Signal strength problems P2 v. P3

There's a bit of a conundrum here. PS3 engines should perform at least as well as PS2 engines.

On the one hand, the PS3 engine runs OK on the test track but fails on the layout, which would point to the problem being on the layout.

On the other hand, other engines run OK on the layout, which would tend to put the problem with the PS3 engine.

A bit more info would be good:

• Have you tried the PS3 and PS2 engines on the same tracks of the same TIU channel? If not, you should.
• What Rev. is the current TIU?
• Are you using any 18 volt light bulbs or engineered filters at the TIU's output? If not, try them and see if there's an improvement. If you already have them installed, remocve them and se if things improve.
• Do the signal tests with the engines stationary and see if results are better.

Thank you. Sure doesn't look like any corrosion as everything looks pretty pristine. Will try the spray.  If that desn't work and it seems like no one has a good solution for my problem, I'll have to decide wether to send it to MTH or buy a Rev L TIU with the hopes that things will work better.That will be the second new MTH engine in a row that I've had to send back. Getting a little gun shy about new MTH engines. 

Thanks again. 

Ed

I'll try that too but it seems the signal strength is quite good with the PS 2 engines. Might be worth trying the test track TIU on the layout. Thanks again Barry.

Ed

This issue is most likely your PS-3 engine.  There were a few issue MTH have seen pop up.  Call MTH Service line with your model number and one of the techs will be able to walk you through possible issues.  One was a pin crimping issue on the 40 pin connector, the other was wire management around the board that interferred with DCS Signal.   Symptoms were similiar to what you are seeing.   G

G,

The bent pin will not let the engine go to DCS mode.  (the wires go to the DCS/DCC switch)  I don't think that is it but.....

There have also been some issues with the black coating on the ground screws in the trucks not allowing conductivity.  Grind off the coating or replace the screw with a non-coated one.

I am curious about this because I have a similar issue.  I have a small siding, with its own drop, where PS2 engines get 10s and my one PS3 engine gets a 2/3. It is probably a layout issue but I sure would like to figure it out. 

Dave

Thanks guys for the replies. I'll try to call MTH tomorrow and get permission to take the shell off without voiding the warranty. It just seems like the engine has trouble consistently processing the DCS signal. When it gets the signal as it sits alone on the test track it runs fine so the electronics must be working properly at least some of the time.

In some ways I hope it's an engine related problem and I don't have to do a major rewiring of the layout to run PS 3 engines. As I think back on this, my friend just bought a new engine and brought it over and it ran fine. I think it was also PS 3. If it is an engine related problem I'll start having some concerns about MTH quality control as this will be the second engine in a row that would have to go back for repair.

Ed

Dave,

As I read your post again, you seem to be having problems on one siding. My problem is over the whole layout. Does you PS 3 get good signal strenght reading when it's off the siding? I think I remember seeing a layout or two of yours in one of the magazines ( very nice layouts! ). I'll try to find the pictures and try to get a visual about the siding.

Ed

Ed,

It gets a good signal on the rest of they layout so it must be the siding.  It is just odd because the drop is almost directly under the engine and the siding is maybe 2-3" long, open on both ends.  So..... I was keeping a close eye on your thread.

Your issue sounds like the coating on the bolt problem.  The techs at MTH are very nice and easy to talk to.  They should be able to help.

Thanks for the nice comment on the layouts!

Dave

Well, I did a little more "homework" as suggested by Barry. Not sure I solved anything though. I checked the signal strength on all 4 channels of the test track TIU with no light bulb and the PS 3 engine. All channels were 8-10. Put this on the layout and could only very sporadically comunicate with the PS 3 engine. The PS 2 engine was excellent.

I did take the original layout TIU to the test track and the signal strength was 8-9 on all channels with the PS 2. With PS 3 there was less signal strength at 4-7 Variable 1, 6-7 Variable 2, and 6-8 on Fixed 1 and 2. The PS 3 engine did what it was supposed to do with signal strength of 7 or better.

Seems to my feeble mind that the TIUs are functioning well enough, certainly for PS 2 to work very well. My friend's PS 3 Aerotrain ran fine which makes me wonder if my PS 3 has something wrong with it where it has trouble consistently processing the DCS signal. Hopefully the MTH service department can help out tomorrow.

Ed

The coated ground screws add resistance to the circuit and the engine will draw more current, but I am not sure it interferred with DCS signal.

When you test the engine on your Layout, are all other engines off the layout?

The wire management issue around the PS-3 board, caused the engines to have low signal strength and misbehave with other engines present.  G

G,

The low signal strength is present with or without another engine on the track. On the layout and  the test track the signal strength was less with a PS 2 engine on the track. Is this a fixable problem?

Ed

Wow!, I am having the same problem with my one and only PS3 engine (SW9).  Some of the symtoms are: Horn works intermittently, engine does not respond to commands such as brake, reducing throttle, check track, no engine on track and engine fires right up before I use the start up button (I think that is because I throttle up my transformer very slowly according to Barry's book which I just received and is very well done! My track terminals are about 35 feet apart. I called MTH and a tech told me to use 16 gauge wire, 15 or more feet between the TIU and the track. I did that but did not notice any change.

Any ideas? Paul 

Hi Paul,

Misery loves company.I don't understand why the wire change would make any difference, especially if your PS 2 engines run well with good signal strength. I've had all the issues you describe. The PS 3 engine just runs erratically on the layout despite good PS 2 signal readings. I'm hoping MTH tells me to open it up and guides me through a simple process to fix it...not optimistic, but hopeful.

Ed

Ed, If your symtoms are similiar to mine, then hopefully when you get your 'fix' from MTH, would you be kind enough to pass on to me what they advised you to do? Thanks, Paul

Absolutely! I hope to call MTH service this afternoon.

Ed

Hello again to everyone and happy to report some progress. Talked to Don at MTH service who was very nice and helpful. Discussed the problem of poor PS 3 signal strength and also mentioned some of the theories mentioned here on the Forum. Don thought there were two likely causes for the problem that I could fix at home.

The first possibility was that in some of the PS 3 engines the wires were bundled too close to a donut shaped transformer next to an 8 pin connector. The proximity of the wires could potentially cause interference with the DCS signal. If this appeared to be the case, one could cut the tie wrap and move the wires away from the little donut.

The second possibility, as mentioned on this thread, is that there is a coating on the ground wire screws going to the trucks. With the coating the metal to metal contact could be markedly reduced.

I took the shell off and the wires looked good. I then removed the black ground wire screws from the trucks and filed off the black coating from the underside of the screw head. While doing this it was pretty evident that no electrical continuity would be achieved through this coating.

Well, the engine runs much better! There is good signal strength of 7-8 and above on most of the layout. There is still a 10-15 feet section on the inner and outer loop, in pretty much parallel sections of each loop, that the signal strength is quite poor at 1-4 ( PS 2 signal strength in these areas is 8-9 ). Even at 4 the engine will at least stop, blow the whistle and ring the bell in those sections of the layout. The signal strength is not enough to use the headlight on/off or smoke on/off functions without getting the dreaded "check track " message.

I'm at least functional and relatively happy. I realize that each layout running under DCS probably has it's own digital "personality" and potential issues. I'll try to tighten up the blocks where the signal strength is low. I hope this information is helpful to those friends on the Forum with similar problems. After DCS, I think this Forum is the best thing that has happened to the hobby.

Ed Kazarian

Ed, Thanks for the info. Did Don at MTH give you any idea on what engines the wire bundle problem might exist? I am going to do what you did and I will get back to you on the results. Thanks again. Paul

Ed,

I've had a few PS3 engines with the screw coating problem.  It is a pretty easy fix.  I am glad it worked for you.

The MTH techs are very good at problem solving!

Paul,

Try the screw fix first.

Dave

Paul,

I was trying hard to understand what Don was saying as I can barely tell the difference between one electrical component versus another. He did say that this was not an engine specific problem indicating to me that this has been noted on engines other than the GP 38. On the Gp 38 the repair was pretty easy. I say this with no false modesty intended but if I can do it with my feeble tools almost anyone can do it. I might take a little more of the black stuff off tonight but it is definitely running better. Perhaps the bigger question is why would someone put a coating like that a grounding screw in the first place. Please let me know how things work out for you.

Ed

Thanks Dave. It really was quite easy. I got all worked up over the lousy signal strength and then read your post about losing your friend Doug. That gave me a needed reality check. Last time I lost a friend like that I cried for days and then concentrated on all the joy he brought to my life and realized the joyful memories have supplanted and lasted a lot longer than sadness. I'm very sorry for your loss.

Ed

Ed, glad you got it.  Glad to hear that the black oxide coating can improve the DCS signal also, I thought it effected current draw more than DCS Signal.  Another solution is to change over to the stainless screws.  I did mention the wire bundle issue.  So the idea is trying to ensure that the harness wires are not bunched and too close to the circuit board, especially near the coils.  G

Thanks GGG. I would probably change the screws but am nt sure what size they are or what they are called in order to get an exact replacement. I'd like to replace them because ther remains some of the coating in the threads. I didn't want to do too much filing and really mess things up.

Eureka! I don't what I did but it seems to work! First I removed both black screws that were attached to the trucks and filed on the underside of the screw head, put it back together and it didn't help. Maybe as GGG said, use stainless screws. Secondly, I took the shell off again and started looking for donuts. I couldn't even find a breadstick! There were two main groups of wires that had a strap on them. I cut the strap on both and spread out the wires. There was a coil of copper wire about 1/4" in diameter that was near an eight pin connector. Is that my donut? Anyway, I put it back together and put it on the track and ran it completely around the loop, (10' X 32'), using the horn, bell and reverse direction button. They all responded like they should! Thanks again Ed and everyone else that had imput to this perplexing problem. This is one of many reasons why this forum is so great. Paul

Paul,

Glad to hear your engine is working!

The black screw is the one that connects the ground wire to the trucks.

Dave

That's the toroid "donut" they were referring to.

Thanks guys, I thought it was my imagination but my B&O PS3 E8 works great now, all I did was clean up the two black screws, why did they do that ? the centre rail pickup screws are stainless, strange !

Are these screws a standard size? If so, does anyone know where I could pickup a few in stainless steel?  Thanks, Gunrunner John for verifying my 'donut' and everyone else for their imput. Paul

This has been very helpful. About two months ago, I received several new Dash 9s with PS3, and I've been wondering whether PS3 was more sensitive to signal issues ever since.

While the new engines loaded into DCS fine and ran fine when testing, they seemed much more sensitive to signal issues than their PS2 counterparts. This was apparent running them in multiple unit consists (the only way I operate). I noticed signal errors, one engine in the consist not responding to commands on certain parts of the layout and things like that. I could run them OK if I usually limited it to one consist of two engines on the track, but things seemed to be worse the more engines were on the track. If another train is on same channel, things went south fast in ways that don't happen for me with PS2. Similarly performance would go downhill once more than two engines were added to a consist. I'll give some of these fixes a try.

RM

Rich, Your symptom is another one for the wire bundle wrapped to close to the Torrid.  Do as Paul did. 

Screws:  I don't remember the exact size, but take one out and go to the hardware store.  You should be able to get a match.  I don't remember if it is metric or US thread.  G

Still thinking about the signal strength issues with P2  versus P3. There must be some difference between the two, at least on some layouts, with the way the DCS signal is processed. I still have significant areas of my layout where the P2 engine gives 8-10 readings and the P3 engine gives 0-2. I'd like to figure out why in case I get some more P3 engines. Also, I don't want to do a lot of additional wiring at this point.

I'm using SuperSnap track( ouside rails are not connected electrically by a metal tie) and there is one problem area where one of the outside rails must be isolated to some extent because the voltage reading is 9 whereas the other outside rail is 17. P2 DCS signal is great in that area but P3 is not. Also going to try and figure out if more leads are needed around switch areas with P3 versus P2. Wondering if P3 engines need the Rev L TIU to run at their best. I don't have a Rev L TIU to run comparisons. Sounds like others are having similar problems with some of their P3 engines. Hopefully someone will come up with a "magic" cure like the P2 lightbulb.

Ed

 I did not have a problem yet when adding a ps3 engine to a consist. I only have one and it's a dash 9. The whole layout stayed strong and the consist runs well. Not sure what else you guys are seeing. Maybe just the certain models as stated.

d,

By any chance is your PS3 engine a 2-Rail/3-Rail model?

There is a 2 rail/3rail switch on the bottom. It's being run on 3 rail.

Ed

Ed,

Ok, that's where the issue is.

Nothing's "broken", rather, because the 2-Rail/3-Rail engine's have wheels that are isulated side-to-side, only the wheels on one side of the engine can make a Common (outside rail) connection. If the engine is on an insulated outside rail that's on the "wrong" side of the engine, the DCS signal is actually returning to the TIU via a car's wheelset rather than directly from the engine.

The engine's power circuit is also getting completed this way, however, for power that's good enough.

The DCS signal, however, is being degraded because it follows a path that's something like this: engine wheel, outside rail, car wheel, car axle, other car wheel, other outside rail, TIU channel output terminal.

There's nothing wrong. This is normal behavior for all 2-Rail/3-Rail capable engines, be they PS2 or PS3.

I was working toward that theory last night with my volt meter and DCS signal strength decrease on specific areas of the layout. I would not have ever figured out about the signal coming from only one side of the trucks. Thank you very much. As Columbo would have said, " I have just one more question". If PS2 and PS3 trucks are similar, would that explain why the PS2 signal is 9 and the PS3 signal is 1-2 in those sections?

Ed

Ed,

If PS2 and PS3 trucks are similar, would that explain why the PS2 signal is 9 and the PS3 signal is 1-2 in those sections?

It would depend on exactly how different are the trucks, however, in general all 2-Rail/3-Rail engines should react similarly, PS2 or PS3. Regardless, it shouldn't present any really big problems.

These engines also may have issues tripping the auto non-derailing mechanism on some switch tracks that use control rails that bridge to Common.