Seeing as how I’m sort of “between projects” right now (waiting on parts for 3 projects!), I decided to try to repair my LionChief Polar Express PCB. This board came in a 1225 I bought thru the Bay as parts only, and I found that the board worked, but VERY intermittently. So intermittently, that most of the time it just didn’t work. When it did work, everything worked - when it didn’t work, the Universal controller acted as though it had lost the signal.
The board
So a closer examination showed just 3 possibilities for parts replacements, a 16.0Mhz crystal (lower left corner on the receiver board) and a couple of electrolytic caps (lower right corner on the main board), all parts that were available from Digikey. I replaced them this evening and found … no change. I previously had reheated/reflowed all accessible connections with a VERY fine point on my soldering pencil, also with no change.
So in one last desperate measure, I applied the finger test – this is a test where you stick your finger everywhere, mostly to see if a part is getting hot – judicious application is required under those circumstances. But it also can reveal other things. In doing this, I noticed that when my finger got closer to the little black glob on the receiver board, things started to stabilize. If I rested my finger on the black blob, I had a steady signal 100% of the time. Hmmm, a crude RF link… So I looked for a broken antenna connection – apparently they are using the little zig-zag foil section of this board as the actual antenna – appears like a 2.4Ghz type of signal must be used to have an antenna of this style. Two SMD caps are feeding this antenna – I reheated the connections at this point … no change. So as a last desperate act, I soldered a 6” wire to the last cap … BOOM! Not only is the signal reliable without the help of my finger, but now I can even walk into my garage to control my train in the basement (frankly not what I was trying to accomplish) – previous best range was about 10ft.
The fix
So I guess even a blind squirrel finds a nut now and again. For just a couple of dollars in parts that I didn’t need, and a little time, I have regained the use of a now redundant PE 1225 board – yeah, I bought a new PCB back in January and fixed the engine right up. So I’m guessing this one may find a home in a slope back tender behind a 1615 or a 1662 switcher, or maybe a 2018! Hmmm, or maybe behind an engine with a DC motor - almost forgot! I just have to remember to NOT push the crew talk button, lest Tom Hanks speaketh out awkwardly.
Just thought I would share – never know who might have a similar problem … plus I was tickled pink to have repaired it!
George
