Up in a puff of smoke!

Well after lots of hours of automatic control the system of Yeovil Town failed.  We tried swapping out the ZTC controllers, the Power Booster, the leads etc. and could not track it down.  There seemed to be a short somewhere and it was drawing about 2 amps. 

Eventually the both power boosters broke but we found the cullprit...  It was a Capacitor Discharge Unit (CDU) that had burnt out!  I resolved to try and fix the power boosters so the following weekend I stripped them both down.

Both were the same issue PCB but one had a link on the supply line and the other had a surface mount fuse.  I concluded that this must have been a problem in the past so copied the the other Power Booster and linked it out.  Hey Presto we have now have a working Power Booster... The other one will take longer to fix as I think it's the Comms bus that is broke - I will need to swap out a couple of chips for this.

Next Wednesday we should see the layout up and running again (CDU has been replaced).

The rest of my time has been spent developing the MIMIC and we have found that the MERG decoder sinks the output when we needed it to source the output for the Bi-Coloured LEDs.  Rattling the little grey cells came up with a solution which is to use the decoders outputs in independent mode thus giving us 8 outputs per decoder (for less than a tenner!) and use a relay to switch power to the LEDs.  With the parts on order both MIMICS should now be up and running by Christmas.  A short footnote here: 1 relay = 30mA, 2 LEDs = 25mA so each way has about 55mA draw, multiply this by 24 for each MIMIC and we have nearly 1.5 Amps per MIMIC - Me thinks we need a separate PSU to power these so that the Points motor operations will not dim the lights!