Thanks for your reply. I have gone to their website, did find the problem, and have corrected it. The decoder now works as designed.
This is a DIY DCC decoder that was featured in a Garden Railway article. I would suggest you go to their website and review the reader comments and the links to the corrections...
Modeling BNSF and Milwaukee Road in SW Wisconsin
Definitely need more info on what this is. Google hints this may be something for large scale trains, since one hit was Garden Railways magazine?
But in general - are those ICs in sockets or soldered right to the board? If in sockets, swap components. If soldered directly to the board - one of them could have been damaged by excessive heat when soldering. And check for solder bridges between pins, it's VERY easy to get a little too much solder on a pad and have it touch the adjacent pin. Use a magnifier.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
What are these decoders, More info needed.
Jay
C-415 Build: https://imageshack.com/a/tShC/1
Other builds: https://imageshack.com/my/albums
The first one I built works great.
However, after completing the first decoder I have built 2 more and have been unsuccesful in making them work. On the one I just completed I have verified every connection and placement of all components. All match the schematics and diagrams and all match the one that works. I have the 22 volts and the 3.25 volts in all locations. I have cut the trace on JP1 and jumpered trace 3 on JP2.
I have done a comparison voltage reading at various points on the circuit boards between decorder 1 (the working one) and decoder 3. At most points they are identical, the differences are significant lower voltage at pin 3 of J1 and pin 3 of U2; no voltage at M1 and M2; and no voltage at R2.
Are there test points and readings at these point that I can troubleshoot?
Help!