MTH Railking Problem

[Independent Operator]

I received a used MTH Railking Dash 8 Diesal Engine with Proto Sound recently.  These engines from what the manual tells me will work on both AC and DC track power.  DC has limitations where all the bells and whistles won't blow but the diesal sound will work.  I run with a DC 1-22 Volt transformer and the engine runs and the diesal sound works.  Problem I'm having on both of my layouts with it is that the speed will go slow to fast and fast to slow with out me changing the throttle on the transformer.  In the manual there is mention of some kind of speed control when running with AC volts that lets you lock in a constant speed or use throttle control for up and down hills.  I'm wondering if somehow this control is locked in from prior AC use and is now affecting me in my DC use.  I've contacted their customer support people but according to the website they are backlogged in getting out replies.

Any input from the RailKing users here would really be appreciated.  Thanks.

[DMUinCT]

   Do you have enough Power from that Analog DC Power Supply?   The MTH Dash-8 diesels have dual motors, a fan driven Smoke Unit, and a 3 watt sound system.   The speed control should be ON when in DC without DCS Control.

  Try turning OFF the Smoke and Sound, the two "Trim Pots" behind the front door of the "Wide Cab" locomotive.  (left cab door in "Narrow Nose" version) 

   How about dirty track?

   Can you find a Lionel AC Transformer with Bell and Whistle Buttons, or the MTH 75 watt AC Transformer?  (they also make a 100 watt version).    That would let you turn on and off Speed Control, Cab Talk, Bell, Whistle, and Station Announcements already installed in your locomotive.  Of course, if you end up with more MTH locomotives, the DCS System would give you full prototypical control .

   "ProtoSound 1" was sound only, "ProtoSound 2" was designed for "O" gauge (AC) but designed to run on AC or DC. With DCS you put a constance 18-22 volts on the track and transmit a command signal directly to the locomotive that tells it what to do.   It is install in there "O" and "G" scale products. (I run 20 volt DC with the MTH/DCS system)

[Independent Operator]

DMUinCT

   Do you have enough Power from that Analog DC Power Supply?   The MTH Dash-8 diesels have dual motors, a fan driven Smoke Unit, and a 3 watt sound system.   The speed control should be ON when in DC without DCS Control.

  Try turning OFF the Smoke and Sound, the two "Trim Pots" behind the front door of the "Wide Cab" locomotive.  (left cab door in "Narrow Nose" version) 

   How about dirty track?

   Can you find a Lionel AC Transformer with Bell and Whistle Buttons, or the MTH 75 watt AC Transformer?  (they also make a 100 watt version).    That would let you turn on and off Speed Control, Cab Talk, Bell, Whistle, and Station Announcements already installed in your locomotive.  Of course, if you end up with more MTH locomotives, the DCS System would give you full prototypical control .

   "ProtoSound 1" was sound only, "ProtoSound 2" was designed for "O" gauge (AC) but designed to run on AC or DC. With DCS you put a constance 18-22 volts on the track and transmit a command signal directly to the locomotive that tells it what to do.   It is install in there "O" and "G" scale products. (I run 20 volt DC with the MTH/DCS system)

Finally had a chance to get it back on the track because of the weather.  You hit it on the head exactly.  Turned off the smoke and the jerkiness stopped.  I don't do smoke that much anyway.  Thank you.