I have an HO scale first run Athearn Gennsis SD-70I that is probably 22 years old. I have a digtrax decoder in it, I think it is an old board style decoder. I can’t get the speed settings correct. I am trying to use the simple CV2,5,6 method. Going forward the engine takes off like a rockets and quickly accelerates to Mach 1 while in reverse it slow (like a tortise) accelerates and eventually gets to a reasonable speed. What can I do with programming the decoder to fix this? Currently I can’t MU this engine with anything else because of the speed difference.
Sounds like CV2 is too high, although then it would take off in reverse, too.
Step one would be to reset the decoder. If it’s a Digitrax, setting CV8=9 should do a reset, unless it’s a really old one. The model number of the decoder should be on the shrink wrap. If it’s a really old one, like a DH121, or it has onlyt a 2 digit number, I’d repalce it with a newer decoder.
–Randy
I have one of those, a great runner. I added the LED headlight and ditch lights.I think used an DH126, but I’ll take the shell off tomorrow and check.
It is one of my best running locos.
Mike.
CV8=8 is the reset, not 9. Fat fingers.
–Randy
OOOPS! I posted the wrong picture in my first response. [:$]
Here’s the old Genesis SD70I. Haven’t figured out how to delete the first picture.
It didn’t have a board, I hardwired a decoder, and ditch lights.
CV8=8 is the correct reset.
Mike.
Remember, though, that putting a DCC decoder into a DC engine will only work well if the engine works well already. A poorly running engine will be even worse on DCC.
I did the reset. I can adjust the reverse speed with CV2,5, and 6. However forward it still takes off like a rocket. Are there any other recommendations or do I need to replace the decoder?
What are CV3 and 4 set at? Also, CV66 is forward trim, CV95 is reverse trim. You may have to tweek these. Joe
What speed step mode are you using? For the DH121 this is important, as the DH121 only supports CV5 and CV6 and speed tables properly in 14-step and 28-step speed modes. If you’re using 128-step mode, nothing you do to CV5 and CV6 will affect top-speed and mid-speed settings.
The DH121 also, if I recall correctly, does not support Ops Mode programming.
Once I realized these limitations, I went through and replaced the few DH121s I had.
The later DH123, DH126 correct this, and this has never been a problem for the DH163/DH165/DH166-series decoders.
I think it would be good to know if this forward/reverse motion behavior was also observed in DC mode. If this forward/reverse behavior is observed in DC mode you have a mechanical problem to fix.
You have an EDIT option available on your own posts. Simply click on it and remove the photo if you wish.
Wayne
If you did a hardwire, it would be very simple to unplug the decoder from the 9-pin harness and plug in another decoder and try it. If it runs well with a better / newer decoder, it might have just been the decoder limitations mentioned earlier, or some other decoder issue. If it still runs oddly with the new decoder, then it’s a mechanical issue with the locomotive.
It is a DH165AO style decoder, and the only engine I have that used that decoder. I re-soldered one wire that had come off hoping that would help solve the problem. That did fix the front headlight, but not the speed issue going forward. I will try reattaching all the wires, maybe one has a bad connection now, but I probably need to replace the decoder.
Here’s an article I found in the troubleshooting section of the Digitrx web site, it shows all of the function outputs.
http://www.digitrax.com/tsd/KB364/dh165a0-function-outputs/
It might be of some help.
Like I mentioned in a previous post, mine didn’t have a board, so I hardwired a DH126D for motor and basic lighting.
Mike.
5600 posts and you’ve never posted the wrong picture before? [(-D]
I can’t figure out how to erase the image. I right click on it and I get all kinds of options except “delete image”.
Mike.
Forward and reverse trims only work with speed tables.
Peter
I believe you are using the picture icon to post.
Left click on the picture, it will highlight. Hit the delete button on your keyboard
I forgot that I have to go into “EDIT” before I can delete, as Dr. Wayne posted.
Sorry OP, didn’t mean to interupt your thread with my picture problems.
Mike.
Hello,
I have an older Bachman Spectrum HO EMC Gas Electric Doodlebug, PRR. It is DCC ready with an 8 pm socket. I only used it decades ago when I ran on DC. I cleaned it and am ready to install a decoder. I currently run a NCE power cab and would like to use a NCE decoder. Is there a specific one I should use? Is there a “conversion chart” that outlines which decoders work best for specific brands of locomotives? Thank you for your help.
This is my first post, and if this is not in the appropriate thread please feel free to move.
Rhyfel.