Lionel TMCC K4 to Legacy upgrade questions

@gunrunnerjohn posted:

The thermistor issue is somewhat overblown.  If you have a smoke unit without a thermistor and a RCMC that supports the thermistor, simply connecting a 4.7k resistor between pins 3 & 5 of the smoke output from the RCMC will solve the missing thermistor issue.

I thought the resistor was used to detect overheating of the element and prevent it from melting the plastic housings?

I realize a resistor will "fool it" into working, but doesn't that also come with the risk of overheating?

@rplst8 posted:

I thought the resistor was used to detect overheating of the element and prevent it from melting the plastic housings?

I realize a resistor will "fool it" into working, but doesn't that also come with the risk of overheating?

The thermistor is only used during startup when the board "boosts" the power to quickly heat the element, it's not referenced in normal operation.  Yes, I was surprised to hear that as well.

Think about it, in normal operation, they should have a pretty good handle on the power going to the smoke unit unless the control circuitry goes nuts.

Joe....My lionel order is on the way. Are you still going to upgrade your K4?

Richard

@Rppoind posted:

Joe....My lionel order is on the way. Are you still going to upgrade your K4?

Richard

Sadly, no.  I was away that weekend, last minute changes and did not get a chance to get online to order the parts.  The parts are still in my cart for next year...

@Joe Fermani posted:

Sadly, no.  I was away that weekend, last minute changes and did not get a chance to get online to order the parts.  The parts are still in my cart for next year...

I'd save a copy of the cart if I were you, the cart is stored locally in browser cookies.  It's likely after a year you'll clear the cache and the cart will be gone.

Don't ask me how I know this.

Sorry to hear that Joe. Life does take precedent at times. I'll keep notes.

Richard

Lionel parts order arrived 10/17/23. I used Lionel K-4 1831060 order page. Kudos to Lionel, they did a good job filling and packing. This loco is the same 16-1 ratio as my "core".

Job one is rounding up 1.50mm and 1.25mm connectors used on Legacy boards. Thanks to GRJ for the tip on precrimped 8 position wire and connectors. The wire is 30CM long and all the colors Bruk used on his excellent drawings. I already received the precrimped items and quality is good. There are several JST 2.5mm and 2.0mm connectors on the two main boards that I already have on hand. I ordered the smaller connectors today. When I receive the order I'll use a number 11 hobby knife to raise the tabs and remove the precrimped wires and load them in the correct connectors.

I am writing this all up as the job moves forward and would be glad to provide details to anyone interested.

Richard

Anyone know the location Lionel uses for the Bluetooth module on a K4 or other legacy steamer? I have the wiring diagram. Were should it go for best reception? I see the antenna pc board. Even at 2.45 ghz I don't see how it will receive through the metal.

Richard

Richard,

It's not the metal that we're more concerned with but the size of any openings or holes through the metal.  A 2.4 GHz (Bluetooth) signal will successfully travel through much smaller openings than a 455 kHz (TMCC) signal.

You may be fine anywhere inside the shell, depending on the size and placement of the openings, unlike with TMCC.

Mike

I've always been astonished by the fact that Lionel stick the BT module in the middle of the boiler on the steamers, yet the BT seems to work fine.   I'm going to test that putting the Blunami 2200 module in a K-Line Plymouth.

Thanks Mike......That does make sense. If I have problems there is the under side of the cab. The module is small.

Richard

Thanks John....I'll leave a bit of slack in the wire harness and be able to move it around.

Richard

@Rppoind posted:

Anyone know the location Lionel uses for the Bluetooth module on a K4 or other legacy steamer?

In the saddle between the cylinders.

rplst8 .....Many thanks. I took a look at my MTH "core" and it has an open area on the frame there. Pretty much out of sight.

Richard

@gunrunnerjohn posted:

I've always been astonished by the fact that Lionel stick the BT module in the middle of the boiler on the steamers, yet the BT seems to work fine.   I'm going to test that putting the Blunami 2200 module in a K-Line Plymouth.

Isn’t the fact that many have experienced limited range in BT due to the fact the module is surrounded by a die cast shell?

@superwarp1 posted:

Isn’t the fact that many have experienced limited range in BT due to the fact the module is surrounded by a die cast shell?

I would certainly think so, but since until recently the BT only had a 20-30 foot maximum range, that probably had much to do with the issues as well.

@gunrunnerjohn posted:

I would certainly think so, but since until recently the BT only had a 20-30 foot maximum range, that probably had much to do with the issues as well.

I wondered the same thing on Sid’s install of the Blunami in that brass tender.

Back on this conversion.  Legacy conversion questions. Does legacy board output for led lights require a resistor? I'm thinking no due to being designed for leds. Does legacy lighting common follow TMCC use of return or common as positive lead?

Thanks Richard

NO and NO!

Legacy boards drive LED's directly no resistor.

And there is NO connection to frame ground from any RCMC, BEMC, or LCP2/3 board!  The only frame ground is the power input to the board.  Any other connection to ground usually cooks something on the board.

I've attached a schematic of my RCMC test set so you can see in detail how all the connections are made and used.

RCMC Test Set 1.2 Schematic.pdf

Thanks John. Your PDF turned the lights on for me. I knew that the boards in this class do  not use chassis ground except for incoming power. I now understand the correct led polarity. It's clear on your schematic.

Regards

Richard

@Rppoind posted:

Thanks John. Your PDF turned the lights on for me. I knew that the boards in this class do  not use chassis ground except for incoming power. I now understand the correct led polarity. It's clear on your schematic.

If you wire an LED incorrectly and it doesn't light, just turn it around.

John.......With all the light harness I am making right now I wanted to make sure I got it right the first time! Real pleasure to not have resistors and diodes in the mix. I do have pre crimped pins and wire you recommended so hopefully I will be testing soon.

Richard

I recommend anyone doing their first Legacy to have your pdf and Bruk's  diagrams handy.

Richard