Kato Portram Centram

[Lackawannae8]

Last weekend I impulse bought a pair of these trams at a local show brand new, after doing some digging there isnt much documentation on these and installing localized aftermarket DCC (yes theres a foreign overseas option but daddy trump tariffs Im not playing with). I want to hardwire ESU sound inside them but Im reading 3v motors.. anyone had any luck with these using Loksound or lokpilot to make them go? was thinking about adding a resistor to the motor but Im clueless there or even playing with motor settings to not allow them to go over 3v. any input before I smoke 4 motors?

[milw156]

Setting cv 53 to between 25 and 29 should limit max voltage to motor to 2.5 to 2.9 volts. InTHEORY at least, that should work.

[peteski]

The problem  that regardless what the decoder setting are for the max speed, the PWM motor driver still produces 12V pulses which are averaged out by the motor.  But they still are 12V waveform which might damage a very delicate 3V coreless motor.

I seem to have read somewhere that ZIMO is now making a decoder specifically designed for low-voltage motors like these.

[Dwight in Toronto]

I received a similar Kato tram from Plaza Japan about a year ago, with the thought of maybe, one day, putting an ESU LokPilot in there somewhere.  I have yet to find any such tutorials online.

In an exploratory impulse instigated through curiosity, I dismantled the model, took some pics, scratched my head a bit re: its DCC potential, and then put it all back together. FWIW, here are the photos:


















I still have hopes of one day upgrading this little gem to DCC, but I think I need a more accomplished modeller to pave the way.  Them’s some tight confines there!

[Iain]

The problem  that regardless what the decoder setting are for the max speed, the PWM motor driver still produces 12V pulses which are averaged out by the motor.  But they still are 12V waveform which might damage a very delicate 3V coreless motor.

I seem to have read somewhere that ZIMO is now making a decoder specifically designed for low-voltage motors like these.

https://sbs4dcc.com/products/zimo-mn250-nano-low-voltage-dcc-decoder-hardwire.html

[brill27mcb]

The older Kato Portram drive that Lackawannae8 bought is a different design from the newer Kato Hiroshima Series 1000 "Greenmover" drive. Some people have had trouble with the older Portram drives over time. Kato has announced in Japan a forthcoming run of new Portram tram models due in 2026, but with an updated drive that I suspect will be more like the Greenmover/"My Tram" ones pictured in Dwight's earlier posting here. As a result, modelers in Japan now seem to be selling off more Centram models second-hand (on Yahoo Japan Auctions, for example, the equivalent of Ebay over there), probably in anticipation of the new drive. Wiring in and hiding a DCC decoder won't be at all easy on either drive design.

The Greenmover drive is a miracle of miniaturization, as the photos show. The entire drive unit is below window height, covered with the interior detail piece. Dwight didn't mention that you can simply physically pull the 3 tram sections apart, and each end section can run as a separate unit, as they are both powered and self-sufficient. You can also easily mount the standard Kato passenger car lighting circuit board vertically in the rear of each end section to light the interior of these trams. There are Japanese Youtube videos demonstrating this.

Rich K.

[peteski]

Actually those photos reminded me that these models have a type of semiconductor voltage divider built-in on that circuit board of each powered unit, as they are designed to operate from a typical 0-12V DC throttle.   I have not spent any time tryign to figure out the circuit (I have too many projects). If you can separate that circuit from the lighting circuit on the same PC board and connect motor output of a standard DCC decoder there. That circuit should allow the full PWM voltage range to power the 3V motor.

[Lackawannae8]

Actually those photos reminded me that these models have a type of semiconductor voltage divider built-in on that circuit board of each powered unit, as they are designed to operate from a typical 0-12V DC throttle.   I have not spent any time tryign to figure out the circuit (I have too many projects). If you can separate that circuit from the lighting circuit on the same PC board and connect motor output of a standard DCC decoder there. That circuit should allow the full PWM voltage range to power the 3V motor.

I was looking at that to cutting traces if needed and use the pads or provisions it gets track power out if and isolate things. I gotta find time and tear the cheaper one apart and see

[randgust]

If that has anything in common with the Kato 11-108/9 four wheel chassis (and it looks like it does) that's simply a 12V motor in there.   The 11-108/9 goes directly from the track feeds to the motor leads in DC, period.

I'd be surprised if it's still a 3V motor.  When the 11-105/6/7 first came out like 2005, it had a 3V motor and a 100-ohm dropping resistor in series, on a little circuit board.  Then it got upgraded to a 12V a couple years later, ditched the resistor, left the original circuit board in (empty). and still that way today.

It sure looks like the same 11-108/9 motor to me just with a different flywheel.   I'm a huge fan of the 8/9, it's absolutely brilliant for a four-wheel chassis.

[peaks]

Maybe you can read the voltage across the motor contacts with a multimeter, while progressively applying 12V DC?

[peteski]

It sure looks like the same 11-108/9 motor to me just with a different flywheel.   I'm a huge fan of the 8/9, it's absolutely brilliant for a four-wheel chassis.

Nothing in common at  all. The 11-108 "critter" uses standard size Kato coreless motor (like it is used in full size steam locos).

The Portram motor is much much smaller, and the gearing is totally different.  As I mentioned, there is also a multi-component semiconductor circuit to reduce the motor voltage while providing enough current to keep the motor's torque sufficient.