Actually diodes will drop .6volts. The resistance will change depending on the voltage applied The meter uses a reference voltage to measure resistance. The voltage of the one you have results in 600 ohms. Others can be lower or higher. Semi conductors don't follow the same rules as resistors.
Springfield PA
Minor detail but diodes do have about 600 ohm resistance when forward biased. Check with a common ohm meter. One way no resistance. Reverse the leads and 600 ohms. This is a common trouble shooting method for checking diodes, sometimes called rectifiers. I substituted a variable resistor for the resistor and LED on the PC board and set the resistance so I got 4.2 ma current the same current as with the PC board. I then measured the variable resistor and the total was the combination of resistor and LED. I repeated this about a dozen times and same results each time using different LEDs.
Do the experiment if you do not believe me. Very easy to reproduce.
Again, if someone is not familiar with electronics, any wiring modification is not easy.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Diodes when forward biased have little or no resistence, definitely not 600 ohms. They do however have a voltage drop, about .6 volts, so instead of 12 volts getting to the LED, it's only 11.4. The 1.4k resistor is already too big for 12 volts, even more so with 11.4 volts.
Maybe they were responding to complaints about the E33 electrics - those have insanely bright LEDs lights, and to boot they are the bluish-white variety that are totally out of character for the era of the lcomotive - they look like modern Xenon automobile headlights.
At any rate, as far as I know with the steamer, all the wires come to the circuit board in the tender, so it's not a difficult task at all to just remove it all and attach the wires to the proper decoder leads. Far easier than trying to bypass or replace a surface mount resistor. Maybe I'm strange, but I don;t like surprises - so I tend to hardwire decoders even when there is a socket. So-called "DCC Ready" seldom is anyway. Plus decoders with leads are usually a coupel bucks cheaper than ones with 8 pin harnesses.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Easier said than done for many people. I did hard wire a Richmond 4-4-0 and a 4-6-0 using the 1k resistor.
The 4-4-0 has a single resistor of 1400 ohms and diode (600 ohms resistance) in series with the LED. Total 2000 ohms. Twice the 1k value for 4.8ma current.
The 4-6-0 has two resistors in parallel in series with a single resistor, 1770 ohms plus a diode , 600 ohms with the LED total 2300 ohms. Also the 4-6-0 has a periscope for lighting which further reduces the output a little. More than twice the 1k with 4.2ma current.
A 1k resistor allows about 10ma current. This all based on 12 volts DC.
All are SMT components. The diodes have .7 voltage drop.
Some people mention quite dim lights on the 2-8-0 and Shay. A couple people went out and bought another decoder and the same dim results.
Two ways to fix that. One, jumper past the resistor, and cut the leads to the LEDs and insert proper resistors. Two - just rip out the whole silly diode board and hard wire the decoder, using the proper value resistors. This also eliminates the choke coils that can cause poor running - the pictures I've seen show these coils on the circuit board rather than directly attached to the motor. The capacitor on the motor should also be cut off for best DCC operation.
Some people mention the Spectrums have dim lights. The resistors on the PC bpard that the decoder plugs into is the problem. Not easy to change the resistors.
I own 6 spectrum steamers and 2 (what I call) Bachman Blue box steamers, and after tearing apart both of the blue box ones and 3 of the spectrum engines I own I can tell you this: The only real difference between the spectrum engines and the blue box engines are details, and weight.
The blue box engines lack most, if not all, the lower detail and some upper detail on the boiler and around the drivers. Also they seriously lack wieght so they are not the greatest of pullers. The motor is the same as in the Spectrum engines.
As for the decoders, I have never had any problems with them but then again I have yet to keep one in the engine long enough for it to fail. I usually replace them with a Tsunami decoder. But from what I do know about the decoders that come with them, they are very limited in functionality as the whole engine is meant to be affordable. So you can run them on a DCC system and that's pretty much it. So if one burnt up or just stopped working I would not be surprised.
Hope this helps
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I have a Bachmann Shay and love it. The Spectrum series are right up there in quality with some of the best. They still have a reputation to shake that was earned in the past but I think they've redeemed themselves.
twcenterprises Looks like a suitable thread in which to pose my question. I have a Spectrum 2-10-2 with factory DCC. Last night I was running it around a 22" radius curve (using DC, was running about 10 scale MPH or so), and it quit moving forward. Reverse works fine, as do lights. Opening tender revealed a decoder with a burned out component. OK, so I figured I now need to replace the decoder, the forward circuit is shot. My questions are these: What is the minimum radius for this engine? Are the decoders known for problems, or generally pretty good? And, most importantly, any thoughts on what may have caused a short and how to prevent recurrance? Thanks in advance. Brad
Looks like a suitable thread in which to pose my question. I have a Spectrum 2-10-2 with factory DCC. Last night I was running it around a 22" radius curve (using DC, was running about 10 scale MPH or so), and it quit moving forward. Reverse works fine, as do lights. Opening tender revealed a decoder with a burned out component. OK, so I figured I now need to replace the decoder, the forward circuit is shot. My questions are these: What is the minimum radius for this engine? Are the decoders known for problems, or generally pretty good? And, most importantly, any thoughts on what may have caused a short and how to prevent recurrance? Thanks in advance.
Brad
I haven't heard of any problems like this with the 2-10-2 re shorting. Kinda odd to have a short develop while running on a curve or straight track, not on a turnout. As suggested, I would try posting it to the "Bach-man" on the Bachmann website.
I have a 2-10-2 by the way, a DMIR engine. The decoder that comes with the engine is "OK" but not great; I suspect most of us that run DCC replace it sooner or later. I used a TCS decoder in mine, Digitrax decoders in particular have some issues with the Spectrum light board.
There's a review of this loco in the August 2006 issue of MR - you can pull it up on this website (it says it should handle 18" radius). As for the rest, Bachmann has a forum on their website (www.bachmanntrains.com) that might answer some of your other questions.
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dadret I don't think the one I was looking at is a Spectrum (Bachmann stock number 50801) so I think I may just pass on this one as I really want sound too and I'm not sure I want to try to put a sound decoder in it. BLI has some Mikados that will work on my layout just as well and they have a Blueline Northern too. I've heard from other people too that only the Spectrums are worthwhile.
I don't think the one I was looking at is a Spectrum (Bachmann stock number 50801) so I think I may just pass on this one as I really want sound too and I'm not sure I want to try to put a sound decoder in it. BLI has some Mikados that will work on my layout just as well and they have a Blueline Northern too. I've heard from other people too that only the Spectrums are worthwhile.
The ATSF Northern is one of several 4-8-4's Bachmann recently put out (or updated) for their "DCC Equipped" line. These engines have received excellent reviews in several magazines - Model Railroad News did an extensive review of all 4 engines in 2007. (I'm thinking of getting the NYC Niagara myself.)
http://www.modelrailroadnews.com/pages/sept2007.html
The engine's tenders have openings for a 1" sound speaker in the floor, so no drilling is required. Basically you could unplug the Bachmann decoder, plug in a Tsunami or other sound/DCC decoder, put the speaker in the speaker opening, and put the tender shell back on.
You could also "piggyback" a sound decoder and leave the Bachmann decoder (or replace it with a better 'regular' decoder). I added an MRC "Sounder" sound-only decoder to a Bachmann Spectrum 2-6-6-2 that already had a TCS regular decoder in it. The Sounder cost about $25 and involved soldering two wires to install, it comes with a 1" speaker already attached.
http://www.bachmanntrains.com/home-usa/products.php?act=viewProd&productId=1564
What scale and which Bachmann 4-8-4 Northern are you interested in? If it's the HO scale Southern Pacific Daylight it is NOT a Spectrum model and is, in my opinion, very poor quality. Three members of our local HO scale club bought these and they all had problems with them. One member sent his back twice to Bachmann for repair, and each time it came back in worse shape with something different broken.
Bachmann Spectrum steam engines are the only ones I trust after seeing those three Daylights.
Generally the Spectrum steamers are good runners. The sound equipped come with a factory installed decoder and speaker. The Tsunami is a very good decoder. The downside you might say is less features than a Tsunami you install. Another feature I have seen is dim lights for some Spectrum's which I have found out is because of the resistance on the PC board is higher than 1k which is used for many LED equipped locos. I have the Spectrum 4-4-0 and 4-6-0. MY two locos had a LED resistance of 2.3k.
The below link you can find the layout of the 4-8-4 and it "seems" they have the speaker holes in place for the DCC equipped and DCC ready.
http://www.bachmanntrains.com/home-usa/references.php
More information.
http://www.tonystrains.com/download/PopLocosFlaws.pdf
Not steam, but I have had a good experience with an SD45.
Bachmann Spectrum locomotives are very smooth runners, though a lemon occasionally sneaks in. Bachmann will replace any defective units.
Micro-Mark sells Bachmann Spectrum locomotives with DCC and sound (Tsunami) already installed at very reasonable prices, but he doesn't list the Northern as being available yet. Check them out at http://www.micromark.com
Adding sound should be as simple as opening up the tender, removing the Bachmann decoder, and plugging in a replacement Tsunami Heavy Steam decoder, which is the one I would recommend for this engine.
Anyone had any experience with DCC equipped Bachmann steam locos? I've never been a great big fan of Bachmann but they have a 4-8-4 Northern I like. Also, how difficult would it be to add a sound decoder to one?