Lionel # 28521 Smoke Unit Issue

This unit has a self-contained smoke unit.  If you connect it to 10-12 volts from a transformer, you should get the fan and smoke.

Presuming that works, and you've swapped the R2LC, I'd check the smoke switch next, it interrupts power to the smoke unit

Attached is the Supplement that includes the parts and wiring diagram for your engine, that should help trace the wires.

Thanks John; once I get a chance to T/S further, I'll let you know what I find.

Hi John: Got to do a little T/S this morning.  I ran continuity checks across the switch and it was fine. Continuity on the two red wires from the switch also checked OK. I then stripped the thing down to the motherboard and removed it for a visual inspection and noted nothing wrong. I also did not see an obvious trace on the motherboard that brings power to the red wire on connector J3 which feeds the smoke unit. Could there be an internal trace on the board which is not visible?

Put everything back together and still have no smoke unit operation. I read zero volts at the smoke unit PC board.

You mentioned this is a self contained S/U; does this mean the unit itself lowers voltage to the S/U motor? I was under the impression the S/U motor runs on 5 volts DC or less: if so, where does the AC get changed to DC and regulated?

Still mystified why there is not voltage anywhere near the unit.

Regards,

Larry

Check continuity from pin 5 & 6 on the radio board to the switch, then to the smoke unit. Also check the ground side.

Bill

Larry,  Yes, AC comes in and feeds the element.  The other side is grounded to chassis.  The AC feed also goes through the diode to power a small regulator that makes the 5V for the fan motor.

The lack of heat or fan indicates no AC to the smoke unit.  Or a bad trace on the smoke unit.

As Bill says you need to trace the lines for the loss of power from the R2lC to the smoke unit.  G

Bill & G: Thanks for the info; I'm not real sure where pin 5 & 6 are on the motherboard. Just as a guess I went to pin 6 starting from the left hand side of the MB and got continuity from there to the forward pin on the on/off switch. I haven't found continuity from pin 5 of the MB as yet (is pin 5 to the left of pin 6 (facing front of loco & MB)?).

I also checked the R2LC for any pin orientation and didn't find anything of value on it either.

On the schematic from Lionel for the loco, the pin 6 I used would be counting up from the bottom of the page where it says "Mother Board".

Thanks for the guidance.

Regards,

Larry

The square post is pin one on the R2LC.  The pins number as follows.

1-3-5-7. . .

2-4-6-8. . .

Pin 5 & 6 would be in the third row from the left looking at the back of the R2LC with the connector up.

Hey John, you got two 2's!, I believe the top one is a 3?

John, Bill, & G: Thanks to your pin explanation John, I ran the following continuity checks and found the following results. references are to the Lionel schematic.

1) Smoke unit "power in" (red) is continuous to the 5 pin J3 connector on the M/B.

2) Smoke unit "ground" (black) is continuos to the 5 pin J3 connector on the M/B.

3) Smoke unit "power in" (red) is continuos to the SMK/NO SMK switch center terminal.

4) SMK/NO SMK switch (red) wire is continuos to the 5 pin J3 connector on the M/B.

5) Pin 5 to pin 6 on the M/B R2LC connector pins shows continuity between the pins.

6) Traces on the smoke unit board visually good; resistor is 27 ohms.

Based on the above, my impression is the R2LC is the TMCC "electrical switch" to supply or not supply a ground signal to the Smoke Unit assembly(?). If that supposition is indeed correct, there must not be a good trace between MB R2LC connections at pin 5 or 6 and the J3 connector on the MB where the SU red and black wires pick up their voltage and ground. Do any of you have other thoughts? Bad MB trace?

Thanks for all your help so far-most appreciated.

While this is not a deal breaker for me as I generally don't run smoke in my smaller layout room now, it just bugs me in case I did ever want to sell the unit. I still love the Alco "about to throw a rod" RailSounds suite.

Regards,

Larry

Yep, I fixed it.

Have you done continuity from pin 5 or 6 directly to the smoke unit connector with the switch on?  If that's good, check continuity from the other lead on the smoke unit to frame ground.  If both are good, did you try testing the smoke unit independently with power on the input from a transformer?

You said you have already swapped the R2LC, does the smoke work in the other locomotive you took it out of?

Finally, with the R2LC unplugged and the smoke unit unplugged, try checking pins 5 or 6 on the R2LC socket to frame ground.  You should NOT get a connection, perhaps we're dealing with a short to ground here.

Larry,

    Pins 5 & 6 on the radio are AC hot for the smoke unit. Measure from pins 5 & 6 to the smoke unit, then work your way back if you don't have continuity. Check the ground side of the smoke unit to the frame for continuity.

bill

If the smoke output is shorted to frame, it could be cooking the triacs on the R2LC when you try to turn on the smoke.

John, Bill, & G: I have verified the SU works independently when power is applied. I also verified the "other" R2LC is still operational in its diesel application ( a #28200 D&H U30C).

I have to put this to bed for today as the Commanding General has other things for me to attend to.

I'll keep you posted on progress tomorrow.

Regards,

Larry

Running out of things to check...

Good morning John/Bill/G: One update I can provide today so far - last night I placed the loco on the track and powered it up and got no smoke unit operation. With the engine idling, I took a test lead from the center rail to the "red" power in connection on top of the SU printed circuit board and the SU worked like designed, so I believe we have the ground signal, just not the power signal from the R2LC to the J3 connector on the mother board.

Have you actually measured the continuity from pins 5&6 (either one) on the R2LC to the connector on the smoke unit?  If so, does it open when you flip the smoke switch?  That's the path to power the smoke unit.

I have a dumb question.  Have you reprogrammed the R2LC with the proper code for a diesel with smoke?  I've had them come in programmed for a strobe, and that won't get them smoking.

After you set the engine ID with the RUN/PGM switch to PGM, do the following.

AUX1, 8

Then power down and switch back to run.

I was thinking the same thing John, but he said he tried a different radio and I figured he performed the reprogram.

Bill

I'm running out of ideas Bill.   If there is continuity to the R2LC pins direct from the smoke unit, and the triac has been proven good, what's left? 

Bill & John: The re-program did not accomplish our goal of a working SU. I do not get continuity from either pin 5 or 6 at the R2LC pad to the smoke unit power-in feed (red wire).

Regards,

Larry

Larry,

   Work you way back, pins 5 & 6 to the switch, power in and out on the switch. Then move back and measure pins 5 & 6 where the power wire is connected to the mother board.

John, 

  We are running out out of ideas.

Bill

Well, the missing continuity is clearly the issue, now you just have to find where the wire is broken.

I agree John & Bill; I need to go run some errands with momma. I'll get back to you once I get time to play with this again.

My gut feeling is a broken trace somewhere within the MB as there are no identifiable "outer" traces on either side of the MB going to pins 5 or 6.

What do you think of running an external wire jumper from pin 5 or 6 to the smoke unit for a trial?

Regards,

Larry

Nothing wrong with jumpering it, just make sure the jumper is on the right pins.   I good place to jumper is from pin 5 to the smoke switch, easy to get on each end.

Where did this end up Larry?

Did you get 'er smoking?

Rod

Hi Rod; had to take a break from this and work on some chores. I'll likely work it again Saturday. I'll keep you posted on my findings. The unit itself works just fine once you get juice to it. The issue is turning it on and off via the Cab1 or CabII.

I plan to try a jumper and see what happens....

Larry