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DCC Specialties PSX & PSX-AR Manual Reset

Posted by on Jan 30, 2017 in Tony's Tips |

Buy PSX and PSX-AR


The PSX series of power controllers has two reset modes: manual and automatic. By default, the units are shipped with the reset mode set to automatic. In this mode, the unit will trip when shorted, but try every two seconds to reset. When a PSX resets (turns on), it will trip if the fault is still present or remain on if the fault has cleared. While this is the most convenient mode, it may not work well on your layout depending on your wiring, your boosters, number of power districts, etc.

Assume a solid short on your layout. The PSX trips essentially instantly (< 1ms). After two seconds, the PSX turns its output back on (default automatic reset mode). If the fault is gone, all is good. However, if the fault is still present, then when the PSX turns on, the short is placed across its input terminals and consequently across the terminals of the booster, causing the booster voltage output to drop. Depending on your wiring, how bad the short is, etc. this drop may be only a volt or so (not a problem) or might be almost to zero volts (big problem). Whatever the booster does at this point is seen by all power districts. If the booster voltage drops significantly, then you will see this drop in all connected power districts. While this condition does not last very long, it can cause headlights to flash or other annoying effects. Some boosters, when repeatedly exposed to this situation (multiple reset tries), will eventually trip, shutting down all connected districts. The solution for this situation is to use the manual mode.

In the manual mode, the PSX will trip (< 1ms), but will not try to reset itself. Once the PSX has tripped, the faulted power district is isolated. Since the PSX does not try to reset, the booster remains operating normally and the remaining power districts see no adverse effects from the short. Once the fault is cleared, the PSX can be reset (see below).

The manual reset mode is enabled by installing a jumper from J7-1 to J7-2. Opening this jumper will reset the PSX. If you use a normally closed push button switch in series with the jumper wire, then you can reset the PSX simply by pushing the button once you have fixed the problem. Buy push button here.dsp_psx_reset_switch

If you use a push button lit with an LED, connect the LED + to J5-1 (PSX) or J5-4 (PSX-AR) and the LED – to J5-2 (PSX) or J5-3 (PSX-AR). When the breaker trips, the LED will light indicating a fault. Pushing the button will reset the breaker and turn off the fault light (assuming you fixed the problem). You can also use your throttle to reset the PSX. Just send an Accessory (Switch) ON command to accessory (switch) address 2042 (default). If you have a Digitrax system, install the Digitrax configuration jumper (J7-3 to J7-4 – you should do this in any case), move the program jumper to program, turn on the PSX, wait for the LED to stop flashing, turn off the PSX, and return the program jumper to normal. This will set the default address to 997. SWCH commands at SWCH address 997 will now turn the PSX ON (c) and OFF (t). Of course, you can change this address to anything you want. You can keep all of the PSX units at the same address if you want so that there is a single command used to reset any tripped breaker.