Can I Substitute a Newer AC Smoke Regulator for the Older one? And a couple of related questions.

Your existing 691ACRG104 regulator is a Legacy regulator, the 6208201205 is a TMCC regulator.  It won't work.

@gunrunnerjohn posted:

Your existing 691ACRG104 regulator is a Legacy regulator, the 6208201205 is a TMCC regulator.  It won't work.

Well, that was easy

Any thoughts on the other 4 questions, especially the wiring issue?

@GeoPeg posted:

Well, that was easy

Any thoughts on the other 4 questions, especially the wiring issue?

This is the legacy IR downward facing LED driver board used so LCS track sensors can get data from this engine. It's an infrared LED so only seen with a camera that has no IR filter.

1. Can I substitute the newer AC regulator in place of the old one? NO

2. Can I buy just the impeller for the fan motor? Some searching, this is the smoke unit parts listing https://www.lionelsupport.com/...-PREMIUM-TRADITIONAL

sadly the impeller is out of stock

I'm not sure of the orginal diameter maybe this works?? https://www.lionelsupport.com/...T-IMPELLER-.500-DIAM

3. Where does the mystery cable connect to? the regulator you cannot replace.

4. What's the green "SOFT" module for? As said above the IR TX for sensor track.

FWIW, I am in the same boat on a repair job. I too have a failed legacy smoke regulator, no part is available and no good way (IMO) for a simple bypass like using the r4lc smoke triac.

Update, the green module might be how this series interfaces that speed sensor in the truck for diesel prime mover ramping.

This is why I have seen similar PCBs labeled tach but did IR duty on the VL CC2.

Edit- see this search- https://www.lionelsupport.com/search?keywords=tach

Point being- has nothing to do with smoke.

@GeoPeg posted:

And if that's not enuff,

What's with these truck bottoms? Why the oddball shape?

Appreciate any help that can be offered!!

George

Since Vernon addressed the other things, I'll hit the remaining question.  This is a standard bottom for the twist-off diesel trucks, some trucks have a roller on each end, some only have one.  Usually the ones missing a roller is to provide clearance for the hall effect sensor which I see on the axle on that end.

Sorry for the delay in responding lads, the Day called and I had to go participate! Back to the business at hand.

First off, I really appreciate the responses! But I do have a couple of lingering questions.

1. I noticed that the comment was made a couple of times, once each by Vernon and John, stating that there's no way around a blown up AC smoke regulator. So let's make sense of this - I assume what you are saying is that it's the end of the line as far as controlling this engine with a CAB2. But I also assume in my worst case scenario, that I could slap a 27 ohm resistor in the smoke unit and wire it to the 3RD connector via the Smoke on/off switch and regain some "non-remotely-controlled" smoking capability, correct?

2. Has anybody tried to troubleshoot the smoke regulator board? What seems to be the failing component? I see three  components that might be the primary culprits on this board; first an 8 leg surface mount chip, MQ4CE and I have to think this is some sort of PIC and is programmed at the factory, and therefore is unobtanium. Secondly the Triac mounted to the frame, a 2N6073B. While this triac is obsolete/no longer manufactured, Digikey does offer a substitute, a 2N6073BG. I removed mine from the AC regulator board and it checked good. Lastly, a zener diode, unmarked except for a green band at one end.

If you look closely at the above pics, it does appear to have a possible goobered up area between the brown/copper bands. I'm not that well acquainted with the failure modes of these small glass zeners, so I don't know if that's a big red flag or not. I'll have to remove it to check it, but a quick in-circuit test made it appear functional.

2. I would still like to at least test my AC Regulator before tossing it, but the wiring/connectors didn't come with the engine.

So is the above what the connections should look like?

Your thoughts on these 3 questions?

Problems:

#1 while yes, 27 Ohm smoke resistor is used in many conventional locos and some command control locos- it is off the smoke TRIAC output of an R2LC or equiv (example LCRU2). 27 Ohms is NOT enough for full unrestricted 18V track power. Further problem- anything you do to reduce voltage normally results in heat. In other words, a resistor in series- well that's just smoking hot somewhere else melting your shell. Diodes can be used, but this also generates heat and the amount of diodes to not burn up the smoke resistor is a challenge. Edit- I realize you are asking what size resistor then should you use, and sadly I do not know that value. 30 Ohms??? 35 Ohms? What did K-line use in smoking cabooses- the ones specifically for command?

#2 Catch22- this is a LEGACY with specific coding in the R4LC that no longer uses the normal smoke TRIAC output. So unlike a TMCC engine with an R2LC and that firmware where the smoke TRIAC can be used.

#3 the original smoke regulator uses a tiny microprocessor and code to read the serial data commands (specifically Legacy commands in this case) and then also modulates the TRIAC AC smoke output to "regulate" the amount of power over time the resistor gets (chopped AC waveform). The thing that dies is often the tiny microprocessor- hence it has proprietary Lionel firmware we cannot copy- hence even if you replaced the chip- you would have to write your own custom firmware to do the function.

#4 To test the smoke regulator- since it requires R4LC Legacy serial data- is basically the same wiring as in the engine. Also, I'll add that serial data is a direct pin output of the micro on the R4LC, and since those are near impossible to replace too- I would have a serial buffer in place

I know you are being hopeful and optimistic- but at some point let the reality set in.

You have a few good working components and a few bad ones. The risk of you then further breaking some key working components like the R4LC trying to "repair" a smoke regulator..................

If you are asking how a smoke regulator fails- dozens of ways.

Could be the TRIAC failed, problem there is the if they fail hard enough of a failure they short the AC to the gate lead. The gate is the on/off of the TRIAC, but that also means it's driven by the low DC voltage output pin on the microcontroller. In a failure- this means AC track power can shoot up the pin of the tiny microcontroller- blowing it sky high.

Or, it could be a failure somehow of the voltage regulator circuit needed to power the microcontroller.

Could be one of the MLC (Multi Layer Caeramic) capacitors shorted. This would short the regulator and/or other problems.

Of all the ones I ever tried to "fix" the resulting answer was none. Replacing the TRIAC is the assumed first step, and if that doesn't fix it, it's dead. A 100% failure rate with nothing but wasted time and parts.

I fixed one years ago by replacing the triac, but then I tried half a dozen other ones and never got another working.  I don't tilt at those windmills anymore.

The how we got here- my take on it.

Smoke has been kind of a problem for a long time. In convetional you vary the track voltage and typically, postwar steamers are 8-12V AC as a range of operating. the problem is, sizing a resistor to smoke well at 9V may get way too hot at 13V. Then came the command days and in theory a fixed 18V on the track. But the reality was- that 18V was never perfect or exact either. Lionel's own CW80 transformers chop the power and do not output a measured 18V AC RMS. This led to the whole what power source drives the smoke unit best. So again, smoke unit performance would vary without any form of a regulator and a fixed resistor value.

So- they came out with the smoke regulator- a device that fit into the TMCC/Legacy command control system, used the serial data structure to command the smoke unit levels, measured the incoming track power to chop the wave to a known output level (obviously lower "voltage" thus a lower value resistor 6-8 Ohms).

Again, the fix was, "regulate" a chopped up AC waveform to drive the lower value resistor that operates at low as 8V track voltage source, but also be able to take 18V command voltage and maintain smoke output.

And when it works- everybody is happy. You get steady smoke regardless of track voltage or droop.

When it fails, and they are no longer made, and Lionel has no commitment to maintain them- we end up here.

FWIW, just replaced the TRIAC on the problem one I have (also S03 code) a 2N6073BG is the TRIAC. I used a 6075BG (600V rated variant in same family) and this regulator is still not working. https://www.littelfuse.com/ass...C9-BC84-B8FE00272442