Atlas GP-38 decoder installation


Maytag "Danged Agitator"
I just installed decoders in my B23-7's with no problem. The same Digitrax decoder, DN163AO, is supposed to fit the Atlas GP-38 however when I tighten the bolts that hold the frame halves together it puts the trucks in a bind. I got to looking at the decoder and it appears wider where it mounts in the frame than the stock circuit board did. Has anyone else expeienced this problem with any decoders?
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I installed the decoders in the B23-7's and when I tried to do the GP-38 I have had a problem.
The stock Atlas decoders are not very good. I replaced a couple of mine. They are like an early generation decoder. Not capable of independent control of the ditch lights (no function outputs), no ultrasonic drive and not momentum control.

Maybe Atlas has improved their decoders. I got a decoder equipped B40-8 and I am unhappy with the decoder. I had to hook the ditch lights to the forward headlight output of the decoder.

Ultrasonic drive is a new feature on most decoders where the chopping frequency is raised up to something like 14 KHz to get it out of the frequency spectrum that the motor can respond to. This eliminates the buzzing in the motor at low speed. Makes the motor run like it's on DC.

I'm sorry, I didn't mean to say momentum. I meant to say back-EMF. This feature is programmable and allows you to control how much the loco slows down or speeds up on inclines. It is really an excellent feature for yard operation too. You can set the loco for notch 1 and it will run at that speed. No bumping the throttle up a few notches to get it rolling is required.

From what I have read I think I will get DCC ready locos and install my own decoders at least for now. Seems to me that the factory installed ones are not quite up to par with the aftermarket, I am sure they factory installed will get better
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I don't know about the factory installed decoders, except the BLI brand, but i have had serious problems with the Atlas Decoders. Probably because they sit on the LHS shelves too long. I have scrapped the two that i did use in favor of newer Digitrax and NCE decoders.
Got a reply from Digitrax today and they told me to carefully file the area where the decoder does not fit.