Re: Blackstone K-27

Jim Marlett

Since I have several first run non-runners, I have thought about running a solvent through the motors, but I haven’t been brave enough to try. I have a can of electronics cleaner, but the fear of completely ruining the motor has kept me from trying that approach, especially when I haven’t even tried letting the magic smoke out yet. My plan was to skip trying to do the 12 volt to the motor fix and just install a new assembly from Blackstone, but that was just as they ran out of replacements. They were expecting more, but it looks like that has turned into another K-36 type issue. My guess is that the over-oiling gets lube on the commutator and creates enough resistance that the decoder senses trouble and shuts things down. My fear with solvents is removing insulation somewhere unexpected or just moving the oil all over the place. I guess I should just get off my lazy butt and try letting the magic smoke out.

Jim Marlett

On Dec 15, 2020, at 2:10 AM, Mark Kasprowicz <mark@...> wrote:

The first run of K-27 was affected by over oiling of the motor. In many cases it was possible to burn the oil off by applying 12 volts DC to the motor via the two outer pins of the drawbar connector. Not always a permanent cure and repeating the treatment is sometimes needed. Worst cases need the motor replaced and they are no longer available from Blackstone/ Soundtraxx.
The topic of a replacement motor came up on the Repower and Regear groups but no one has come up with a solution. One of the difficulties is that the small motor fits tightly into a cradle which is part of the underside of the boiler, and there are no replacements with a similar shape. Another is that the shaft must be long enough to be able to fit the chuff sync wheel within the opto sensor.
I managed to fit a Mashima 1220 into the cradle of one but it's not really powerful enough.
So a couple of thoughts. Has anyone pulled the motor out of the cradle and ran it at an angle to allow the oil to escape. Or immersed it a solvent that might thin the oil but not damage the windings. The need of the chuff sensor disappears if you replace the decoder with a TSU2, which also frees up two more pins on the drawbar connector for marker and cab lights. Another bonus is that the original decoder and breakout board were big, the TSU2 is much smaller so that adding a stay alive and an iPhone speaker was quite easy. But it still doesn't solve the motor problem. I have run out of ideas.

Mark K

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