DCS / Conventional vs. Command mode.

Glenn,

The problem most likely isn't with DCS, rather, it's almost certainly with the engine.

Most likely culprits are a damaged tach reader or striped timing tape, or too wide a gap between the tach reader and the stripes. If it's a steamer, a loose or damaged tether is another possibility.

The engine is a 4-6-4 GS-4, MTH # 30-1526-1E

The tether looks as good as the day I got it. The encoder timing tape is intact. The gap between the tach reader and the stripes is about 0.050"

I did the trouble shooting steps that I found on the MTH website. Sounds like a new tach board is the needed repair.

Is there any other problem that might be the cause?

Can I purchase a new tach board or do I need to take it to an authorized repair center?

-Glenn

Glenn,

I suggest that you call MTH tech support and discuss the problem with a tech.

Carefully check the 3-wires right where they attach to the tach board. I recall one board where only upon close inspection did I see that the strands of a single wire had all snapped loose and that wire was not making contact. Another case had a single strand from one wire touching one of the other joints. Presumably you also checked the harness wiring for breaks.

Another case had an oil or grease spot right on one of the two black shiny rectangular "windows" on the tach reader part. Easy to clean off but only obvious after close inspection.

Presumably when the engine takes off, there is NO chuffing. There is a very slim chance that the motor control circuitry broke in a way that it can only provide full power to the motor. If such were the case you would hear machine gun rate chuffing and the tach is working.

And in a parallel universe, there's an even slimmer chance (laugh if you wish) that when the motor control turns on, this somehow messes up tach operation. So with the engine stopped and no bright lights on the tach, manually turn the flywheel. Assuming your engine is set to 4 chuffs/revolution, after the driver wheel turns 90 degrees and every 1/4 turn later you would hear a chuff.

Glenn,

Does the engine work properly if operated with the boiler off? If so, there's a good chance that one of the motor wires is shorting to the boiler.

New to the site,but i must confess the amout of dcs knowledge is overwhelming you guys and gals rock.Sovled my run away train thnaks.