Sturgeon-Phish The solder/lug/nicad wire makes a cold joint and the solder may have cracked. Resoldering is the fix. Glad you got it going! Jim
The solder/lug/nicad wire makes a cold joint and the solder may have cracked. Resoldering is the fix.
Glad you got it going!
Jim
Jim,
One thing crossed my mind about the strength of the coil wire produced as a replacement for the original wire. That original coil wire that I replaced back in January 2010 only lasted 18 months or so. The original coil lasted 60 years or so.
Rich
Alton Junction
green97probe Rich, Form my notes, I have 30-40 ohms for these heaters. I've never had this type of failure in operation, but I know that the leads will break if the cover is removed without them being unsoldered first. If multiple turns came into contact with each other, the resistance would drop, and that will cause it to fail. That is the only thing I could think of given the circumstances. I'd just replace or repair and see what happens.
Rich,
Form my notes, I have 30-40 ohms for these heaters. I've never had this type of failure in operation, but I know that the leads will break if the cover is removed without them being unsoldered first. If multiple turns came into contact with each other, the resistance would drop, and that will cause it to fail. That is the only thing I could think of given the circumstances. I'd just replace or repair and see what happens.
Hi Jim,
Good to hear from you. I agree that at this point I should adopt a "wait and see" attitude since the smoke unit is up and running again and smoking pretty good. You raise a good question. Was the coil wire already broken, or did opening the smoke unit break the wire? Since I was getting no smoke whatsoever, I am guessing that the wire was broken, but who's to say for sure.
lionelsoni The wire resistance is determined by how long it is, not by where it is located. At any particular voltage, the power dissipated is inversely proportional to that length. For example, if you shorten the wire by 20 percent, the power goes up 25 percent and the wire gets much hotter.
The wire resistance is determined by how long it is, not by where it is located. At any particular voltage, the power dissipated is inversely proportional to that length. For example, if you shorten the wire by 20 percent, the power goes up 25 percent and the wire gets much hotter.
Bob,
I agree with what you say. The coil is only contained in the upper portion of the smoke box and I was just trying to be literal in describing it. But, as you say, the wire resistance is determined by the length of the wire.
After my initial reply to Major's post about resistance, I went and found the box in which the replacement wick and coil came in the mail. I had ordered the replacement items from Portlines. I hope Doug doesn't mind my reprint of his web site tutorial in part. It reads:
Open your newly-purchased replacement smoke-wick. Note that the nichrome wire has been pre-wound around the wick, but has two long loose ends. If you have an ohmmeter, check the resistance across the two ends of the winding before you install it. It is likely that it has too many windings, which results in high resistance and low smoke output. The last one I checked had about 75 ohms resistance......about double what it should be ! I had to remove about five windings from each end of the coil in order to get the resistance down to 35-40 ohms, an appropriate amount to produce a good volume of smoke even at slow speeds. Less windings results in more smoke output, but it also reduces the life of the wick slightly.
I now recall that I followed these instructions precisely at the time so that the resistance was in the 35-40 ohm range. Unfortunately, I forgot about this when repairing the broken coil wire this past weekend. Since I had to further unwind the coil to get some extra wire, I assume that my reading is now somewhat under 40 ohms.
Bob Nelson
Thanks for the reply, Major. Now, that is an interesting thought.
When you say that I may have had too little wire left, I assume you mean too little wire wound around the wick in the upper portion of the smoke box. As part of my rehab of the loco the year before, I had ordered and installed a new wick and coil. So, there was plenty of coil wire wrapped around the wick in the upper portion of the smoke box.
I look forward to hearing back from you.
I don't have all the figures available to me as I write this but you may have had too little wire left and it overheated and burned out. I have seen sites that give you what the corrrect resistance reading should be. Too little resistance and it burns out, too much and it doesn't produce much smoke. I'll see if I can find them tonight if someone else doesn't reply before me.
About 18 months ago with some help from Sturgeon-Phish, green97probe, and others, I was able to repair the smoke unit on my 60+ year old steam engine by replacing the wick and coil.
It is really a smoker now, at least until recently. On Memorial Day, my daughter and her family were visiting and I noticed that the smoke unit wasn't producing much smoke. So, I added about 8 to 10 drops of smoke fluid to impress my grandson. But, to my chagrin, no smoke at all was produced after I added the fluid.
I figured that I must have overdone it, so I turned the engine upside down with a paper towel under it and left it. This morning, I ran the engine but no smoke, no glow from the coil. So, I disassembled the engine and examined the smoke unit and discovered that one of the two ends of wire from the coil was broken where I had previously soldered it. I was able to recover some wire from the end of the coil where the break occurred and resolder the end of the wire to the metal tab on the top of the smoke unit.
Voila ! Smoke, once again.
I was pretty proud of myself to diagnose the problem and repair it. But the question remains, what could have caused that coil wire to break. No derailments, no rough handling, nothing.
Any thoughts or suggestions?
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