When it is working right which is 95% of the time by bench is truly relaxting and a joy to run. Then there are the dark times! Melted decoders are not fun, and has cost me what a better command station would have cost.
I like the tail light circuit breaker idea that you kind folks have listed.
http://www.rr-cirkits.com/Notebook/short.html
http://www.wiringfordcc.com/track.htm
I printed out the articles and today while at work I read them a few times, then a dim bulb went on in my head. A circuit breaker is nothing more than a fuse that reset it self. Bulbs light up when there is a short. One method only lets you know when there is a short, other one uses bulb and PTC fuse that kills the power.
Hum, I like the killing of the power part. Why not use both? I will need to find out more about the PTC fuse and if it burns out or will reset it self.
Why not add the taillight and a in line fuse? A good DCC engine should pull around .7 amps with a good drag, is that sort of right? My DH 123 decoders are rated at 1.5 amps max is 2.0 amps. Add the taillight bulb and a in-line 1.75 amp fuse, bulb comes on, poop goes the fuse and train stays where the short happened and the decoder lives to pull again!
Each line has it own power feed off the booster, so there would be 3 fuse's.
Most of the time, I run just one train per line, I could simple add a bigger fuse if I want to run 2 trains. replacing a fuse is much easier than a $20.00 decoder.
Next part is a little of a reach and need to find out more about the PTC fuse. But, why not add a PTC fuse to the problem engines? One listed is a .95 amp fuse so more than likely they will have one around 1.5 amps or so.
Well what do you think, could Digitrax stock go down? Will they need a government bail out?
Sort of thinking again, Cuda Ken
I hate Rust
The bulb method does not stop the flow of power. It merely limits it. One of the many laws (science type laws - like Newton's laws of gravity) of electricity is that all things in a series circuit will have the same current flowing through them. So if your loco shorts out and you have a taillight bulb in the circuit, you have the bulb in series with your loco. If the bulb draws 2.5 amps, then 2.5 amps will also be passing through the loco.
The variation on the light bulb method on the RR-CirKits page takes advantage of the fact that in the two filament type bulbs, one draws about 2.1 amps and the other about .4 amps. A PTC fuse is self-resetting, when it overheats from the current exceeding its rating, it opens up liek a switch, when it colls down, it closes again. The effect in Dick's circuit is to disconenct the 2.1 amp filament so if the short exists for an extended time, it ends up with only .4 amp flowing through it.
PTCs are generally slow acting, probably too slow to save a decoder, especially when they can get an instantaneous 8 amp shot from the MRC booster. By the time the PTC opens, it would probably be too late. The electronic breakers drop out much faster than any PTC. Dunno if the same is true of the newest PSX line, but the original Tony's Powershields had an option for manual reset - if there was s short it would turn off and STAY off until you pushed a button. They way they and other breakers normally work (as well as the ones in the boosters) is that they drop out, then apply power, and if there's still a short, drop out again. Over and over - end result it still fries your 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.
cudakenWhy not add the taillight and a in line fuse? A good DCC engine should pull around .7 amps with a good drag, is that sort of right? My DH 123 decoders are rated at 1.5 amps max is 2.0 amps. Add the taillight bulb and a in-line 1.75 amp fuse, bulb comes on, poop goes the fuse and train stays where the short happened and the decoder lives to pull again!
Randy, did you catch where I all so want to add a in line fuse? Bulb comes on, in line fuse poops and save the decoder and the engine is still where it shorted out so I can fix the problem. Reason for the light is to catch my attention.
Ken
Ken,
Send me a PM and i'll send you some info on this.It has helped me.
TheK4Kid
aka Ed
cudaken When it is working right which is 95% of the time by bench is truly relaxting and a joy to run. Then there are the dark times! Melted decoders are not fun, and has cost me what a better command station would have cost.
I like the tail light circuit breaker idea
Well what do you think, could Digitrax stock go down?
There's no point in a bulb and fuse inline, as far as I can see. Either the bulb limits the current to the point where the the fuse never blows, or the fuse does blow, and you can't see the bulb anyway.
So, I've been thinking a little....
Do you know, 100% for sure, that there is no possibility that any part of your DC section can ever touch any part of your DCC system?
Also, you definitely should have some kind of current protection from your 8A booster. By the time it's protection trips, something's going to burn. You need to spilit things up, either with fuses/breakers or taillights.
Jeff But it's a dry heat!
It's been mentioned several times, the shorts almost HAVE to be between the decoder and the motor, or one of the motor outputs is touching one of the track inputs. That is the kind of thing that smokes decoders. Shorting the track under a running decoder is not going to smoke the decoder. The only thing on the track that can really smoke a decoder is crossing a gap between two power districts with seperate boosters that are not wired properly, or a boundary between DC and DCC. You can in the right conditions double the voltage getting to the decoder, which is bad. But I have always been under the impression that Ken has exactly ONE DCC power supply connected to all his track, no others, so that would render this situation unlikely.
I would liek to see some close-up pictures of the wiring in some of these troublesome locos that pop decoders. It only takes one strand of that super-fine decoder wiring touching the wrong thing and POOF. It also is possible that a wire or wires is actually rubbing on the flywheel or other part of the drive, which is why they can run for days or even weeks with no problems and then suddenly POOF.
The worse that usually happens with the track shorting under workign decoders is that they sometimes can get scrambled brains and need a reset. I've never had that happen but others have, and it usually is prevented by turning off DC conversion in CV29.
First I want to make one thing clear!!! I am only DCC, no DC is hooked to the bench. At one time I was DCC on the B line and DC on the A Line and there was no problems. I have never had a decoder go bad when crossing from one line to the other, and I don't do that much.
Texas ZepherYou and I have a different definition of a "good" DCC engine. I get upset when I have one pulling more than 0.25 amps. Zepher, I used .7 amps as a possible example, with out a DCC power meter it was just a guess. I have only had 2 DC engines converted to DCC eat decoders. Decoder ate 2. BB FP-45, ate 2 and one circuit board, I now konw what the problem was, and it was where I solder the wires to the trucks. Decoders ate 3. OLD PK BL 2, has ate 3 decoders and again pretty good idea what the problem is. Think the truck meatl side frame is hitting the still hot frame. My other BL 2 was wired the same and has not ate a decoder for 20 hours plus. Decoders ate 1. Athearn RTR UP Dash 9, have no clue why it stalled in the tunnel and melted the wires from the tucks to the PC board. It did take a year of heavy run time before it did the BBQ. It has been doing well for some time now. Decoders ate 1. Athearn RTR SP SD 50, problem child off E-Bay. Ate light bubls like I drink beer. High starting power but lasted say 50 hours but was slow. Finely ate a DH 123 while I was cleaing the wheels. Found it had a Digitrax PC board not the Athearn one like my other SD 50 has. Remotor anyway and repleced the PC board that Jeffery sent me. Decoders ate 1. Rio Grand Athearn RTR SD 50. Ran the heck out of this one, could be over 100 hours. It does like to slow down after 15 minutes or so at a slow speed, motor getting hot. Still a good engine. Decoder ate 1. Bule Line GE AC 6000, the Digitrax DZ decoder went south after only 5 hours. New decoder has lasted over a year and heavy drags. I bought the first BL from my LHS to give you a idea how long I have had it. Decoder ate 1. PCM Big Boy, drive locked up and I have yet to open the engine, so that is not a power problem. All of the engines have been plug in Decoders excpet the first 2 I listed, so it is not a install problem. Cuda Ken
Texas ZepherYou and I have a different definition of a "good" DCC engine. I get upset when I have one pulling more than 0.25 amps.
Zepher, I used .7 amps as a possible example, with out a DCC power meter it was just a guess.
I have only had 2 DC engines converted to DCC eat decoders.
Decoder ate 2. BB FP-45, ate 2 and one circuit board, I now konw what the problem was, and it was where I solder the wires to the trucks.
Decoders ate 3. OLD PK BL 2, has ate 3 decoders and again pretty good idea what the problem is. Think the truck meatl side frame is hitting the still hot frame. My other BL 2 was wired the same and has not ate a decoder for 20 hours plus.
Decoders ate 1. Athearn RTR UP Dash 9, have no clue why it stalled in the tunnel and melted the wires from the tucks to the PC board. It did take a year of heavy run time before it did the BBQ. It has been doing well for some time now.
Decoders ate 1. Athearn RTR SP SD 50, problem child off E-Bay. Ate light bubls like I drink beer. High starting power but lasted say 50 hours but was slow. Finely ate a DH 123 while I was cleaing the wheels. Found it had a Digitrax PC board not the Athearn one like my other SD 50 has. Remotor anyway and repleced the PC board that Jeffery sent me.
Decoders ate 1. Rio Grand Athearn RTR SD 50. Ran the heck out of this one, could be over 100 hours. It does like to slow down after 15 minutes or so at a slow speed, motor getting hot. Still a good engine.
Decoder ate 1. Bule Line GE AC 6000, the Digitrax DZ decoder went south after only 5 hours. New decoder has lasted over a year and heavy drags. I bought the first BL from my LHS to give you a idea how long I have had it.
Decoder ate 1. PCM Big Boy, drive locked up and I have yet to open the engine, so that is not a power problem.
All of the engines have been plug in Decoders excpet the first 2 I listed, so it is not a install problem.
Cuda Ken
cudaken cudakenWhy not add the taillight and a in line fuse? A good DCC engine should pull around .7 amps with a good drag, is that sort of right? My DH 123 decoders are rated at 1.5 amps max is 2.0 amps. Add the taillight bulb and a in-line 1.75 amp fuse, bulb comes on, poop goes the fuse and train stays where the short happened and the decoder lives to pull again! Randy, did you catch where I all so want to add a in line fuse? Bulb comes on, in line fuse poops and save the decoder and the engine is still where it shorted out so I can fix the problem. Reason for the light is to catch my attention. Ken
If you are looking for an indicator light when the fuse blows then simply wire a 16V minature bulb (say 30-60ma) across the fuse terminals. Thus when the fuse blows, the bulb will complete the circuit and light, while limiting the current to a small 30-60ma. If you end up blowing a lot of fuses, you may not be happy with this long term but it will serve the purpose you describe.
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
rrinker PTCs are generally slow acting, probably too slow to save a decoder, especially when they can get an instantaneous 8 amp shot from the MRC booster. By the time the PTC opens, it would probably be too late. The electronic breakers drop out much faster than any PTC. Dunno if the same is true of the newest PSX line, but the original Tony's Powershields had an option for manual reset - if there was s short it would turn off and STAY off until you pushed a button. They way they and other breakers normally work (as well as the ones in the boosters) is that they drop out, then apply power, and if there's still a short, drop out again. Over and over - end result it still fries your decoder. --Randy
Yes, the newer PSX series has the option for automatic or manual reset. They also retained the trip current configuration settings but dropped the trip timer option.