Perfect track signal with one loco, but not the other

 Clean the pickup rollers and oil the pin the roller spins on with conductive oil. Make sure the wheels are squeaky clean. Are these engines pulling cars when testing ?  Some lighted cars will effect the track signal.

You can also try to delete the engine and re add it.  I had the same issue, I was gong crazy, with a new layout, I wired it correctly, and the only MTH engine I had was all over the place.  I bought another PS2, and it registered all 10s.  I deleted the other one re added,  it is all 10s now.

Thanks guys for the tips. I tried all of the above, and no luck. Is it possible that these are symptoms of a board that's on its last legs? 

Clean wheels, Clean pickup rollers, but it is possible the board has been over heated and inductor value have changed.  The Dreyfuss has the 5V board in the engine so it is not a tether issue.  You can make sure the battery is good though.  G

Now I'm getting the same reading with both engines. I also have a third engine that I'm borrowing from a friend, and I'm getting the same weak signal in the same block with all 3 engines. This block is at the approach to a drawbridge, and is controlled by a limit switch that cuts off power to the block when the bridge is up. Now I'm wondering if the cause is the length of the feeder wire from the limit switch to the weak track signal block. That feeder wire runs from the limit switch all the way around the layout to the block it controls, so it's the longest feeder on my layout at approx. 25 feet. 

So now my question is what's the longest a wire can be and still transmit a good track signal? All wiring is #12 stranded wire. 

Thanks again for the help. 

John 

1. Use another TIU channel to power the drawbridge block if you have one.  Wire length besides track length can affect the signal and you may be approaching the limit.

2. By-pass the switch and see if that could be the problem.

3. Check all wire connections on the same channel as any loose connection anywhere can cause a problem, even though not on the same block.

I bypassed the switch, no difference. Wire connections are good. New development: I tried running just the engine, and signal is 10 all the way around. As soon as I put the 7 passenger cars on, signal drops but only on the block approaching the bridge. Definite mystery. 

As soon as I put the 7 passenger cars on, signal drops but only on the block approaching the bridge.

There are some passenger cars that can degrade the DCS signal, sometimes severely. Known offenders are easier Golden Gate cars. This may be your problem.

If so, the solution is to insert an RF choke inline with each car's pickup rollers, as discussed on page 157 of The DCS Companion 3rd Edition and page of The DCS WiFi Companion 2nd Edition:

Some, but not all, TMCC engines will degrade the DCS signal of any DCS engine with which they are in close proximity. This effect varies both by individual TMCC engine and by the distance between the TMCC and DCS engines. In many cases, an RF choke inserted in the Hot wire between the pickup rollers and the TMCC engine's circuit board will correct this problem.

Some lighted cabooses, most notably those manufactured by Atlas O, may degrade the DCS signal, as may some engines or passenger cars with constant voltage (CV) lighting boards. Again, an RF choke inserted in the Hot wire between the pickup rollers and the circuit board in these cars will generally correct this problem. Although a number of different RF chokes may be effective in reducing interference from CV boards, one that has an electrical value of 22uh (micro henries) is known to work well.

This and a whole lot more about DCS is all in MTH’s “The DCS Companion 3rd Edition!" This book is available from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at MTH's web store!

This and a whole lot more about DCS WiFi is all in MTH’s “The DCS WiFi Companion 2nd Edition!" This book is available from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at MTH's web store!

Thanks Barry--these cars are MTH premier 18" heavyweights. Ok, now it's time to get off my butt and order your book. Marty told me I was going to need it!!

John

This is just a shot in the dark. I had an issue years ago with a simple lift out bridge. It was wired to the main layout and isolated from the yard. The main layout was on a different channel than the yard. With a change in weather the benchwork and everything shifted a bit. The 2 channels joined one another through the center rail  sending the track signal south. While juggling some cars on the layout before running. I blew a fuse in the yard. Without realizing it.. With the center rails touching now. One channel was trying to feed to much track. The permanent fix was to trim the track and epoxy a piece of styrene between the 2 center rails.

 The fact that you have a lift bridge. Any chance you may be bridging 2 isolated blocks with the rails slightly touching. The fact that the engine on it's own generates a 10. It seems the cars are the issue. Can you park the engine in the block with the track signal running. Should be a 10. Using your hand push one passenger car into the block at a time. Just to see where the change is in signal. As far as your wiring. Using 12 gauge wire that should be fine for a long run. Is the 12 gauge a buss wire ?  Or does it go directly to the rails as a feeder ? Remember. Even though you have isolated blocks. The passenger cars will bridge 2 blocks with their rollers.

Dave_C posted:

This is just a shot in the dark. I had an issue years ago with a simple lift out bridge. It was wired to the main layout and isolated from the yard. The main layout was on a different channel than the yard. With a change in weather the benchwork and everything shifted a bit. The 2 channels joined one another through the center rail  sending the track signal south. While juggling some cars on the layout before running. I blew a fuse in the yard. Without realizing it.. With the center rails touching now. One channel was trying to feed to much track. The permanent fix was to trim the track and epoxy a piece of styrene between the 2 center rails.

 The fact that you have a lift bridge. Any chance you may be bridging 2 isolated blocks with the rails slightly touching. The fact that the engine on it's own generates a 10. It seems the cars are the issue. Can you park the engine in the block with the track signal running. Should be a 10. Using your hand push one passenger car into the block at a time. Just to see where the change is in signal. As far as your wiring. Using 12 gauge wire that should be fine for a long run. Is the 12 gauge a buss wire ?  Or does it go directly to the rails as a feeder ? Remember. Even though you have isolated blocks. The passenger cars will bridge 2 blocks with their rollers.

 

 

Dave C, just got home from work and will give this a try. I was thinking the same thing on my way home: park the loco on the problem block and wheel the cars in one at a time. 

All wiring, buss and feeders, is #12, except for the power going to the bridge. For that, I used a trailer wiring harness, which I think is #16. I used that for ease of disconnecting the wires in the event of having to remove the bridge. 

Thanks for the recommendations. 

John

After testing, it appears the cause of the signal loss is the lighted cars. I parked the loco (PS3 Blue Comet) in the bridge approach block, set the track signal test, and started to add cars. With each car added, the signal dropped significantly. After adding 3 cars, the track signal was down to 1, sometimes 2. As soon as I removed the cars, back to a solid 10. What seemed to cure the problem is running another feed from the buss to the bridge approach block. Even with the cars on the track, the signal went to 10 when I did this. So, I'm thinking if I put in 2 limit switches (1 on each side of the bridge) and have each switch control the block on its side of the bridge, instead of 1 switch controlling both blocks, it looks like the problem may be fixed. Even with the lighted cars, the signal is a perfect 10 everywhere else, except for when the engine is in the block approaching the hinged side of the bridge, which is the longest feeder run on the layout. Thanks for the help. 

I think you'll probably find you have a few items that affect the DCS signal.  I keep a generous supply of 22uh chokes around in various current ratings for that reason.  My track powered electronic products all include a 22uh choke as well to avoid that issue.

Some ERR upgrades will gave negative results on the DCS signal 

John,

   Hope all is well in your neck of the woods!   Before adding any chokes, try replacing a few of the lights in your lighted Passenger Cars with LED's and see what happens.

PCRR/Dave

Don't rewire the layout if the problem is in the passenger cars. Fix the actual problem - the passenger cars.

Matt,

I've added chokes to a number of TMCC and Legacy locomotives.  Interesting enough, some ERR upgrades affect the signal, others don't. 

gunrunnerjohn posted:

I think you'll probably find you have a few items that affect the DCS signal.  I keep a generous supply of 22uh chokes around in various current ratings for that reason.  My track powered electronic products all include a 22uh choke as well to avoid that issue.

John, do you have any tricks up your sleeve for replacing the grain-of-wheat bulbs for the observation marker lights and drumhead? I'd like to eventually go with your LED car lighting kit, but I still run conventional as well as command.