The Dx5e is a nice inexpensive 2.4 GHz spread spectrum radio that has seen major acceptance in both the model airplane and model train communities. I purchased one several years ago to control my live steam loco and over the last few years have used it for battery powered locos and trail cars along with Del Taparo’s RailBoss R/C system.
My radio performed great for several years. Soon after building my first trail car I started experiencing loss of signal at the receiver even when the transmitter was in close proximity. It appeared to be some sort of intermittent connection because tapping on the case would often restore the link. A search of the net found this to be a fairly common problem with several suggested fixes. When the problem happens the battery indicator stays lit while the radio link to the receiver is lost just as if the radio was turned off.
You can’t always believe what you read on the net 
The descriptions and video documentation of the problem are accurate, but the fixes are full of mis-information and don’t address the problem at all.
Myth #1 - There are two separate circuits in the switch; one for the indicators and one for the transmitter section
Myth #2 - The problem is the switch
Myth #3 - Replacing the switch by wiring a new one around it will solve the problem.
At first I had no reason to not believe the myths. They seemed logical since switching the power on and off or banging on the case in the area of the switch would cause the receiver to link up. I opened up my radio and didn’t like the look of the solder on the switch leads, so I heated them up and flowed a tiny bit of fresh solder on them. A quick test with the case open made it appear like this was the fix, so I closed up the case. The radio functioned correctly for several weeks so I figured I had solved the problem.
I figured wrong. The problem came back. Only once in a while at first, but more often recently. It happened to us at Bob’s TrainOps session. Fortunately the loco was stopped when the link was lost because the RailBoss will continue doing what it was last commanded to do when the radio is turned off. This is a nice feature when you intentionally shut off the radio, but a bit scary when your loco is headed down the tracks to a collision when the link is lost.
Still believing it was the switch I planned on wiring a new one around it and opened up the case tonight to start the process. Before following net advice to create solder bridge shorts on the existing switch I decided to do a little investigating by following the traces connected to the switch. Fortunately this is a single layer board and quite easy to trace with magnification.
I immediately disproved Myth #1. True it is a Dual Pole / Dual Throw switch, but it only selects both poles of the battery pack between the circuit board (ON) and the charge jack (OFF ).
By disproving the two circuit myth, it also ruled out the switch as the problem. If the battery indicator lights are lit, the switch is passing power. If the switch isn’t the problem, replacing or wiring around it isn’t going to fix anything.
So now, having disproved all the fixes posted on the net I’m on my own. I donned my Optivisor and started looking closely at every solder joint. I found only one joint that wasn’t shiny. It was located where a jumper was tied into what probably is the logic chip. The other end of the jumper leads directly to the transmitter module. This is a pretty good candidate for the problem. I heated the joint and added a bit of solder. A quick test with the case open proved I didn’t break anything, so I buttoned up the case.
I ran trains for about 2 hours after the fix never loosing control once. I’m hopeful that this is the fix, but only time will tell.
While I was buttoning up, I decided to add some insulation under the two long crews that support the switch. They could possibly bridge two traces. I have no evidence that this is a problem, but it only took a few seconds to add some self-adhesive vinyl under the screws.
Keeping fingers crossed
