LCRU problems

I'm trying to get two LCRU boards running, plus this is my first foray into TMCC, so there is much I am learning, and I'm having some issues.

I have two Command Bases and two CAB-1's, both purchased used and said to work by previous owner. No reason not to believe him, but they are unknowns.

LCRUs - both sold to me in "Unknown" condition - both old style with large pins for soldering

SETUP: I did a bench mockup which includes the LCRU hooked to an electric coupler, a headlamp and a "smokelamp" to simulate the load of the smoke unit. Chassis ground is hooked to the U terminal on my 1033 transformer, and the power (red) lead from the LCRU is hooked to the A terminal. The whole affair is hooked to a known good motor from a 600 series diesel (single field winding).

Wiring:

F to "smokelamp"

E to headlight

C - NC

D to rear coupler

N (black) to run/pgm switch

M (white) to chassis ground *

I (violet) to run/pgm switch

B (black) to ground *

* Per installation guide, white+blk both tied to ground for a steam engine w/smoke

RESULTS: When started up with the Command base unplugged, board #1 runs ok in Conventional, i.e. it has forward, neutral, reverse, neutral, etc. However in both neutral states, the "smokelamp" flashes at about 1 pulse/second, while the headlight is steady ON - is that normal? I found a wiring diagram for the 610-8043-001 C&O Hudson that shows E is the smoke terminal and F is the headlight, opposite of what's in the LCRU installation guide. That same Hudson diagram also shows M and B both tied to ground which is the same configuration I am using from the installation guide (for a steamer.)

When the command base is powered up it has a green power light and when the CAB-1 speed knob is adjusted, the Command Base provides a flickering red light. When various CAB-1 buttons are depressed, the Command Base once again provides red blips. The problem is that the engine continues to run in conventional mode. There's no apparent recognition of the TMCC signal.

The other board you ask? Board #2 is dead as a doornail. Nothing, nodda, zip. I swapped the PIC chip and the "deadness" followed the chip, so I'm fairly certain I have at least one dead PIC chip.

Questions: So is my wiring correct? Is there another combo I should try? Is there a more definitive test?

In any event, I suspect the PIC chip that provides conventional operation (but no TMCC) is damaged, just not all the way.

Anybody have a spare, known good PIC chip (LCRU 0412) they would be willing to sell?

George

Original Post

George,

I'm not in a great position to grab my notes at the moment, but here are a few thoughts off the top of my head:

1) You didn't mention that you wired an antenna to the LCRU. If you didn't, it might cause the behavior you describe of no TMCC operation.

2) I THINK that's normal behavior for the smoke output in neutral. In order to prevent cooking the smoke element in neutral, the output was pulsed. (These LCRU1 boards were pre-fan-driven smoke units.)

3) Didn't I get you an extra PIC chip for these boards already?

TRW

PaperTRW posted:

George,

I'm not in a great position to grab my notes at the moment, but here are a few thoughts off the top of my head:

1) You didn't mention that you wired an antenna to the LCRU. If you didn't, it might cause the behavior you describe of no TMCC operation. I hooked the antenna wire to the chassis ground, then to the hot (center roller) lead - same result. Then I swapped the transformer leads since I "rediscovered" that the 1033 is supposed to be wired A to outer rail, U to middle rail, plus I swapped the antenna lead again. All possible combos with the same result.

2) I THINK that's normal behavior for the smoke output in neutral. In order to prevent cooking the smoke element in neutral, the output was pulsed. (These LCRU1 boards were pre-fan-driven smoke units.) Exactly what I suspected, but didn't want to "lead" the response - thanks!

3) Didn't I get you an extra PIC chip for these boards already? You know, I forgot about that, but yes, you did! It's the two-broken-leg chip (nice soldering BTW) and it's the one that at least provides conventional operation. Now that I know you had already tested the chip, that kind of points me in a different direction. Unfortunately I'm at a bit of a loss on where to look next. I'm missing something....

 

1) The antenna wire is just that -- an antenna -- and it shouldn't be connected to anything. Grounding it out will force the board into conventional mode, and I'm afraid to even know what connecting that output to the center rail will do. Connect a six inch wire or so to that antenna stickpin on the board, and don't connect the other end to anything.

3) That's what I thought. The board it came from had some physical damage, but I tested the chip in both conventional and TMCC modes (in a known good LCRU1) before sending it to you. Unless it was damaged (see above), it should be fine.

TRW

PaperTRW posted:

1) The antenna wire is just that -- an antenna -- and it shouldn't be connected to anything. Grounding it out will force the board into conventional mode, and I'm afraid to even know what connecting that output to the center rail will do. Connect a six inch wire or so to that antenna stickpin on the board, and don't connect the other end to anything. My bad, I didn't read what you wrote. I do have a 6" wire hooked to the antenna lead on the LCRU bd. I was telling you about the antenna wire coming from the Command Base. 

3) That's what I thought. The board it came from had some physical damage, but I tested the chip in both conventional and TMCC modes (in a known good LCRU1) before sending it to you. Unless it was damaged (see above), it should be fine. No damage since I didn't actually hook the LCRU antenna to anything. I guess I'll wander back down to the dungeon and re-read the installation instructions to see what I missed. BTW, the wall wart for the command base is plugged into a heavy duty strip which is plugged into a 3 conductor 110v receptacle, so the system is grounded via the house wiring.

 

To continue this saga I'm looking at the possibility that my earth ground to the Command Base may not be adequate. All that I have done so far is to plug in one of the Home Depot AC wall plug testers, the kind that has 3 neon bulbs and if the proper two are lit, says you have correct wiring - my AC plug passed this test. Would you think this is a guarantee that I have a proper ground?

Those LCRU are very old and very well can be bad or have bad receivers.  Do you have a TMCC engine that is known to work to test the CAB-1s?  G

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GGG posted:

Those LCRU are very old and very well can be bad or have bad receivers.  Do you have a TMCC engine that is known to work to test the CAB-1s?  G

Unfortunately, I do not. That said, I have tried 3 different CAB-1's and two different Command Bases, mixed and matched them all, but all had exactly the same results. I feel reasonably confident that the LCRU is the problem, but I just want to make certain that my TMCC newbie status isn't causing me to miss something (like a good earth ground) that more experienced users would catch right away.

Hooray, I just found the schematics for the Command Base and the LCRU! Got the scope warming up, and I'll start anew!

George

George,

I think George (GGG) is on the right path by suggesting you put your hands on a good TMCC locomotive to verify that your set-up is OK.

As he mentioned, the LCRU1 boards (or any TMCC receiver board, really) can have a functioning microprocessor but a bad radio which would also cause the problems you're seeing. 

TRW

I gotta' sing with the chorus here, I'd find a known good TMCC locomotive and start from there.  You need to eliminate causes one at a time, and obviously the first to eliminate would be the environment.

You did not mention programming the LCRU.  Is it programed and did you move the program / run switch back to run ? The LCRU RF section was a bit flaky, if you hooked the antenna to ground or center rail you may have fried the RF section of the board.  J

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