Constant Voltage Board

The instructions are written on the assumption that you are converting an engine with PS/1 or QSI electronics, both of which employ a separate CV board for the lights and (sometimes) the smoke unit. The lights and smoke on a TMCC engine are connected to the motherboard, therefore there is no CV board as such. The constant voltage comes from the TMCC setup. If I remember correctly from the one PS/2 conversion I did a couple of years ago, your best bet is to just replace all the light bulbs with the ones that come with the PS/2 kit, unless they are the same voltage (I don't know what voltage Lionel uses). As for the smoke unit, I don't know how you get a Lionel or TAS smoke unit as used by 3rd Rail to work properly off the PS/2 wiring. Maybe someone else who has done this particular conversion can tell you. You could  just wire the smoke switch straight to the track and bypass the DCS, but then you wouldn't have puffing smoke or be able to turn the smoke on and off from the remote. You could always buy an MTH smoke unit, which is intended to run off a PS/2 system, or get ahold of an old PS/1 smoke unit and follow the instructions with the conversion kit to adapt it to PS/2 operation. Of course, if you do that you will have to mouse up a mount, which might not be easy. If the inside of that Allegheny is anything like the 3rd Rail 4-12-2 I once had to rebuild a smoke unit on, it isn't easy to get at and getting proper stack alignment might not be fun. 

 

On old engines with PS/2 or QSI electronics, the CV board powers the smoke unit if it is a Seuthe type unit. A fan type unit typically runs off track voltage. 

BRice,  Just follow the light leads.  If they go to the mother board they are powered by the TMCC.  If they go to a wire nut that connects to the center pickup rollers and chassis ground they are powered by track power,  If they go to a small electronic board that is totally separate that would be a CV board.  They do come in all sizes and depending on the engine some Lionel engines use them too.  Usually when there are more lights used on the engine then the TMCC circuitry can control.  What is your engines model number.  G

some Lionel engines use them too.

You learn something new every day. I've worked on a fair number of TMCC setups, never seen a CV board. I guess I just never had a locomotive with that many lights. 

 Inside the 3rd rail Allegheny w/TMCC, there was a connection board attached to the front boiler plate and another small cv board floating inside. It got it's power from the front set of drivers and then shared it.

 I was about to change the front headlight. I tested the original and it lit with six volts so I left it alone.

The 1990 700E uses a seperate 5volt constant voltage board. So do a couple of diesels. TMCC engines use 16 volt bulbs, so no constant voltage boards are used. Marker light LED's are controlled by TMCC Radio board. Some Pre-TMCC diesels use a 5 volt flasher circuit board

Chuck,  I beg to differ.  The TMCC R2LC only supports so many lights.  Some of Lionels 38000 series steams have CV Boards.  Look at the JLC Challenger (large CV board), the N&W J (small 5V CV Board).  These are TMCC engines with RS 5.0 and they use CV boards.  Part numbers and pictures available on Lionel's web site.

 

Also, K-line TMCC use them much more extensively, including CV boards to drive roof fans on the diesels.

 

Basically as more detailed lighting was added to higher end engines, CV boards had to be included.  Also they started using the RS board in the tender for Markers and backup light.  Anything with an IR tether had to use power from the tender boards to handle lighting features.    G

 

 

You're right.

Thanks gents for the help. I contacted MTH service, they were great. The CV board is in the boiler. MTH advised to just use the factory board with the PS2 kites. I anticipated the smoke unit problem and ordered a complete smoke unit from MTH. I was able to unscrew the brass funnel and install the factory brass funnel from the Lionel unit and the entire assembly fire perfectly in place. Busy with other projects right now, but will post video of finished project. Thanks Brad

Is there a reason a guy can't wire the ps2 harness to the lionel smoke unit if you remove the cap, diode and transistor.  Wouldn't this be the way mth has you wire a ps1 unit on ps2?  I am doing the same thing to my lionel allegheny and that was my plan so if it won't work that would be good to know now.

The problem is that Lionel smoke unit PCB has copper traces that ground to the screws and the frame of the smoke unit for one end of the smoke element.  You need to isolate the smoke element from the chassis ground.  If you do that and the element is isolated you can than use the smoke unit.

 

The only other problem is the heating element resistance.  MTH uses 2 16 ohm in parallel for effective 8 ohms.  If you have a single 8 ohm resistor in the Lionel unit, it may draw too much current and have a shorter life.  You may want to go with 16 ohm element, and live with reduced smoke output.  G

thanks barry I see the ground paths and we have a fix for that.  as far as the heating element if i have to replace it anyway the short life is of no consequence unless someone knows where to buy the resistors individually then one could be added to the lionel board.

 

I am not Barry...:-) .  I sell the elements, the issue is if 2 can fit in the Lionel unit since they are designed for one element.  MTH has separate holes in the PCB for each smoke element.   G

Aw crap g sorry had post open in different windows at once and a Sunday cocktail to confuse me!!! My apologies.  Ya I think I can fit them easy enough.  If you don't mind, email me a price for a few of those plus shipping and paypal name if you do that.

No e-mail displayed in your profile, mine is in my profile.  G