R2LC tuning

What are you using for Command Control? Base1Ls are known to have issues.

Also this could be caused by antenna issues in the engine in question. 

Pete

Don't know about the base. But I replaced the R2LC in the engine and it runs

fine. Thats why I think the origional R2LC might be a little off frequency.

Plus the fact that my other engines don't have a signal problem.

Joe

Try this.

With the R2LC installed in the engine, blow the whistle repeatedly as you slowly tune the slug in one direction.  When the whistle stops responding, stop tuning.

Now, keeping track of the turns on the slug, slowly tune the other way as you blow the whistle repeatedly.  When the whistle stops responding, stop again.

Let's say you turned it 3 1/2 turns from end to end when the signal dropped and the whistle stopped.  Turn it back 1/2 of the distance, in this example that would be 1 3/4 turns.

See if that helps.

What John says, but you may also find that doesn't work.  The other issue is the Radio chip is damaged.  Can happen.  G

Is this a plastic shell engine? I had one that had a scratch thru the trace that goes to the antenna output on the board. It resulted in the board working weakly thru the air by the remaining bit of trace on the board.

John,

Are you talking about that metal object with the slot in it? (slug)

Kinda hard to do, cause when the R2LC board is plug in, the components

are facing the motherboard. So I would have to remove, tweek, replace

and test. But its not impossible.

Thanks

Joe

Chuck,

I checked the board and I don't see any damaged traces. Also the shell is off at this

time while I'm testing.

Joe

Are you guys sure about the function of the "slug"?

The concept of "tuning" in the sense of setting an adjustment to the mid-point of operation may not apply.  The greatest effect on the center frequency of the receiver is the 455kHz narrowband filter labeled 55F as shown above.  This is a 455kHz filter with the so-called "F" bandwidth; this component is not adjustable.

AFAIK the adjustable "slug" as shown above controls the FM demodulator.  Depending on the circuit design, when "tuning" a demodulator you attempt to maximize (rather than center) the output.  That is, I believe the slug adjust how many Volts the output swings for a given shift in frequency.  In most cases you want to maximize this.

Stan, going back and forth to the failure point and picking the center point should get it close.  That's the only adjustable part on the board, so it's worth a shot, testing is free.

Stan that has been recommended as a possible fix and the only adjustable part.  It really is hit or miss.  Long time ago I was researching this for an LCRX that was weak.  I did find that the RC helicopter guys had the same radio chip as the R2LC and one of the technical guys figured out the radio chip could be degrade easily if one of the resistors on the chip was damaged.  The best you can do, or go buy a new R2LC for $40.  G

All I know is that doing this same adjustment on the TMCC base per Dale M.'s instructions fixed my issues a year ago.

Boy is that "slug" sensitive. First I tried a 1/4 turn clockwise.
Engine took off racing. Turned back to origional setting. Engine
responds but still looses signal at usual place. Turn 1/4 turn
counter-clockwise: better reception. So if a little is good, more
is better, right? Wrong. Engine took off racing again. So logic
says if 1/4 was good maybe 1/8 turn counter-clockwise is all it needs.
Bingo, works great. Don't even get the flashing light that indicates
a weak signal anywhere on the layout.

Testing wasn't as hard as I thought it would be either.
Learning point: keep your thumb over the "HALT" button, just incase!
Thank you gunrunnerjohn !
Problem Resolved.

Thanks for the feedback, interesting result.  I had never tried tuning that, but it's the only "tunable" thing on the board, so I figured it was worth a shot.

Good pickup John.

Joe,

   If Gun's tuning fix does not work, spend the $40.00 for a new Chip as GGG recommends, something may have been damaged.

PCRR/Dave

To all, thanks for the information concerning the TMCC system and "tuning" it for better reception/response.  The expertise and knowledge one acquires from this forum is immeasurable.  And all for the betterment of others in our hobby, for the hobby itself, and increase in the enjoyment of others as they observe, witness, this fine hobby and those who love it. 

To All... a salute to those who serve/have served on this Veterans Day, giving their best and all in defense of our America.

God bless.........

Jesse

okay my BB has issues responding to commands from cab-2 other times works ok would this possibly be my issue? item # 6-11436 lionel big boy #4005 cab-2 legacy system and a max transformer.

Different situation Paul, that's a Legacy locomotive with a totally different receiver.  I'd be looking for possible antenna issues, or perhaps some layout ground plane issues.

gunrunner john, thanks already addressed the ground plane issue no change.

I cannot figure out how to remove fake wooden roof to see if an antenna wire has a poor connection.

somedays it responds to smoke and aux tender on/off commands other days it needs a finger on antenna to accept commands!

all connectors and pcboards seem snug and connected inside the engine.

The TMCC Base's output frequency (nominal 455 KHz) can be tuned with one of those cans.  Legacy has crystals that control the frequency accurately without adjustment.

If you are going to occasionally run on a Legacy system (such as a club or demo), you might want to do any locomotive tuning on a Legacy system.  This might mean that you might then need to tune your home TMCC Base to match the re-tuned loco.

FWIW, my Legacy Base outputs 454.88 KHz when idling.  John, have you ever measured a Legacy Base's output frequency?  (Measuring the idling frequency is an average of the NoOp FSK frequency shifting.  A long sampling gate is required.)

The TMCC frequency does drift as the Base warms up, sometimes quite a bit.

Dale, it appears my results are about what you get.

TMCC Base, just powered on.

After running for a few minutes it's at 456.277, the Legacy base hasn't moved.

Legacy Base, just powered on.

My "final picture" for the TMCC base, after about 30 minutes it stabilized at 456.124khz.

The TMCC base drifted down in frequency 330hz as it warmed up.  Actually, not as much as I might have expected for a plain LC circuit.