mth challenger 4-6-6-4 30-1195-1

John would you have one of the 10 pin connectors with the pc board attached for soldering, i need to replace it and i hate to   buy a whole harness just for the sake of the connector?

Alan

I don't right now, but you can get those from MTH.  There are several styles, so calling Midge at MTH with an exact model number of the engine would probably be best.

You have a Positive Voltage short.  Does this engine have the MUX boards?  Sounds like you may have a damaged MUX board in the engine.

If no mux, take the PCB off the engine and look at the diodes for signs of shorting/damage.

Also test yellow to white through the tender harness un connected.  See if they internally shorted.

Maybe the shell is contacting the PCB and shorting it, or you have bridged a solder joint on the PCB.

Your PCB is a AG-0000061 according to MTH parts list.  G

yes George it does have as mux board in the tender!

Alan

George there is  MUX board in the engine and in the loco. the mux in the engine the diodes look the it's cooked, are they a special diode or can i use a standard diode 2 amp 3amp do you know what the amperage rating is for the diode on the left from the front of the pc board. the board in the tender look's OK

but the mux in the loco definitely needs a new diode or the whole board replaced.

What would you recommend George to replace?

Alan  is the part number for the board you gave for the engine mux board or the loco mux board!

the diode bad is on the left front side nearest to the gray wire and capacitor connector

I think i found out what caused the diode to short (burnout)the orange wire feeding the marker light socket center of the bulb wire got pinched in the frame. do you also think that's what i  think caused the smoke to keep running even thought the remote i had it shut off using DCS remote!

Alan

A short to the frame for any of the wiring in a PS/2 loco can cause all sorts of undesirable behavior.  Everything, other than the input power leads, are isolated from the frame.

thanks John. i just ordered the mux board bad diode, I'm not sure but do you know if replacing the diode will repair the mux board or are they usually fried ounce they hit with a short!

Alan

Hard to say what happened, but it's cheap to stick a diode on it and see.

Those diodes are standard for providing the PV for the engine from the motor leads.  Engine MUX is cheap enough, it may have logic chip damage too.

PV shorts are not as damaging as 5V or PCB ground.  While not direct ground to AC outer rail, the PV comes directly from the 8A rectifier, and that feeds the engine diodes for providing ENG PV when a harness line or MUX is not used.

You can tell a PV short because of the higher amps it typically draws.

Always need to be careful placing shell back on.    G

so what kind of diode can i use 1n4005 or similar and at what amp rating would be capable to handle the load, how much current is usually drawn threw the left diode usually.i mention 1n4005 as i know i have some of them and is the cathode up or down from a front view of the board, diode was burnt so bad that i can tell where the line is top or bottom?

Alan

George and John check your email i sent you picture of mux  board and answer question please!

Alan

Well after replacing a bad diode on the loco mux board, and wire tying all the small wires out of the way so they would not get pinched, i reassembled the engine and tried her out. Worked perfectly whistle ,bell, psa sounds chuffing rate set to 2,filled smoke unit,and powered her up and ran perfectly,!

The diode actually goes across a small filter on the left side of the mux board! 

Now the engine runs great with ps2 3 volt board installed and 4 ohm speaker.

Now just have to mount the plastic boards holder and connect heat sink to the bottom of the tender and install a 3 volt BCR .

Only wish i was able to reset the odometer and miles but as i understand it that can only be done buy MTH computer software, otherwise everything else is perfect!

Thanks to all who helped and aided with there knowledge. that especially for the tips George GGG!

Alan Mancus

I don't know of any way to reset the clock on the modules.  It's good the diode did the trick, now you have a spare MUX board.

Alan, Glad you got it.  I had obligations last night so I could not post a pic.

Your lucky it did not knock out a lighting fet on the board.   G

thanks all for your help. thanks George you sent me right to the correct problem, and i then found it quickly. I did not suspect the mux board at all glad you had me check it first, plus when i new the boards were good as they worked in another engine it proved everything else was good and that the problem had to be in my challenger engine. Its a beautiful engine and run's great and i especially love the sounds of whistle and Bell and they are very loud on  this ps 2 3 volt boards!sounds like the real challenger steam and whistle it goes right threw me terrific!

\Thanks all

Alan

P.S. i used small wire tires to make sure no more wires got pinched to ground!

Thanks

check out my thread on a ps 3 steam engine with garbled sound!

Alan

John and GGG i called MTH the other day with the part number George gave me but was told that 10 pin engine cab connector is no longer available.midge told me she would reseach it and came up with a similar 10 pin connector the only catch is the board dimentions are just a little bit bigger, so she said she would try to get me the bigger one and add it to my parts order. the one in the cab engine i repaired but the board has been burned from overheating when the original problem was that made the engine fail in the first place.probably PS 2 5 volt board failure!Ilike the engine and it has Great volume and good sound quality depth when the whistle or bell or PSA sound are great too!

Alan