"Chattering" DCC auto reverse unit

[Rosenblad]

Hi!
I have a Digitrax AR1 Auto Reverse Unit that operates very well on most locomotives. There are a number of exceptions that I consider very important to my operations.
When I run my old Athearn SW1500 (blue box) and all my Hamo locos (2-rail DC with permanent magnet fields) the AR1 unit "chatters" as long as these locos are within the return loop. All these locos are equipped with various Digitrax decoders.
I have tried adjusting the AR1 according to the instructions that came with the unit but the results are still the same. I have written to Digitrax technical support but their answers were totally useless. Is there anyone who can help me?
Tom Rosenblad

[NZRMac]

I had the same problem, I threw them over my shoulder and got a PSREV from Tony's. Never had a problem with them, all solid state no relays to click.

Ken.

[Anonymous]

Try putting a small mylar cap across the motor brushes. I bet those old motors are generating "noise" that fools the autoreverse into triggering. Fred

[Rex Beistle]

You have the "TTC" adjustment set too low for the high current draw locomotives. Read the instructions to find which direction to turn the control.

Visit the Colorado Railroad Museum in Golden, Colorado - USA

[claycts]

Of the three answers, I went with Tony's when our AR-1 had the chatters. I read the directions and had our Digitrax distributer come over and he said USE TONY'S. Some times the AR-1 can not handle it, period. MRC is worse.
Just my $.02

[Texas Zepher]

QUOTE: Originally posted by flee307
Try putting a small mylar cap across the motor brushes. I bet those old motors are generating "noise" that fools the autoreverse into triggering.

Please explain in more detail. On a DCC unit the track power never "sees" the motor as it is separated by the entire decoder circuit, so I don't understand.

[Anonymous]

QUOTE: Originally posted by Texas Zepher

QUOTE: Originally posted by flee307
Try putting a small mylar cap across the motor brushes. I bet those old motors are generating "noise" that fools the autoreverse into triggering.

Please explain in more detail. On a DCC unit the track power never "sees" the motor as it is separated by the entire decoder circuit, so I don't understand.

Just because you have a decoder in place don't mean that the motor isn't hooked to the track. Where does the power come from? Old motors generate lots, and I mean lots of RF noise, some may be feeding backwards through the decoder (decoders are not rf sheilded and all diodes have reaction times and reverse leakages) into the track which the reverser sees as a short, and that's afterall what triggers the autoreverser to reverse. In the old days motor RF was so bad your neighbors could watch you run your trains on their TV. Some of this digital stuff is real untolerant to such "noise" so it's IMHO worth the 10 cents to put one in and see if it helps. Beats buying a new autoreverser rigth away. LOL Fred

[Rosenblad]

Hi!

Thanks for all the answers!

QUOTE: Originally posted by flee307

Try putting a small mylar cap across the motor brushes. I bet those old motors are generating "noise" that fools the autoreverse into triggering. Fred

The capacitor sounds like something an old guy like me can relate to! How do I determine the size to use? I think I want to try this before I dump my AR1.
[:)]
Best wishes,
Tom

[Anonymous]

QUOTE: Originally posted by Rosenblad

Hi!

Thanks for all the answers!

QUOTE: Originally posted by flee307

Try putting a small mylar cap across the motor brushes. I bet those old motors are generating "noise" that fools the autoreverse into triggering. Fred

The capacitor sounds like something an old guy like me can relate to! How do I determine the size to use? I think I want to try this before I dump my AR1.
[:)]
Best wishes,
Tom

I would just pick a lokety and experiment. Start with say a .1 uf (or any small cap you have) and see what happens. .1 is what I use to fix flashing in LED lighting caused by spikes and such generated by the motor. Fred

[Anonymous]

Let us know if it helps or makes it worse LOL. Fred

[NZRMac]

QUOTE: Originally posted by flee307

QUOTE: Originally posted by Texas Zepher

QUOTE: Originally posted by flee307
Try putting a small mylar cap across the motor brushes. I bet those old motors are generating "noise" that fools the autoreverse into triggering.

Please explain in more detail. On a DCC unit the track power never "sees" the motor as it is separated by the entire decoder circuit, so I don't understand.

Just because you have a decoder in place don't mean that the motor isn't hooked to the track. Where does the power come from? Old motors generate lots, and I mean lots of RF noise, some may be feeding backwards through the decoder (decoders are not rf sheilded and all diodes have reaction times and reverse leakages) into the track which the reverser sees as a short, and that's afterall what triggers the autoreverser to reverse. In the old days motor RF was so bad your neighbors could watch you run your trains on their TV. Some of this digital stuff is real untolerant to such "noise" so it's IMHO worth the 10 cents to put one in and see if it helps. Beats buying a new autoreverser rigth away. LOL Fred

The reverser doesn't see the decoder as a short, if it did the DCC controller would see it as a short too. The short is created by a metal wheel crossing the insulated gap. Try running a train with metals wheels backwards thu a reverse section your reverser should trip.

The AR1 is just really tricky to set up every loco may draw a different amount of power the AR1 reacts differently to this by clicking as it see the different amps drawn. Two locos are different again, then try some sound locos. Very frustrating so I biffed mine and bought one from Tony.

Capacitors wont help they actually interfere with the DCC signal.

Ken.

[Anonymous]

A cap on the motor side of a decoder will not interfer with the DCC signal. It would on the rail side, but on the motor side it's just pulsed metered DC. And a short generated by a revese spike from a motor differs how from a short from a metal wheel bridging a gap? Fred

[Rosenblad]

Hi!

Thanks again for all your answers! I have just ordere a PSrev from Tony's! I have high hopes that this might be sound advice!

Best Wishes,
Tom

[NZRMac]

Indeed it is. I'm sure you'll have no trouble.

Ken.

[Rosenblad]

Hi!

The PS Rev from Tony's arrived today! That's what I call extremely good customer service (thanks Tony!)! The unit works perfectly with all my locos now. Special thanks also to Ken who gave me this advice in the first place!

Best Wishes,
Tom

[NZRMac]

Great News!! Enjoy Tom, I'm yet to re-install my reverser, alot more track to lay before I get into loops (new layout)

Ken.