My LHS has asked me to look at a half-dozen locomotives that he has on consignment. The consignee had both DC and DCC units, but he could no longer remember what was what. He had not operated his layout for quite some time.
IS there a protocol or set of steps to try, for identifying whether an engine is DC or DCC (or both)? He does not want me to take them apart, although maybe that is the best way. He want to be sure that they actually run, before he puts them on the shelf ( which means, if DCC, I know what teh address is ( which is the same to me as assigning an address that will work).
Any suggestions on how I go about checking these units out would be appreciated;
MrMick
York, MAane
Put them on the program track. The controller should read back a message if the loco has a decoder.
Also, a loco with no decoder, it will start at a lower DC power pack setting than one with a decoder which may not move at all if it does not have a dual mode decoder but a decoder made only for DCC. But as I think about this, some decoders do not like DC voltage as I believe the old SoundTraxx decoders where like that and I guess some where toasted by using DC.
Others may have a better idea.
The below link "might" help ID a decoder.
http://00200530.pdl.pscdn.net/002/00530/MRH04/DCC%20Shortcuts%20Card.pdf
If the loco has no decoder, the motor will buzz but not move. Some older style decoders can cause some loco motors to buzz.
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.
If he does not want to open the engine, I would beware. In 95% of the cases it is easy to pull the shell. Just does not sound right to me.
My worth
Cuda Ken
I hate Rust
A simple test to see if a loco is DC is to measure the resistance between the drivers on each side. Many motors measures about 100 ohms or less. A loco with a decoder, will have a much higher resistance.
cudaken If he does not want to open the engine, I would beware. In 95% of the cases it is easy to pull the shell. Just does not sound right to me.
Ken,
I think that you are feeling much too cautious. I can see where the guy doesn't want someone opening up the engine by removing the shell. Too many opportunities to break a tab or a grab bar or whatever.
Alton Junction
richg1998 Put them on the program track. The controller should read back a message if the loco has a decoder. Rich
This is what I would do too. Put it on the programming track. If the message "cannot read CV" comes back, chances are pretty good that there is no DCC decoder inside the shell.
I agree with rich that using a dc power pack to test for a decoder will fry the decoder. I have not heard of testing the resistance between the drivers. I am assuming that you are not drawing any track power to do this test. My question would be what about dual purpose setups like bachman and what would a sound system do to the readings? I have always been a firm believer in "better safe than sorry" and I would have a peek under the hood to be sure' After all you would'nt buy a car without checking it out completely
boston albany fan I agree with rich that using a dc power pack to test for a decoder will fry the decoder. I have not heard of testing the resistance between the drivers. I am assuming that you are not drawing any track power to do this test. My question would be what about dual purpose setups like bachman and what would a sound system do to the readings? I have always been a firm believer in "better safe than sorry" and I would have a peek under the hood to be sure' After all you would'nt buy a car without checking it out completely
I was talking resistance were there is no power to the loco whether on or off the track. If you measure on the track, make sure nothing else will contaminate the readings. Best to use a short section of track. You never try to measure resistance when power is on.
Sound or no sound, dual mode or no dual mode, with a decoder the resistance will be quite high, say around 30 to 40k ohms. With just a motor and light bulbs, 100 ohms or less are pretty good numbers.
I have measured under both options.
Runnign a decoder-equipped loco on DC is not goign to fry anythign unless it happens to be an old SOundtraxx LC sound decoder, one of the few that could actually be damaged by DC power (and they said so in the instructions). However, it would be hard to prove. If the decoder was set to not allow DC operation, then it wouldn;t move and most likely it would mean there is a decoder - however it could be a jammed motor or bad gears. If it DOES move, well, it can be anything - decoder or no decoder. The voltage difference with a plain motor decoder is very small, and given that many plain DC locos have diode bridges for constant lighting - it would be nearly identical to the same model without a decoder.
Even putting them on a DCC programmign track isn't absolute proof - if the loco is equipped with a decoder that doesn't read back, it will report no ack or no loco detected, same as a non-DCC loco.
The most reliiable way remains takign the shell off. You should only have to do this once per loco - I would assume you'd write down the information so that when someone later asks you cna just read it off the sheet instead of opening up the loco.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I would agree that the thing to do is put the engine on a programming track and read back the address. If it doesn't match the cab number, make a note of that, too, for the new owner. No address = no decoder, or at least not one that's worth keeping.
But, your LHS asked someone to do this for them? It might be time to look around for another, more knowledgeable LHS.
It takes an iron man to play with a toy iron horse.
Thanks to all for the above discussion. Here is some more information and the results of the task; my LHS had acquired about 25 locomotives from an elderly client who was moving; the client only knew that some had DCC, some had not. His system was an MRC Command 2000(?) system. He had not run trains for quite some time. I was asked to check out about half of the units.
Following the suggestions from above ( and the enclosure from richg1998, Thanks!), I checked each loco first on the program track, and about 2/3 did have a decoder, but most would not respond to any controls on the Main track until I had gone back and set CV19 to zero ( even though it had indicated zero before I re-set it to zero), then the locos operated from commands on the main track. (generally only forward/reverse and stop, some had lights that worked, but not all).
The behavior that made me pursue reprogramming cv19 was the fact that when i attempted to run the loco on main track using it's address, it would not respond; however, if I cycled a function button, it would take off - and not stop until I grabbed it. I had read somewhere that it could be that the decoder did not properly reset cv19 after consisting.
If I saw nothing from asking it for an address on the programming track, or for some other CV values, I then would try DC. Most of the rest then performed well, on DC.
I did pull a couple of shells, with some of the DOA models, and at least one probably did not work due to the extreme amount of corrosion on the soldered joints (it had a decoder). I did not pull any Steam Loco shells, however.
I estimated that the decoders were all mid-90's vintage, and I recommended that when someone buys one of the units, even though it works, they should probably plan on installing a newer decoder.
Thanks again for all your help and suggestions.
Mr.Mick
If the locos were converted to DCC around a Command 2000 system, odds are pretty good they are old and limited function decoders - they may only operate on 14 speed steps, and only handle short addresses. They may also reguire physical register programming and only support a few registers (limited CV access - but they aren't exactly the same).