so, at a steady 12V that's .6 watts. That gets warm. I've got old (60's and early 70's vintage) structures that have melted parts because a GoW bulb got too close to the structure - the layout we used to set up every year always had all the structures lighted, usualy with the expedient of drilling a hole under it and sticking the leads of a GoW bulb down. Since we didn;t totally fasten the bulbs in place, they were somewhat free to move so if the structure was shifted to better place it, the bulb might touch the side, or in at least one case, the bulb stuck up too far and touched the roof, and there is a very obvious melted spot in that one now. That was just loose contact - that same bulb fitted to a hole drilled in a loco shell would most definitely melt the shell. The early trick was to use a piece of brass rod, this would help conduct heat away fromt he bulb and not all just intot he shell at the point of conact. I just as a matter of course replace any incandescent bulbs with LEDs when I put decoders in my locos. Some locos come with LEDs but they ar eeither too orange or too blue - thse get repalced as well, the golden white color seems to me to be best for late seam/early diesels that I run. LEDs do get warm - but not the little ones we use in locos, at least not on the outside of the case. Ones used in LED light strips - they definitely get warm, and the biger ones used in LED repalcement bulb for household lighting - those bulbs are often suprisngly heavy - that's the heat sink, because a 10-20 watt LED needs the heat removed to keep from cooking the LED.
Randy, thanks for rounding out the learning on this area.