HO spectrum mountain SP4361 vanderbuilt tender disassembly

[pjcxb]

Please tell me how to open up the tender - the sound decoder has a fault and needs to be replaced.

With thanks
Peter

[richardl]

Hope this helps.

http://www.bachmanntrains.com/home-usa/board/index.php?topic=21059.0;wap2

I think it has a tight fit also from previous post.

Take time to look at the diagram for the tender in the Parts/Product Reference page.

What is the problem with the decoder before tackling this?
No idea your level of experience but sending the loco and tender back to Bachmann might be a better option.

The last I knew, the tender has a PC board with eight pin socket and a separate PC board/decoder that plugs into the eight pin socket PC board. Bachmann does not sell the sound decoder though you can plug in your own sound decoder. It is rare that a SoundTraxx Tsunami decoder fails.

Rich

[pjcxb]

Thanks for your very prompt reply.

Sadly, the tender on my loco (Bachmann #84204) is not the same as the one which you referred me to, which is #84202.  There is no curved bottom which is shown as removable in the 84202 diagram, the bottom is flat and there is only one screw at the end of the underside, at the coupling end.

The loco stopped running although the sound is fine.  The motor is also fine but there is no dc from the tender plug and it is impossible to read CVs so it seems that the decoder is not seeing the motor.  I suspect a broken motor wire within the tender but cannot see how to open it.

Any further help would be much appreciated.

Peter

[richardl]

I figure you mus know, the four pin connector uses two pins for the light and two pins for the motor.

Bachmann has changed the design of the tenders some. One picture I saw, there is a Phillips screw on each end of the tender at the TCS decoder page.
I think I remember seeing a mention of a snug fit but do not have the tender.

Did you get a diagram with the loco? Sometimes hidden under the foam packing or is this a loco from a private sale or is it a factory installed loco?

I have Googled bachmann spectrum vanderbilt tender shell removal and still looking.

Rich

[electrical whiz kid]

I have pulled a medium Vanderbilt tender from off of the shelves, and the aft end under the forward end there is a tab on the bottom.  These tenders are really tightly fit together-but this is in response to the exacting eye of the model rail.

NOW...As per RichardL, have you done your research on this decoder?  I will hazard a guess that it is a fractured solder
joint, or even a broken wire.  Those Bachmann decoders are pretty ballsy, and I don't see failed workmanship on any of this newer Bachmann line.  If we were talking twenty or so years aback, We might be well advised to take it out of the tender for a good long look-see.  Do check the simplest things first-oh, and if you do not have a VOM, get one-get a decent one.  You do not need a Simpson or Sperry for this gig, but a simple Allied one will do the trick.

Rich C.

The OTHER Rich...

[richardl]

I have a six year old Bachmann 4-6-0 with on board sound and it has two square PC boards. As I said before, one is the decoder and plugs into the Bachmann PC board with the eight pin socket. From what I know, that has been the standard set-up since Bachmann has been selling sound on board steam locos.

You will see two inductors. They might be wire wound or look like green resistors. Near them will be capacitors. While you are there, cut the caps out. The motor current passes through the inductors to the connector. The EU and UK require those components.
With the tender only on the track, try it out. You should see DC voltage at those two inductors. Check both sides. An inductor could have opened.  If you had an Oscilloscope, you will see 12 to 14 volt pulses that get wider with more speed.
Since you say you cannot see the decoder with the system, that might be a place to check carefully, visually and electrically.

Rich

[electrical whiz kid]

Errata:

I must have been more tired than I thought:
What I meant to say is that the [rear] end of the tank will part from the main body.  I haven't looked, but there may be an IPB (illustrated parts breakdown) in that "parts, service, information" section  of this site.
now...  The aft end cap, upon which two ladders are moulded, should come apart; there is a tab just aft of the connecting pin.  From there, I can suggest you look at that IPB, plan your moves, and do not paint yourself into a corner; figuratively  speaking...

Rich C.

[electrical whiz kid]

Errata 2:

On this "BACHMANN" SITE, go to the "Parts, information" part.
Go on the info page, scroll down to "Hicken Vanderbilt" tender.
This is a concisely clean straightforward page.  You shouldn't have any trouble, as this gives an exploded view of the whole assembly.

Rich C.

[pjcxb]

Many thanks again to Richardl and WhizKid for your helpful posts.

I have a copy of the tender exploded view but it does not help with disassembly.  I will try to remove the rear end as suggested.

HOWEVER, I must admit to having jumped the gun a little...  When I tested the resistance across the 2-pin connection on the loco I saw about 40 ohms and just assumed that that was the motor connection.  Then disassembled the loco and checked the motor resistance - no connection!  Very surprised I was.  Not sure why the wheel - wheel resistance was so low, it was much higher when I re-checked it.  Anyway, I am surprised that there was a motor problem as the loco has not had much use, probably a couple of hours at most.  Took it out and got it running again, gave it a little bit of oil and reassembled it.  So there we are. 

Thank you once again.

Peter

[richardl]

Good troubleshooting. Nice to hear of success.

Rich