I just recently hooked up my Power Cab and had 3 or 4 shorts caused by a runaway loco that hit other trains so hard that they derailed and shorted out the track. Each time there was a short, the Power Cab screen would fill with X’s and the whole system would shut down. I now want Short circuit protection and I looked into buying a NCE EB3, but I discovered that there is a known problem with using Sound Decoders as mentioned here. http://www.mrrc.com.au/sse-004.htm . I already have a Digitrax PM42 power management board that I bought for a double reverse loop and ended up changing to PSX-AR because of known problems with it when using it for Auto-Reverse. So now back to my question, is the PM42 a good choice short circuit protection and if not what is?
I have used the PM 42 for short circuit protection without any problems for about four years. I divided my layout into 8 power districts and use two PM 42s for short circuit protection on each district.
Thanks Charlie, I noticed a ground wire on the PM 42 instructions that is supposed to be connected to the booster, but Power Cab doesn’t have a ground. Do I need that?
I use a light bulb for short protection when there is a short the bulb light,s up useing the power up preventing damage to the cause of the short.
Maybe I don’t understand it exactly, but doesn’t that add an extra load to the track? I’m already worried about this tiny little power supply that comes with the Power Cab. I have a small fuse panel that I salvaged from something, I guess I could use 1 amp glass fuses, but I do have this PM42 that’s not being used. I just bought a Athearn F45 w/ Tsunami Sound and I got scared when I read about NCE EB3 having trouble with Sound decoders. I know the PM42 is not problem free, but I don’t know if it has sound problems like the EB3.
Johnny, The bulb is wired in series in the feeder or buss When there is a short in that section (block) the bulb will light and prevent the controller from seeing the short and the rest of the layout will continue to run. Using a 1157 tail light bulb and both filaments will give you about 1.5 amps protection if I remember right. There will be little load caused by the light until there is a short or you have a bunch locomotives in the block which will increase the current draw. As current through the light increases the resistance increases and the filaments start to glow. Gary
I’ve read about this before and I even saved some 1157 bulbs for this purpose when I was doing my DC layout, but that was 3 or 4 years ago and I couldn’t remember how to hook it up. I thought I had a diagram some place in my train notes, but I can’t find it. So it is in series with one line. I got to say I’m not comfortable doing this on DCC.
Wow, I just read about Marcus Ammanns experiments and watched Joe Fugates video about it and I’m convinced. I am going to install them everywhere I can without exceeding the limits as Marcus Ammann has set forward with his experiments. This so great that now I wonder why anybody would pay $50 for a power management board. Thanks everybody, I’m now armed and hope not dangerous.
If you ned a DCC circuit breaker, the PSX is probably your best choice. PM4(2) and the NCE breaker are old school. They both work, but still old school. PM42 would would work with your Powercab if it can be set to a lower trip voltage. Out of the bag, its defaulted to 3 amps. Your Powercab would still shut down before the PM42 tripped. While it could be set to as low as 1.5 amps, you would need a Digitrax throttle to change its settings. Light bulbs in series act as current limiters, not circuit breakers. While there are certainly advantages to using the bulbs, you will need to find a different bulb with the Powercab. 1156 and 1157 bulbs will limit the current to 2 to 2.5 amps (depending on the bulb). That's higher than the Powercab"s output so its internal circuit breaker will still trip. An 1156's inrush current will trip a PM42's default 3 amp setting. I've tried in repeatedly with more than one bulb. 1157's are even "hotter" if the brighter brake light element is used. The key to using bulbs as current limiters is to fix the short ASAP. A loco sitting on a fouled turnout with no attention can eventually be damaged. The lit bulb usually gets attention as long as it is located where it can be seen. The bulb also gets hot, so don't have it in contact with any material that would combust. Martin Myers
Hey thank you very much Martin, I was just about to connect the PM42 up, but only because I already had it and I’ve had about 10 short circuits just this weekend. So I guess I’m going to have to put it up for sale, because I don’t think I’m going to be buying a Digitrax system any time soon. I’m learning that there are a lot of disadvantages to the Power Cab that might have swayed my purchase if I had known. I’m very disappointed in the NCE USB adapter and the way it interfaces with Decoder Pro as well as the low current rating. After I get the rest of my layout finished I may have to buy a booster to handle the current. Plus I just found out that it doesn’t work with older decoders like my old Digitrax equipped Atlas GP40-2. And now I find out the 1156 will not work either.
1157 won't work but a smaller bulb would. #97 was suggested. IIRC, that's a side marker light bulb. Same auto parts store, different bulb #. What is the trouble with your Powercab and your GP40-2? It should work. Could just be an errant CV setting. The older Digitrax decoders didn't have a reset CV so getting them back to defaults can be a little harder. It's simple with JMRI. Just bring up the programmer for that Digitrax decoder and "Write all sheets" using the default settings that come up when the programmer is opened. Default on older Digitrax decoders is CV1 is 03 and CV29 is 06. The rest of its CV's are 00. Martin
Well I finally got the GP40-2 to work this morning. It turned out to be a 14/28 speed step issue. baffled: I’ve only had my DCC in operation for a week so I’m not up on the DCC CV settings and I surly don’t know anything about 14/28 step stuff. I guess the NCE can’t handle a 14 step decoder, but anyway that’s history because someone showed me how to change the Decoder to 28 step. I have not tried to use the Decoder Pro yet because I still don’t know what decoder to select in Decoder Pro to see the decoder. It’s a Digitrax DA120 decoder and not supported by Decoder Pro, but that’s another story. I haven’t looked into the #97 yet, but I need to do something soon because I’m have troubles when my locos go through some of my Kato turnouts. I don’t know what is causing the problem but I think something is hitting the Kato frog. err:
I like the light bulbs to and use the CP6 from NCE. Out of the 6 possible districts I use 4. I subscribe to the KISS method, and this fits the bill. Also, I thought the Powercab was limited on the boards that one could use with it. i don't remember the specifics though someone surely knows the limitations.
Select Digitrax Early Decoders from the menu. From the drop down menu, either DH120 or DZ120 will work. Those were the generic wired versions of the DA120 decoder. They have the same CV settings. Martin Myers
There are two choices of bulbs for the CP6. The shipped item has 0.83A (10W) lamps (Osram-Sylvania 6411) with an optional 1.75A (21W) lamp (Osram-Sylvania 6476). The problem faced with electronic breakers is the trip current is generally higher than the rated output of the PowerCab. This is where the CP6 comes into play and is a good relatively inexpensive option. As John puts it - the KISS method.
The CP6 was mentioned earlier, but I thought the CP6 was a fuse panel and I did not want to change a fuse every time I had a short. Now that I know this, I’m going to order one tonight as soon as I get home from work, thanks :thumbs_up: The only problem I had with the car lamps was the installation. I prefer a holder for the bulb.
