Help diagnose a sick loco

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RJasonB

ITS_MFRR est. 2010
Greetings all. I model HO scale and operate using NCE PowerCab. I rolled an MTH Big Boy out of the roundhouse today and had a scare. It started up fine, rolled out of the roundhouse, onto the turntable, and out to the yards fine. I backed it up to a consist of 13 cars and headed for the main. After approximately ten feet on the main, it died. Just prior to dying, I heard a strange buzz come from the loco. Couldn't tell if it was the engine or the tender. I glanced at my throttle and saw the ammeter had spiked to 1.29 amps. This unit rarely draws above 0.56 amps with the smoke unit running. Anyway, there it sat. Dead. No response to the throttle at all. I powered down the layout and let it sit for about a minute. I repowered the layout and hit F3. Big Boy started up and responded to all horn and whistle sounds, but not to forward or reverse commands. No headlight, but the reverse light on the tender illuminated when reverse was selected. No cab lights or number board lights (F5), but the red marker light on the tender lit up when F5 was selected. I shut Big Boy down (F3) and started up an MTH Challenger. Ran fine with no issues. Then ran an MTH 9000. Ran fine with no issues. I recalled Big Boy and pressed F3. Started up, but again responded (or failed to respond) to the throttle as above. I shut down Big Boy and powered down the layout. I removed everything from the layout except Big Boy and then reapplied power. Big Boy immediately took off running without any command. It ran at a high speed relative to what I normally run, without any response to any throttle commands at all. I killed power to the layout and now am stuck. I inspected the loco and found nothing obvious. I took apart the tender and found nothing obvious. I am not comfortable disassembling the engine to inspect it, but I would guess the motors are not fried considering that it took off on its own as described. Perhaps a fried decoder? I vacuumed the layout and cleaned the rails the day prior. Any insights would be helpful. I have sent an inquiry to MTH for assistance.

Let's try to keep this focused on the problem and not let the thread turn into and 'MTH Sucks' fest.

Thanks. Jason in northern Colorado
 

Motley

Active Member
Jason sorry to hear thats happened to you. But it sounds like the decoder is fried.

You'll have to call up MTH on the phone, describe what happened, and they can RMA it and repair it for you.

You will need proof of purchase. And they accept ebay/paypal reciepts also.

Good luck...
 

Dave S

Tree Farmer
How about swapping decoders with another engine and see if the problem moves with the decoder or stays with the loco?
 

bnsf971

Gomez Addams
Staff member
I had this happen with a BLI engine, and the decoder had shorted out. One direction, nothing, the other, it took off like a bat out of hell, and the sounds did not follow what the engine did or did not do.
 
Jason,

I had the same thing happen to my big boy. I ended up calling MTH repair and all they could do was tell me to send it back. I didn't want to send it in because their repair department is known for being a black hole. To make a long story short one of the wires soldered to the top of the draw bar under the cab had come loose. Check that out. After a few hours of running they tend to do this. Less if the layout has tight radii.

Keep us informed!
 
Last edited by a moderator:

RJasonB

ITS_MFRR est. 2010
Thanks for the replies. I've not yet received any response from MTH to my e-mail inquiry, but I've heard this is not uncommon. I will need to place a phone call on my next day off. I've been told this is the only certain way to reach someone there.

I'm a bit leery about taking the engine apart, but I think I will give it a shot. My soldering skills stink, but if it's something as easy as irocinblue89 suggested, it's worth a try. I'll keep you all posted. Jason.
 

RJasonB

ITS_MFRR est. 2010
Was able to try a few more tests today. I have two of these Big Boys. 4004 is the 'sick' loco, 4006 runs fine. I attached 4004 tender to 4006 engine and everything was normal. I put 4006 tender on 4004 engine, same symptoms as with its own tender. I put 4004 tender on the track all by itself. It responded to all sound-related commands, i.e., start-up, whistle commands, bell, PFA announcements, etc. So, it seems the problem is likely somewhere in the engine. I checked the draw bar wiring as suggested. They look and feel solid. If there are bad connections, it is somewhere in the engine and I have yet to muster the guts to disassemble this beast. Does anyone know, are all decoders inside the tender? Is there one in the engine itself? If all (both) decoders are in the tender, and the locomotive will actually take off on its own with no command response in the presence of track power, I'm guessing the problem is not fried motors or decoders, but a wiring issue somewhwere inside the engine.
 
Was able to try a few more tests today. I have two of these Big Boys. 4004 is the 'sick' loco, 4006 runs fine. I attached 4004 tender to 4006 engine and everything was normal. I put 4006 tender on 4004 engine, same symptoms as with its own tender. I put 4004 tender on the track all by itself. It responded to all sound-related commands, i.e., start-up, whistle commands, bell, PFA announcements, etc. So, it seems the problem is likely somewhere in the engine. I checked the draw bar wiring as suggested. They look and feel solid. If there are bad connections, it is somewhere in the engine and I have yet to muster the guts to disassemble this beast. Does anyone know, are all decoders inside the tender? Is there one in the engine itself? If all (both) decoders are in the tender, and the locomotive will actually take off on its own with no command response in the presence of track power, I'm guessing the problem is not fried motors or decoders, but a wiring issue somewhwere inside the engine.
There are boards in both. I had 1 apart Friday fixing it. To take it apart you must pop the steam dome off. It comes off easy because it is held on with a small magnet. I use tweezers with electrical tape on them so I don't damage the paint. Under that is a screw. The one I was messing with the shell came right off, but look under the cab on the bottom and see if there are screws there. i cannot say for sure but I believe there is. After you get all the screws out it should come off real easy. Use a foam base or something to cradle the loco. This thing is heavy and easy to drop. I was very very miticulous when I did mine but they are not that bad. I am really surprised it wasn't the draw bar wire. They are heat shrinked and sometimes they break but don't look/fell like it. I am attaching a link to the repair diagram. Let me know if it doesn't work. I will email it to you. http://www.mthtrains.com/sites/default/files/download/exploded/80st10760e.pdf

Seann
 

RJasonB

ITS_MFRR est. 2010
Seann,

Thanks for the link to the exploded parts diagram. That was a huge help! The steam dome screw was the only thing holding the boiler shell on. It came off quite easily. Once removed, I put a bit of light on the thing and found the problem. The brown power wire to the front driver assembly had come loose. Looks like the solder had failed. I called the nearest hobby shop to me... over an hour drive away... and they wanted nothing to do with a quick resolder repair. I've gone this far on my own. I suppose I will forge ahead and see if I can pull it off myself. Will repost.
 
Seann,

Thanks for the link to the exploded parts diagram. That was a huge help! The steam dome screw was the only thing holding the boiler shell on. It came off quite easily. Once removed, I put a bit of light on the thing and found the problem. The brown power wire to the front driver assembly had come loose. Looks like the solder had failed. I called the nearest hobby shop to me... over an hour drive away... and they wanted nothing to do with a quick resolder repair. I've gone this far on my own. I suppose I will forge ahead and see if I can pull it off myself. Will repost.
1 thing to think of. Not just a hobby shop can repair it. An electronics repair shop should be more than qualified to solder a wire on. Just a thought.
 

RJasonB

ITS_MFRR est. 2010
Well, I managed to reattach the errant wire to the driver... even put down a presentable solder. As obviously necessary as it was and as pleased as I was with my apparent success, the repair did not bring Big Boy back to life. My guess now is that the decoder, or some other component on the engine's board, is toast. My only option may be to send it in to the abyss of the MTH repair shop and hope for a nice Christmas surprise in the form of a repaired Big Boy returning home.
 

Motley

Active Member
This should be a fairly slow time for MTH. So you may get your repair back sooner than you think.

Just give them a call and they can give you an estimate on the repair date.
 

RJasonB

ITS_MFRR est. 2010
I called MTH on Aug. 14 and was pleasantly surprised with the level of customer service I received. Seems you read nothing but negative about that very issue. The tech I spoke with listened to my description of the problem and seemed genuinely interested in helping me. Looks like I will need a new boiler board. They will also check the motor just to be sure it was not bad to begin with and caused the board to blow. He checked their stock and told me that all the parts necessary were in stock... another contradiction to all the negative crap you read about online. I immediately received and RA number and shipped my Big Boy the next day. I was told to expect 8 to 10 weeks for a return (with an apology for the long wait time). I checked online and saw my Big Boy was in the queue. No complaints so far... other than being without my Big Boy. I'll post with an update as soon as I have one.
 

Motley

Active Member
Well thats good to hear they treated you well.

I also don't know where all the complaining comes from, I've called them several times and they are very helpful.

They repaired my SD70Ace, and they told me it would take 8-10 weeks, but I got it repaired and shipped back within 4 weeks.
 

RJasonB

ITS_MFRR est. 2010
A quick update for those who have asked and for those who are interested. I received a phone call from MTH today advising that my Big Boy has been repaired and is in the mail. Ten weeks almost to the day. The technician confirmed that the boiler board was shot and had to be replaced. He also went through and checked all solder work. Should return to me good as new. The cost will be $54. MTH would not consider this a warranty repair as I bought it privately rather than from a dealer. I was not expecting a freebie anyway and was actually expecting the bill to be at least twice that amount. All things considered, I'm pleased. The only thing that remains is to get the beast back on the layout and see how it runs.
 




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