Rev L TIU issues

Hey Barry, and Ben, as Barry stated my TIU is at MTH now as it lost DCS signal to engines just the other day, on all 4 channels and yet switches and other functions still worked fine. Odd to say the least that SO many of these failed in the same time frame almost to the day!. Sounds like a software virus/bug implanted for failure. Mine is under 1 year for warranty and like it equal to legacy , just a different experience and for total option functions for my PS-2's and 3's. Hope this is a long term fix. My legacy eats up batteries so each has a down side at any given time. Barry thanks again for your trouble shooting help the other day. Happy Railroading to all,I am on shut down until my Tiu returns and my wife keeps asking when I can start going back downstairs again.

Hi all,

I have installed 20+ Rev. L TIU's on various layouts, including the NWTL, since they were first released.  I believe we have installed at least one case of Rev. L's from each production run.  Of those 20+ TIU's we had one unit with a variable channel failure which we repaired under warrantee.  IIRC, that one TIU was from a batch delivered in early 2012.

Ben, any chance your failed TIU's are a similar vintage?

Originally posted by: gunrunner john 

I was just wondering if MTH might consider an extended warranty if this turns out to be a bigger issue with the Rev. L TIU's. 

If there is an identifiable manufacturing error it's a distinct possibility.  MTH has repaired items for free well past the normal 1 year warrantee in the past.  In fact, MTH performed upgrades to original Rev. G TIU's free of charge for several years after their release.  They also horror the 1 year warrantee for products that dealers sell as new up to seven years after the original production .  They are very good about taking care of the customer, they just don't make much of a fuss about it.

Hi Dave

We purchased all six last June so they were all in the same lot.  I have purchased the spares seperately in steps since then  One of the spares was the last one that went bad.  Has the 50 volt output problem on VAR 1  Third one of them with that problem

Very strange to have the VAR 1 put out 50 volts. I wonder if the TIU puts out the same voltage using FIXED 1 for power instead of Auxiliary power?

Joe,

Very strange to have the VAR 1 put out 50 volts.

That's a lot more than strange - it's impossible. The TIU is not a power supply and cannot manufacture power.

I won't deny that a meter may have read 50 volts, however, that voltage was either a meter aberration or was coming in to the TIU from somewhere else. Regardless, of course, it shouldn't be happening.

My TIU failure was the loss of the DCS signal on all 4 channels.

I can't figure out how they're getting 50V on an output, has anyone explained that?

I'm thinking that somehow an Auxiliary transformer is out of phase with the transformer for the Input of the TIU causing it. It shouldn't be happening, but maybe it is leaking over inside the TIU somehow.

my TIU was also DCS lost signal on all 4 channels

That's exactly what happened to mine.  I have voltage out of the fixed and variable channels, the AIU works, and I could even connect it to the PC and communicate with it, just no DCS signal from any channel.

Maybe...maybe not.  I have a new Legacy system that is currently sitting dead and has been problematic from the get-go.  Just waiting for Big Mike to return from China.

The only problem I've had with DCS was with the remote's thumbwheel on the earlier versions.  No problem with the newer versions, and no problems thus far with the TIU (old version or Rev L).

Everybody says its impossible  I guess I have to get my eyes checked because every meter I used shows it  Either that or I have to learn how to count again.     With no load  No Load  Reading is 50 volts out of Var 1   Add a load it drops to about 10 volts no matter whats put into it    All are set to fixed BTW.  

No real reason for waiting, aside from liking to razz my friend Mike a bit and visit with him from time to time.  Also, there's no real hurry to get it fixed.  Life involves too much hurrying around as it is, and I kind of like taking it easy with my hobby stuff. 

Ben and vinn,

What is the wiring configuration when you read 50 volts?

What transformer(s) are connected to the inputs?

Is the transformer(s) connected to any other TIU's, accessories, switches, or in any way connected to the track?

Is there an aux power supply connected?

If so, what is the aux power supply?

Are the TIU outputs connected to the track?

If so, what is the reading if the outputs are disconnected?

Hopefully, someone here who is experiencing the problem will answer each of Dave's questions in a simple and descriptive way.  That should greatly help to track down the source of the reported problem.

Dave that was really me Ben   Vinny left himself signed in and I responded thinking it was me
What is the wiring configuration when you read 50 volts?

Connection from a Z4k output to the input of the TIU   No load meaning nothing connected to the output except a meter

What transformer(s) are connected to the inputs?

We use all Z4000's   18 of them in all or track power

Is the transformer(s) connected to any other TIU's, accessories, switches, or in any way connected to the track?

Fixed 14v of each transformer control switches on that line otherwise no other connection  Right from the Handle to the TIU with one terminal board in between

Is there an aux power supply connected?

There is an AUx power supply to every TIU   Its a Z750 brick

Are the TIU outputs connected to the track?

Not when reading 50 volts   Once a track load is connected it reads 10v

Readings have been consistent with Craftsman meter, Triplett meter, Simpson meter and Fluke meter

Nothing has changed in the configuration other than the TIU's

Ben,

Connection from a Z4k output to the input of the TIU   No load meaning nothing connected to the output except a meter

Maybe just stray voltage??

There is an AUx power supply to every TIU   Its a Z750 brick

Does this one have the polarized plug? Or the early one that doesn't have the polarized plug. Just wondering if the aux transformer might be out of phase causing it to show high voltage. If it's the older one try reversing the plug and see if you still get 50 volts. I know it shouldn't make a difference on the aux but......

Hi All,

In the "for whatever its worth" department; I'll put in my 2 cents worth on this TIU issue as maybe it will help.  I wonder if the issues with the Rev L could be related to certain production runs - specifically the most recent run.

In anticipation of my son's Christmas visit from Florida; I purchased my first TIU from one of my local hobby shops in late September (Let's call it TIU #1).  When his vacation time was confirmed, I bought a second one for him in late November (let's call it TIU #2) which had to be ordered.  When he arrived, we set up a 6 by 9 foot oval under the tree and hooked up the September TIU (#1) and it performed flawlessly.  We then swapped the (#1) TIU for the Nov TIU (#2) - it was completely DOA.

After Christmas the Nov TIU (#2) was returned and a refund issued as the dealer had no more in stock.  I purchased a third TIU (#3) from a different local shop.  This "January" TIU (#3) at least worked initially for about 10 days (but only about 1 hour of actual run time) and then it died - no output from either fixed or variable with a Z-1000 brick as a power source.  The dealer exchanged this TIU (#3) for another one (let's call it #4) that was on his shelf at the same time as when I purchased #3 from him.  So far #4 is still hanging in there.

Timing MAY be everything...

#1 was purchased from the first dealer as he was stocking his shelf with it so it was NOT old left-over stock as of early Sept 2012.

#2 had to be ordered by dealer #1 and took about a week to arrive in late Nov 2012 - it was DOA.

#3 came from dealer #2 and was in stock but was a recent arrival as of the first few days of Jan 2013 - it died within 1 hour of use.

#4 is from the same delivery batch as #3.  My fingers are crossed

Could there have been a batch that made it out of the factory without proper testing in the rush to stock the Christmas shelves???  Who knows!  I just thought I'd share my personal knowledge of TIU failures and the timing of these failures in hopes that it may help others understand their issues.  Anybody else experience TIU failures within these approximate time frames?

Best,

Dave

Dave I think your experience really could be of interest. Especially since you have such a good log of timing and purchases and to say something might have been overlooked in production during a Christmas rush is not too far fetched to believe unless they are totally computer/robot driven in which case it could have been some sort of sequence update in their subroutine. Would be interesting to overlay other users models and purchase times to see if that might match up production runs. Just MHO.

TheDude23112,

   Let me say this, if you are deciding to purchase the latest DCS.  My DCS is working fine after replacement of the one NIB.  I still have no idea whether it was a shipment problem or not.  My Remote control does need the wheel replaced, however I am told the new remote control units no longer have this problem.  Dave Garman may have a point, some of these DCS TIU units may have gotten out before fully QC inspected, and are causing problems.  However mine are working perfectly.

I would have no problem investing in another DCS unit.  I would however stay away from where Ben is purchasing his, just to avoid that particular lot.

PCRR/Dave

Let me join the club my Rev. L just went, no DCS out put!

And when was this one purchased?

Been reading this thread.  Wonder if there are voltages being backfed from other TIUs as when train crosses from one TIU to another, but earlier versions withstood it?   Since we aren't privledge to see how L outputs compare to previous versions schematics, L's output stage may be identical or not, especially if they improved the signal generator configuration and/or interface to achieve higher drive.

Don't shoot the messenger.

It would be interesting if someone from MTH (Maryland) would chime in here...

Thanks for the replies Ben.  Given your answers, we need to eliminate a couple possibilities.

Have you ever check the phase between the Z-750 brick and Z4K for this particular TIU?  It is possible for the TIU to function without any harm if they are out of phase.  There's no direct connection from the common on the AUX Power port to Variable 1, but there is a path through the circuit board via the transistor that chops the input power.  That could account for the no-load reading.  Again, there wouldn't be any danger to the TIU or anything else.  The phase difference could be caused by either the brick or Z4K being wired opposite each other internally or by running them off of different electrical circuits in the building.

You say that once the output is connected to the track the voltage drops to 10.  Is Variable 1 set to fixed?  What is the input voltage from the Z4K?  Does the Z4K's digital readout also drop to 10 or just the meter?

You say nothing has changed other than the TIU.  Have you checked the no-load voltage readout with other Rev. L's and/or and earlier TIU?

There is useful information in this thread, and if there truly is some systematic problem with Rev L TIU's (mine works just fine), I imagine the input here--particularly the input that provides details--will lead to some reasoned answers and perhaps even a solution.

Someone on this Forum must have close access to MTH.

I purchased it on 12/27/12 at Trainworld.

I purchased a Legacy and DCS close to the same time 2 1/4 years ago. Never a problem with either. Run trains almost every day. Just an FYI. (rev L). 

I know Ben will chime in and say my first mistake was buying it from Trainworld.

My brother recieved one from Jason's on 1/8/13. He had pre ordered it and had to wait, so this one must be from the latest batch. He has no problems so far.

I got a REV L delivered right after Christmas and it has been terrific. My impression was that it came from a recent shipment. I know it's not a long history with it but the improved signal strength has been wonderful and no glitches yet. Hope I didn't jinx myself with this post.

Ed

I got mine from Hobby Lobby in May.

 Dave

All phasing is correct  All track power transformers and TIU's are on one phase.  The Z4k output stays consistent at 19 volts   Measurement on other good Rev L's are consistent with the Z4K output.  Every Variable channel of all 6 TIU's are set to fixed.  I am thinking of trying everything in passive mode right after our open house 

Trainworld!!!!  Whats wrong with you Luigi

Hi Ben,

Here's my best guess, and it's only a guess.  You might have a half fried TRIAC on the variable channel.  You did not say if the variable channel is set for fixed, but I'm betting it is.  A TRIAC essentially consists of two diodes that are turned on and off by the base (gate) voltage.  I suspect one of the diodes is functioning properly, which is governing half the input voltage (19 in cut down to 9.5 or 10).  The other half of the TRIAC is fried and isn't letting any of the Z4K power through, but it is leaking voltage from the base leg that's giving the no-load 50 volt reading.  If this turns out to be the case I'd be concerned with what caused the TRIAC to fail.  Passive mode should be a good test.  The signal generator is past the TRIAC in the circuit.  If track voltage comes up to 19 in passive mode it's a pretty safe bet you'll replacing the TRIAC.

I have 1 Rev L TIU on my service bench that gets knocked around a lot.  It has worked perfectly until this afternoon, when I couldn't even get a reply when trying to read the TIU version.  This evening I took the cover off, moved the antenna wire, made sure the RF module was well setted - now it is working fine.

Jim,

This evening I took the cover off, moved the antenna wire, made sure the RF module was well setted - now it is working fine.

The next time you have the cover off of the TIU, place a piece of foam on top of the transceiver board before replaciong the cover. This should keep the transceiver well-seated in the future.

This also works for the DCS Remote.

Will this cause a heat issue?

Will this cause a heat issue?

It hasn't for me in 10 years of operation for many TIUs and remotes of different vintage.