TMCC Issue - Need Guidance

You have a TAS EOB setup.  First stop, closely check the wiring between the flywheel sensor board and the EOB motherboard.  Many times one of the wires will break right at the tach board connection and that will result in a runaway.

With the shell off, and the engine powered, try slowly rotating the flywheel.  You should see an LED on that tach sensor board blinking with the crossing of the light stripes.  If you don't see that, check the spacing between the sensor and the flywheel, it should be very close to 1mm.  If all that checks, and the wiring is good, you probably either have a tach sensor board failure of the motherboard failure.  My bet is on the wiring or the sensor spacing.

Thanks John

Wires as shown here on the sensor strip are all in place well and the wiring and connector look good.

I have no opportunity to adjust the distance from the sensor strip to the flywheel because of the little black "shim" (I placed it on top of the flywheel in the pic).  It goes between the sensor strip and the motor governing that distance it seems.

Have not tried it powered up to observe the light.....but I believe (not certain) that it was on steady.

I really can't advance the throttle because it just takes off at full speed making observations of the light impossible.

I did try disconnecting the sensor lead from the motherboard but the same thing happens..full speed.

Dave

For whatever reason .....the engine will move at only one slow speed...somewhat poorly.

The red light on the sensor board is solid always.

Dave

Well, this picture shows the sensor WAY farther than 1mm from the flywheel, at least that's what I see!  1mm is only about the thickness of a dime, that looks more like many times that!

That picture was taken after I loosened everything up to check the 3 wires to the board and remove the "shim".  I just displayed the shim on top of the motor.

Everything is back together now with the dime distance between the sensor and the flywheel.

Still no joy.  It will now move/crawl as opposed to taking off when throttle applied.  But it is erractic...start/stop, no speed and red sensor light is always solid.

So I guess John as you said, I will have to try new parts.....sensor and/or motherboard.

Can I get these parts from somewhere?

Thanks

Dave

John could this be a R4LC board. I remember having a bad R2LC board in a engine and it would run fine then take off like a bat out of you know where. 

Probably not. From reading what you have said the sensor should blink, so if it's not would you not start with that board?

Thanks Bill for your reply.

Not sure how to proceed.  I've done a search here on OGR - EOB and read quite a lot about this.  I have zero experience with EOB.

I guess parts are pretty much not available.

Can someone advise the best path forward to get this engine going again?

Thanks

Dave

I'm fairly certain parts are available, from either lionel, or maybe ERR. I would maybe take it to a service center and have them look at it before you make any purchases.

This is a TAS board, and the parts needed are not available from Lionel or ERR as they had nothing to do with this board.  If the light is on steady on the tach board, I'd start with that board as all it takes is 5V power to operate the light and sensor.

Bill, there's pretty much zero chance this is the R2LC, it has nothing to do with the speed control.

Okay

If I have this right???

As per pics attached:

1) 3 top boards are Lionel

2) Motherboard is TAS

3) Tach Sensor board and smoke board are TAS

4) Motherboard is no longer available

Questions:

Can the tach sensor board be bought?  And/or can I disable cruise entirely and fix this issue?

Thanks

Dave

I have a couple of the TAS diesel boards and associated sensors.  Obviously, since I don't have extra sensor boards, I'm not really willing to let go of just the sensor.

Can't Cruise be turned off ?  I see a plug on my board that says Cruise /Conv.  I don't think they are talking about Conv as in F-N-R,  however I would not bet I am right on this as I have not read the complete manual yet.  Something that happened the first time I tried to set minimum and maximum speed on a Lionel TMCC loco I got the sequence backward and set the maximum speed But I used the minimum button sequence and the loco would only run at a scale 80mph.  Dave, I wonder if that might be your problem.  I did the reset sequence and things were back to normal. However just out of curiosity I tried setting the max speed with the loco running as slow as it would without stalling and sure enough the top speed was just above a crawl.   Dave are you wearing a grounding bracelet while handling your boards?  Static can do crazy things to these boards.  Another thing you might check, many of the TMCC and DCS boards are rather old and some of them were made during the period of the capacitor pox. The EOB board I am working with has at least one bad cap and I ordered 20ea of the three values of Ecaps on the board. figure I'll run into more TAS EOB boards.  I am going to set it aside till the caps come as I have a bunch of Lionel and Digital Dynamic TMCC boards that I can use in the Atlas Erie Built I was planning on installing the EOB in. I'm thinking the EOB board  may be better used in a steamer.  I have 3 TAS SAW boards also and though they are all working I'm thinking I should replace all the Ecaps before any fail. You never know what else the cap may take out when it goes.   Any board that has a date on it between 2000 and 2005 is a likely candidate to receive new Ecaps. 

   Something related to working on circuit boards I have not seen anyone on the forum mention, some soldering irons have a voltage potential on the tip. If you connect your VOM to the tip of your solder iron and a good ground you can read a voltage. I have three old Weller soldering guns with a tip potential of 30-40V. They are not suitable for work on the command boards in toy trains or most other modern electronic circuits.  Though the iron I use most is rated to use on electronics and it has a three prong grounded plug it too reads 3V on the tip when plugged in. I connected a ground wire to it's shaft above the tip and now it reads O volts.  One old iron I have will shock the XXXX out of you if you are grounded and touch it to metal that you are in contact with. I use it to solder brass loco details. The  250W Weller gun is good for that also but keep them off electronics. SO, before you touch any soldering tool to a circuit check the voltage potential at the tip.  J

John is clearly correct about soldering irons, you should always use an ESD Safe iron for working on circuit boards.  I use the Hakko FX-888D that is certified to be ESD Safe.

Thanks JohnActon for your reply.

Here is an update to where I am at on this.

The switch on the frame Conv-Cruise ON/OFF does not seem to turn the cruise off in Command.  I suspect it is bypassed in Command Mode.

I was able to use the sequence in the manual and turn off the cruise in Command.  This worked, cured my issues and the engine ran fine - but without cruise.  It actually runs quite nicely in non-cruise mode.  Cancel the command and put the engine back in cruise and the crazy behaviours return.

I "borrowed" a sensor board from another engine and the engine in question is now performing as it should in cruise mode - Command.  So....the problem was the sensor board...defective somehow.

Now I need to buy a sensor board if anyone has one to sell !

You can set the cruise to 32 or 128 speed steps.  Control is very good but I find ERR just a bit better.

My soldering iron has been long overdue for replacement.  Your information and GR John's suggestion of the HAKKO put me over the top and I just ordered a HAKKO FX888d from Canada at a good price (I am in Canada).

Dave

Given the fact that the tach boards are in short supply, I'd consider repairing that one.  Top suspect on that board is the LM358 op-amp given the fact that the LED stays on all the time.