Atlas FP7 Diesel Decoder fitting

[Sunshine Express]

I would like to fit a Lenz one function decoder to my Austrian made Atlas FP7,which is in good condition.I have fitted older Athearn Diesels OK but am in need of experienced assistance with this one,by way of any illustrations or instructions.

[Hunt]

It is lacking some particulars; but, possibly this link will help you.
Click http://www.tcsdcc.com/decoderpics/Atlas%20FP7%20older%20style/Atlas%20FP7%20Older%20style.htm

[Sunshine Express]

Hunt  Thank you,very good illustrations,will follow up.

[MrMunchkin]

I followed these instructions EXACTLY and my loco won't run (it ran fine before on straight DC) I think my decoder might be bad.

[Jim Banner]

I followed these instructions EXACTLY and my loco won't run (it ran fine before on straight DC) I think my decoder might be bad.

The lower brush holder in this locomotive is not insulated from the chassis.  So any poorly insulated joint that accidentally touches a chassis component will short the decoder.  If you use lights with one side connected to the chassis, this will short the decoder.  And if you connect anything to the right side of the circuit board except the orange decoder lead, this will short out the decoder.  I am not sure if the trucks have enough freedom to allow a wheel flange touch the locomotive frame in a derailment, but that is another way of shorting out a decoder in Atlas/ROCO locomotives with this particular style of motor.

Unfortunately, not all decoders protect themselves when such shorts occur.  Unprotected decoders can be destroyed even by very brief short circuits.  If your decoder was one of the unprotected ones, there is a good change that it is now bad.

It is only slightly more work to make a washer out of .020 styrene to insulate the bottom brush holder (it should look just like the red one on top of the motor) and then solder the orange decoder wire directly to the brush cap.  This can save a lot of grief on Atlas/ROCO locomtives.

[MrMunchkin]

Hey, thanks, I'm gonna try that later today.  P.M.