Lionel 6-28639 Berkshire steam engine E unit board burns out

You should check the worm gear of the motor and part #53 - wheel set with gear for wear or binding. I can't recall exactly if the motors are a known issue - only that they are small and lack really good pulling power - more reports of the gears binding/wearing/ than motor replacements.

Get a new axle set with the new motor. Pull light trains.

You can find some old threads on the early berk jr. in the polar express livery more than the NYC. 

The later series 2 mabuchi motors were the solution. No, they will not retro fit into the series 1. 

Carl's usually right about things, but a series 2 motor will fit in a series 1 engine. just need a round jewelers file. 2 things will kill a 103 / 107 reverse unit. A bad motor will take it out and so will a transformer with heavy spiking, IE CW80. I would first disconnect the motor and try running with DC from an HO powerpack or DC source. see if it overheats.

That little motor is a frequent failure item, I didn't realize that you could fit the larger and more reliable Series 2 motor in those, that's a good solution.

That reverse unit is very low power, one thing that does help them is to add heatsinking to the drivers.

Thanks, Chuck. The original Polar Express berk can be saved, then. Thanks for sharing the tip. 

Does the gearing work with the original wheel set gear?

Yes, gears are the same. Just need to file the screw holes a little and the collar hole.

That's great information Chuck, I never realized that that would work.  The Series II motor is vastly superior to the original.

Thank you all. The amount and quality of help provided by everyone was amazing.

A fellow member of our O guage group was amazed by OGR responses. So now he wants to become a member!🙂

I have a few more questions. Gun runner, you mentioned putting heatsinks on the drivers. By drivers are you meaning the 2 power transistors?    What would I add and how?    I have never added a heatsinks to a componet mounted on a printed ckt bd.   As I mentioned in my original posting the power transistors started overheating giving but they  didn't blister. Do you think the board may be damaged? I am ordering the new motor, should I order a replacement bd also?

Anyway thank you ALL again!

The heatsink is bolted to the holes in the driver transistors.  I believe that the two pairs have to be isolated, so probably two pieces of aluminum would have to be used to do the job.

A good source of heat sink is junked desk style computers.  If you can not safely bolt or drill and screw on the additional heat sink,  glue it on with J B Weld metal filled epoxy.  I have done that successfully with an over heating transistor on a vintage stereo receiver.

Charlie

Thank you Choo Choo I was planning on heading to HD for some aluminum scrap. Great idea!