I am sorry for the delay in reporting back. I did my testing on Monday and then on Tuesday I ran in to a problem accessing my Web Browser. Today it is working correctly so here is my report on my testing.
Here is what I experienced today (Monday). As I said I have the sister Locomotive to my problem child. I removed both boiler Shells from 1361, my Problem Child, and 3876, which appears to be working correctly. I got my meter out and here is what I discovered. As you are probably aware the "Run/Prog" switch is a single pole double throw (SPDT) switch. As I surmised the center lead on the switch goes to case ground. Each engine registered Zero ohms when one lead on the center lead and with the other lead on a screw attaching a wire to the chassis, hence continuity. Also noted was that the lead comported to be the "RUN" lead has no wire soldered to it.
When the switch is moved to "Program Mode" on both Locomotives testing for continuity/opens began. Chassis Gnd/Center Lead to Program lead showed Zero Ohms and continuity. "Program Lead" (meaning the lead on the side of the Label "PROG") to the Center Lead (Case Gnd) a reading of Zero ohms was recorded. This made sense to me. As usually this indication to the circuitry of a Gnd condition means this function is active. "Run Lead" (meaning the lead on the side of the switch Label "RUN") to the Center Lead (Case Gnd) a reading of Open was recorded. This made sense to me, as I would assume that there is no electrical path between the two as the switch is not making an electrical path between the two.
I then moved the switch to "RUN Mode" on both Locomotives but this time I made different readings between the two engines. Chassis Gnd/Center Lead to Program lead showed 50K Ohms on both Locomotives. I do not know what to make of this reading unless I was reading circuitry in the electronics and it did make sense to me after thinking about it. "Program Lead" (meaning the lead on the side of the switch Labeled "PROG") to the Center Lead (Case Gnd) a reading of Zero ohms was recorded on Locomotive 1361. This does not make sense to me as the switch should not be providing an electrical path between the leads. When making the same measurement on Locomotive 3876 a very high, 5 Megohms, was recorded. This is close to an Open but does show some leakage. "Run Lead" (meaning the lead on the side of the Label "RUN") to the Center Lead (Case Gnd) a reading of 0 ohms was recorded. This made sense to me, as the switch is making an electrical path between the two leads.
FINDINGS
If I am correct, this analysis would demonstrate that the switch on Locomotive 1361 is defective. Even with the switch in the "RUN Mode" there was a short between the Center lead and the Program Lead. In my mind this should have demonstrated an "OPEN". I am somewhat concerned regarding Locomotive 3876. I would have surmised a definite Open should have been recorded when the switch is in "RUN Mode" between the Center lead and the Program Lead. Could this High reading still be interpreted by the circuitry as an open?
I would appreciate your critic of my methods or my findings. Thank-you for your review.
