Stuttering GP7s

[Flashwave]

Maybe you canhelp me with an odd conundrum. I own two NYC GP7s DCC ready, 5607 and 5608. On their own, they run fine. However, of they occupy the same piece fo track, (consisted, hadn't thought to not run MU'd) they start to stutter, that is a ghalf second of running, then they stop, run a gain for a half second, stop, lather rinse repeat. not unlike a block with too many engines on it, but that's not the case. Introducing   third locomotive causes no problems for said locomotive (I didn't have any more Bachmanns with me to test with) and if I pull either 7 off the other begins to run normally. Dispatching and re-aquiring did solve the problem short term twice. 

Additionally, the layout just ended from a large ops session, and we did have to dump the memory once, although while both engines were on the layout, only one was operating. It's a Digitrax system.

So, is this a Digitrax issue, or a known bachmann problem, or what? I think it unlikely, as P2K, Digitrax decoders and Soundtrax units all worked fine in the same vicintity, although as I said, there was a large volume of rail traffic on the layout.

[Jim Banner]

The term "DCC ready" means "designed in some way to make installing a decoder easier."  It does NOT mean that there is a decoder in the locomotive.  So first question, have you installed decoders in these locomotives or were you running them on dc (address 00)?  If you have installed decoders in them, what brand of decoders did you use?  If the decoders were other than Bachmann decoders, did you clip the capacitors in the locomotives before installing them?  These capacitors can cause the problem you describe if left in place when an ultrasonic (silent) decoder is installed.  The capacitors draw a lot of power from the decoder at the high frequencies that ultrasonic decoders use to drive motors.  The extra load on the decoder can cause it to intermittently go into thermal shutdown to protect itself.

Having to clear the slots in your Digitrax system reflects bad operating procedure, namely failure to set the speed to zero (not just stop) and dispatching it out of the system when removing a locomotive from the track.  Depending on how you do it, clearing the slots can also remove all of the consisting information from the system.  If that were the case, then only the lead locomotive in your consist would still be running after clearing the slots.  To run the other locomotive, you would have to reacquire it under its own address.  That assumes the locomotives have decoders and you used universal consisting.  If they have no decoders and you were running them consisted on address 00, this would be a basic consist and would not be affected by slot clearing.

Jim 

[Flashwave]

The term "DCC ready" means "designed in some way to make installing a decoder easier."  It does NOT mean that there is a decoder in the locomotive.  So first question, have you installed decoders in these locomotives or were you running them on dc (address 00)?  If you have installed decoders in them, what brand of decoders did you use?  If the decoders were other than Bachmann decoders, did you clip the capacitors in the locomotives before installing them?  These capacitors can cause the problem you describe if left in place when an ultrasonic (silent) decoder is installed.  The capacitors draw a lot of power from the decoder at the high frequencies that ultrasonic decoders use to drive motors.  The extra load on the decoder can cause it to intermittently go into thermal shutdown to protect itself.

Having to clear the slots in your Digitrax system reflects bad operating procedure, namely failure to set the speed to zero (not just stop) and dispatching it out of the system when removing a locomotive from the track.  Depending on how you do it, clearing the slots can also remove all of the consisting information from the system.  If that were the case, then only the lead locomotive in your consist would still be running after clearing the slots.  To run the other locomotive, you would have to reacquire it under its own address.  That assumes the locomotives have decoders and you used universal consisting.  If they have no decoders and you were running them consisted on address 00, this would be a basic consist and would not be affected by slot clearing.

Jim 

Jim, these are the DCC On Board GPs. 5607 is the current release and is in the catalog, and 5608 came before it. (Not in the catalogs anymore). These are using the stock decoders as they came from Bachmann. (Don't recall who made them for Bach, they're stripped down decoders though)

The slotmax issue was due to a large volume of engines being ran at the time and a part of the Digitrax brain having been out of commission more than it was failure to dispatch, but that problem is known. (I'm not up on part numbers, but it was essentially a part of the RAM). When I tried to run 5607 and 8 as a consist, they were stuttering, but if I took 5607 off and ran the consist under 5607 as the lead number, 5608 would respond normally as it should to the commands. Likewise, if I took 5608 off the track and ran just 5607, even consisted, it ran normally. There seemed to be something that they didn't like about each other.