I was recently given an sd7 and on the box it says “DCC ready” with plug. Being new to dcc, I’m not sure where the plug is or if there is a cover over it. To change it over, is it just a matter of plugging in a decoder or is there some other preparations needed?
Thanks, Larry
Larry,
You’ll have to remove the body of the locomotive to access the DCC socket. Once the body is off, you’ll find a small 8 pin plug on top of a circuit board. You’ll remove the existing plug and install your decoder into the socket on the circuit board. You might need to research the voltage of the lights on the loco; some decoders don’t limit the voltage to the lights and will burn out the bulbs as soon as you turn them on in DCC mode. If the decoder doesn’t limit the voltage, you might need to install a resistor inline or change the bulbs to a higher voltage rating.
Don Z.
Thanks Don, I have been reading up on this stuff so much lately I tend to get confused. One article had me cutting through an “X” thing or something on a circuit board and I wasn’t sure if the sd7 needed something like this. I will check the headlight.
Thanks again, Larry
If it needs a track cutting (I doubt it as this I think was limited to the P1K line) then it should be described in the documentation for the loco.
Thanks again, the engine was given to me and the documentaion didn’t come with it but I’m going to give it a try.
Larry
If there are resistors on the dummy plug then you will need to either swap out the exsisting bulbs or add 1000 ohm resistors to your white and yellow leads.
David B
I believe Digitrax makes a decoder specifically designed for Proto 2000 locomotives, with resistors built in. It’s the 165LO, the best one would probably be with the plugs soldered to the board.
Time for my annual suggestion that the makers start putting the decoder plug in the fuel tanks to ease installation and trouble shooting. I guess I’ll just to have to stop thinking outside the box.
Not a bad idea! But keep in mind that this would make the loco top heavy and it wouldnt track as well.
David B
I disagree about the top heavy. They are so full of weight now and before they started putting it in the carbody the rule was weight had to be low to avoid that and it hasn’t proved to be a problem. We aren’t talking pounds of material being removed. more like an ounce or two.
Isn’t putting the plug in the fuel tank bringing more weight closer to the rail head thus less top heavy?
Jon
Larry,
I have two of the P2K sd7s that I’m going to put decoders in this weekend. On the circuit board there is an 8 pin socket with a dummy plug in that you need to remove. You can plug in any decoder with the 8pin NMRA plug. Also, my locos have printed on the circuit board “cut for dcc” next to a black wire. If your don’t cut the wire the lights don’t work correctly. The lights are 1.5 volt bulbs so you don’t need to do any thing other than plug in the decoder for the light to work. However they are not very bright. I’m replacing mine with leds, which complicates the process.
Mike
Mike,
The only lettering on the circuit board is 432 x001r1. There is nothing about cutting a black wire. It does have the dummy plug. I’m very obliged to be given this model but it’s frustrating to not have the instructions. It’s model # is 8086 and it’s undecorated. I think I will hold off for a while until I learn more about it, thanks for your help and good luck this weekend with the instalations.
Larry
Larry,
If you can wait until tomorrow, I’ll scan the instruction sheet and diagram from my SD7 loco and post them here for you.
Don Z.
Sure can Don, thanks
Larry
The early SD7s used the board with the dummy plug. The bulbs are 3 volt, changing to 12 volt or adding resistors is required.
The shell is held on with very fragile latches that engage the frame. Care must be used for removal and also for assembly as you will no doubt damage one or more of the six latches. The fit is fairly tight so I found that filing the latch made R&R of the shell very easy.
I found that after installing a plug in decoder that there was interference with the plug and the inside of the shell making proper fit immpossible. Some of the roof details had protruding half melted installation pins that need to be scraped away.
The Digitrax 160? LO decoder doesn’t work in these early units, they are made to replace the entire board and the plug only wires the board itself. The 3 volt bulbs don’t need changing with with these decoders, the board has the resistors.
Larry,
Well, I shot my mouth off before I knew what I was doing…I found the box for my SD7, but no paperwork was in the box. I took the shell off of the loco and here’s the data you need:
I used an NCE D13SRP decoder in this loco WITH the factory bulbs. The decoder plugs into the light board that has the resistors to reduce the voltage to the lights. My shell comes off by squeezing 6 tabs that extend from the body through the frame. I’ll keep looking for the paperwork and post it when I find it.
I hope this helps,
Don Z.
Thanks Don, and Bob. The plug on my model is on the resistor board also. I’ll give it a try. I have two diesels now on dcc, one I soldered a decoder in and a bachman I prchased. After 27 years of running dc locos I found out how dirty the track was. I can’t believe how finicky dcc is in this respect, but I wish I had done it years ago.
Thanks again, Larry
I just got into DCC. I also have an B&O SD-7 (actually several B&O engines) that i am converting, and was wondering if there is much prefernece in LEDs. I’ve seen then listed as 1.5V and 4.5V. What gives? I bought the yellow glow one and even with 1K of resistance, they seem awful birght. They work fine, but to get thwen to simulate a dmmmer headlight I obviously would have to increae the resistance to maybe 2K or more to get the desired results. Any expereincves in this?
Paul, Chester, PA
Modeling the B&O/Reading/WM in the 60’s and 70’s.
My locos are all first generation diesels (plus a few steamers - can;t model the Reading and NOT have a T1 or two around the place). I’ve repalced all my incandescent bulbs with Miniatronics Yelo-Glo LEDs, I don’t find them excessively bright with a 1K resistor, at least not in Proto 2000 locos with all the plastic theyhave to shine through. I did use 2.2K in my Stewart/Bowser switchers - they have a straight shot light pipe from the LED to the headlight lens, which is both shorter and more optically clear than what Life Like used and they were very bright.
The Yelo-Glo LEDs are a warm white, for the sealed beam lights more commonly found on second generation and newer locos, a Sunny White type might be more accurate, they are a brighter white without the blue tinge some white LEDs have. I like the Yelo-Glo ones, in those cases where you cna look into the headlight lens and see the LED (the Stewart switchers, for one), you see the little yellow speck in the center like it’s the bulb in the lamp housing. The LED itself has a clear case, so there’s no orange thing sitting back there - some of the other Golden White LEDs use an orange case so that the resultant light is warm white, but when off, the orange is kind of goofy looking.
The P2K SD7 I converted indeed had the “cut traces marked with an X” board - like all my other P2K locos, I just removed the entire thing and hard wired the decoder.
–Randy