I think I must need a new motor for my Rivarossi Allegheny locomotive. It's one of the first ones to come out years ago, it's DCC ready, and I've had a small Digitrax DZ123 decoder in it for a few years. The decoder has an 8 pin socket under the boiler shell. The other day the decoder burned up (litterally) while pulling a pile of cars. 45, various freight, I would guess. I ordered a new DN 136 plug in decoder, it ran great for about an hour with no load on it, but after hooking up about 45 cars, the decoder burned BADLY after running about five minutes! Shot the 3amp fuse on the power pack, and died. Decoder unrecognizable... I put the blanking plug back into the socket, and the loco has been running on DC for over an hour without issue. Pulling the same load! Do I need a MOTOR, or a better decoder? Does anyone know where to find a MOTOR for this thing?? This is one of my favoritest locos...HELP!
Mike C.
Mike,
A few questions for you. You state that you "shot the 3amp fuse on the power pack":
Given that you exceeded the 3A fuse, no wonder you fried the decoder. Most decoders are only rated at 1A continuous/2A peak running. Do you have an ampmeter or multimeter to measure the stall current of your Allegheny? That will tell you how much current your motor draws.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
I have been running it in DC for a while now since the first DCC decoder burned up. I wanted to go back to DCC so I could run it on the layout with the rest of my DCC engines. The original decoder, which has been running for years, burned up a few months ago. It was a tiny little dz126 basic decoder. I have always pulled long consists (on my FLAT layout) with this engine, since it did so well!. I suspected the motor was getting "tired", and was putting a strain on the tiny decoder. I'm running a MRC TECH 6 system, which switches from DCC to DC with a push of a button, since I still run some old DC locos that I probably will never change to DCC. The loco seems to run GREAT on DC! I disassembled the motor last night, cleaned it up on the inside, cleaned the commutator, brushes. Checked the brush springs, cleaned out the grooves on the commutator, dressed up the brushes a bit. The motor "seems" fine! With an analog volt meter on the layout, the train begins to pull at about 3 volts DC, and travels along at about 6. No fluctuating while running. I have a digital multimeter that measures amps, but I don't know how to use it for that. I set it on 10 amps, put the probes on the track while the engine was running, and it immediately blew the meter's internal fuse. I obviously did THAT wrong! I really would like to try a new motor, but my online searching has come up with ZERO! Does anyone know who distributees Rivarossi in the US? Is it Hornby? Edit: do they make a more "durable" decoder that won't just BURN UP under load? I also noticed when I installed the new DN 136PS decoder two days ago, the decoder immediately got noticeably warm to the touch, just by running the loco back and forth on a three foot test track to check it's functions. Is THIS normal?
To read current, you are suppose to put the meter in series with the load. I thought that was common knowledge. Only for DC thoiugh, not DCC.
I use the same meter with an added circuit for DCC.
http://www.trainelectronics.com/Meter_HF/index.htm
What I have done for years. I have used these meters a lot.
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.
Not "common knowledge" for me...! Exactly how do you do that? Do I disconnect a lead to the motor, and put the meter in line, and run it at the same time? Do I put the loco against a stationary object, and try to stall it out while testing? My meter ranges from 20ma to 200ma, then 10a. What should I use to start out?
If you get ambitious, a DCC amp meter. I built two of these.
http://www.circuitous.ca/DCCammeter10.html
wobblinwheel Not "common knowledge" for me...! Exactly how do you do that? Do I disconnect a lead to the motor, and put the meter in line, and run it at the same time?
Not "common knowledge" for me...! Exactly how do you do that? Do I disconnect a lead to the motor, and put the meter in line, and run it at the same time?
I posted the link before. Go look. I have been using meters since 1953.
Dave at NWSL has many motors and has helped me.
http://nebula.wsimg.com/02d6e40c2d04190212ed400d3ccb2472?AccessKeyId=08BEE66B97B387F20C0D&disposition=0&alloworigin=1
You can email Dave and ask him for a suggestion. He has answered me.
I was BORN in 1953!! (and I thought I was old !) So now I guess I can do it at the power pack, and not the loco? Now makes sense, and looks like something even I can do...if the motor pulls much over 1amp under load, do I need a motor? I pull a whole lot of lighted passenger cars (LED and bulbs), and don't blow the 3amp fuse.... maybe I should call nwsl, their motors are probably better anyway... thanks man, I'm always learning stuff! "I love the smell of Napalm, and burning decoders, in the morning!"
Give Dave a try. It has been a while since I contacted him.
If it is an open frame motor, some put in high strength magnets. Don’t remember what they call them.
I am not old, just ancient. Still work out, ride a bicycle and dance a lot even at 77.
Getting old is not for wimps. Three younger brothers never made it. Two Nam Vets who came home. I never made it to Nam.
It's definitely NOT an open frame motor. Was not meant to be taken apart, but I have a cutting torch and a crowbar... I work on Harley's for a living...! I have found over the years, that BEMF on some locos will begin to get irratic on old motors. I take em apart, clean and polish em up, and they're like new! This one, I don't know about... I can't keep buying decoders...
I think I figured out how to do the amp meter. I hooked it up in series with one lead coming out of the power pack on DC. While running the loco at approximately 6volts, medium-slow speed, the amp meter showed .4-.5 amps on the 200ma scale. I was pulling 48 freight cars while doing this. The meter only got to 1.0amps when operating loco at 15volts, and it was about to fly off the track. I even grabbed the loco and held it, slipping wheels, amps did not up when running at medium speed. I'm on the verge of wheel slip with all these cars anyway. If I'm reading this right, the motor is OK? Why am I destroying decoders??
In my opinion this may be related to some characteristic of the square wave pulse modulation used in DCC. That's why a special circuit for DCC 'equivalent amps' that can account for some potential issues with the system will be valuable.
After having read about the three equally bad circuit breakers, I'm a bit hesitant to rule out multiple bad decoders here. But the correct way to analyze this problem is not repeated magic smoke testing. The problem is that you don't have anything like a logic analyzer to see what's going on with the engine under power but receiving commands, or if there is some kind of resonance effect causing the effect of overpower in part of the decoder circuitry.
As a start, you might post pictures of the 'fried' decoders, at reasonably high resolution. That might give the experts here a leg up on what the likely cause(s) might be (even if most of the device is carbonized).
So you got a max of 1 amp while holding the motor from turning at 12 volts? This should be fine - by modern standards it on the high side but well within the rating of most decoders which are typically 1.5 amps continuous and 2 amps momentary peak.
The primary reason for a decoder frying is the motor leads coming in contact with the track pickups. Not sure how those locos are set up, but if the frame is connected to one side of the motor, but insulated from the rails, it may SEEM Ok to just plug the decoder in, but if a wheel derails and touches the frame - poof. Such cases are hard to actually find, because you can put the meter all over the place in continuity mode and never get a beep - because it takes a special case like a dertailment with the wheel pushed just so for anything to happen. The problem is, typical decoders have absolutely zero tolerance for this - even a quick momentary contact that immediately breaks can damage the decoder.
The best way to make sure this can't happen is to make sure the two wires coming from the motor brushes touch absolutely nothing - not the frame of the motor, not the frame of the loco.
Another place a problem can occur is if any wires have been rubbing on a gear or shaft and the insulation has worn away. That can be the case where the loco worked perfectly fine for a long time and suddenly starts smoking decoders.
-Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
You cna go ahead and post pics of the fried decoders - although if they are shrink wrapped it's not going to tell much, and if they are under warranty, you can get a repalcement if you don't molest it. Some brands have "goof proof" warranties where even if it's your fault the decoder fried, they will replace it with a new one - once. But definitely check out the loco before putting another decoder in, something has to be wrong for it to keep blowing them.
I suspect a picture of one sans heat shrink would show a chunk popped out of the main H bridge driver. The failure with lots of smoke like that is almost always the motor and rail leads somehow coming into contact.
--Randy
Where the decoder is located in the loco is behind the boiler, in front of the cab, surrounded by plastic. It almost burned through the floor it was sitting on! I had to break it loose to get it out... The socket is just above, and in front of, that on a small circuit board with one resistor, and a diode, for the incandescent bulbs, I guess. When the loco stopped, then the 3amp fuse blew, I checked for a derailment, etc, replaced the fuse. The headlight and the firebox LED was still working, and could be turned on and off from the decoder. It seemed the rear light no longer worked in reverse, but neither did the motor. It all works properly in DC. The first decoder burned a small hole thru the heatshrink on one side, the new decoder is burned up badly on both sides. A real "Joan of Arc", I'd say...if some sort of intermittent shorting was occuring while running, wouldn't I see SOME jumping of needle on the volt meter, OR fluctuating amperage reading? Everything is very steady going around the track, through switches, etc. at all speeds. Kind of surprised at the lack of fluctuations... my track work must be better than I thought...!
Is it sensible to solder a little 1amp fuse between the motor and the decoder? This last one almost burned up a $400.00 engine!! Fuses are cheap...oh, and I don't have a clue how to post pictures on this site...
OvermodIn my opinion this may be related to some characteristic of the square wave pulse modulation used in DCC. That's why a special circuit for DCC 'equivalent amps' that can account for some potential issues with the system will be valuable.
Isn't the MRC Tech 6 just a DC power pack that allows you to operate dual-mode decoders and activate certain CVs? That's different than it actually being a DCC system...
Actually, when this thing is switched to DCC, I can do pretty much anything with it. Set any, and all cv's, and all my DCC locos are set NOT to respond to DC. Everything is operating on 128 speed steps. I can change that as well, I think, although I never have. The only limitation this thing seems to have is it will only do single digit addresses from one thru six. That hasn't been much of a problem so far. I don't have THAT many DCC locos (yet)... when in DCC, the voltage at the track is just under 15 volts constant, on the AC scale, not DC. Put this to a DC loco, and it don't sound too good...!
Hey, I wonder if I could have SOCKET/CIRCUIT BOARD problems?? Should I maybe hardwire the decoder next time? Maybe at least the track pickup and motor leads wired directly to the decoder?
You won't hear me oppose that idea. If the lights are LEDs, make sure you have a resistor for each one if you remove the factory circuit board and hard wire the decoder. I'm not so sure, after 2 decoders, I'd be quick to dismiss that as the only cause of the problem though.
The headlight and tender lights are regular bulbs. I think that's why there's a resistor, diode, and zener diode on the board. IF I remember my color codes, the resistor is 150ohms. There's an indication that resistor got really hot somewhere along the line, but I can't figure that one out. The lights work fine, even after the motor stopped, and I replaced the fuse. Headlight and (LED) firebox flicker working fine. I had two 680ohm resistors in series going to that. One little bug from the get-go was, I couldn't turn the firebox OFF! It was wired to the f1 output, but stayed on all the time. IF I changed it to a Mars light, strobe, or any of the other ones, F1 would turn it on and off. Something fishy going on? I found out I had my amperage meter wired incorrectly. My ACTUAL readings are around .28-.31amps on startup, around mid speed, it got up to .38-.42. At higher than normal speeds, it averages right around .5, and if I grab a car and stall it out, wheels spinning, it got up to a MAXIMUM of .72. I ran it for over thirty minutes, all over the layout. No change. Nothing wrong with that motor... checked all the wires. Can't see a problem. Front driver group picks up left rail, rear the right. Same with tender. I'm baffled... Need to buy decoders in bulk, and hope nothing catches fire!