Hello , both recent purchases the 79966 ran fine on my Marklin C-Track test track but would constantly stall on my K-Track which was resolved by 'stretching" the pick up shoe. Have run both in on my test track and once reasonably speed matched now running on my layout however still showing abnormal jerky running particularly the 79798 "Lokomotion". I have noticed on both locomotive's that CV2 has had to be very high to get a consistent low speed @ speed step 1 of a scale speed of 4 kmh (RZ Tech Speedbox). My other Roco Locomotives usually CV2 set around 20 but these latest are around 45 which as I am running a maximum speed of 100 kmh I suspect has narrowed the speed table to low or they both need a little bit longer to "free up" in there gearboxes. Any advice would be greatly appreciated. Thanks so much. Richard.

German Translation (Google Translate) below.

Hallo, beide kürzlich gekauften Modelle 79966 liefen einwandfrei auf meinem Märklin C-Gleis, blieben aber ständig auf meinem K-Gleis stehen, was durch „Strecken“ des Schleifers behoben wurde. Habe beide auf meiner Teststrecke eingefahren und die Geschwindigkeit stimmt jetzt einigermaßen überein Läuft auf meiner Anlage, zeigt jedoch immer noch ungewöhnliche ruckartige Fahrten, insbesondere bei der 79798 „Lokomotion“. Mir ist bei beiden Lokomotiven aufgefallen, dass CV2 sehr hoch sein musste, um eine konstant niedrige Geschwindigkeit bei Fahrstufe 1 einer Maßstabsgeschwindigkeit von 4 km/h (RZ) zu erreichen Tech Speedbox). Meine anderen Roco-Lokomotiven haben normalerweise einen CV2-Wert von etwa 20, aber diese neuesten liegen bei etwa 45, was, da ich eine Höchstgeschwindigkeit von 100 km/h fahre, meiner Meinung nach die Geschwindigkeitstabelle zu niedrig eingeengt hat oder beide etwas länger brauchen, um „freizugeben“. " Da sind Getriebe drin. Für jeden Rat wäre ich sehr dankbar. Vielen Dank. Richard.

Update the 79966 has improved with CV56 from default 33 to 63 the 79798 now has lost all drive but still has sound and lights any suggestions ? Other than returning to dealer.

Have you tried to reset the decoder with CV8=8? This should usually bring all CV's to factory default.

Maybe it is enough to check the CV's 9, 56 and 57. Default is usually for Zimo decoders:
CV9=55 (or CV9=0 for MS-decoder)
CV56=55 (or CV56=0 for MS-decoder)
CV57=0 (or something arround CV57=100 to check the principle function)

Usually the Zimo-decoders with default settings of the motor control work quite good with Roco locomotives.

Maybe it is also worth to check the CV5 (maximum speed) and CV6 (middle speed).

Regards

Michael

Hi tried reset procedure several times on the 79798 it did start running once again although very jerky at the beginning then smoothed out ran for approx 30 minutes at half speed before stopping once again (lights and sound still present) and now tried numerous resets all with no improvements. Returning to dealer. Disappointed.