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RIO GRANDE UP HERITAGE LEGACY SD70ACE 6-28377 Uncoupler Pocessed

RO Randy OwensOGR Forum Member

Rear coupler randomly opens several times a minute.  Sitting idle, there is the audible solenoid buzz and the coupler pops open.  Close it and wait a few seconds and it happens again.  

Since the engine isn't moving, I doubt its dirty pick-ups.  It'll do this underway or just sitting.  I think it's ok other then this problem, and dang, it's been a great engine until now.

What board needs to be replaced / where should I start?  I know there are a number of interconnected boards internally, but I'm not clear on which does what.

I also have a UP Flags SD70ACE that has a mechanical problem with it's front coupler--it comes open sometimes in a lash-up, but that problem doesn't appear electrical.  I need to look into that one, too.

Thanks for any advice, fellas.

-Randy

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illinoiscentralillinoiscentralOGR Forum Member DIGITAL SUBSCRIBER

If you press down on the resistor it lights slightly. Shooting from the hip, maybe you have some designed for 120Vac, so the resistors would be much higher, and then the resistance (or resistance and capacitance) of your hand is allowing enough milliamps to pass thru to see a bit of light???

If you press down with something insulated like the handle of a plastic spoon, and the same thing happens, there goes my theory.

SteimsSteimsOGR Forum Member DIGITAL SUBSCRIBER

Randy, I suggest you remove the cab from the Rio Grande and look around specifically for any pinched wires.  This happens frequently during reassembly.  The coupler wires are typically both black.  Try and follow the wires to the board they are connected to (R4LC according to G) and remove and reconnect there.  See if that corrects.  If not, then I would swap R4LC boards between your 2 different SD70s and see if the repeated uncoupling problem migrates with the board.   If so, then replace that board. 

Here is a link the Lionel site to order parts.  They seem very light on the parts for your Rio Grande but all the parts are listed under the #1870 Katy:

 Lionel Parts - #1870

 

Last edited by Steims
RO Randy OwensOGR Forum Member

That was my thought as well: swap board and see if the problem follows the board.  GGG was kind enough to get me to the proper board, but the link from you for the replacement is really awesome.  I hope to get to this over the long weekend.  I have this pesky Arduino controlled turntable that I am wrapping up that is sucking up all my time (a little more hardware there, update the software, and repeat).  I keep coming up with too many great ideas...

Thanks, guys, for the advice!

-Randy

RO Randy OwensOGR Forum Member
gunrunnerjohn posted:

If reprogramming worked for a short time and then reverted to no coupler again, replace the R4LC.  It must be forgetting it's programming.

It's not that it doesn't have a coupler (or forgets about the coupler).  The coupler randomly opens and closes -- jitters.  You can directly address the coupler with the remote and it will respond (open).  Close it and it will open on it's own.  It's being pulsed randomly by the controller board it seems.

I still haven't have a chance to tear into it, so it's still guessing at this point.

I appreciate all the advice!

-Randy

gunrunnerjohngunrunnerjohnOGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER

Well, clarity is key when you're describing issues!  This is what you said...

Randy Owens posted:
Marty Fitzhenry posted:

Reprogram the engine with aux code 2.

I tried that already.  Interestingly enough, that worked for a short while (like an hour or two, if I remember)....  I think the next time I went to run the engine it started acting up again.  Very strange....

-Randy

I'd have to be a mind reader to know that your latest description is what is really happening.

Now that we have a clearer description of the issue, I'd do this.  First, look for ANY shorts in the wires coming from the coupler to the motherboard.  Next, install a 1uf 50V non-polarized capacitor directly across the coupler inputs on the motherboard.

RO Randy OwensOGR Forum Member
gunrunnerjohn posted:

Well, clarity is key when you're describing issues!  This is what you said...

Randy Owens posted:
Marty Fitzhenry posted:

Reprogram the engine with aux code 2.

I tried that already.  Interestingly enough, that worked for a short while (like an hour or two, if I remember)....  I think the next time I went to run the engine it started acting up again.  Very strange....

-Randy

I'd have to be a mind reader to know that your latest description is what is really happening.

Now that we have a clearer description of the issue, I'd do this.  First, look for ANY shorts in the wires coming from the coupler to the motherboard.  Next, install a 1uf 50V non-polarized capacitor directly across the coupler inputs on the motherboard.

Thanks, John.  My First post said this:

Rear coupler randomly opens several times a minute.  Sitting idle, there is the audible solenoid buzz and the coupler pops open.  Close it and wait a few seconds and it happens again.  

Since the engine isn't moving, I doubt its dirty pick-ups.  It'll do this underway or just sitting.  I think it's ok other then this problem, and dang, it's been a great engine until now.

What board needs to be replaced / where should I start?  I know there are a number of interconnected boards internally, but I'm not clear on which does what...

Based on that, I thought it was pretty clear what was happening.  Someone else misunderstood about it losing it's programming.  I was just trying to clarify and bring things back to my original query.

I do appreciate all the help.

I ran the engine yesterday for an hour or two, and didn't notice any erratic behavior.  However, it just stopped after that time.  Sounds were working fine, but it refused to move.  I could blow the horn and adding power increased the engine pitch accordingly (the fake diesel sound).  I tried the Aux-2 reset, but no go.  It's definitely got some issue.

-Randy

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