I have two of these locos which are about 10 years old. They are DCC with sound. I sent an e-mail to TCS tech support asking if one of their capacitors would work in my SW7s. Their reply didn't give me specific instructions for this loco but did say I would need to figure where to attach the blue wire (common) and black/white wire (ground). I have no idea which wire should go where. The decoder has a 4 wire plug, black/yellow/green/red, which are wired to a smaller board under the roof of the cab. There is additional wiring under the decoder which is screwed in place above the motor assembly. If I were to guess based on my limited knowledge of these types of electronics, it would to be that the red and black wires in the plug are the power wires and that these are where the capacitor wires should be spliced to. But since I don't want to guess, I thought I'd ask more knowledgeable people than myself how to procede. I need to know which wires to attach the capacitor to and where that splice should be made. Also there is not a lot of room inside the shell to put a capacitor. It looks like the only available space is inside the cab.
The other opion they gave me was to replace the decoders with one of the decoders with Keep Alive already installed. That might be the simplest solution but probably the more expensive as well.
Stay Alive leads have to be connected to the DC power on a decoder. Usually at the plus and minus output of the full wave bridge rectifier.
With shrink wrapped decoders, the blue wire, plus common and find a negative connection on the decoder board. The below site shows different decoder connection points.
http://www.members.optusnet.com.au/mainnorth/alive.htm
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.
richg1998 Stay Alive leads have to be connected to the DC power on a decoder. Usually at the plus and minus output of the full wave bridge rectifier. With shrink wrapped decoders, the blue wire, plus common and find a negative connection on the decoder board. The below site shows different decoder connection points. http://www.members.optusnet.com.au/mainnorth/alive.htm Rich
So if I am understanding this correctly, I won't be splicing the KA1 wires into an existing wire but will be soldering them to a terminal on the decoder. I just have to figure out the correct one.
One other thing I forgot to ask in the OP. The TCS website says the following:
"All TCS decoders shipping with date codes from January 2012 support the Keep-Alive feature."
Since these are not TCS decoders and are quite a bit older than 2012, is it possible they will not support Keep Alive?
I'm wondering if the better but more expensive solution might not be to buy one of their new decoders and install the old SW7 decoders in some of my non-sound diesels.
Try this web link - lots of good examples of using various sound decoders;
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
BLI locos from 10 years ago will have a QSI sound decoder. If Marcus does not explicitly show a QSI decoder, the information presented there will point you in the right direction to find where you need to solder wires for the keep alive. This will not be soldering to a tab on the decoder, but soldering directly to a component on the board. I'd mention voiding the warranty but at 10 years old there's no warranty anyway. If you are careful and use a good fine tip soldering iron this isn't really a big deal, but if you don't work carefully and take your time you could destroy the decoder.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinker BLI locos from 10 years ago will have a QSI sound decoder. If Marcus does not explicitly show a QSI decoder, the information presented there will point you in the right direction to find where you need to solder wires for the keep alive. This will not be soldering to a tab on the decoder, but soldering directly to a component on the board. I'd mention voiding the warranty but at 10 years old there's no warranty anyway. If you are careful and use a good fine tip soldering iron this isn't really a big deal, but if you don't work carefully and take your time you could destroy the decoder. --Randy
The website I looked at had instructions for two different QSI decoders, Revolution A and Revolution U. The A instructions had a picture that looked nothing like my decoders and looking at my decoders, there is no way I would attempt to solder to any of the tabs because they are way too small, much smaller than the connections in the picture.
The instructions for the U seem more up my alley. There are no pictures, so I can't verify that is what I have but the instructions say to connect to the wires. This is the entire instructions:
Yours would not be either of those. Revolution A is an Atlas/Athearn format board decoder and Rev U is a wired version of the same. Both are the products from QSI that came out after the ones used in the BLI locos.
It's not a misprint, the Rev A and the older ones have a keep alive on board, but it only powers the cound portion of the decoder, not the motor. The Rev U has the cap attached to the decoder by wires. One side of it goes to the proper place on the decoder, so you can just solder to the wire.
The key to having a keep alive power the whole thing and not just the sound is, if you looked through the page, getting the keep alive attached to the main DC supply for the decoder, which comes right after the rectifier bridge. The blue + wire for functions is often attached to the main DC + source, but there is not normally a wire attached to the main - side as mothing needs that (except a keep alive). That then needs to be soldered right to the component on the decoder board.
rrinker Yours would not be either of those. Revolution A is an Atlas/Athearn format board decoder and Rev U is a wired version of the same. Both are the products from QSI that came out after the ones used in the BLI locos. It's not a misprint, the Rev A and the older ones have a keep alive on board, but it only powers the cound portion of the decoder, not the motor. The Rev U has the cap attached to the decoder by wires. One side of it goes to the proper place on the decoder, so you can just solder to the wire. The key to having a keep alive power the whole thing and not just the sound is, if you looked through the page, getting the keep alive attached to the main DC supply for the decoder, which comes right after the rectifier bridge. The blue + wire for functions is often attached to the main DC + source, but there is not normally a wire attached to the main - side as mothing needs that (except a keep alive). That then needs to be soldered right to the component on the decoder board. --Randy
It sounds like it is anbody's guess as to whether there is even a Keep Alive capacitor compatable with my decoders and where they should be attached.
It's a matter of following the board traces from where the track pickups connect. The first components they should connect to would be either 4 diodes forming a bridge or a single bridge rectifier. It's compatible, but you must find the main circuit + and - connections, and of course it won't just plug in.
This is response to the first question on this topic – could a current-keeper be installed in a Broadway Limited Imports (BLI) EMD-SW7 switcher to help avoid engine stalling when going over switches and crossovers. I have a BLI Paragon-2 EMD-NW2 switcher and this was a question I also had. I believe the inter-workings of these two engines are the same. From the comments related to this topic, the general consensus was a lack of space for a current keeper. To address that question, I removed the shell of the engine. To do this, first remove the 2 back handrails that go between the shell and the frame. Then looking at the bottom of the engine you should observe 2 front and 2 back tabs. Gently squeeze the shell at either the front or rear tabs and slowly pull up on the shell. Once the shell slightly releases, do the same for the other tabs.Once inside, I observed there is a fair amount of space above the decoder at the back. Taking a few measurements, it appeared that a TCS KA1 Keep Alive (1.063" x 0.35" x 0.244") might fit and it does. The next issue was locating where to solder the wires. The information of an excellent site on current-keepers (http://www.members.optusnet.com.au/mainnorth/alive.htm) indicates that I needed to find DC-positive and DC-negative connection points. For this decoder with plug-in connections for everything, it was going to require taking DC voltage measurements using a multi-meter at the bridge-rectifier diodes. These are the square chips located near the large capacitor. With the engine on the a powered and circuit protected track, I was looking for a two solder points on the diodes that would supply +12 DC-Volts. Do not use to the + terminal of the large capacitor as a test point as this only supplies power to the sound system and not to the motor. However, the other terminal of the large capacitor can be used for the DC-negative as it shares a connection to the DC-negative on the diodes. These DC-positive and DC-negative are shown on the photo below. (NOTE: the blue wire has already been attached to the DC-positive connection point)
NOTE: I was unable to post pictures with this reply. If you desire photos, email offline.
Once DC-Positive and DC-negative are found, the next task is attaching the blue wire of the Keep Alive to the DC-positive connection point and the black/white stripe wire to the DC-negative connection point. This is not for the faint-of-heart as the working space is small and connection for DC-positive is very small. Making these connection required me to use a strong head-band magnifier and a solder iron with temperature control and a small pointed tip. A steady hand is also needed. Realizing that the DC-positive connection would be the most difficult because of its difficult location, I started with that one. I first tinned the connection point on the diode by placing a small drop of liquid flux on the connection point and using the solder iron set to 550-F degrees to tin the connection point using a solder with 4% silver, 56% tin and 40% lead. This tinning should happen quickly. If heat is applied too long it could damage the diode. I then trimmed the blue wire, stripped off 1/4" installation, tinted the wire with the same solder and then trimmed the tinned wire to 1/8". Then using tweezers, I placed the tinted blue wire on the tinned diode and apply heat and the solder of the two should melt together to form a strong connection. The connected blue wire is shown in the photo above.Desiring to know if I have done any damage to the decoder, I placed the engine back on the track and everything still worked. In connecting the black/white stripe wire, I used the same process but it was easier as there was more room to work. Then back to track to see if everything still worked and if the Keep Alive was functional. Everything worked and the Keep Alive keep the engine running for 6-8 inches on non-powered track. The next step was securing the Keep Alive with Kapton tape. The Keep Alive was placed fairly far back to avoid contact with the larger components on the decoder board to avoid overheating issues.(see photo below).
The last step was to re-install the shell while being careful to correctly arrange the wires. Once done , I have a much better running engine. I hope this information is of use to someone.BN-Steveharsh@msu.edu
jecorbett I have two of these locos which are about 10 years old. They are DCC with sound. I sent an e-mail to TCS tech support asking if one of their capacitors would work in my SW7s. Their reply didn't give me specific instructions for this loco but did say I would need to figure where to attach the blue wire (common) and black/white wire (ground). I have no idea which wire should go where. The decoder has a 4 wire plug, black/yellow/green/red, which are wired to a smaller board under the roof of the cab. There is additional wiring under the decoder which is screwed in place above the motor assembly. If I were to guess based on my limited knowledge of these types of electronics, it would to be that the red and black wires in the plug are the power wires and that these are where the capacitor wires should be spliced to. But since I don't want to guess, I thought I'd ask more knowledgeable people than myself how to procede. I need to know which wires to attach the capacitor to and where that splice should be made. Also there is not a lot of room inside the shell to put a capacitor. It looks like the only available space is inside the cab. The other opion they gave me was to replace the decoders with one of the decoders with Keep Alive already installed. That might be the simplest solution but probably the more expensive as well.
The answer the original question (though it may have already been resolved, but I'm a new member to the hobby), in my experience, the best option is go with the smallest fomr factor decoder of a manufacturer of your choice. All of them have those.
This will give you some extra space compared to the bigger OEM decoders.
Secondly, the Keep Alive super-capacitors are usually not installed onto the decoder PWB, but made as a stand-alone unit. So you have to do your measurements and do some research what space you have and what you can fit in there.
Thirdly, I find these could be bulky for some smaller locos, too. I do my own custom designs, because that allows me to use the space more efficiently: one capacitor over the flywheel; another two besides the decoder motherboard; another one under the hood in front of the cab, etc. and just connect them all together.
Another benefit for doing my own design, is all pre-made Keep Alive units have limited max voltage, which limits the discharge time. Making my own design allows me to use higher voltage on the track in order to increase the discharge time with smaller value (and smaller size) capacitors.
You can find a few online schematics, they're pretty much the same and not complicated at all. You just need to have some soldering skills :)
Good luck!
This is a reasonably sized 4-axle locomotive. I would not expect it to need a keep-alive if trackwork is properly powered, particularly frogs on longer turnouts.
I would first examine why you think you need or would benefit from a keep-alive. Do you have plenty of feeders and powered metal frogs? Loosely fastened track depending on rail joiners to maintain power for too far or long plastic frogs or unpowered frogs can lead to stalling. I was lazy at first, but finally got around to powering my frogs and noticed significantly better performance right away.
It takes an iron man to play with a toy iron horse.
The original ones like this with the QSI decoder were pretty light - so they came with traction tire wheels so they could actually pull something. So they don't actually pick up with all 8 wheels if the traction tire wheelsets are installed. Basically you can pull a reasonable number of cars for an SW-7 and suffere from poor power pickup, or get decent power pickup but have trouble moving a train that a smaller Bachmann 44 tonner can easily more.
MisterBeasley This is a reasonably sized 4-axle locomotive. I would not expect it to need a keep-alive if trackwork is properly powered, particularly frogs on longer turnouts. I would first examine why you think you need or would benefit from a keep-alive. Do you have plenty of feeders and powered metal frogs? Loosely fastened track depending on rail joiners to maintain power for too far or long plastic frogs or unpowered frogs can lead to stalling. I was lazy at first, but finally got around to powering my frogs and noticed significantly better performance right away.
I started this thread 5 years ago although I had a different screenname back then. I have two of these locos and they do stall on my insulated frogs. I have Atlas #6 turnouts through the yard. If they are moving very slowly which is how I like to run them, they will sometimes stop over an insulated frog. At this point, powering the frogs is not an option I am willing to consider. I have a 12 track double ended yard plus additional turnouts the switchers must negotiate and I am not willing to go to the time and expense of rewiring them so that the polarity to the frog can be switched.
I also have the same problem with a BLI K-4 Pacific. I have traced that problem to not getting pickup in the drivers on the left side of the loco. It only gets left side power from the tender. I have taken it appart to try to see what the problem is but haven't located it. I've read about others having similar problems with BLI steamers.
know2go You can find a few online schematics, they're pretty much the same and not complicated at all. You just need to have some soldering skills :) Good luck!
As I said in another reply, I started this thread under another screenname five years ago and no, the problem has not been resolved. I bought some Keep Alives last year that were suggested by Tony's Train Exchange but I have not gotten around to installing them. My problem is that when it comes to electronics, I am illiterate regarding many of the terms. Some of the explanations I have read as to how to wire them might as well have been written in Chinese. I need something along the lines of Electronics for Dummies. I am very much interested in your suggestion for simple schematics online but have yet to find any. Do you have one or two that you can recommend. Something along the lines of, "Hook the blue wire here. Hook the white wire here.". All the instructions I've seen so far tell me I need to figure out which wire is which. That's why the Keep Alives are still on the shelf.
Going to have to find someone who's done it then. The closest thing to the simple explanation is the part of marcus' page that shows you how to figure out the right part of the circuit for most any decoder. I'm not even sure BLI uses the same decoder board layout in each loco, so it may be very specific to the SW-7, so someone with a different BLI diesel might not be a help either. If I had one, I could probably figure it out. If you can get some good in-focus close up pictures of the decoder board - one showing the whole thing, and then perhapst 3 even closer of the front, middle, and back - I or someone else here might be able to mark the correct points.
Just as a data point, I recently figured this out after not too much effort. There's Larry Puckett's excellent short version of what's needed to know when dealing with keep-alives in his DCC Corner column (pg 54-55) in the October 2019 MR. I followed his suggestion to check out the websites that could be helpful, several which have been cited previously in this thread.
Finding the blue common + is easy and usually labeled and ready to use. The negative - common is trickier as it's usually not labeled, especially in older decoders. There is an easy test to confirm finding the common - Negative, though. Put the red + lead of your multimeter on the blue common + Positive. If you have the correct point identified for the common - Ground, when you touch the black negative lead of the multimeter to it, the meter should read somewhere around 13.5 volts positive if you have the command station output set around 14.5 volts. Ths drop is due to the voltage drop across the bridge rectifier or "H" bridge, indicating you are in the right spot needed to connect the keep-alive's negative lead to.
Many modern decoders may have a solder pad to make connection easier. That's what I found when I shucked the Digitrax DN136D out iof its shrinkwrap. Turns out that the solder pad was right at one corner to make connecting the common - Negative easier on the tiny decoder.
The DN136D was already fitted into my Shay, so I just needed to make room for the keep-alive. The smallest Digitrax decoder with a plug-in keep-alive option was about twice the size of the DN136D, so the hack gives you options you wouldn't otherwise have. However, if the process is too intimidating, it's money well spent to have a functioning unit bought RTR. The performance enhancement is well worth the investment.
Mike Lehman
Urbana, IL
mlehman Just as a data point, I recently figured this out after not too much effort. There's Larry Puckett's excellent short version of what's needed to know when dealing with keep-alives in his DCC Corner column (pg 54-55) in the October 2019 MR. I followed his suggestion to check out the websites that could be helpful, several which have been cited previously in this thread. Finding the blue common + is easy and usually labeled and ready to use. The negative - common is trickier as it's usually not labeled, especially in older decoders. There is an easy test to confirm finding the common - Negative, though. Put the red + lead of your multimeter on the blue common + Positive. If you have the correct point identified for the common - Ground, when you touch the black negative lead of the multimeter to it, the meter should read somewhere around 13.5 volts positive if you have the command station output set around 14.5 volts. Ths drop is due to the voltage drop across the bridge rectifier or "H" bridge, indicating you are in the right spot needed to connect the keep-alive's negative lead to. Many modern decoders may have a solder pad to make connection easier. That's what I found when I shucked the Digitrax DN136D out iof its shrinkwrap. Turns out that the solder pad was right at one corner to make connecting the common - Negative easier on the tiny decoder. The DN136D was already fitted into my Shay, so I just needed to make room for the keep-alive. The smallest Digitrax decoder with a plug-in keep-alive option was about twice the size of the DN136D, so the hack gives you options you wouldn't otherwise have. However, if the process is too intimidating, it's money well spent to have a functioning unit bought RTR. The performance enhancement is well worth the investment.
I don't fully understand how that is going to tell me which is the negative lead but I'll check out the article to see what it can tell me. I know one thing. I've fried enough decoders for one month with mistakes. I'm not going to proceed unless I am 100% certain I am attaching the Keep Alive to the correct connections.
John-NYBWI'm not going to proceed unless I am 100% certain I am attaching the Keep Alive to the correct connections.
If you have power to the decoder and are sure of the Blue + Positive that the red multimeter lead is applied to, then you probe for getting a the ~13.5 volt reading.
Then the question is can you solder the lead from the keep-alive to it? I lucked out and found a solder pad where I needed to attach.
On many of the pictured examples at those websites, the soldering was done to a PCB trace or to the lead of an attached component, making it a delicate task to attach a wire without unsoldering something else. Discretion is the better part of valor here. If it looks like it's beyond your soldering skills, then even if you're certain about the right spot, it may be best to try a newer decoder already set-up to use keep-alive.
mlehman John-NYBW I'm not going to proceed unless I am 100% certain I am attaching the Keep Alive to the correct connections. If you have power to the decoder and are sure of the Blue + Positive that the red multimeter lead is applied to, then you probe for getting a the ~13.5 volt reading. Then the question is can you solder the lead from the keep-alive to it? I lucked out and found a solder pad where I needed to attach. On many of the pictured examples at those websites, the soldering was done to a PCB trace or to the lead of an attached component, making it a delicate task to attach a wire without unsoldering something else. Discretion is the better part of valor here. If it looks like it's beyond your soldering skills, then even if you're certain about the right spot, it may be best to try a newer decoder already set-up to use keep-alive.
John-NYBW I'm not going to proceed unless I am 100% certain I am attaching the Keep Alive to the correct connections.
Last night I opened up one of the switchers and looked under the hood and what I saw was nothing like you described. It is a Quantum decoder and there is a date on it of 2003 which I'm guessing is the manufacture date. Apparently decoder technology has changed a lot since then. It really doesn't matter because even if I were to be able to figure out where to solder the Keep Alives, there is no way I would attempt to do so. I think the most skillful person with a soldering iron wouldn't want to take on that task.
What I have discovered about my two BLI switchers is they only stall on certain turnouts. My yard ladder consists of Atlas #6 turnouts with insulated frogs. Last night I slowly ran the switchers over the ladder. When one axle is on the frog and the other is on the point rails, the stalls occur. That tells me some of my turnouts aren't getting adequate juice to the point rails. That should be a much easier fix than trying to solder a Keep Alive to old decoders that are otherwise still working perfectly.
I'm sure I can find another place to use the two Keep Alives I have. I have a pesky BLI K-4 Pacific that for reasons I have not been able to figure out yet is not getting pickup from the driver wheels. It should get pick up from both the drivers and the tender. I determined that by putting it on the rails with the bell clanging. On the right side I could tilt either the driver or the tender wheels off the track and it would continue to clang. When I tilted the left side drivers off the track, it would also continue to clang. It was when I tilted the left side tender wheels off the track that it went quiet. Unfortunately, this is about the same age as the two switchers so I'm guessing it might have the same issue with the Quantum decoder. If that is the case, the only real solution would be to fix the problem with the left side driver wheels.
The components needed to solder to would be among the ones with the largest pads, out of necessity because they need to carry current for the full load of the decoder. However, if you aren't confident of your soldering skills, more harm than good could be done.
For the steam loco - check in the tender where the wires all plug in to the board. There should be two sets of track pickups - a pair from the tender, and a pair from the connector to the loco. The problem with mine (A PCM of similar vintage, which just means it has an ESU decoder not QSI) was that the one pin on the connector from the loco was not properly insered into the plastich shell that forms the plug side. As such, when the plug was inserted into the circuit board, the one wire was pushed back out of the connector shell instead of being pressed over the pin in the socket. The other wire went into place as it should. So I was getting power from both sides fo the tender, but only one side of the loco. The pins are tiny, you may have to use magnifier, but the way they are made is that they have a tiny tab on one side which is supposed to latch into the shell to keep the pin from being pushed back out. In my case, the pin was rotated so that this tab was not on the side of the shell that has the cutout to catch the tab. All I had to do was put it back in the correct way, and make sure both pins seated when plugging in to the tender circuit board, and I've never had any trouble with it since.
The connectors looks like this item, notice the tab sticking out on the left side:
https://www.digikey.com/product-detail/en/molex,-llc/0797580001/WM12450-ND/5806727?utm_adgroup=Cable%20Assemblies&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Molex_0900_Co-op&utm_term=&utm_content=Cable%20Assemblies&gclid=EAIaIQobChMIwZb5yeyu6QIVJYFaBR11JgzHEAQYAyABEgJXTvD_BwE
The shells look something like this (picture on left). The wire comes in from the top left, the slots in the right side of the connector catch the tab and keep it from being pushed out the back of the shell:
https://www.aliexpress.com/item/32982601205.html
Hello Mike,
I followed your post but I find two solder pads showing the same voltage when I test them agains the blue +. Which one did you take in the end? Are they both the same?
Best
Roland
rolandwartenberg Hello Mike, I followed your post but I find two solder pads showing the same voltage when I test them agains the blue +. Which one did you take in the end? Are they both the same? Best Roland
FWIW a 20 year old decoder would have been made long before the various "keep alive" gizmos hit the market, so it's not surprising you had trouble finding any info since they weren't made with the keep alive in mind. However, many decoders even then had a small capacitor either attached or that could be attached; sometimes you can attach the keep alive to those wires and it will work.
p.s. red and black wires normally connect the decoder to track power; orange and gray connect the decoder to the motor. Blue, white and yellow are for headlights.
Blue is positive ground, so that's why it's used for lighting outputs (along with the requisite negative function wire).
Keep in mind that AFAIK, modern BLI decoders (Paragon) use a negative ground on their decoders. My understanding is that no other decoder mfr does that (they're all positive grounded).
Nice to see this three year old thread I started get revived but even with the additional information, I have no clue where to solder the Keep Alive to this ancient decoder. Apparently nobody else in the world does either. If they do, they are keeping it a secret.
As is typical, I'm just now getting back into model railroading after taking the warm weather months off. I have not operated my layout in many months and have been just trying to get things cleaned up and organized. I've come to the conclusion I will either have to learn to live with the occasional stalling in my switchers or replace the decoders with modern ones with Keep Alives. Maybe I can find a use for the existing decoders in another loco.
John-NYBW Nice to see this three year old thread I started get revived but even with the additional information, I have no clue where to solder the Keep Alive to this ancient decoder.
Nice to see this three year old thread I started get revived but even with the additional information, I have no clue where to solder the Keep Alive to this ancient decoder.
Alton Junction
richhotrain John-NYBW Nice to see this three year old thread I started get revived but even with the additional information, I have no clue where to solder the Keep Alive to this ancient decoder. John, I missed your much earlier post where you indicated a screen name change a few years back. Just out of curiosity, what prompted you to change your screen name? Rich
John, I missed your much earlier post where you indicated a screen name change a few years back. Just out of curiosity, what prompted you to change your screen name?
I just went back to the OP and discovered I actually started this thread back in 2015.
I can't remember the exact details of the problem but it had to do with sign in issues. Having going back and forth with the MR support team trying to come up with a solution, it was decided the best solution was to delete the old account and create a new one.