rrinker I wouldn't consider it a design flaw. It's more DCC Ready than some things are that say that on the box - since the term is really meaningless. As it comes, even with the screw grounding of the motor to the frame, the motor IS completely isolated from the track pickups, the key component of being DCC ready. Now, granted, a derailment can knock a wheel against the frame, destroying that separation... --Randy
I wouldn't consider it a design flaw. It's more DCC Ready than some things are that say that on the box - since the term is really meaningless. As it comes, even with the screw grounding of the motor to the frame, the motor IS completely isolated from the track pickups, the key component of being DCC ready. Now, granted, a derailment can knock a wheel against the frame, destroying that separation...
--Randy
OK, how about this? "Almost DCC Ready". To me, and I would bet to most people, DCC Ready means that if you wire in a decoder, you are ready to go and that the decoder will not be fried by excess current reaching the decoder.
One thing that you pointed out earlier in this thread, Randy, is that excess current can reach the decoder even though the motor may be isolated from the track pickups and even if the wheels don't touch the frame. Here is that comment.
"I always thought the wheel itself could easily touch the frame in a derailment situation where either the opposite rail drops down off the railhead, or the flange of a wheel rides up on the railhead. It might instead be the pickups, or the point where the track power wires solder on to the trucks. The same truck doesn't have to touch the rail AND the frame, the track pickups are wired in parallel so if the rear truck stays ont he raila dn the front truck rides up on something and touches the frame - same thing, track power applied ot the frame."
I think that the latter part of your statement is what happened in my situation.
If it is not a design flaw, then, at the very least, the early Proto S3 was not DCC Ready. The orange wire was screwed to the frame and needed to be rerouted to the brush, and the metal tab touching the frame needed to be clipped and insulated so that there was no contact with the frame. Also, there is some debate about whether the metal motor mount screw needed to be replaced with a nylon screw.
Rich
Alton Junction
I wouldn't consider it a design flaw. It's more DCC Ready than some things are they say thatont he box - since the term is really meaningless. As it comes, even witht he screw grounding of the motor to the frame, the motor IS completely isolated from the track pickups, the key component of being DCC ready. Now, granted, a derailment can knock a wheel against the frame, destroying that separation...
BTW I posted my pics of isolating the motor in an S1 in July 2004. Probably mentioned it here, too, since I was a posting fiend back then, too. And doing a better job of keeping my web site up to date as my construction progressed.
I think this will work: http://community.webshots.com/album/163958178NgaXTy 7th photo, one captioned "motor tape". The complete caption says "Apply a piece of tape to the lower brush cap to insulate the motor from the frame. That's the whole point of this exercise, so don't skip this step!"
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
davidmbedard Sigh...... As a professional decoder installer, my first and primary goal is to install a decoder into a locomotive only once. Hence, the advice I give on these boards is to reflect this practice. If th OP followed my origional advice, the install would have gone smoothly and would have been worry free. David B
Sigh......
As a professional decoder installer, my first and primary goal is to install a decoder into a locomotive only once. Hence, the advice I give on these boards is to reflect this practice. If th OP followed my origional advice, the install would have gone smoothly and would have been worry free.
David B
Trouble was, David, you weren't around when I first installed the decoder back in 2004. Blame Proto, not me. It was an acknowledged design flaw by Proto. I only found out about it after the decoder got fried and others on this forum advised me how to work around the flaw. That was a few years back.
This time around, the failed workaround was my fault, I guess, since I did not know enough to insulate around that metal tab touching the frame. But, again, I blame Proto, and I think fairly so, for the design flaw.
It wasn't "DCC Ready", contrary to their marketing claims and their label on the box.
Two months later, I finally got around to replacing the fried decoder.
I got some Kapton tape and fully insulating the decoder and the motor from the frame. I cut off the metal tab and insulated that area as well. I added a nylon screw to hold the motor to the frame. The orange wire now is soldered to the brush.
So far, so good. This is my second replacement decoder. The first time I fried one when the loco derailed on a open switch. I thought that I took the necessary steps when I replaced the decoder by rerouting the orange wire from the frame to the brush. I made sure that the decoder and motor were fully insulated from the frame. But, at the time, I was unaware of the problem with the metal tab touching the frame.
So, I am keeping my fingers crossed that I have properly addressed the "Proto S-3 Problem".
If I blow any more decoders on this loco, it will be sold on eBay as a DC loco.
Yes, there is that too - the frame IS painted, which is ostensibly insualting, liek painting frog points with nail polish to cure shorts. But it can and does wear off if contact is made. With the tab removed thant he motor taped you should not get any continuity between eithe rmotor wire and the frame, scratch off some paint up inside the shell to get a clean contact spot that won't show when the shell is on
rrinker I always thought the wheel itself could easily touch the frame in a derailment situation where either the opposite rail drops down off the railhead, or the flange of a wheel rides up on the railhead. It might instead be the pickups, or the point where the track power wires solder on to the trucks. The same truck doesn't have to touch the rail AND the frame, the track pickups are wired in parallel so if the rear truck stays ont he raila dn the front truck rides up on somethign and touches the frame - same thing, track power applied ot the frame. Once the isolation is accomplished, there's no problem, even if something does touch the frame, because neither motor wire is in any way connected to the frame. --Randy
I always thought the wheel itself could easily touch the frame in a derailment situation where either the opposite rail drops down off the railhead, or the flange of a wheel rides up on the railhead. It might instead be the pickups, or the point where the track power wires solder on to the trucks. The same truck doesn't have to touch the rail AND the frame, the track pickups are wired in parallel so if the rear truck stays ont he raila dn the front truck rides up on somethign and touches the frame - same thing, track power applied ot the frame.
Once the isolation is accomplished, there's no problem, even if something does touch the frame, because neither motor wire is in any way connected to the frame.
Randy,
This all makes perfect sense, and I appreciate the explanation and the time and thought put into it. Most appreciated.
One upshot of all of this is the logical conclusion then that the metal motor mount screw is just fine and should cause no problem since the tab is removed and the brushes are isolated from the frame.
rrinker I always thought the wheel itself could easily touch the frame in a derailment situation where either the opposite rail drops down off the railhead, or the flange of a wheel rides up on the railhead. It might instead be the pickups, or the point where the track power wires solder on to the trucks. The same truck doesn't have to touch the rail AND the frame, the track pickups are wired in parallel so if the rear truck stays ont he raila dn the front truck rides up on somethign and touches the frame - same thing, track power applied ot the frame.
Now, that explanation, I can buy. That is most likely what did happen.
richhotrain I was doing some continuity tests this morning with an ohmmeter, and I could not get any reading when touching both probes to the frame. So, now I am totally confused. Doesn't the frame act as a conductor?
I was doing some continuity tests this morning with an ohmmeter, and I could not get any reading when touching both probes to the frame. So, now I am totally confused. Doesn't the frame act as a conductor?
Let me amend that statement. After some prompting from a train buddy, I went back and checked the frame for continuity once again. At first, I got no readings when I touched the two ohmmeter probes to the frame. But, then, I noticed some silvery nicks along the edge of the frame and touched the probes to two of those spots and I go,t a reading. So, I guess the metal frame, which is painted glossly black, must be "coated" in such a way that continuity cannot be checked simply by placing the probes on the surface of the frame.
The Atlas ones are slightly different, but very similar. The motor even loosk the same, but perhaps it's not exactly.
The frame of the Protos is not conencted to the rails in any way, so you should never see continuity between any wheel and the frame. If you've removed the tab on the motor and put a layer of tape around the motor, then the motor is also no longer connected to teh frame, so you should see no continuity from either motor wire to the frame. In this condition, you are perfectly safe and theonly way for a decoder to get fried would be for one of the wires to actually break off and touch somehtign it shouldn't. Or the motor coil to burn out and suddenly draw way more than normal current.
Unmodified, the bottom brush of the motor is connected to the frame via that tab. Up top, they have an orange wire screwed to the frame with a ring terminal that leads to the 8 pin plug. Under normal circumstances this is OK as wellsince the track pickup are isolated fromt eh frame, there is nothign to short. Except if the wheel or some portion thereof contacts botht he rail and the frame. This now puts track voltage to the motor output of the decoder - poof. I always thought the wheel itself could easily touch the frame in a derailment situation where either the opposite rail drops down off the railhead, or the flange of a wheel rides up on the railhead. It might instead be the pickups, or the point where the track power wires solder on to the trucks. The same truck doesn't have to touch the rail AND the frame, the track pickups are wired in parallel so if the rear truck stays ont he raila dn the front truck rides up on somethign and touches the frame - same thing, track power applied ot the frame.
Thanks, Pete, that all makes good sense.
I am still hung up on one issue and that is the metal screw that holds the motor to the frame.
Randy says leave it, David says replace it with a nylon or plastic screw.
I have seen differing opinions on this elsewhere as well.
NCE now make an ATL-S4 decoder and motor isolation kit specifically designed for the Atlas S1 through S4 switchers. In the manual, it says to replace the metal screw with the enclosed plastic screw.
So, what the heck is the right answer?
Rich.
There is a big difference between a frame connected to a rail and one connected to the motor. There are many examples of hot framed locos that have one rail connected electrically to the frame. Brass, and Atheran blue box units are a couple. These operate normally and when a derailment happens the breaker trips in the DCC system and the decoder mostly comes out unscathed. It is when one motor brush that has contact to the frame is when there is a great possibility of frying a decoder. Motor brushes should always be electrically attached to the decoder only. The orange and gray wires should only contact the motor brushes and nothing else. There are many split frame locos that have decoders in where one side of the frame is hot to one rail and the other side is hot to the other rail. As long as the decoders orange and grey wires are to the brushes and nothing else there is no problem in the operation of the loco.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
Richhotrain...........
Weird things happen in derailments, stuff that can cause shorting and "fried decoders" is just waiting patiently out there to happen someday. Which means I'm still on borrowed time waiting for my first "cooking session"........................
ENJOY !
Mobilman44
Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central
I got to thinking more about this overnight. Since we are correctly, I believe, blaming that tab that touches the frame for blowing the decoder, it seems to follow that the frame can cause the short by touching both rails. Because I am contending that the wheels are not touching the frame, is it conceivable that on a derailment, where the loco is forced off the rails, the frame touches the opposite rail, resulting in a short ?
rrinker If you hadn't mentioned that it derailed, I would start checking other things, liek maybe a pickup wire came loose or something, but the derailment leading to the decoder blowing is exactly what the pro installer sites like Litchfield mention about this loco.
If you hadn't mentioned that it derailed, I would start checking other things, liek maybe a pickup wire came loose or something, but the derailment leading to the decoder blowing is exactly what the pro installer sites like Litchfield mention about this loco.
The worst part of the entire situation is that the derailment was caused by "operator error".
I was testing a newly created gapped section of track for occupancy detection. I had set up a series of flashing crossing signals near my downtown passenger station, and I had installed an occupancy detector for a section of track. I carelessly placed the S3 on the track outside the gapped section without being careful to align the wheels on the rails. I applied power to get the S3 running and a second or two later, the front coupler caught the frog on a double slip due to the misaligned loco.
I still think that the wheel touched the opposite rail, and I recall that happenng. Try as I may, I could not get the wheels to touch the frame when I manipulated the trucks by hand just a few minutes ago.
Once I install the new decoder, dare I test my work by seeing if I can blow the decoder by touching the wheel on one side to the rail on the opposite side? Is there a smarter way to test the new setup?
The frame extend over the trucks, if the flange ends up on top of the rail it will lift the wheel enough so that the top of the flang will hot the bottom of the frame, instant short if the motor tab still touches the frame.
Rolling along on the rails, in a straight line, it makes no difference if that orange wire is repalced or not. The pickups on boh trucks are already isolated fromt eh frame. Only if track power somehow comes in contact with the frame is there a problem unless the motor is isolated. However it happened, that's probably what happened and blew your decoder. It's pretty easy to see, swivel a truck and then tip it, the movement will be stopped when a wheel hits the frame, not due to lack of movement in the universals or truck mounting clips.
rrinker The different witht he Proto S switchers is that it's NOT a rail conenction grounded to the chassis, it's the MOTOR. Both rail pickups ARE isolated from the chassis. The stock lock witht he DC dummny board in palce conencts the ORANGE wire tot he chassis - disconnect that orange wire and the loco won't move - it's the only path from the wheels via the dummy plug to the motor. That's why everything is fine until a derailment puts a wheel in contact with both the rail and the chassis - NOW there is a direct link from the track pickup to the motor.
The different witht he Proto S switchers is that it's NOT a rail conenction grounded to the chassis, it's the MOTOR. Both rail pickups ARE isolated from the chassis. The stock lock witht he DC dummny board in palce conencts the ORANGE wire tot he chassis - disconnect that orange wire and the loco won't move - it's the only path from the wheels via the dummy plug to the motor. That's why everything is fine until a derailment puts a wheel in contact with both the rail and the chassis - NOW there is a direct link from the track pickup to the motor.
Maybe I am missing something, but I don't see how the wheel can touch the frame. I thought that the issue was when a derailment caused the wheel on one side of the truck to touch the rail on the opposite side energizing the frame and frying the decoder via that infamous copper tab.
I took the loco apart this morning, cleaned and lubed it, rewired it and clipped off that tab that touches the frame. I fully insulated the entire motor from the frame with electrical tape.
I have to order a new decoder so I tested my work in DC. At first, there was nothing. No movement, no nothing. i did a quick test and confirmed that the pick up wires were routing power to the circuit board, so I began to wonder what I did wrong. Did this whole incident screw up the motor? Did clipping off the tab do something bad?
Then it hit me. I needed to replace the original PCB. Did that and everything was fine.
So removing that tab and soldering the motor wire to the brush makes it safe to add a decoder and operate in DCC. At the same time, you can still operate in DC without the decoder by re-installing the original PCB. Redirecting that orange wire to the brush still provides the necessary ground for DC operation. Am I understanding that correctly?
I didn't change screws, I reinstalled the same metal screw - the brush caps are insulated from the rest of the motor frame by that plastic block they sit in. There's no danger inthe motor frame being grounded to the loco frame, it's the brushes that need to be isolated. Same thing with old locos where it was common for them to have a wire or strap connecting one brush spring to the motor frame, while BOTH brush holders sat on a bakelite fo fiber insulator. Simply cutting that wire or strap is sufficent to make a motor 'isolated' for DCC purposes. In fact, for a while Bowser offered "DCC" versions of their older motors to replace th ones in the steam loco kits. The only difference between the normal motor and this DCC motor was that both brushes were insualted, neither one connected tot he motor frame. Isolation achieved.
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.
Probably to late but here is what I did for a smilar install.
I use 0.002 inch thick phosphore bronze. I have a few feet of the stuff.
Used nylon screws. I made sure the screw holes on the frame where smooth or if not, the edge of the screw hole can punch up through the Kapton tape and cause a short which one did. I found the short before powering up.
I also used the Dremel and routed the frame a slight amount to clear the PB.
rrinker The frame and the brushes aren't connected to each other, at least none of mine were, that's why the motor has a plastic end cap with the brushes in it With only one screw thought he motor can turn and put that remnent of the tab in contact with the frame, .or even make the brush cap contact the frame, hence the tape. None of this actually is a problem with this loco - until you derail and jam a wheel between the rail and frame, as happened. My first batch of kapton tape I got from Litchfield, since they sold short lengths of it instead of having to buy the whole roll. The roll I currently have I picked up from a vendor who shows up at most of the train shows with lots of DCC parts and accessories. Most of the DCC vendors have it, I've never seen it in a big box store, too specialized I think. Looking back at my photos from my site, I just used a square of electrical tape, and I DID totally remove the tab. First 8 photos on my decoder install gallery. Skip the frame miulling part in the remaining photos since I cut it out to fit the DH163L0 for no reason other than I had one on hand. --Randy
The frame and the brushes aren't connected to each other, at least none of mine were, that's why the motor has a plastic end cap with the brushes in it With only one screw thought he motor can turn and put that remnent of the tab in contact with the frame, .or even make the brush cap contact the frame, hence the tape. None of this actually is a problem with this loco - until you derail and jam a wheel between the rail and frame, as happened.
My first batch of kapton tape I got from Litchfield, since they sold short lengths of it instead of having to buy the whole roll. The roll I currently have I picked up from a vendor who shows up at most of the train shows with lots of DCC parts and accessories. Most of the DCC vendors have it, I've never seen it in a big box store, too specialized I think. Looking back at my photos from my site, I just used a square of electrical tape, and I DID totally remove the tab. First 8 photos on my decoder install gallery. Skip the frame miulling part in the remaining photos since I cut it out to fit the DH163L0 for no reason other than I had one on hand.
You make that too easy for me with pictorial spread of the motor assembly and disassembly.
Interestingly, the text on the instruction sheet says that there are four screws on the underside, two to hold the shell to the frame and two to hold the motor to the frame. But, there are only three screws, two for the shell and one for the motor. The exploded diagram only shows the three screws as well, two for the frame and one for the motor.
I plan to follow David's advice and replace the metal motor mount screw with a plastic one. Do you recall if you did that?
davidmbedard Guys, you need to do a continuity test between the steel body of the motor and the brushes. You WILL find that one of the brushes is grounded to the steel frame of the motor. What you NEED to do is isolate the entire bottom of the motor from the frame with Kapton tape and secure it with a plastic or nylon 2-56 screw. From the factory, the motor is secured with a metal screw and that is part of the electrical path to the lower motor brush. If you dont do this, you will be blowing decoders until the cows come home. David B
Guys, you need to do a continuity test between the steel body of the motor and the brushes.
You WILL find that one of the brushes is grounded to the steel frame of the motor.
What you NEED to do is isolate the entire bottom of the motor from the frame with Kapton tape and secure it with a plastic or nylon 2-56 screw. From the factory, the motor is secured with a metal screw and that is part of the electrical path to the lower motor brush.
If you dont do this, you will be blowing decoders until the cows come home.
David, thanks for that info. I will follow your advice.
The motor is secured to the frame on the S3 by a single metal screw on the underside of the frame. I assume that is the screw you are referring to which should be replaced by a plastic screw. Correct?
One other question. Where is Kapton tape most readily available? Home Depot? Radio Shack?
rrinker I think I actually took the tab itself completely off - just be careful not to loose the brush spring or brush when you unscrew the cap. The tab is just a big ring connector that is threaded on the cap. WHile the cap was off I poked the end of the wire in that hole and soldered it. Probably ok with the tab like you have it, if you wrap it with tape. In fact this very loco was pictured in Bruce Petrarca's DCC column in the latest MRH magazine. --Randy
I think I actually took the tab itself completely off - just be careful not to loose the brush spring or brush when you unscrew the cap. The tab is just a big ring connector that is threaded on the cap. WHile the cap was off I poked the end of the wire in that hole and soldered it.
Probably ok with the tab like you have it, if you wrap it with tape. In fact this very loco was pictured in Bruce Petrarca's DCC column in the latest MRH magazine.
Thanks, Randy.
locoi1sa Rich. I soldered mine to the little tab and cut the part of it off that goes around the plastic. Pete
I soldered mine to the little tab and cut the part of it off that goes around the plastic.
Thanks for that additional info Pete.
rrinker The key is cutting off that copper tab on the bottom brush cap, and also putting a layer of tape there so the cap, wire, or remnents of the tab cannot touch the frame in any way.
The key is cutting off that copper tab on the bottom brush cap, and also putting a layer of tape there so the cap, wire, or remnents of the tab cannot touch the frame in any way.
I understand the part about curring off the copper tab and insulating so that nothing touches the frame.
But, where did you solder the motor wire on the bottom brush? Is it OK to leave the soldered connection where I had it (see second photo)? Or should I move the wire to the remnant of the copper tab?
My first one I posted pictures of, I went through the effort of actualyl milling the frame so I could plug in a DH163L- and keep the lights. The two I've done since then have been hardwired, all the Proto circuitry ripped out and the light bulbs replaced with LEDs. The rest of the install is the same. They key is cutting off that copper tab on the bottom brush cap, and also putting a layer of tape there so the cap, wire, or remnents of the tab cannot touch the frame in any way. Mine are S1's but it's the same frame and motor, basically the radiator housings are different on the shell.