Bachmann DDA40X help - DC works, DCC programs but does not run!

[ryan_wilkerson]

So I have a Bachmann DDA40X, the DCC one from a few years ago. It's DCC (no sound). Has been working just fun but has been sitting for a few months since the last time it was run.

I put it on the track today and it started going forward full speed with the beacon flashing away. So I quickly pull it off the track and put it on my programming track. I pull up the loco in JMRI and read the values and it has the 4 digit address. The DC mode is "ON" so I turn it off and write the value. Put it back on the track and it sits (good). I put the 4 digit address in my throttle and it won't turn the lights on nor move.
So back to the programming track...I change it to the short address "3" and write it. Put it back on the track and nothing again.
Back to the programming track and I do a factory reset. Then on to the layout and it takes off forward full speed again (the reset had set the DC mode = "ON" so this is expected).
I go back to the programming track and turn off the DC mode. Back to the layout and it won't respond (same as before).
So I put DC mode = "ON" and put it on a piece of track with a DC throttle and it runs perfectly in both directions, flashing the beacon.
I tried another reset but no improvement.

What's so strange is that I can read all the CVs just fine and I can hear it reading them so I think that means the power is running through the motor (the typical creep while CVs are read)..

Any ideas of things to try?
Is the stock decoder bad?
Thanks in advance for the help!

[C855B]

That sounds like it's failed. Maybe try another full reset? I've always had them come back after a reset.

The sudden jackrabbit thing is something I see every so often in the [ahem] dozen or so I have. It's usually due to a momentary short elsewhere on the layout or any other problem that interrupts the DCC. Thanks for reminding me of the DC-off "fix"; I need to do that. I've been contemplating putting power-kill panic buttons everywhere on the layout primarily because of this nasty bug. I haven't dumped anything off the benchwork yet because of it, but unless I do something it's going to happen sooner or later.

These have a simple but seriously lousy decoder. It's bad enough they have nearly no functionality - what's a speed curve? - the internal voltage drop is so severe that I can hear the slowdown when any of them cross into an auto-reversing block controlled by a solid-state reverser.

[ryan_wilkerson]

Thanks for the reply Mike.
So I'm doing the reset through JMRI. Is there another way to reset it that might be different? It's not that I don't think the reset is doing it's job because it looks like it is (address set back to 3 and DC=on).

[C855B]

Yeah, I always do it through JMRI as well. I think something in the DCC power control has died in yours.

On the grand list of projects is replacing the decoders. Between the jackrabbit problem, voltage drop, poor speed matching and that I would like to control the beacon independently (which I am also replacing), they're going to get TCS M4s. I don't feel completely awful about the cost of doing this since most of the fleet was acquired when several online sellers were blowing-out inventory a couple of years ago at 70% off MSRP. While there is detailing to tend to, it is a nice-running model for the (street) price. Jackrabbiting notwithstanding.

I can't speak to the sound-equipped model, however, should anybody interpret this discussion as applicable for the newest version. The one sound-equipped Centennial I have I picked-up as an eBay bargain, the seller mentioning it had problems (sound decoder was intermittent). I didn't care, it was going to get a laryngectomy anyway as I hacked the frame for a DD35.

[ryan_wilkerson]

So this has taken a turn!
I swapped out the power supply to the PHP and no change.
I recut all the wires and reseated them. No change.

I finally went to a completely separate system. I plugged in my PowerCab and the DD40AX works perfectly!
So that's good news for the DD but bad news for the PHP.
Might need to send it to NCE...I'll do some research to see if there are any steps I can try at home.

Thanks for the help!

[peteski]

What the heck is PHP? 
I hate when acronyms are used without explanation.  I work for a large computer company and the acronym abuse there is rampant!  Oy! 




I'm a proud member!   

[Jbub]

What the heck is PHP? 
I hate when acronyms are used without explanation.  I work for a large computer company and the acronym abuse there is rampant!  Oy! 




I'm a proud member!   

I'm guessing power house pro since he's talking about NCE dcc systems

[peteski]

I'm guessing power house pro since he's talking about NCE dcc systems

Well, the Powercab he used ( which worked) is also an NCE product, but I think you're right. Make sense. TTFN.