An mth premier dreyfuss engine is behaving strangely with respect to speed control in command mode. If I move the speed dial from 0 to 1 mph, it starts slowly and then goes automatically up to maximum speed. I cannot change the speed by rotating the remote dial. I can, however, change speed by using the throttle on the z-4000 transformer.

I have tried another engine on the same track--it works perfectly and shows all 10's on signal test.

I have checked the tach (it is the painted on type I believe as this is a relatively new engine) and all stripes are clear and not muddied on the dreyfuss.

2.4v battery seems fine and fully charged.

What could be causing this? I greatly appreciate any help on this.

BTW, I was previously running this engine in conventional mode prior to hooking up the tiu to this track.

Hey Dr. I had the same thing happen to a RS-3. I deleted the engine and started over. Good Luck

For an extra step to *really* start with a clean slate: do a factory reset on the engine.

-- gary ray

I have done a factory reset and re-add engine several times to no avail.

All PS2s will limit their speed to the fastest that the track voltage can support, so the fact it responds to the handles is normal.

The cruise circuit doesn't seem to know that the engine is moving by your description. Boy, that sure sounds like the reader: is it "clear" (i.e., no dirt or debris on the little chip)? Is it close to the tape? Mine are, ah dunno, maybe 1/16 or 1/32 inch from the surface. Finally, the reader itself may be bad.

-- gary ray

Thank you gearbox for your note above.

I have looked at the tach now and find it seems to be in good shape--no smudges or blurry lines. I can move the wheel (is it the flywheel) it is on very easily around a complete revolution. Is that correct or does that indicate the wheel is loose and needs to be somehow tightened?

Also, how do I check to see if the reader (I assume the little thing on top of the wheel--a dime's width away from the wheel) is clean and working properly?

Many thanks for your help.

john l

If your fly wheel on the motor is the correct distance from the tach reader and the tape strip is intact (no smudges, scored lines, etc), you probably have a tach reader problem. If the reader cannot read the stripes on the flywheel, it will takeoff as you described. It could be the tach reader itself, (my first guess), or pinched or loose wires going from the reader to the boards, or the boards themselves have a problem. The tach reader side facing the stripes should be very smooth, if you see any bumps or scratches on the surface, that is probably causing your problem. Any service center can check this out for rather quickly if you have one near by. Hope this helps!

Many thanks Brian.

Yes, I think I need to send this in for checking.

I appreciate your help.

john l

Has the engine ever run correctly before this problem?

quote:

can move the wheel (is it the flywheel) it is on very easily around a complete revolution. Is that correct or does that indicate the wheel is loose and needs to be somehow tightened?

Based on this information, it could be that the flywheel is not securely fastened to the motor shaft. If the wheels do not turn when you turn the flywheel, then it is definitely a loose flywheel.

Barry:

Thank you for your note above.

Yes, this engine worked fine when new about a year and half ago; it developed a short of some kind and would not operate. The DCS worked fine until the short. In June 6, 2008, MTH returned it from service to me. I have just now two days ago taken it out of the return shipping box for the first time as I have had no layout until now.

The first time on the track with DCS a couple days ago, it would not operate and behaved as I have noted in the first post above.

I have spoken today with an MTH service technician who thought it may be the tether. So, he had me read the ohms between the orange, blue and gray wires from the top of the tach reader on the engine to the connection of the board of the tender of these wires. All three connections are good.

So, I imagine it must be the reader problem, and will need to send in to MTH to get repaired. The wheels turn when I turn the flywheel and the painted-on black and white stripes are not blurred or damaged as far as I can tell.

Many thanks for your help on this as I know you are all very busy at York just now.

john l

Dr. John: when you run the loco in conventional does the chuff work as designed? If it doesn't, it could either be the tach reader board or the tether or tether board. I have been having a run on pins on tether boards needing to be resoldered, and have changed a couple of tethers, also. If you could run the loco upside down in a cradle, and wiggle the tether, see if the chuff comes back and the speed control works. I work for an ASC and do MTH repairs if I can be of any help, although there should be someone competent locally, depending on where you live.

Just another thought, if the smoke unit doesn't puff it might also be that the tach reader info isn't getting to the main board.