Well folks, into the vat again.  The front stack on the BB stopped smoking with no fan air and no heat and I got the 4 blink sequence in the cab light.  Up to that time, both stacks were smoking bellows along with the whistle after Mike's overhaul.  Got about 20 minutes of run time.
So, I bit the bullet and took the boiler off and snapped the following pics.  I disassembled the dual smoke unit and you can see the innards.  
Learned the following: The left side of the board and left fan and left heating element is designated smoke 1 on the board and is for the rear stack.  The right side of the board and right fan and right heating element is designated smoke 2 on the board and is for the front stack.
Noticed the following:
Both funnels feeding the heating elements were charred a bunch.
The heating element for the front stack was more black than the one for the rear stack.
The thyristor for the heating element for the front stack was 1/4 inch from its heating element.
The thyristor for the heating element for the rear stack was 1/8 inch from its heating element.
The wick for the left side for the rear stack looked burnt - don't know if that is normal.
The wick for the right side for the front stack looked more burnt.
The black reservoir containing the wick was bubbled out on both sides due to over heating.
So, now for questions:
What component failed - fans, heating elements, thyristors, entire board.  How does one check each component?  Any help would be appreciated.

IMG_0229IMG_0220IMG_0223IMG_0231

RickM46

And now it starts.

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bigdodgetrain posted:

one thing I noticed is not enough smoke fluid, which caused the wicking to burn.

Thanks BDG, I have fallen into my nemesis - that being starving the units.   Smoke was bellowing out of both stacks before the front one stopped; so, now I am thinking that volume of smoke is not the only indicator; time is the other factor.  After 10 minutes of running, I should have added more fluid.  BUT the gotcha is if you add too much, you mess up the fans and any other circuit boards around.

RickM46

And now it starts.

Have been searching for topics on the forum regarding what I called the thyristor - don't know if that is the right name for the component next to the heating element.  A spec was mentioned in the forum for how close it had to be to the heating element.  I think I saw somewhere where Jon (retired) of Lionel mentioned it.

RickM46

And now it starts.

The thermistor should be vertical off the board parallel to the smoke unit.  That seems to produce good results for my VL-BB.  When I had very poor blowdown smoke, I checked that smoke unit and the whistle smoke unit.  The whistle had it parallel with the smoke resistor, the blowdown had it leaning in right next to the resistor.  I adjusted it to be like the whistle, problem solved.

You need to disconnect the fans from ANY electronics, then you can try powering them with a 1.5v battery.  Any smoke fan that's good should spin on 1.5 volts.  I believe the smoke motors for the VL-BB don't have plugs, so that complicates it a bit, you have to take the leads off the motor, note where the red one goes before you do.

gunrunnerjohn posted:

You need to disconnect the fans from ANY electronics, then you can try powering them with a 1.5v battery.  Any smoke fan that's good should spin on 1.5 volts.  I believe the smoke motors for the VL-BB don't have plugs, so that complicates it a bit, you have to take the leads off the motor, note where the red one goes before you do.

Thanks GRJ, per the pictures below, do I still have to disconnect the leads:IMG_0232IMG_0231

RickM46

And now it starts.

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If you have it out like this, you still have to disconnect one lead to make sure you don't cook the circuit that normally runs the fan motors.  As long as the PCB is totally isolated otherwise, you can leave one lead on the PCB.

There has got to be a reason for Lionel wick premature burning other than not enough fluid. Looking at the pictures posted I think we can see the reason. Looking at the smoke unit housing the cut out for air flow would make me think that the impeller needs to spin CCW to allow more air passing through the cutout over the resistor. Too me, looking at the impeller the way it’s mounted, it would need CW rotation for air to be pushed away from the impeller allowing maximum air flow. If I’m correct on the CW rotation the air would hit the casting in the opposite direction needed and not allowing the air to fully excape in to the resistor area causing overheating. 

Rod Miller

Just found some comments in my Lionel notes by Jon Zahornacky regarding the placement of the thermistor to the heating resistor; found them somewhere in the forum (have been looking for them again for hours but no luck) and put the comments in my notes:

Jon Zahornacky, aka SanaFeFan (smoke unit engineer for Lionel, retired) said that the smoke units were engineered for the factory block of wick to work with the heat resistor, a thermistor located 1.6mm from the heating resistor and with the wick block a certain distance and density to the heating resistor.  You cannot buy the factory block of wick.  So, it is critical that you locate the replacement wick and its density and thickness and depth as close as possible to the original factory block and not block the fan air holes.

1.6mm converts to 0.0629921 inches which converts to 1.009/16ths.

Correction to the description to Jon's career: Jon was more than a smoke unit engineer; he was a great engineer and inventor and held many patents for his work; happy retirement Jon!!

RickM46

And now it starts.

RickM46 posted:
RickM46 posted:

Another question, when putting new Lionel wick 691SMKP008 in each compartment, how many ropes after shredding per compartment?

Any ideas?

Thanks Rod!!  Am waiting for comments on your fan rotation above.

RickM46

And now it starts.

romiller49 posted:

There has got to be a reason for Lionel wick premature burning other than not enough fluid. Looking at the pictures posted I think we can see the reason. Looking at the smoke unit housing the cut out for air flow would make me think that the impeller needs to spin CCW to allow more air passing through the cutout over the resistor. Too me, looking at the impeller the way it’s mounted, it would need CW rotation for air to be pushed away from the impeller allowing maximum air flow. If I’m correct on the CW rotation the air would hit the casting in the opposite direction needed and not allowing the air to fully excape in to the resistor area causing overheating. 

I see the point you are making and I noticed the same thing in another VL engine, the Baldwin Centipede, which has four single smoke units. In those units, however, the fan motor was wired so that the impeller would spin CCW so as to propel air directly into the cut out leading to the resistor.

However, I'm not sure that this would account for the sort of heat damage caused here, which is not minor. Also it would be a design defect, meaning that it would have appeared in other VLBBs and (a) I have not seen any reports of that and (b) it has not happened in mine. Going back to the OP's original post, everything (fan, heater) failed, which might indicate a main board failure.

As this engine was serviced by Mike R. I'd email him to ask what he thinks. I would not discount lack of smoke fluid as a cause of overheating as in my experience these units use up fluid very quickly. Mike R. also referred to this in the instruction video made in connection with the issue of engine, which I took as a kind of warning to keep them topped up.

In the pictures above if the impeller spins CCW the air is being pushed via the concave portion of the impellers. The air needs to be pushed via the convex portion of the impeller. I checked this against an MTH unit and they engineered the air to be pushed via the convex portion. There is no way to get this with the Lionel unit as is. You may try pulling the impeller out and turning it over so as to push air on the convex side of the impeller. I’m not trying to discredit the Lionel engineer that designed his smoke unit but I think it is a flaw. 

Rod Miller

Gentlemen, thanks for all the help on the smoke unit.  I am now thinking about what components I can check to determine which one is at fault.  I can test the fans but would like any advice on how to check the resistors and thermistors.

RickM46

And now it starts.

The Smoke Elements should read about 8 ohms.  You can measure them right on the PCB since you have it disconnected from the loco.  The fans should spin at 1.5v.  They can take up to about 6v without damage.  I usually put ~3v using a couple of AA cells to check them out.

The damage to the smoke funnel looks like things got very hot.  The batting looks charred, but in reality it is not charred, it is the fluid that burned and produced the burnt residue on the batting.  This is a common misconception that the batting burns, the matted batting in this loco does not burn or char.  It is the burning of the fluid (it is a lamp oil) that produces the residue.  Using the newer "string like" batting does melt however, and the reason it smokes more is the temperature is hotter with the less dense material.

Having designed the electronics system in this loco, I believe the reason your loco failed is the thermistor could not sense the temperature created by the element due to the residue.  The temperature path for the element to the thermistor is through the fluid dampened batting.  When the batting is not saturated, the temperature rises on the element, but the air between the thermistor and the element is a poor conductor of the heat, relative to a saturated batting material. Low fluid level will cause this condition to happen, and then the element will overheat.  The smoke unit can handle this for the most part, but repeated power cycles with low fluid levels will cause the damage you have.  Again, I am guessing a bit here, it may be you just have a failed RCMC smoke circuit...

You may have damaged the RCMC, but the only way to know is to repack the smoke unit and try it.   If the element is ~8 ohms, then you should not get a 4 blink.  It is possible the thermistor failed, it should read about 50k ohms cold, you can measure it with a meter as well.  If the thermistor fails, you will also get a blink code.

I also suggest Lionel premium smoke fluid, as it is non-conductive.  Unless you get the RCMC fully saturated with Lionel premium fluid, RCMC should not be damaged.   Just wipe it off best you can.

Hope you get your loco back running!

jon

Lionel LLC (2006-2017)

Jon,

Thanks as always for your detailed explanation and insights.  Is the original "block" style batting material available anywhere for purchase?  I think Lionel no longer sells it and switched over to the angel-hair or I believe you referred to it as "string-like" batting.  Thanks.  

Glad retirement hasn't taken you off the Forum, but do hope you're enjoying it (and your trains).   

Dave 

Dave

S happens

TCA, NASG, ACSG W&OD

x-Chief Wrench & Bottle-washer of Precision Flyer Repairs 

Jon, thanks a million for your explanations above.  They certainly bring to light your engineering technology and thought that went into the smoke unit and even the rest of the design of the components of the VL Big Boy.   At this point, in my use of the stack smoke units, I think I am the 500 pound gorilla that kicks around Samsonite luggage in that commercial totally ignorant of what it took to create that marvel.  I have always been too conservative in feeding my smoke units fearful of overflowing and ruining circuitry and then drowning others - the aforementioned gorilla. 

I am only using Lionel smoke fluid now and glad to know it will not harm circuitry.

Also, this needs to be said, due to my mistreatment of smoke production, Mike R. rebuilt all the smoke units in my engine and replaced the RCMC located way rearward of the stacks (I drowned that by overfilling blow down way back).  His repairs were first rate;  he did them so that you can't even tell the original fixtures were touched and still look like factory; very neat and precise.  But, enter the aforementioned gorilla again. 

However, I have noticed that the whistle unit shows no charring and the resistor looks clean - yet another clue.

I have no electrical/mechanical skills and would not know how to use a meter; but, really want to get the BB stacks going again - only the forward stack failed; the rear one was still functioning.  To that end, I have ordered all available components from Lionel parts for the dual stack smoke unit including reservoir, both fan motors and fan blades, divider, wicking, and the complete board with funnel, resistors, thermistors.  I do not plan to assemble it myself; am hoping for the skills of someone on the forum - anyone care to help?

Two questions:  You mentioned that the new RCMC located way rearward may have been damaged due to the front stack failure; didn't know that could be a result?   In some previous threads, you mentioned that the thermistor should be located 1.6 mm from the resistor, is that true for the stacks?

Thanks immensely for your help!

RickM46

And now it starts.

BTW, the RCMC was never under the main stacks.  It's always been in the middle of the boiler under the cover with all the switches.

As for repacking these things, I need to do that to mine as well as it has never smoked well at all.  So the thermistor needs to be down in the wicking as does the resistor so that it does what it suppose to do?  That's good to know as I would have probably moved it closer to the PCBA.

Sinclair, as you know, I have been knee deep into my VL BB since April.  With each step, I have learned a bunch.  Now, as this goes on, with smoke units: wick must be wet enough and firmly packed enough to allow the thermistor and resistor to work using the wet wick between them as a means of temp sensing; the distance between the thermistor and resistor is critical; smoke fluid used must not obstruct the latter; char must not obstruct the latter; the thermistor and resistor must rest enough onto the wick but not covered by the wick (resistance felt against the wick when mounting the board) ; lastly, density of the smoke plume AND run time is critical.

RickM46

And now it starts.

Per Jon's advice, I put a True RMS meter on the components of the smoke unit board and got the following results:

Smoke 1 - left side of smoke unit - rear stack - still working: Resistor has 8.5 ohms, thermistor 49.6k ohms.

Smoke 2 - right side of smoke unit - front stack - not working: Resistor has 12.8 to 13.5 ohms, thermistor 50.5k ohms.

Don't know what the readings mean.

RickM46

And now it starts.

RickM46 posted:

Per Jon's advice, I put a True RMS meter on the components of the smoke unit board and got the following results:

Smoke 1 - left side of smoke unit - rear stack - still working: Resistor has 8.5 ohms, thermistor 49.6k ohms.

Smoke 2 - right side of smoke unit - front stack - not working: Resistor has 12.8 to 13.5 ohms, thermistor 50.5k ohms.

Don't know what the readings mean.

The Smoke2 resistor is not in spec. and why it flashes an error code.

 

RickM46 posted:

Sinclair, as you know, I have been knee deep into my VL BB since April.  With each step, I have learned a bunch.  Now, as this goes on, with smoke units: wick must be wet enough and firmly packed enough to allow the thermistor and resistor to work using the wet wick between them as a means of temp sensing; the distance between the thermistor and resistor is critical; smoke fluid used must not obstruct the latter; char must not obstruct the latter; the thermistor and resistor must rest enough onto the wick but not covered by the wick (resistance felt against the wick when mounting the board) ; lastly, density of the smoke plume AND run time is critical.

Absolutely correct!!!

jon

Lionel LLC (2006-2017)

Thanks a million Jon; with all your help, now we will know how to diagnose the components.  I take it that my RCMC board may still be shaky but only way to know is to fix the smoke unit????

Last question:  Does your spec of 1.6mm space between the thermistor and resistor still hold for the stacks?

Thanks for your patience.

RickM46

And now it starts.

Hello Rick; "tuned" my VL BB smoke smoke units (blowdown/whistle/main smoke) about two weeks ago  with the strand wicking.  Left the gap between thermistor and element as I found it; about 3/32" to 1/8".  Checked elements and fan motors; all good; elements had brown residue and cleaned each VERY carefully with denatured alcohol and toothbrush.  Really was generous on the Lionel premium smoke fluid in soaking the wicking (40 drops?) before assembling.  The best tip as per Jon Z is to simply ensure the element and thermistor use the wet wicking as a "pillow" to rest on and conduct heat as necessary to the thermistor.  There are some great youtube videos on the VL BB smoke units:  "120 drops of Lionel Premium smoke fluid" is good info.  I am not a newbie to this as I have a lot of scar tissue on these "tune ups"; you have some great info above.  Wish you well; you will do fine; Falcon70

 

RickM46 posted:

Last question:  Does your spec of 1.6mm space between the thermistor and resistor still hold for the stacks?

Thanks for your patience.

The spacing is not that critical, I usually recommend the element and thermistor leads are 90 degrees to the PCB mounting surface.  I really never measured the distance the PCB mounting holes are in the correct spacing for the sensing.

jon

Lionel LLC (2006-2017)

Jon, thanks a bunch for your help; you have certainly put us in the right direction for maintaining our smoke units.  In my own experience with my board, the thermistors when perpendicular and parallel and at the same height to the heating elements have a gap of 1/16 inches exactly.   When installing the board for them to meet the wick, be careful not to bend them out of alignment.

Now for the wait for the new parts to arrive.  Many thanks to the gents on the forum for participating in solutions!

RickM46

And now it starts.

FWIW, that's what I did with mine when I had an issue with the blowdown.  The thermistor was bent up really close to the resistor, and I got very little smoke.  I just straightened it out like the whistle smoke, and it works great now.

I add my thanks to Jon for continuing to contribute here and in particular the explanation of the thermistor sensing function, which is news to me. 

In RICKM46's position I'd hope replacing the front stack resistor would do the trick without having to replace a board but all you can do is try. But if you are getting the complete smoke unit PCB with resistors already installed it's a relatively simple job to screw that to the existing reservoir with a proper amount of smoke fluid in it and see if the front stack functions. Obviously if the existing reservoir has heat damage you'll want to replace that but again what you need to do is pretty self-evident from just looking at the way the smoke unit is assembled. Good luck!

Thanks GRJ; straight up gives a gap of 1/16 inch on my old board.

Thanks Hancock52; with the new board, I will also still have to install the fan motors into the reservoir, install the fan blades on the motors, and then solder the red and black leads to the board.  Don't know if the board has holes in it for the leads.  Don't know how the fan blades are fixed onto the motors.  When they arrive, I will be consulting the forum on them.  If all goes well with the new board, I may just order new resistors for the old board and install them - nothing like spare parts.

I will keep the forum up on my progress.  Got a real charge out of using my meter for the first time and getting the ohms on the components.  Also, taking the boiler off to get at the components is easy - be mindful of the wires for the lights at the front - they are short.  However, there are boards that are buried - I would not attempt to replace the RCMC.

RickM46

And now it starts.

RickM46 posted:

Got a real charge out of using my meter for the first time and getting the ohms on the components. 

You're easily amused.

gunrunnerjohn posted:
RickM46 posted:

Got a real charge out of using my meter for the first time and getting the ohms on the components. 

You're easily amused.

In that case, so am I! I'm never so delighted as when something I try actually works.

sinclair posted:
RickM46 posted:

I would not attempt to replace the RCMC.

It's not that hard as long as you take your time and lots of photos (Hence why the top is off of mine and why I know where the RCMC is.).  But then I've never been afraid to dig in.

I hear you.  I never considered taking apart any of my locomotives - thought they were too complicated.  Now, since I have gotten into the Big Boy - right into the jaws of the behemoth - I would  give the others I have a shot once out of warranty.  Nothing like having the guys on the forum for help.  The innards of the Big Boy were masterfully constructed. 

RickM46

And now it starts.

gunrunnerjohn posted:
RickM46 posted:

Got a real charge out of using my meter for the first time and getting the ohms on the components. 

You're easily amused.

Yes, easily amused; never used my small 1987 Radioshack meter for anything other than voltage and continuity; was amazed when my new meter (True RMS) automatically switched from ohms to K ohms for the thermistor.  Management of electrons has always amazed me.

RickM46

And now it starts.

RickM46 posted:
gunrunnerjohn posted:
RickM46 posted:

Got a real charge out of using my meter for the first time and getting the ohms on the components. 

You're easily amused.

Yes, easily amused; never used my small 1987 Radioshack meter for anything other than voltage and continuity; was amazed when my new meter (True RMS) automatically switched from ohms to K ohms for the thermistor.  Management of electrons has always amazed me.

Just havin' fun with you Rick.

gunrunnerjohn posted:
RickM46 posted:
gunrunnerjohn posted:
RickM46 posted:

Got a real charge out of using my meter for the first time and getting the ohms on the components. 

You're easily amused.

Yes, easily amused; never used my small 1987 Radioshack meter for anything other than voltage and continuity; was amazed when my new meter (True RMS) automatically switched from ohms to K ohms for the thermistor.  Management of electrons has always amazed me.

Just havin' fun with you Rick.

Ha!!  More fun with electrons: Just tested Smoke 2 fan with a cobbled up 1.5 volt battery that I soldered wires to.  Disconnected the red lead from the old board and connected the battery - it ran fine; so good spare parts.

RickM46

And now it starts.

Ordered my parts last Tuesday; called to see if they shipped yet; they haven't due to personnel constraints at Lionel for the summer; will ship later this week; no worries; Big Boy is apart and sitting on my work bench (dining room table) looking all kinds of forlorn with its hat off; will keep the forum up on progress.

RickM46

And now it starts.

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