Hi Max,
Not the same Bob. Both are very knowledgeable. Bob Sobol more on the Diesel modelling side from what I've learned online. I have also learned a lot about Pittman motors from 2 other experts: Jay Criswell and Rod Miller.
For example I learned that earlier Pittmans used Alnico (conventional) magnets. Later models used modern Neodymium magnets. I can speak from my own experience that the older ones are current hogs, the newer ones much more efficient. As I recall, the Alnicos have a "1" as the third digit in the model number e.g. 8514 as found in many Weaver drives. The rare earth magnet ones have a "2" as the third digit.
I have been frying decoders in O scale since 1994 but I only have 1 Loksound. I have been working with Digitrax and then NCE with DSX sound added, then recently Tsunamis and now TCSWOWsound. So much to learn!
The gears Weaver used were made a long time ago and were a press fit on their shafts. They crack as the plastic shrinks. This happens anyway, even if the loco was never out of the box. I have 7 Weaver drive sets (some in other brands of engine) and all top sprockets were cracked when I got them, and several bottom sprockets too.
Re the humming, I am trying to say that the cracked gears may be causing it. if the Loksound works by adjusting PWM to attain constant speed, then the cracked gears are loading up the drive several times per wheel revolution. Then if the Loksound drops the PWM frequency way down into audible range to try and generate enough torque to overcome the gears, that's when you get the hum.
If the top sprockets are cracked it's happening several times per wheel revolution as the gear reduction happens at the axles on a stock Weaver drive.
I have an early NCE D408 which has user adjustable PWM frequency. You can take it up to about 16kHz and not hear any motor hum. But the loco wouldn't pull the skin off a rice pudding! Turn the PWM down to a few kHz and it will pull the side off the building. But it hums so loud it's unbearable.
Is your DC setup smooth power or pulsed?
I may be way off base here as I don't know how the Loksound works, but just in case it helps, I really would check for cracked gears first. You can do that easily just by taking off the shell and manually turning the driveshaft from the motor. You'll feel a hard "notch" every 1 turn of the drive shaft, and see the chain climbing out of the sprocket each time as the teeth each side of the crack are too large a pitch.
HTH
Pete
Originally Posted by MaxSouthOz:
Hi Pete
I'm using a Loksound Select. A commonly used decoder by members of the Loksound group, for O scale locos. I've also used V 4's, but not this time. I record my own sounds and make sound projects, so I'm very experienced with them.
I'll be very disappointed if it has cracked sprockets, as it's new; straight out of the box. I'll tear it down and have a look anyway.
Thanks for the link. I'll have a look.
Is there anywhere I can get help with my earlier question about the photos?
Cheers
