Older Athearn DCC conversion

[richd286]

I wired a Bachmann 1 Amp decoder into an Athearn F7 (Vintage Blue Box) and found that the decoder reaches temps that are way too hot to allow to remain in this configuration.   A bit of research finds that the old Athearn may draw more than 1 Amp and the decoder is rated only 1 Amp.  Am I right in assuming then that this decoder is not suitable to interface with the older Athearn engine?  I am thinking that swapping the shells for a Bachmann DCC on board would be less work!

Any suggestion to guidance is appreciated.

RD

[jward]

your best bet would be to find a decoder rated at 2 or 2.5 amps if you want to keep the athearn drive.

[Nigel]

The least expensive/easiest conversion is to put the shell on a Bachmann DCC On Board F unit chassis.

More expensive and not difficult: change the motor in the Athearn unit.

As noted; to keep the original Athearn motor; you need a really large and expensive decoder.

[Doneldon]

rich-

What you have is a bad mismatch between a decoder, an old, inefficient motor and a locomotive which you presumably like. At least one of the three has to go. They won't work together. You can buy a larger capacity decoder but that will be expensive and the loco will still draw an amp from your DCC system. Depending on the system, this could represent all or just a healthy fraction of your system's power. I vote don't get a new decoder. You can replace the existing motor while retaining the loco and decoder. This is an inexpensive option but it does require some work (shouldn't be too hard though you'll have to hardwire the whole magilla) and you'll be able to retain your old loco. Only you can decide how important it is to you that the loco remains on your rails so I have no vote on this option. Third,you can replace the loco with a new one. This could be either just like the one you have or something else. You can probably fit your Athearn shell to a new chassis without major surgery. It would probably be cheaper overall to get the new loco with a decoder already installed and save your current decoder for another project. However, this work-saving option is the most expensive. If the old loco isn't especially important to you, I'd vote for this option. It allows you to replace your fossil with a modern, efficient loco of your choice (both road and type). Perhaps you can remove the motor from your old Athearn F-7 and use it as a dummy to be paired with the new loco. You could even use it as a dummy to transport a sound system for your railroad. Whatever you decide, good luck with the project. I hope you tell us what that choice is because I, for one of probably many, am interested in how this story ends.
                                                                                                                                                                                                  -- D

[Jim Banner]

Generally, the Athearn gold coloured, flat sided motors draw one amp or less.  The older black motors can draw more.  But keep in mind that faulty motors can draw a great deal more.

The hot tip for the day is to do a stall current test for EVERY locomotive you install a decoder in.  Even if you have to set things up for the test, it still takes less than 5 minutes.  And if you are doing several locomotives at a time or have a permanent test setup, then the tests take less than a minute each.

Jim

[richd286]

The test set up is good advice.  The Athearn motor is vintage and will draw a lot of power from the system.  A new motor will also require flywheels and a drive mechanism and a lot of time.  This old unit has had details added and is the head end of a Northern Pacific passenger train.  I would like to introduce it to my DCC system.  Soooo

I pulled the shell from a new Bachmann FT-A and identified only two modifications required.  The coupler opening on the front end will need very minor modification and the chassis will need additional support to hold the shell at a prototypical height and alignment.  E-bay lists the loco at a lowest price of $38.95.  The old chassis and new shell will make a good dummy unit with the motor and drive assy removed.

Thanks for the feedback.
RD

[Len]

If you want to use the original chassis & body combo, A-Line http://www.ppw-aline.com/re-power.htm makes an good upgrade motor for the Athearn F7 that includes dual fly-wheels and wiring leads, item #70321, $60.95. I've done several of these conversions, and highly recommend also getting the Motor Mount Cradle Weight, item #12404, $5.50. It's not absolutely essential, but it makes the conversion a lot easier. These parts are also available through Walthers using the same item numbers with Mfg #116.

With the new motor, and added weight, you'll be able to use the decoder you've already got and have a "stump puller" to boot.

Len

[jerryl]

Digitrax has a kit, including a decoder to convert the older Athearn. Don't know the price, You'll have to check.

[Doneldon]

Len-

$66+ to put a blue box F7 back on the rails, plus a decoder? Doesn't sound
economically sound to me unless the loco has great sentimental value.

                                                        -- D

[Len]

Len-

$66+ to put a blue box F7 back on the rails, plus a decoder? Doesn't sound
economically sound to me unless the loco has great sentimental value.

                                                        -- D

Beats $99 for a new Athearn 'DCC Ready' unit. He already has the decoder and installing it during the motor conversion process is fairly simple. Plus the dual fly-wheel A-line motor is way better than what comes in most "starter" level locos.

Len

[jward]

ok here's the question nobody asked, but seems quite obvious:

why not just replace the athearn motor with an athearn flat side motor? you can probably salvage one from another athearn, and convert that locomotive to a dummy. that way, you could reuse the athearn mounting for the motor as well.

even if you had to buy an athearn motor new, it would run about half the price of an a line motor. and the motor has never been the weak point in the athearn drive, the sintered metal wheels and electrical pickup system is.

to be honest, if i were going to sink that much money into a locomotive ($66 + decoder) i'd probably buy new.