MTH PS2 5 volt

I have one from 2006, replaced battery with BCR, runs and operates great!  The first new Loco I bought was also in 2006, still run it today with no problems, it also got a BCR installed. Figured after all that run time I should replace that old white battery before it failed, LOL.

I have a number of 5V PS/2 locomotives that run just fine, those boards have to be 18-20 years old at least.  Virtually all of them were out of the supply chain by the end of 2004.

If you're buying, just price it based on the possibility you'll have to replace the board.  I typically discount around $150-200 of what I'd pay for a PS/2 3V engine when I'm looking at a 5V engine.

gunrunnerjohn, could you please give me the Digi-Key part # of the Supercap that you would recommend to replace the 8.4 volt rechargeable battery for the early PS2 5 Volt MTH Locomotive? It would be greatly appreciated. Thank you in advance. Thanks for all the help you give everyone here on the forum.

@Gary P posted:

gunrunnerjohn, could you please give me the Digi-Key part # of the Supercap that you would recommend to replace the 8.4 volt rechargeable battery for the early PS2 5 Volt MTH Locomotive? It would be greatly appreciated. Thank you in advance. Thanks for all the help you give everyone here on the forum.

Well, you need two of the 5V supercaps for the old 5V boards.

This is the one I use, the AVX SCMR22C155PRBA0, you can get it at Mouser.com.

gunrunnerjohn, thank you very much. Just a couple of questions, do you wire them in series or parallel? Also plus + on the supercap to the plus+ on the battery connector (small clip, and the minus - on the supercap to the minus - on the supercap, or reverse them? Again, thank you for your help.

@Gary P posted:

gunrunnerjohn, thank you very much. Just a couple of questions, do you wire them in series or parallel? Also plus + on the supercap to the plus+ on the battery connector (small clip, and the minus - on the supercap to the minus - on the supercap, or reverse them? Again, thank you for your help.

We are trying to replicate the function of a 9V battery. The capacitors are label rated for 5V MAX.  In order to charge a 9V battery the circuit would go higher than 9V so you need a battery or equivalent that can take 9V or higher.

5V +5V in series = 10V rating

Part 2, how to connect the battery snap.  Because when you buy battery snap connectors that are prewired- they are made to snap onto the standard 9V battery as a SOURCE. Key there, again, they are wired assuming the snap they are plugging into is a 9V battery. However, we opposite to that, want to attach the wires of this snap and act like this snap is a battery. The problem with this type of connector is each side switches polarity.

So, again, because you are buying cables and snaps made to plug into normal 9V batteries, not emulate a battery the wiring is reversed. Red wire from the battery snap to the negatve or white stripe of the capacitor. The black wire goes to the positive terminal of the supercap. Again, when buying the typical bulk pre-wired 9V snap connectors, for our purpose, they are backwards.

That said, if you buy the specific 9V connector without wires that was shown by gunrunerjohn, then you take an actual 9V battery, note the postive terminal, and then make the postive of the capacitor being soldered to the terminal match a normal 9V battery

.

again, this style without factory wires, the round male is the positive, and the castle female socket is negative- just like a normal 9V battery.

FWIW, Dallee, who also makes a lot of train electronic modules, has a diagram that duplicates the above information

Again, notice, they explain the typical commercial readily available 9V snap is pre-wired reverse compared to our usage scenario, so they reverse red and black to the supercap connection.

The Keystone #68 is also readily available, and with heatshrink and the two caps, it makes a convenient package.

Thank you all for your help. It's greatly appreciated to know how to do it right the first time and not burn anything up!😁