# DCS51/PM42, separate issues



## brendang2000 (May 18, 2018)

Hello All,
I’m having some Digitrax woes. My 4x8 N scale layout is still in the building stages, I have track laid out and now working on wiring. I have an older Digitrax system that doesn’t seem to work correctly and also a new PM42 that doesn’t seem to work correctly either. I’ll list the issues separately as they aren’t connected.

First, I have a DCS51 that seems to have an issue sending throttle speed commands. I have a small N scale layout with three locos, a Bachmann Spectrum factory equipped DCC, a Bachmann w/DZ126 decoder installed by me and an Atlas with factory equipped NCE N12A2. The only unit that moves every time I tell it to is the Spectrum. Most of the time, the DZ126 and Atlas units will not move when commanded to. I have control of these units though as the light with turn on and off when commanded, and light will switch with direction of travel lever. They just won’t move. I thought maybe the DZ126 loco was bad, as it’s not an expensive unit, but the Atlas unit is brand new and behaves the same way. The first time I tried the Atlas it didn’t move, but I left it powered on with throttle set to forward full. After about 5 minutes it started moving. I shut down the power, powered it back up and it would no longer move. After about 5 minutes, it starts moving again. The DZ126, I can hardly get it to move at all. Sometimes it will go, but mostly I can just turn the lights on and off. I’m confident my decoder is installed ok, and since this isn’t the only loco that shows this kind of behavior I think the decoder is good. Anybody see this kind of behavior before? This DCS51 has always been suspect to me. I was messing with HO scale years ago, a small circle setup, and I could not get a TCS decoder to move either. Next issue.

I think my PM42 is not working correctly. When any district has a fault, it trips all districts and shuts down the booster. I’ve gone as far as disconnecting all leads to my layout and any district will still shut down the booster. I’ve triple checked that my wiring is correct, there is no continuity between solder joints on the 44 pin connector or between districts on my layout. Any thoughts here? 

Thanks for any input/thoughts, and if I’m just plain doing something wrong, please let me know! Brendan


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## mopac (Feb 24, 2011)

Just throwing this out. May help or not. But it did fix my digitrax problem with a DCS200.
It was acting goofy. I don't know if a DCS51 has an internal battery. If it does, pull the battery for about 5 minutes and reinstall. Of coarse with no power to the unit. Pulling
the battery does a complete reset. Puts everything back to what it was brand new out of box. It really did fix my digitrax. I have a PM42 but have not used it. No help here.


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## brendang2000 (May 18, 2018)

mopac said:


> Just throwing this out. May help or not. But it did fix my digitrax problem with a DCS200.
> It was acting goofy. I don't know if a DCS51 has an internal battery. If it does, pull the battery for about 5 minutes and reinstall. Of coarse with no power to the unit. Pulling
> the battery does a complete reset. Puts everything back to what it was brand new out of box. It really did fix my digitrax. I have a PM42 but have not used it. No help here.


Thanks for the reply. The Zepher has no accessible battery, no way to get into the unit at all actually. I'm guessing the screws may be behind the rubber feet. I did a factory reset via program, switch, 39, CV-WR though. It didn't help. Oddly enough, the locos are running great right now, except the Spectrum which is in runaway mode and I have no control of it! So the one that did work no longer works and the ones that didn't work now work. If there was a Simile for _frustrated_ I would have put that here


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## Mark VerMurlen (Aug 15, 2015)

Regarding the PM42 not isolating shorts in one district, you should read the Digitrax Tech Note at http://www.digitrax.com/tsd/KB988/using-pm42-with-zephyrdcs50/. This might be your problem.

Mark


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## brendang2000 (May 18, 2018)

Mark VerMurlen said:


> Regarding the PM42 not isolating shorts in one district, you should read the Digitrax Tech Note at http://www.digitrax.com/tsd/KB988/using-pm42-with-zephyrdcs50/. This might be your problem.
> 
> Mark


Thanks Mark! That describes exactly what is going on with my DCS51/PM42. I did like the tech note said, but this did not fix the problem; any section with a fault will still shut down the DCS51. I’m starting to suspect that maybe this power issues stems from the DCS51. Maybe it is not outputting enough current, at lest it seems maybe under 1.5 amps. Maybe if there wasn’t enough current, I’d be able to control the locos light, but not be able to make it move?

As a test, I disconnected the DCS51 from my layout, connected the Rail A&B outputs to a single piece of flex (30”) and tried to get the locos to move one at a time. The DZ126 failed to move, but I was able to control its lights. The Atlas I did have control the second time I tested it, the first time it failed to move but I was able to control the lights. I had control of the Spectrum. One note about the Atlas, when it moves, I need to give it at least 50% throttle before it will even begin to move. Not sure if this can be fixed in the CVs, or if it’s also an indication I don’t have enough current. But until I can get a reliable system, I’m keeping the decoders as close to factory as possible. I've opened a ticket with Digitrax, maybe they'll have some input too. Thanks again!! Brendan


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## brendang2000 (May 18, 2018)

I did the voltage test on the DCS51 that Digitrax instructs on how to do, http://www.digitrax.com/tsd/KB909/track-voltage-measurement-on-dcc-layouts-with-dire/ and it was within spec. Although current could still be low. I was only getting 5vAC at the track, isn't this low?


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## mopac (Feb 24, 2011)

5 VAC is low. Should be around 14 VAC. Unhook the wires at the terminals on the
DCS51. Get a reading at the terminals. If it is around 14 VAC and only getting 5VAC
at the track, problem is somewhere in between. Use large enough wire to track. Check
connections at both ends of wires. Let us know what you find out.


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## brendang2000 (May 18, 2018)

mopac said:


> 5 VAC is low. Should be around 14 VAC. Unhook the wires at the terminals on the
> DCS51. Get a reading at the terminals. If it is around 14 VAC and only getting 5VAC
> at the track, problem is somewhere in between. Use large enough wire to track. Check
> connections at both ends of wires. Let us know what you find out.


That test was on the single piece of flex, but I wanted to be 100% and tested on the terminals like you stated. This time it was 4.21vAC with throttle at "brake, stop" and 6.8vAC with throttle at "forward or reverse, full". It would spike to 12-15vAC when selecting a direction, then fall quickly to the 4.21vAC. That is testing with both meter leads to Rail A&B terminals, nothing else connected. I tested the DC power supply (PS314) as well, and that seems good. I'm actually hoping this unit is bad. It would make all the years trying different decoders because they didn't work finally have a reason! Thanks!!


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## brendang2000 (May 18, 2018)

I was able to get the PM42 to behave, I guess, closer to normal. When I was changing the OpSw's, I did not have the PM42 in program mode. Here is a link to the article on how to enter setup with a DCS51:
http://www.digitrax.com/tsd/KB488/pm42-programming-op-switches-with-a-zephyr-dcs50-o/
The PM42 will now trip one section, but if the fault is not removed it trips all the sections. The booster does not shutdown though. I'm guessing this is still incorrect as cutting power to all sections is the same as shutting down the booster. But hey, getting better!


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## Lemonhawk (Sep 24, 2013)

4-5 volts A/C? Something is not right. It should always be around 14 independent of the throttle setting. What does the power supply to the DCS51 read? It should be around 14v also. Might also be part of the problem with the PM42's


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## brendang2000 (May 18, 2018)

Lemonhawk said:


> 4-5 volts A/C? Something is not right. It should always be around 14 independent of the throttle setting. What does the power supply to the DCS51 read? It should be around 14v also. Might also be part of the problem with the PM42's


That's what I'm thinking about the PM42 as well! The voltage out of the PS314 was good, 14vDC with no load. 

EDIT: To be sure, I have a regulated 13.8vDC power supply that's rated to 30A. Ham/CB radio guys use these I guess. Anyway, I used that instead of the PS314 and Rail voltage was still 4.xxAC.


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## DonR (Oct 18, 2012)

Brendan

I would suggest that you go to the Digitrax
web sight and discuss the voltage problem.
Give them your voltage readings from
Digitrax gear. Avoid mentioning the non
Digitrax unit.

Your track should always be around 14 Volts 
modified AC.

From your tests it appears the Zepher is not
presenting the right voltage to the track.

Digitrax has an excellent warranty service.

Don


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## brendang2000 (May 18, 2018)

DonR said:


> Brendan
> 
> I would suggest that you go to the Digitrax
> web sight and discuss the voltage problem.
> ...


Thanks Don,
Digitrax replied to my "ticket" this morning and I'm sending the unit in for repair.

For now, I'm going to assume that the issue with the PM42 is also related to the DCS51. Thanks everyone for your help and input!! Brendan


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## DonR (Oct 18, 2012)

I have used the Digitrax warrenty. I accidentaly
damaged a decoder...they replaced it at no charge.

I do have a question though...why are you setting
up blocks that use a PM42?

I have a room size DCC layout and have never found
a need for isolated blocks. My brother has
a basement DCC layout 4 times the size of mine and
he also has seen no need of a PM42. These are usually needed
on very large, possibly club, layouts that often are manned by
more than one operator. The PM42 permits a short
in one block without affecting the other operators.

By the way, the individual units of the 42 can be
used as reverse loop controllers if you have such
on your layout.

Don


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## brendang2000 (May 18, 2018)

DonR said:


> I have used the Digitrax warrenty. I accidentaly
> damaged a decoder...they replaced it at no charge.
> 
> I do have a question though...why are you setting
> ...


Hey Don. I'm sure I don't need it, but plan on having a reverse loop and figured if I want an auto one, just get the one that can do 4 (or blocks). Yes it was more money, but I know how I am and a year from now I might have 4 of the AR1s


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## Magic (Jan 28, 2014)

brendang2000 said:


> Hey Don. I'm sure I don't need it, but plan on having a reverse loop and figured if I want an auto one, just get the one that can do 4 (or blocks). Yes it was more money, but I know how I am and a year from now I might have 4 of the AR1s


Be aware that if you have one reverse loop you'll need another to get the train to run in the original direction again. 
That or a wye to reverse the train.

Magic


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## mopac (Feb 24, 2011)

Using a PM42 can help you narrow down where a short is. Instead of shutting down the whole layout. Necessary no, but helpful. I have an 8 amp command station, too much
for whole layout and the PM42 allows me to cut the power down to separate sections.
Power management.


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