Help Mth....

I've seen alot but never seen this. What's strange is it does it in the same places on the track each time it goes around. Mark your track where it does it then swap your track pieces around to a different location and see if it does it on the same track pieces.

Make certain that the tether is securely plugged-in. If it's loose, the turn may be causing it to momentarily lose contact, such that the PS2 board does not "see" the output of the tach reader,

If it is secretly plugged-in, there could be a broken connection in a tether wire or a bad solder joint on the tether plug, either in the engine or in the tender.

I think the engine is briefly losing power at some spot .   Loose tether?  Do you need another lock on? dirty track?

We've all had a proto-2 stall briefly and then we  give it a push. It wants to take off before settling down to normal speed.

Barry Broskowitz posted:

Make certain that the tether is securely plugged-in. If it's loose, the turn may be causing it to momentarily lose contact, such that the PS2 board does not "see" the output of the tach reader,

If it is secretly plugged-in, there could be a broken connection in a tether wire or a bad solder joint on the tether plug, either in the engine or in the tender.

Im sure it has something to do with that, I opened the tender and ran it like that. and I think there are a few wire loose, also I think theres a wire thats shorting, because all the lights flicker on it.

It does it on my layout to, it starting doing this the day before christmas, i tihnk its wires or the board

Probably not the board. This seems to have a mechanical component - that is, the tether as mentioned above. Could be the plug-in situation, or almost-broken wires. Also as mentioned.

These locos are built like diesels - 2 swiveling trucks with 1 motor each that imitates an articulated, but enables it to take tight curves. Your speed control sensor and tape are on one of the vertical motors, on the flywheel. If this sensor or motor is loose, the physical turning of the truck/motor could be dislodging the sensor briefly. This is probably not it (I vote for the tether), but it is easy to investigate. 6 - I think - boiler shell screws and it should come off. Take a look around that tach-tape motor - anything pertinent feel loose? (Gently.)

In fact, look around a bit; get familiar with it under the hood.   

 It seems to do it after exiting the corner. I'd go with Barry on the solder joint on one of the tether boards. It seems as long as it's turning left there is enough of a strain on the joint to keep the connection. As soon as the engine straightens out. The strain on the tether moves the pin slightly on the board until it settles back down and runs smooth again.

 Have tried running it in the opposite direction ?  If so what was the result.

Dave_C posted:

 It seems to do it after exiting the corner. I'd go with Barry on the solder joint on one of the tether boards. It seems as long as it's turning left there is enough of a strain on the joint to keep the connection. As soon as the engine straightens out. The strain on the tether moves the pin slightly on the board until it settles back down and runs smooth again.

 Have tried running it in the opposite direction ?  If so what was the result.

It ran OK, but I didnt run it for long, there is a micro scopic tear in the tether, so that might be it.

Replace tether and make sure no broken solder joints at the PCB on engine that tether plugs into. G