Lionel intermodal crane controller- what is inside, insight on contoller repairs.

If convenient, can you reverse the AC wires going in to the accessory?

Stan, thanks for the suggestion.  I did it this morning and ... now the slower speed is in the opposite direction than when I started.  You obviously have some theory and I am about to give up on my original thought about a diode on a rectifier.  Are these dc motors and if so what common component is reversing the polarity to them? 

There are some diodes and resistors in the controller.  I tinkered with the resistor values in the controller to improve the operation.  There was also a number of other minor mods to the pickup arms to enhance reliability.  You do need to make sure that the gear case is well lubricated, that made a significant difference in mine.  Here's a thread where I started by complaining about the operation and then described my fixes.

Lionel 6-12781 Intermodal Crane Question

John, I will do the lube you describe (I assume you mean the up / down gear box on top) and thanks for the link to your past efforts.  this one does suffer from the grabber issues you mention so I plan to try your mods.  I don't have any RK trailers but i see them in my future. 

Next of course, will be open up the controller and see what is going on.  If I understood what you did, it seems you paralleled the resistors to decrease the equivalent R and increase current / voltage to the motors. I hope it is easy to try various R values out on the bench using jumpers to see what happens. 

I also assume it would be a good idea to try to lube the gear box for moving the grappler sideways- that looks like a PITA to get into. 

Once I get into the controller, I plan to check the diodes too, hoping it will be obvious what they do.  Any theories on why reversing the AC leads (stan's idea) would appear to  reverse the direction of the poor motion?

I reduced the value of at least one resistor by paralleling, and dropped in a higher value for one of the speedy ones.  I believe they were 5W resistors, but don't hold me to that, it was a few years ago.

Yes, the gearbox for the traverse movement needs lube, all of them were pretty dry when I looked.  And yes, it was somewhat of a PITA to take it all apart.  I'm tempted to try to obtain the metal gears for mine in case the plastic ones croak.

The only thing I can think of with the odd behavior reversing the AC is check to see if the transformer has a DC offset.  If it's getting a pure AC waveform, I can't imagine how swapping the leads would accomplish anything, and obviously it does in your case. Certainly check the diodes while you're in there...

I am curious what made Stan think of swapping the AC leads, that never entered my head!

My first thought was double-pole switching to reverse a DC "bus" voltage from a bridge-rectifier for bi-directional operation.  Then I looked at a photo of the controller (I've never seen one in person) and, frankly, it looks like something where cost was minimized.  Diodes cost pennies and a penny saved is a penny earned.  Half-wave rectification saves a few pennies in diodes and now you can use single-pole switching of a DC+ bus and a DC- bus.  Save a few more pennies! 

I figured reversing the input would take only a few seconds to try.  If you have another transformer try that.  Or if you have a meter, set it to measure DC voltage and see if you have substantial DC offset on your input power when you operate the crane.

But as you're going to open the controller anyway to tinker with resistors for speed control, please post some photos!

Interesting point, the half-wave operation could be introducing a DC offset that affects things.  If mine wasn't all boxed up right now, I'd open up the control box to display my mods.

Took things apart tonight and for the record, here is what it is.  My meter is not fast enough to get a good measure on the dc offset, there is a lot of noise going on- operation is pretty quick on the up- down and back and forth for the grabber.  seems this is the cheap circuit you were thinking of.  The sketch is in the sequence of the levers on the controller.  My bench transformer seems to be a bit better on reducing this effect  (cheap, 6-4060 trainmmaster- at least it has dc too  than the z-4000 it runs from on the layout.  I did lube the top gear box- still tinkering with the one with the grabber.

one more illustration relative to grabber mods noted in the previous thread- is this correct?

Start small with the mods and test.  For the tips of the arms, I just filed a little off at a time and tested with all the sizes of containers.  I think it was 1/4" total half from each side, but it's been quite a while...  For the sides of the arms I did the same thing.  The excess "flash" inside the arms kept the over-center lock from locking the jaws and it would drop containers.  After fixing it so it could close properly, it didn't drop them.

Measure twice, cut once, just like carpentry.

Thank you for posting the clear photos and schematic.  So here we have an O-gauge accessory that requires an AC supply to operate.  And I thought it was just those vibrator accessories that couldn't operate on DC!

I am curious about you initial comment about this being a "recent problem."  Did you recently add/change loads on whatever supply is powering the crane?

Stan, here is the evolution.  I first had it on a ~14v circuit that had a lot of other stuff on it (switches, floodlights, etc.), it was probably getting about 12.5 volts.  I bought a z-4000 and was running this at about 15-16 volts (meaning it was seeing 14 maybe).  I thought I had the issue solved but to be honest it was not a rigorous exercise of operation.  recently I have gotten organized with various trains (consists?) that I expect to do x, y, and z and when I had to run the crane it was performing erratically.   that is the "not very scientific" history and why I said recently. I assumed something had gone south.  I think it might be a combination of the dc offset and the fact it has been sittingtoo much, needed some of the lube discussed above, and needs to run.  Other than using John's idea on the resistors (my immediate target is the 20 ohm), is there a simple way to address the dc offset as you see the board situated? 

By the way, what causes that?

BTW to John, good advice on the take it gradually concept.  I am trolling that auction site for a cheap RK car with trailer to use with the grabber  test. 

hokie71 posted:

Other than using John's idea on the resistors (my immediate target is the 20 ohm), is there a simple way to address the dc offset as you see the board situated?

The idea of tinkering with the resistors was not to fix a DC offset, but rather to normalize the speeds of the various functions.  I found that I had to slow down the traverse action and give more beef to the crane vertical motion by changing the resistors.  I never addressed a DC offset issue, as I never saw any evidence of any DC offset, and that issue never even occurred to me.

hokie71 posted:

BTW to John, good advice on the take it gradually concept.  I am trolling that auction site for a cheap RK car with trailer to use with the grabber  test. 

Well, it's easy to file/cut material off, not so easy to file/cut it back on.