I have a 681 turbine with a reproduction pellet-type heater installed. Even with the smoke unit cleaned out and a new liner installed, the output was very weak. I removed the heater from the locomotive and measured the resistance of the heater. It was about 19.5 ohms. I unsoldered the end of the nichrome wire from the eyelet holding the ground strap and unwound two turns from the coil. Then I inserted the free end of the wire back through the eyelet, wrapped the excess around the ground strap and resoldered the connection at the eyelet. Now, the resistance is about 15.2 ohms. Will it produce more smoke?
Jim
Yes, it should. It will also significantly decrease the life of the heater, although. I never found it necessary to remove more than one turn.
There’s also a chance that the resistance may be too low and it will burn out as soon as you apply power.
If you can, I would suggest adding one coil back in and experimenting from there.
Ben,
I just removed one turn at first, but it didn’t seem to make a difference.
Jim
Jim,
If one turn didn’t do it, two is probably okay.
I don’t recall the resistance of a pellet heater unit right off the top of my head, but 15 seems kind of low. I’ll have to check some of the units I have lying around.
Anyway, removing turns is a great way to increase the smoke output, provided that you understand the trade-off of shortening the heater life.
Another way to handle it that doesn’t involve modifying the smoke generator is to put a voltage-dropping element, like a shorted bridge rectifier, in series with the motor. (Making the motor voltage lower than the smoke-generator voltage is the same as making the smoke-generator voltage higher than the motor voltage.)
Ben,
I checked an original pellet heater I have, and it measured 16.1 ohms, so I think the heater in my 681 will be fine.
Jim