Was Slave Board info needed, now motor info.

Pete, both of the FET's are IR LR024N parts.

Thank you again John. 

Pete

The chip can burn up fast on a stall, or if the motor lead is not a sound connection between Lead and Slave.  MTH did some work and recommended twisting motor leads between LEad A to external harness, in the b unit harness and also in the Trail A where slave is.

If still no work after chip replaced theres is a small current limiting resistor that may have opened and then the logic chips.  G

Thanks G. I have ordered the FETs and will check out those other items.

Pete

NORTON, another cause I have seen stall a motor, is when a traction tire comes off and gets tangled in the gears.  If one is missing, it could have been the cause with the previous owner.  I did a repair last January, that during Christmas, a guy had his MTH diesel running around the tree when a traction tire got tangled in the gears. Luckily one of the gear pins pulled out and saved the board from a long motor stall. He brought the engine to me with only the gear. MTH told me we had to buy the complete truck because they didn't have pins. I called the guy and asked him to cut open his wife's sweeper bag. Well he got lucky again and found the pin in the bag with the pine needles and cat hair.    

Good tip Dave. It did seem to run initially at least for a few feet, then ran briefly only in reverse before shutting down completely. Add checking traction tires to the pre flight checklist.

Pete

I killed a 5V PS/2 board when I threw a traction tire, it only took a few seconds of stall and it was gone!  I was not impressed.

gunrunnerjohn posted:

I killed a 5V PS/2 board when I threw a traction tire, it only took a few seconds of stall and it was gone!  I was not impressed.

What did you kill on the 5V,  a motor fet?  Never seen that and I have seen some 5V engines customers had been running with one motor locked up and dragging.  G

Yep, it was the FET, cooked the board around it, and made it impossible to replace it.  It's difficult to replace those anyway and get the new ones on with that funky heatsink, but with the board mangled from the heat, this one was a goner.  Since it stalled and a traction tire was jammed in the truck, I have to believe that's what killed it.

Ok, I think George diagnosed the problem with the blown FET correctly as a stalled motor. I replaced the FET and the motors still do not turn. It seems both motors have bad contacts or burnt brushes. I removed one and connected it to my DC supply and the motor runs but by wiggling one connector I can start and stop the motor.

First time I have seen this with any Mabuchi motor. I think the armature should read about 6 ohms but the ohmmeter fluctuates between 12-50 ohms. The second motor does the same.

The engine appears to have been test run only. Little wear and the traction tires are tight and look brand new.

Anyway It appears I need to replace both motors. The engine is a 20-2453-1 EMD E6. I need the motors for the slave A unit. MTH doesn't show the part numbers when looking up parts for this engine. Can anyone here give me the part numbers or have the motors. If not I will try and contact MTH.

TIA

Pete

I wonder if the motors were damaged by a stall or the like, both motors being bad at the same time is VERY unusual!

The E6 from around 1998 used the BE-0000065 motor, (RS-385PH) (8.0X24.0mm worm gear) (16.0mm threads) (9.0x30.0mm black or brass flywheel)

It's likely that your E8 probably used the same or a very similar motor.  Sadly, no parts listing available for that particular locomotive set.

I thought it was odd as well. The windings appear to fine, no signs of being burnt and it will run normally if I put pressure on the connector. I will check the gear dimensions against the one you found. Thanks again. If I can find replacements I will pull this one apart to see what happened.

BTW mine is an E6 too.

Pete

Pete, I think I have a pair of motors that were stripped out of an engine that I bought the guts of. I don't have any record of that engine. I wonder if there is an easy way to identify if they'll work for you? 

I found a couple more of the same. Too modern?

Joe, The one laying horizontal with the gear facing the steel rule (no tach tape)  looks like it has the same flywheel. I will check the gear pitch and gear diameter tomorrow. The one John found is not the same, different flywheel and not sure about the gear pitch.

I have started to pull one motor apart. It appears the gear has to come off before I can pull the armature out. I have to modify my flywheel puller before I can get the gear off. 

I appreciate your offer. Stay tuned.

Pete

Have you spray cleaned them with electrical motor cleaner?  If these are unused or rarely used motors on a NOS product, I would not think both motors would be bad.  G

G, I did spray them with no difference but found one motor in fact OK. It was my clip lead that was bad. The other did not not respond to cleaning. I found another motor I had and transferred the gear and flywheel to it. MTH has not responded to my inquiry about a replacement motor.

Current situation is the FET was replaced, motors reinstalled and it runs in reverse. Neither motor turns in forward. I am assuming its a slave board problem or the lead engine tether. I checked the slave tether and all ten wires ring out to the board. The B unit has not been used, only A to A.

I will probably swap out the other FET as its easy. I also removed the relay to check it and its OK too.

As an aside, while removing the flywheel can be done without damaging the motor if you have a proper puller, I have yet to find a way to remove the gear without damaging the motor. Vitually no way to get puller jaws under the gear. I ended up using heat, first from a butane mini torch and then from a Mapp gas torch getting it red hot and I still had to pry it off. Here is what a Mabuchi 385 looks like inside.

The gear was drilled for a sliding fit and drilled and tapped for a pair of 4-40 set screws.

Pete

Norton posted:

I ended up using heat, first from a butane mini torch and then from a Mapp gas torch getting it red hot and I still had to pry it off. Here is what a Mubuchi 385 looks like inside.

The gear was drilled for a sliding fit and drilled and tapped for a pair of 4-40 set screws.

Pete

I did not know there were set screws used. I'd be afraid of heat transferring down the shaft inside the motor so I have to guess you had some type of heat sink? For the amount of effort, I would get another. I do find the inside view interesting and helpful. You guys go farther in than I have patience to do myself!

 I got a set of NWSL G scale trucks that one worm was drilled too large. No matter what anyone attempted that worm comes loose. I saw evidence of solder before I got to it. It appeared to come that way from them. I have tried everything on it and ended up ripping it out. So that engine drives with 3 of 4 axles and lost 50% pulling power? That leaves me hesitant to try it again on anything. I think these worms are under heavy stresses driving engines with tires. Even a set screw without a corresponding flat, would leave me fearing it coming loose.

Joe, the gear is a press fit. I installed the set screws so I could use the gear on another motor. No way to press it on without bending the shaft. The gear is what is unique. It was more important to save the gear than the motor so it gets sacrificed. 

Pete

Ahhh. Thanks!

THROWN TIRE FRYING BOARD;  I know some service stations recommend not gluing traction tires on ,guess it makes their job harder. However this is why I glue tires on. I had a Williams steamer throw a tire ,  in a tunnel just out of reach,  back in the early 90s.   It fried the Williams electronic e-unit, much cheaper and easier to replace than todays command boards. So no loco with traction tires goes for more than a test spin on the layout before I glue the tires on.   j

Tires are not the problem here. They are tight to the wheel. 

Pete

If I want to save the gear on the bad motor, I cut the shaft with Dremel, then press old shaft out, or punch it out.

If I want to save motor with a bad gear, I cut horizontally on the motor gear carefully until it splits or is close to splitting.  At that point you can press the motor shaft out by tapping or with a fixture you can get under the gear (I Have one).

Then press good gear on good motor carefully and knowing how far on the shaft it has to go. 

If you give me the gear length and thread length example 17mm long and 12mm thread length, plus motor size 365 or 385, and flywheel dimensions 30mm dia and 9mm thick, I can get you a part number of a suitable substitute.

As far as moving in forward, you need to check closely for gear binding.  I have seen the E-8 with split drive gears.  If the gearing binds, the motor does not overcome the gearing until a higher speed setting.  Basically you drag the trail unit.  Try testing with both units up on blocks with no friction.  IF they work you can see which motor may lag in starting or not turn and work from there.   G

Thanks G. The flywheel is pictured above as is the motor which is a 385. I believe its 9mm thick. I will have to pull a motor to get the gear dimensions. I will check the worm gears when I do that. If I ever have to pull a gear again I will cut off the shaft. I have saved a motor by cutting the gear and in fact that is the motor I am using now.

Pete