Confused- used to work, doesn't now, and contradictory evidence (DCC)

Model Railroader Layouts and layout building
1

Hello, all. Hopefully there’s someone out there who can help me with a really confusing situation involving a Digitrax DB150 command station.

This used to work just fine- I could run trains, program, etc. Then, I made the mistake of trying to hook up the LocBuffer I recently completed. (Oh-ooh…) Nuttin- DecoderPro monitor didn’t see any action on the bus at all. Well, just to assure that the command station was still working right, I started by trying to program a loco (BLI E-7A) from the DT-400; what I would hoping for was at least seeing those commands on the bus. Still nothing, and more worrying was, the loco didn’t respond to the programming commands.

OK, take a step back. Disconnected the Locbuffer and tried the programming again- still no response. Tried to program another loco (DH-163-equipped C30-7). Still no response. Now I’m getting worried.

Put a THIRD loco on the track (this, a BLI SW-7) which had been previously programmed, and tried to just run the darned thing- still nothing.

Wiring problems? I switched over to DC (there’s a DPDT switch in-line), and had no problem running the two BLIs. Bad sign- sounds like there is some problem with the DB150.

OK, let’s step back further- all locos off the track, flip the DPDT switch back to the DCC side, and get out the VOM. I measure ~16VAC at each of the following locations: at the control station, at the command-station-side of the DPDT switch, at the track-side of the DPDT switch, at the quick-disconnect between the control portion and the track (this is a portable layout), and AT THE TRACK!!! Doesn’t look to be a wiring problem, and I’m getting the 16VAC, suggesting that at least the booster portion inside the command station is working.

NOW we get contradictory, though… try the “coin test”. Take one nice, clean US quarter, and put it across the track.

NUTTIN’. The command station SHOULD beep and fla***he warning light. Nope-nuttin.

Final hope- RTFM

2

Sounds like a job for “Rinker Man”…

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Whozzat, and how do I get in touch?

Brian

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Randy Rinker he’s the resident DCC guru.

http://www.trains.com/community/forum/member-profile.asp?id=56423

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Couple of things.

You have voltage at the track terminals of the command station? How about running some wires to a couple of spare pieces of track and seeing if any trains run there. If you toggle the track power on and off with the throttle, does the LED on the command station come on? Does the track power dot in the throttle come on? Try selecting address 00 and turning it all the way up. the track power LED Ont he command station should change to more red or more green. Switch directions, if it was red, it shoudl go green, and vioce-versa (never a full solid red or green - it’s a bicolor LED and even at full speed on address 00 there has to be some signal at the opposite polarity, so the LED colors never go pure).

After you do the OpSw 39 reset, power everything off, forget the sleep mode thing.

Are you SURE it was 8 beeps? 9 beeps is a Loconet problem. Disconnect all Loconet connections at the command station and plug your DT400 in right there. What voltage does it display? (When you first plug it in you will see a version number and then for a couple of seconds the voltage on the Loconet (if you don;t have a battery in the throttle, which you don’t need except for wireless))

All else fails, do a REAL reset - power down and opent he command station. Inside you will see one of those round lithium batteries. Take it out and leave it out for 5-10 minutes, to make sure the command station memory is TRULY erased. The put the battery back in, reassemble, and try again.

It’s pretty hard to screw up the Loconet conenction on the Locobuffer (you said ‘built’ so I’m guessing you build one of Hans’s), it basically leads from the RJ jack to the optoisolator - unless you have that chip in backwards. You can test it with JMRI without connecting to the Loconet - there is an option to read the Locobuffer version in JMRI which will work without being attached to Loconet. That will verify commnucations from your PC to the Locobuffer, and that the Locobuffer

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Just a couple?! I’d hate to see what you had to say for a LOT of things! [:)]

Actually, that’s effectively what I have- this is my “workshop” track which I carried into my den, where the computer is. 6’ of flextrack on a 2x4.

Yes, as does the voltage to the track.

Yes

Well, I just tried, and can’t see any difference. Problem is, I’m seriously red-green color-blind, so I can’t actually be certain that it ISN’T changing!!! For assistance, I could try other residents of the house tomorrow, but I’m not sure who will be more help in such a thing- the spouse who has negative interest in anything trains, or the almost-five-year-old with the corresponding attention span… [}:)]

Well, it was unplugged a couple of times in between. Just tried that, no change.

  1. Yes, unfortunately, I just listened again.
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Well, I hate to say this, since I KNOW it’s going to sound stupid…

but WHAT battery? I’ve opened up the command station, and can see the following clearly (from front-left CW around the back:

  • two honkin 6800uF capacitors

  • large white rectangle labelled 5W 0ohm 1J

  • bridge rectifier attached to the heat-sink in the back

  • 7805 voltage regulator

  • 25LC640 8-pin IC

  • PIC

  • speaker attached to the RH wall of the case

I can post a picture if necessary.

Again, this is a DB-150, a little over a year old. This isn’t a DC-100 or Zephyr. Any possibility that this model doesn’t have such a battery?

Brian Pickering

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Can the 5W rectangular object be removed relatively easily? That may be it.

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No, looking in the Mouser catalog, it looks suspiciously like a Xicon axial-mount cement power resistor (lower-right corner of http://www.mouser.com/catalog/625/489.pdf). This makes sense- short-term over-current protection.

Sorry, don’t see anything that looks like a battery. I can recognize a “button” battery well-enough.

Brian

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Images:
http://www.geocities.com/bpickeri/View1.JPG
http://www.geocities.com/bpickeri/View2.JPG
http://www.geocities.com/bpickeri/Underside.JPG

Sorry 'bout the low contrast, I don’t have a good powerful lamp here in the computer room.

Brian Pickering

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No my goof, I thought DCS100, not DB150. No battery in a DB150.

The Loconet voltage seems a bit low, but I ony have experience with a DT400 on my Zephyr. The Zephyr track voltage is about the same as a DB150/DCS100 set to N scale, and my DT400 shows 11.9 volts when I plug it in.

If you can’t see the colors of the LED< you can do th test with your meter. Set to DC volts and test between Rail A and the Gnd terminal. Check between Rail B and Gnd - they should be withn .1 volt or so of each other as long as Address 00 is not selected or at least set to speed 0. Keep in on one side or the other, select 00, and advance the throttle. The voltage will either go up or down. Switch directions, if it went up before it now should be below the original voltage, and vice-versa.

You are correct on the IC orientation for the Locobuffer, so that should be OK. Check the orientation of the transistors too. Did you install the parts for the Loconet Termination? Make sure you have that jumpered to be DISABLED - you do not need Loconet termination if you are plugged into a command station.

Commands are definitely getting through on the Loconet, otherwise the power on/power off from the throttle wouldn’t do anything. If the Locobuffer was working, in the JMRI Loconet Monitor you would see GPON and GPOFF commands as you turn the power on and off. What I can’t see is how anything done at the Loconet side would break the track output. Could just be coincidental. Check the address 00 thing and see what happens.

–Randy

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Thanks to all who offered assistance, but I’ve gotta come clean- I found the problem and it wasn’t the command station.

I’ll only beg forgiveness for falling victim to lots of success with the general troubleshooting theory of, “The last thing to change is likely the thing that broke it.” (with the correllary that fixing one thing can cause something else to break.

SO… when all the problems occurred the moment I attached the LocBuffer, I tended to concentrate on that, and anything directly hooked up to it that might have gotten screwed up by odd signals.

But, I kinda passed by rrinker’s first suggestion, that of, “is the command station connected directly to the tracks?”. Well, almost, I replied… there’s a DPDT switch in the middle so I can break in new locomotives on DC even if they don’t have a decoder yet (yeah, I know I could use channel 00, but I had the good pack anyway, and need it for the turnouts, so why not?) I had checked voltage at a couple of points, and swear I remember checking the voltage at the track, but… checking again this morning revealed that one side of the switch doesn’t work… ONLY ON THE STUPID DCC SIDE OF THE TOGGLE!!!

Running a jumper straight to the track, and voila. Works from the DCC.

Feh.

Dropped by Radio Shack today, got a replacement, will wire it in later tonight.

After that, I’ll try getting back to the LocBuffer… hopefully that won’t be such a soap opera now.

Brian Pickering

13

Oops.

Don’t worry, you’re not alone, we all make goofy mistakes now and then.

–Randy