Testing RCDR and DCDS for proper operation in 6-11155, 2-10-10-2 steam

Check for contact from motor housing and the frame to the wheels. The one end of the motor field has to be grounded for the system to work.

I made my self a little test harness to test RCDR boards.  Yours is the earlier version that was used in TMCC and early Legacy with the 9-pin connector.  Based on your comments, I'd suspect the DCDS as the suspect, you have serial data if the tender sounds work.

Thanks Paul and John for the feedback.

Paul,
I did check the motor housing to frame to outside rail for continuity.  Initially there was none, but I tighten the motor mounting screws and got continuity.  Still no improvement in the operation.  Not sure how the motor frame being grounded would have any impact of the motor working???

John,
I think that is the case also (bad DCDS).  I re-tested the engine with tender.  The rear coupler fires, the whistle and bell sounds when activated along with the other sounds.  The back up light comes on when I change direction.  Still no movement with the engine motor.  I am working on repairing the smoke units to see if those will work. If you recall, on this engine the whistle and blow down aux smoke unit pulls the vapors through the fans.  They were plugged with smoke residue solids.   I am really interested in seeing if the whistle steam effect unit will work when I activate the whistle on the the cab2 remote.  As I mentioned before, I cannot get the chuff sound to take place when I manually rotate the wheels (activating the chuff switch).  I have yet to check to see if the chuff switch is closing or not.

With the cab lights not working, I would guess that could be tied to a bad DCDS???  There are lights for the instrument panel that I need to check. I don't think they were illuminated before I removed the shell to work on the smoke units. I'll report back to what I find.

@DaveGG posted:

I did check the motor housing to frame to outside rail for continuity.  Initially there was none, but I tighten the motor mounting screws and got continuity.  Still no improvement in the operation.  Not sure how the motor frame being grounded would have any impact of the motor working???

The motor can doesn't have to be connected to anything.  The brushes and armature are totally insulated, and the field is obviously permanent magnets.

@DaveGG posted:

I think that is the case also (bad DCDS).  I re-tested the engine with tender.  The rear coupler fires, the whistle and bell sounds when activated along with the other sounds.  The back up light comes on when I change direction.  Still no movement with the engine motor.  I am working on repairing the smoke units to see if those will work. If you recall, on this engine the whistle and blow down aux smoke unit pulls the vapors through the fans.  They were plugged with smoke residue solids.   I am really interested in seeing if the whistle steam effect unit will work when I activate the whistle on the the cab2 remote.  As I mentioned before, I cannot get the chuff sound to take place when I manually rotate the wheels (activating the chuff switch).  I have yet to check to see if the chuff switch is closing or not.

With the cab lights not working, I would guess that could be tied to a bad DCDS???  There are lights for the instrument panel that I need to check. I don't think they were illuminated before I removed the shell to work on the smoke units. I'll report back to what I find.

The DCDS would be the entity that knows when the locomotive is moving.  I'd trace the chuff switch wires and see where they connect.  The wiring diagram for that unit will be considerably different than most early Legacy for obvious reasons.

My guess, based on other Legacy steam of that era, is that the chuff switch is connected to the DCDS and that generates the chuff signal in the output serial data from pin-2 of the 10-pin connector.  That would explain the missing chuff and also matches what the early Legacy Big Boy did for the chuff switch.

I'd be checking the wiring around the DCDS, maybe it's just not getting power.

I did confirm the chuff switch wiring does go to the DCDS.  And confirmed track voltage is getting to DCDS inputs.

I found a similar DCDS (code S-16 compared to code S-19) in my spare parts.  I switched out the DCDS and the engine motor moved and chuff sound worked as it should.  I'm sure that some of the features are not the same, but at least I now know the original DCDS is bad.

When I looked the the failed DCDS I did not see any apparent damage.  The MOSFETs look fine (not over heated), but not sure I can test these while they are still soldered in the DCDS.  My guess there is something wrong with how the DCDS is handling the communication input signal.  There was some light corrosion on the back side of the DCDS which I was able to clean off using an old soft bristle toothbrush.  No improvement after cleaning.  Not sure if there is any repair that could be done.  I guess I'm in for purchasing a new DCDS board. This board is mounted directly under the main smoke unit.  Excess smoke fluid and its resulting over heating could have lead to root cause of failure.

I'll complete the smoke unit repair and test the smoke fan control board (P/N 691SFC1101) next.

Well, based on the logic not working on the DCDS, I'd say it's probably not the driver FET's, but probably some other failure on the board.

Have you tested the motor itself?…..does this engine have the big Cannon motor in it?….Cannon motors can fail, and take the driver with them to doomsville…….Cannons ain’t exactly what some of us would consider top shelf stuff,….

Pat

Pat, it runs with a replacement DCDS, so it's unlikely to be the motor.

@DaveGG posted:

I found a similar DCDS (rev 16 compared to rev 17) in my spare parts.  I switched out the DCDS and the engine motor moved and chuff sound worked as it should.  I'm sure that some of the features are not the same, but at least I now know the original DCDS is bad.

I'd run it and see if you notice any issues in operation.  Chances are good that you will never see the difference.

Thanks Pat for the comment.

Yes.  I tested with an external DC power supply.  Motor worked fine.  As John mentioned, I also replaced (as a test) the original DCDS-J (S19 code) with a DCDS-J (S16 code) I had in spare parts.  The engine responded well and motor worked as it should. The chuff sounds also worked on the tender.

The engine has the smaller Bulher Motor GmbH.

@gunrunnerjohn posted:

Pat, it runs with a replacement DCDS, so it's unlikely to be the motor.

And more than likely this is true, ….I should’ve worded my question for the OP a little better,……did he test the motor/driveline on straight DC power  ( with the electronics disconnected of course )  to rule out a mechanical issue, or a possibly a failing motor? …..that’s a whole lot of locomotive with lots of things happening all at once …..

Pat

Good point Pat.  I'll conduct another test.  I would not want to replace the DCDS and then cause another failure in the replacement board. Initial test was a very short test with straight DC power.

Is there a way to tell if these motors are starting to fail?  If it was pulling high amps, I would have expected to see some heat damage to the original DCDS-J motor driver. Right?

@DaveGG posted:

Thanks Pat for the comment.

Yes.  I tested with an external DC power supply.  Motor worked fine.  As John mentioned, I also replaced (as a test) the original DCDS-J rev. 17 with a DCDS-J rev.16 I had in spare parts.  The engine responded well and motor worked as it should. The chuff sounds also worked on the tender.

The engine has the smaller Bulher Motor GmbH.

Good deal Dave, ….I’m kinda surprised with all that motion happening they went with a small Buehler motor,…..sounds like I don’t wanna ever see inside one of those ……😳

Pat

You can run the motor on plan DC, make sure you remove all the connections to the motor from the electronics.  I use a bench supply that monitors current and also has a current limiting feature.

@DaveGG posted:

Good point Pat.  I'll conduct another test.  I would not want to replace the DCDS and then cause another failure in the replacement board. Initial test was a very short test with straight DC power.

Is there a way to tell if these motors are starting to fail?  If it was pulling high amps, I would have expected to see some heat damage to the original DCDS-J motor driver. Right?

Not necessarily if something small like a trace popped on the board where it’s hard to see.……but like John said, if it’s running it should be ok, ….but I’d just verify it running it on rollers or a test loop on DC just to rule it all out and remove that variable all together,…….

Pat

Bit more information.

The correct motor control driver board is the DCDS-J (S19 code) Lionel P/N 691DCDS117.  I corrected this is my earlier post.  It is not the rev 17.

I confirmed the issue is a bad motor control board.  Replacements not available from Lionel. I am still trying to revive the old original board, but looks to be a bad trace.

The spare DCDS-J (S16 code) motor control board, P/N 691DCDS114, does operate the motor.  So far, the difference found.
1) The firebox flicker does not work as before.  The firebox lights come on, but does not flicker (steady light only).  It gets brighter when the engine starts to move.
2) The cab lights do not work.  Could be a different issue.  I'll continue to test and update findings.

The good new is the motor runs as it should.  Chuff sounds work and all smoke unit work as they should. This includes the chuff synchronized smoke, blow down smoke unit and whistle smoke unit. Headlight, number board lights and maker lights all work. Rule 17 lighting works. Lights for the cab gauges work.

I'll update as I do more testing.

If any of you know why the firebox lights don't work as they did, let me know.  Maybe there is a work around, including replacing the firebox lights with other, rewiring, adding a resistor, etc.  Not sure why they would get brighter when the engine starts to move.  Maybe it's following the rule 17 operation???  Still would like to get the flicker part working.

Previously, I posted a question asking differences between codes / revision of the DCDS boards.  There was no reply.  If there is any information, please share. I would guess I am not the only one that has used the "incorrect" motor control board in order to get an engine operational.

The different rev levels are the code that drives the 10-pin connector lighting options.  Obviously, the S19 had the flickering firebox and automatic cab light, the S16 appears to have different functions for those pins.