Voltage Drop Problem

["Ira Schneider" <ira_schneider@iname.com>]

Jim's note about the voltage drop problem has one major flaw - we don't know what is causing the problem
and we are just trying anything we can think of to solve it.

We currently have three ways for the power to flow around the layout:

1. The track pins connect each adjacent track section - the power should flow through them
2. Adjacent track sections, except for the bridge track, are soldered together - the power should flow through
the solder
3. There are cables running all around the layout, connected to the track in each module - the power should
flow through the cables, powering all tracks evenly
4. We have a jumper cable from the powered corner to the opposite corner - the power should start evenly
at each of these corners

Even with this redundancy, we have severe power problems. At the last two events, we have seen
entire sections of the layout where our trains slow down. This implies that the power is low in these
sections. The "low power" section seems to include one of the non-powered corners and several modules
next to it.

We don't have the time or resources to analyze this problem at a train show. We need to schedule a work
day (and I mean an entire day) to set up the layout, using all of the modules (or all of the modules in two
shifts), run some engine(s) on the layout, identify where the power drop is, and determine what is
causing the power drop. We can't fix the problem if we don't know the source.

I can speculate as well as the rest of us. But, this won't help us solve the problem.

Jim's suggestions include:

1. Resolder all track joints - Solder itself is not a very good conductor of electricity. It is really intended to
hold conductors together, not improve conductivity. Any "to do" articles I have read about soldering
always state something like "make a strong mechanical connection before soldering - don't expect the
solder to provide strength."
2. Add 1" of copper wire across the joints of any track which doesn't have 3 rails soldered - This should
be done to all joints. We should probably use around 18 gauge stranded wire.
3. Replace the track pins at all junctions where all three solder connections are broken - This sounds to
me to be a waste of time. If there is a wire soldered between the adjacent wires, it will carry the power.
The track pins would only be relied upon for mechanical stability, and old track pins will work just as
well as new ones.
4. Resolder the connections bring power to the tracks - There are two ends to the wire. If we were to
resolder the connections we have to resolder both the connections at the tracks and the connections
to the cables going across the modules.

All of Jim's suggestions make sense as guidelines for constructing new modules if we continue to use
sections of 10" track. If we change our guidelines to use single 38" track sections on new modules
(which makes sense to me), these suggestions are a moot point.

We need to analyze what is going on before we try to implement any of Jim's suggestions on a large scale.

In thinking about the problem, we had several contiguous modules (including one corner) that showed
what appears to be a voltage drop. Either the soldered joints, the connecting cables, or the corner
jumper cables should have isolated the problem to a single module. Since it didn't, it looks like the
power is being blocked, at the same points, by both a failure of the track pins to carry the current and
the cables to carry the power across the modules. This doesn't make any sense to me. I know when
I first joined the club and brought my new module to the first run we found that I had wired the connectors
backwards. Adrian's solution was to not connect the cables to my module. This means we had an
absolute break in the loop of cable going around the layout. Nobody noticed any power problems
during that run. That tells me that breaking the cable (i.e. a high resistance connection at the Jones plugs
or cold solder joints) wouldn't necessarily cause the problems we are seeing.

I am suspicious that we have a power leak in one of the modules, which is causing a power loss
spread across several modules. This leak could be a partial short in one of the cables or a bad
insulator on the center rail of one of the tracks. Of course, since the problem seems to go across
several tracks, this may not be the problem either. Again, we have to assemble the layout, identify
the affected modules, isolate these modules, and run resistance and voltage tests on the modules
to find out what is causing the problem. Once we know what is causing the problem we can determine
how to fix it and prevent it from happening again.

Ira