PS/2 5V board repair?

Kind of sounds like it's toast, The only thing I can think of is... a motor lead wire touching the motor casing? that's a take off for sure.

I'm sure you've already checked it out.

Could be a shorted motor FET under the long heat sinks.  That maybe repairable, though getting the heat sink back on can be a bear.  5V boards have 2.  G

George, I was assuming that was a likely candidate, as I believe the motor was stalled when the traction tire got jammed into it.  What are the part numbers of those FET's?  Maybe just replacing both of them might bring it back to life.  I do have a hot air rework station, maybe that'll make it easier to get the heatsink back on?

Hi George, I was told by another member that you can offer me advice on servicing MTH engines? Do you do the repairs yourself?

I have 2 engines that are in need of repair. Both engines are having electronic board issues.

one engine (my favorite) MTH Premier DDA40X that has an 5V? board that needs to be fixed as well as a few light bulbs. What do you suggest for fixing this model?

Next engine is a MTH Amtrak Premier E8 set and that has a PS2 1.5 volt board that has a board issue as well.

Any advice or suggestions would be greatly appreciated.

Thanks!!

-Matt

John,  I have seen 28N05L and LR2905 on the PS-2 5V boards.  The slave boards use a IR LR024N.  G

Matt, I sent you an e-mail.  G

Any reason to prefer one over the other?

But broken motor FET(s) do not explain the lack of sound. If you pull the motor connector, does the rest of the engine (sound, lights, etc.) work?  Maybe the sound was being drowned out by the engine taking off.

Even with the motors disconnected, you should be able to reverse direction (and hear the relay click) and see the directional headlights switch if your engine is so equipped.   That is, before your place that DigiKey order, make sure you don't need a new sound chip or whatever!

I found one of the FET's shorted dead, so I'll test again without it in the circuit.  Good point about unplugging the motor leads.  It took off so fast that I didn't give it much time to do sound, it was an immediate projectile!

Edit:

Hooked it all up without the shorted FET, everything else runs.  Sound, even runs in reverse.  Just doesn't go forward anymore, so I will get those on order from Digikey, I already had a few things queued up anyway.

I had to replace both shorted FETs on a PS-2 3.0V slave board for an F3 trailing A Unit a few months ago to correct this exact problem. I used an IR MOSFET from Mouser, 55V, 17A, P/N IRLR024NTRLPBF. I believe it's a direct replacement for the MTH component.

Bob Di Stefano

Digikey has the exact IR part, and I'm ordering some other stuff anyway, so I'll just include a couple of these.  I think I'll just replace the one, since the thing cooked going forward when it threw the traction tire and jammed up the truck.

Gregg, it's one of the larger parts, the small parts are more of a challenge at times!

John,  One may be obsolete, or they are equivalent depending on who the manufacture was.  Also find variations on the 3V board which only uses one FET.

The Slave board definitely uses a different part number.

Stan, I have found the lack of sound on these run aways with shorted FETs do occur.  The engine never fully starts up.  Either the load from the shorted FET or the awe cr_p moment prevents folks from hearing any sounds.  G

We'll see when the parts arrive.  I was going to tear one off an old PS/2 board, but decided I should start with a new part.