Initial Load at Elite Power Up

[St1ngr4y]

Here's a question for the electronics experts out there...
For quite a while I have successfully used a slightly out-of-the ordinary setup. I have an Elite controller, a power booster module, and two buses around my layout. The first bus is connected to the track output terminals of the Elite and is used solely for my accessory decoders - 4 ADS8s, 2 ADS2-FXs and 1 R8247. The second bus connects to the track outputs of the power booster, which in turn is connected to the Elite's power boost terminals.
A week or so ago, the track bus went dead. There seemed to be no power from the Elite to the Power Booster, but the Elite's track output to my accessory bus was working ok. I decided to invest in a RJ12 cable, to connect the Elite to the Power Booster using the Xpressnet sockets on each. However, this did not work either. The only thing left to try before sending the Elite back to Hornby to see if it is repairable, was to join both buses together (in parallel), without using the Power Booster at all. Having done that, as soon as the Elite is powered up, the red error light comes on. At first I thought there must be a short somewhere, but I tried each bus individually using the Elite track outputs, and each worked ok. So my next thought was that maybe the initial load may be too much for the Elite to handle in one go. So I connected up only the accessory bus and switched on the Elite, then I manually joined the two wires of the track bus, and that, too, stayed on without tripping the Elite. I have since installed a push-to-break switch on the track bus so that I can hold this down while powering up the Elite, then release it once the Elite has fully booted. This seems to work fine. It is also useful if I get a short during running, because I can hold in this button, reset the Elite, switch points if they were to blame for the short, then release the button.
After all of that, my questions are simple - is it because of the sudden load of a dozen DCC locos on the track + 20 or so Traintech signals + the accessory decoders I mentioned earlier, which is causing the Elite to trip? Also, am I risking anything running the way it is at the moment i.e. connecting each bus seperately?

Ray

[Flashbang]

Hi

I think you have somewhat answered your own question!... The tripping is caused by all the CDU capacitors all charging at once and demanding a high in rush current that exceeds the Elites 3.0Amp track output. (1.0Amp is reserved for the 15v DC output of the 4.0Amp total)  

 Fitting an On/Off switch or using a press to open PB will overcome the issue.

[St1ngr4y]

Ok - thanks for that, I just needed reassurance.

Ray

[96RAF]

From memory the Elite itself only burns about 280mA so in a no load situation at startup it must be your peripherals that are loading the output and causing the trip, but I would be surprised if you are overloading a 4-Amp PSU, so it must be the 3-Amp Track output of the Elite being swamped per Flashbang's theory.

 

Also from memory there are three ways of connecting a booster module to the Elite, but I don't have the manual handy to state them here. Not that either would have additional loading capacity over any other.

[Fishmanoz]

Just for record purposes, the 3 ways of connecting the booster are:

 

-  Using the Xpressnet connections with the correct RJ12 cable from Elite to booster

 

-  Using the boost output of the Elite connected to the boost input of the booster

 

-  Using the track output of the Elite to connect to the boost input of the booster

 

Ray, when it first went faulty, had you changed the things connected to track or booster output such that either was seeing a higher load on startup?

 

Irrespctive, when looking for something that might be faulty, it seems to me the booster may be.  What happens if you disconnect the accessory bus from the Elite and fire it up with the booster connected?  Do the locos work or do have either an overload or just no power to the track?  You certainly shouldn't have an overload on the Elite as input power to the booster should be low.  If the Elite is showing overload, then that points to the booster.  Anyway, tell us what applies. 

[Fishmanoz]

I too am sceptical like RAF, that what you have connected on track and accessory buses will be enough to cause the overload if everything is working as it should.  Although I'm not going to discount it outright.  But I would try disconnecting accessory decoders one at a time in turn to see if one of them is now drawing more than previously.  You could also try fewer locos on the track. The problem is that, if the load is only just over tripping point, then removing anything, even working correctly, may be enough to get the current bsck in spec.

 

If if there isn't anything obvious that when disconnected leads to startup without overload, then maybe initial current is too much and your push button switch is your only solution.

 

Then one final thing to try. Connect both buses and start up using your switch.  Now shut down and restart straight away, so hopefully the CDUs won't have had time to discharge.  Will it start without overload the second time?