I have been running my LTI American Flyer Trains with a post war ZW transformer. I had a derailment with a short and the engine began jump starting when the throttle is just barely opened, so much that its impossible to couple cars without crashing into them. So I replaced the E unit, the engine was able to “creep” at low speeds again, then a short happened again and it started all over again. I began to take an inventory of my other LTI engines and noticed they too had this jump start issue (Alco’s and my EP-5). Is there a simple resistor that is malfunctioning here? How can I eliminate this without replacing an E unit only to watch another engine bite the dust. Should I look at running them in D.C.? I am really at the end of my rope on this one any help would be appreciated.
Thanks
Have you tried using a Lionel CW-80 for the new American Flyer by Lionel? Before going to DC try a new transformer, post war transformers start out at six volts or better, modern transformers use lower starting voltages and have better circuit breakers to keep from frying modern electronics.
Lee F.
Lee,
Thanks for the reply, the CW-80 is a good tranformer, unfortunately I am still having the same problems with no matter what transformer (AC at this point) I use. I fear one or more of the resistors is being fried during a short? not sure, I am going to disassemble a board and take a closer look. I wish I had a scope or VOM… hmm any Ideas guys as fars as what tools I should use to root cause?
A short circuit per se can’t harm your locomotive, since there is zero voltage across the track during the time the short circuit exists. What likely harmed your locomotive was an inductive voltage spike when the short circuit cleared. The short circuit probably happened and cleared many times during what appeared to be a single mishap, producing numerous voltage spikes in the hundred-volt or more range. I doubt that a resistor could be harmed by this; but semiconductors can be very vulnerable to such high voltages.
The best protection against this kind of problem (I will say it again) is a transient voltage suppressor. You can find part numbers and ratings discussed many times in older topics.
You might find the problem by reverse engineering the board. But, if there is any kind of proprietary semiconductor device on there, you won’t get very far. My advice is to just replace the thing and try to protect against another occurrence.
Bob,
Thanks for the reply, today I ran the locomotive in DC and it runs fine, so I am assuming that something has gone wrong with the AC circuit logic of the chip. I have a circuit protector from lionel hooked up at the transformer. this did not save the voltage spike as I agree a short would not cause a resistor to burn up. Hmm a voltage suppressor. I will research this.
Speaking of reverse engineering, I measured the input of the voltage at the tranformer was at 3 volts, I was getting 6 to 7 volts at the output of the circuit board to motors. when the transformer was at 6 volts the output at the circuit board was 12v. at 12 to 16v I was getting 24 volts! So as a quick fix instead of having the motors wired in parellel, I cut 2 feeds and wired them in series… and what do you know it worked… for some reason the damage to the logic chip caused the voltage to be amplified by 2, well needless to say I was back in business this morning and I can get the loco to creep again… but I really would like to understand what a voltage suppressor does to eliminate future damage.
Thanks,
John C.
Bob,
Thanks for the info, is this something Lionel sells already that can be purchased? Or is this a custom circuit that needs to be made?
It’s just a single 2-leaded component that you wire in parallel with the track voltage. You can get them from various electronics distributors. The Mouser part number of a suitable TVS is 625-1.5KE36CA-E3:
http://www.mouser.com/index.cfm?handler=home