Model Railroading > Digitrax PM74 power management - Loconet issue

Hi all.

I'm in the process of updating my Digitrax system from a single DCS100 (Super Chief set) to a DCS100 command station and DB210 Booster. The main power supply comes from Digitrax's PS2012, with the wiring done as per the diagrams provided (where the positive from the power supply is connected to the + input on both the command station and the booster, whilst the negative goes to the Ground Return.

The DCS track outputs go to a PM42, which out issue.

I have a NEW PM74 connected to the track outputs from the DB210 Booster. I have three blocks powered up (one spare at present) with the track power coming in. I'm also powering the PM74 with a 12V power supply. This all works fine, but when I follow the instructions and connect a Loconet cable from the command station or the booster, the net light goes off on the command station and or booster, and whilst I can enter "OPS" mode on the PM74, I can't send any instructions as the throttle (to send a close command) does not respond. As soon as I pull the Loconet cables from the PM74, the net light comes back on, and normal operation resumes. I've tested my cables with the Loconet tester, and all are fine. I've tried the different outputs, and different cables, all with the same result. The unit does provide short circuit protection without the Loconet cable connected (so that is good), I just don't have detection or transponding.

Just moments ago I stumbled accross a Youtube clip by Richard Dutch (Clip titled - Digitrax PM74 - Loconet problem (video #25). This video displays similar behavour to what my set up is doing.

Does anyone have any other experience with a PM74 and similar issues with Loconet dropping out when connected?

Down here in NZ, it's going to be a little difficult to send back to the states for a warranty repair. I can try the retailer I purchased the unit from, but keen to hear what others have experienced.

Many thanks in advance.

Regards,

Allister
New Zealand.

I have had this problem before with various Digitrax devices.  Right now, my BXPA1 and my PM74 are disconnected from the loconet because of the issues you describe.  I have had this happen with a SE8C and a UP5 also.  There is no solution (that I know) other than to replace the device and send it back to Digitrax.  I have spares on most of my devices for things like this, because there is about a 3 month turnaround on Digitrax repairs.  Fortunately, I don't really need the loconet connection for my BXPA1 and PM74, so I just live without it.  They still work just fine in their primary function as power control/reverse loop management.