Need help with MTH RailKing UP 3982 4-6-6-4 Challenger and mismatched tender

Looks like you have a PS1 version, shows QSI on the chip.  What is the product number on the box?  Also it appears that is the wrong tender. It looks like the small chip says Wabash Hudson on it if I can read it correctly.  Was there a 9 volt battery connected?  Should have been. You are lucky that it ran at all.  PS1 engines are famous for scrambling the chips if the battery is no good.  You need to get a proper tender which won't be easy or have someone upgrade it to PS2/3 which will be around $250-350.  Do you need command control?  If not the upgrade is not worth the trouble or expense.  PS1 engines have not been made since 2000, so it is all but 20 years old. Hopefully someone else may chime in with a better solution. 

Could the three wires  go to the volume pot. Is it missing?   It's been a while since my proto-1 days.

Thanks guys for the replies. There is a 9 volt battery harness that is intact but without a battery. It makes sense that the mystery wires would go to a volume control. Unfortunately, there is no pan pot. I had no idea this thing is so old. What damage will I do if I plug in a 9 volt and attempt a run?

Do not plug in a battery yet !!!!! Wait until either GRJ or one of the electrical gurus here offers a solution. Are you running with DCS? Depending on how much you have in this loco, how much you love it, and if you're only running conventional but want sound, why not simply add a ERR RailSounds Commander for $90?

If all else fails send the unit off to forum members John or Marty . Both those guys can fix nearly everything MTH.

The PS-1 system is designed to run with an 8.4 volt Ni Cad rechargeable. If you hook a regular alkaline to it the board will try to charge it and it may explode, making a huge mess. You can use a 9 volt Li-Ion rechargeable. I am guessing since you plugged the tender into the engine and it ran, both are PS-1 so that is good. In order to make sound that speaker needs to be plugged into the board. There is a 2 pin plug for the speaker, it may be marked. If not someone can chime in with the correct plug location. As I recall the pot you need (for sound volume) is a 10 K ohm. Any 10 K pot will do. It will not likely make sound without the pot. The 4 wire tether uses 2 wires to supply AC power to the board from the engine, and 2 wires to supply DC back to the motor for movement. I forget the colors, but no matter if it already moves. You may be able to order the correct PS-1 chip from MTH to get the correct challenger sound file, not sure. Last time I checked they still had lots of various PS-1 chips. This engine is pre-command era, meaning it responds to variable AC to the track for speed, and power interruption results in direction cycling.

Hope that helps,

Rpd

A lot can be done all depending on how much $$$$ you want to plow into this. My suggestion contact forum member Alex Mallie this engine can be built up into a full Lionel TMCC version.

The 3 wires do go to the volume pot.  The pot is 10  ohm.   Without the right tender, sell it for parts.  Do we have the MTH item number?

The only Item Number I have: MTH RailKing Union Pacific 3982 4-6-6-4. Does that help?

Post a more descriptive subject heading.   I may generate even more/better ideas.

Here is what I found searching the MTH site:

Item 20-3000-1

Premier Challenger 4-6-6-4 cab no 3982

2 smoke units, Pittman motor

Constant voltage headlamp

Protosound

Lighted marker lights, back up light

First articulated die cast locomotive

Delivered June 1994

Rod

You guys are the best. 

Actually I just checked and I am pretty sure the PS_1 volume pots are 10 K ohms (ie 10,000 ohms); not 1 meg as I stated earlier. Any 10 K pot will work. Sorry for the misinformation. I corrected my earlier post.

Also the blue wire is the center connection (wiper) to the pot. The others connect to either side.

Rod

Just curious, did you get the manual when you bought it?