The connecting cable

The connecting cable has several issues. Applying the pins to flexible 6 conductor Telco style wire results in a cable that has a high failure rate. The stranded wire is simply so fragile that a small nick while stripping caused some of the strands to break off making the connection more fragile. I wound up using a fairly expensive stripping tool to avoid nicking the conductors. This fixed that problem.

The socket pins are tiny and difficult to apply to the wire with my large hands, I should probably find a 6 to 10 year old to work with them - on second thought maybe a 14 year old would be better because they could do the crimping as well. I initially was soldering them on but that makes the wire more likely to fracture when installing it in the field and one bad wire makes the board not function properly. So I bought a special crimping tool to apply the pins to the cable. The small gauge wire turns out not to have the strength to resist the handling forces when the cable is tugged on. I found that folding the conductors over the sheath and then crimping improved that situation but I still have too many fails making the cables.

I am still trying different wire to improve the durability of the cable. My latest attempt is a wire of a larger gauge but the flexibility is now somewhat of an issue. The wire has to be long enough to be able to come out of the head a few inches but needs to be short enough to not have a lot of surplus that needs to be in the base box.

The existing LB (head box) has to be modified

The existing LB (head box) has to be modified so the connecting cable can comfortably connect to the board. The LBs are from different manufacturers and are in two basic styles one is made with rounded ends and the other is square ended. I decided to remove the square ended boxes and install rounded boxes at all locations as we go along replacing the old signals when they fail. Progress has been slowed because Richard likes to repair the old boards and not update them,

First the box has to be restored to its original depth so I use the radial arm saw in the shop to slice off the extension that was glued onto the box before.

Next the feed hole needs to be reamed at an angle using a Unibit to make it easier to connect the board and slide it into the head for use. I had moved the location of the connector on the circuit board in the final design to the rear side of the bottom of the board to minimize this need but it turns out that it is still necessary.

Further changes

Since we started using the boards, I decided to remove the transistor socket pins and the LED socket pins. The reliability of the boards have made the need to be able to unplug these components unnecessary. I left the IC socketed because it turns out that it is the only component to fail from time to time so it can be field replaced easily.

Part of the reason to remove them is that the pins were difficult for me to solder onto the board. I did decide to socket the MOVs onto the board as they can be easily replaced in the field when they have been damaged by lightning from storms. I also got the club to get grounding rods and they were installed around the property so we could ground the track common rail. This made a major change in the failure rate of the signals. We also tried MOVs in the signal base boxes, at Tommy's suggestion, to short circuit any disturbances before they got to the signal head. This helps with the reliability as well but when they short they cause the signal head to do strange stuff. We decided to remove them because of the strange stuff but it turned out to be the lack of the ground that caused them to short out in the first place so we reversed ourselves and put them back in the base boxes.