Repairs for Lionel Polar Express Berkshire 6-28649

Clearly something in the motor or drive is causing the motor to draw way too much current!  I see that's the original PE Berkshire with the small set motor, those were infamous for crapping out due to overload.

First thing I'd do is see if the drivetrain is free, rotate the flywheel by hand until the drivers go through a complete revolution, my guess is you'll feel some binding somewhere that is causing the excessive current.  You need to find and fix that.

Thanks for the quick reply.  Rotating the flywheel both forwards and reverse through several revolutions of the drivers didn't reveal any binding - seemed very smooth.  When I have the engine on the test track by itself, it draws between 1.5 and 2 amps at around 12 to 15 volts. 

@Dale K posted:

When I have the engine on the test track by itself, it draws between 1.5 and 2 amps at around 12 to 15 volts.

also

"then after maybe 30 seconds or so, smoke starts coming from the circuit board "

Well, that's why you are cooking the transistors on the 103 board.

Replacement series 1 motor

https://www.lionelsupport.com/...SHI-SERIES-1-BERK-JR

On the tender whistle PCB- no you can't just use a rectifier unless you want it to blow constantly until it burns up.

Like so many of these things- that PCB is no longer stocked by Lionel, so repair- replacing the one transistor on it, is the fix most times.

The 103 style reverse board is no longer available from Lionel either, and right now, if it still cycles F-N-R, then don't further damage it by trying to run that damaged motor drawing near double the current. Again, right now, might still be semi-OK, but if you keep trying and cooking it, well then that's another cost.

Ok thanks for the input.  I'll try to inspect the internal gearing on the loco to see if something is causing a higher load.   Since the flywheel and drivers turn easily, I'm not sure I will find anything.  But you think the motor itself is causing the high amp draw?  Is there anything in the electronics that could cause the high amp draw?  I didn't see anything that looked like a short.  The loco still does cycle F-N-R so I guess I lucked out there, and I'll take your advice and not run the engine.

Regarding the tender PCB transistor, I'm a bit of a newbie re. transistors - How do I know what transistor to order to replace it?  I don't see any printing on it.  Is there a test I can do using a multi-meter to determine if the transistor is bad?  I think there are a couple resistors and capacitors on that board too - can they be tested?  Here's a picture of the PCB:

Thanks again for the help!

@Dale K posted:

Ok thanks for the input.  I'll try to inspect the internal gearing on the loco to see if something is causing a higher load.   Since the flywheel and drivers turn easily, I'm not sure I will find anything.  But you think the motor itself is causing the high amp draw?  Is there anything in the electronics that could cause the high amp draw?  I didn't see anything that looked like a short.  The loco still does cycle F-N-R so I guess I lucked out there, and I'll take your advice and not run the engine.

Regarding the tender PCB transistor, I'm a bit of a newbie re. transistors - How do I know what transistor to order to replace it?  I don't see any printing on it.  Is there a test I can do using a multi-meter to determine if the transistor is bad?  I think there are a couple resistors and capacitors on that board too - can they be tested?  Here's a picture of the PCB:

Thanks again for the help!

Honestly, I'm not sure if that is leaking out of C1 or just the picture. Q1 is the transistor and it is marked- etched in the flat face.

The thing is again, this engine is old enough and with the recent changes at Lionel parts division- no longer stocking these boards along with dozens of others.

What that means for you is- take care of this engine. Repairs could get costly or more and more difficult.

As stated, motors wear out. This motor is somewhat known to draw higher amperage as it ages and fails. You are knee deep in that cycle and got a decent lifespan out of it- it owes you nothing. Buy the new motor- hope to save and protect your reverse unit board.

On the whistle- guess what- the same thing- those motor bearings get dry (lack of oil), the motor draws more current each time the whistle blows, that then heats the transistor- the transistor having no heatsink goes into thermal runaway and that's the end of that. Also, capacitors age and fail, often leaking in the process.

Another fact about that whistle board. In testing, I have found you can blow those up just by testing the tender with no other load on many transformers. If you raise the track voltage higher than about 1/2 throttle and then activate the whistle function, it gets stuck on and then cooks the transistor. You really need a secondary load on the AC track power, like a lightbulb or the engine.

So- I question- you may not have a problem with the whistle- it might not have been working because the train what consuming high amounts of current because of the failing motor in the train. At the same time- use caution when testing the whistle tender by itself and do not turn up the transformer voltage much above 1/4 when testing standalone whistle operation.

I suggest lubing the whistle motor bushings with a needle light oil applicator, only a drop at each end- with the impeller side being the really hard one- you might have to take it apart to ensure you got that end.

Again- given the age of these- you are just running into known eventual failure- possible wear and tear.

The trick that a couple of us do is on the reverse board, we replace the TIP31,and TIP32 transistors with the equivalent TIP41 and TIP42 versions.

The difference is a higher current rating, but that rating is related to how hot they get for a given current so in theory they run cooler at higher amperage before thermal runaway happens.

You can also add a heatsink for the transistors, that does wonders for them.  Just a flat plate of metal between the rows bolted in through the tabs works well.  Use copper or aluminum.