Updated! Atlas F-3 Low Smoke Output

I just picked up the f3 9962 units.  I had an issue with the b unit not being able to make an O54 curve.  But while on the Phone with Atlas I also had fan noise and limited smoke on the b unit.  They walked me through a few different key commands on my legacy remote and it did reset with no further noise and smoke works great.  I cannot remember the key sequence but would recommend submitting a request on the Atlas site.  Think it was about 1-2 days from my request to the call with good support in resolving both issues 

Thank you that will definitely help.

RRAddict posted:

I recently purchased a new old stock Atlas CB&Q F-3. It has a really low smoke output. I checked and ensured the wick was in the unit and that it was not flooded. I also notice that the resistor had a ceramic coating which none of my other smoke units have from the other brands. Does anyone have a solution for this? I am running in TMCC not conventional. Any suggestions would be appreciated.

If it's the TAS smoke unit with the thermistor, the coated resistor is what they have, it should be a 10 ohm resistor.  Since Atlas has used different smoke units in the course of production, how about a picture or two of the smoke unit?

I will get some photos but yes it is the ceramic resistor with an addition wire pressed against it.

The "wire" should NOT be pressed against it, it should have at least 1/8 to 3/16 space between that thermistor and the smoke resistor.

John, thank you,  would this be causing the low smoke output problem. Bill over at Atlas told me that any 10U wire wound resistor would work. Do you know who makes thoses, Lionel or MTH?

If the thermistor is right against the smoke resistor, I'm surprised you get any smoke at all!

This 2W wirewound 10 ohm resistor would be a good choice.  Bourns FW20A10R0JA.

Would breaking the coating from around the resister help, leaving only the exposed wires? That seems to be the norm with today’s smoke units. 

Well, the TAS unit with the thermistor always used the coated resistor, and it functions pretty well, so I'd try it that way.  However, if you were looking to try one with the coating off, I find using this one is easiest.  I put the package in a vice at a 45 degree tilt and then just take a turn on the handle and it crushes the outer shell and leaves you with the bare WW resistor.  It's easier than knocking the powdered coating off the round ones.

https://www.digikey.com/produc...J/A137434-ND/2365743

Thanks much, I have ordered some. Will these work in any other brand of smoke unit?

Not with a 10 ohm value, that's only found in the TAS smoke units AFAIK.  Lionel uses 8 ohms in Legacy and some TMCC and 27 ohms in in other TMCC locomotives.

Thanks and good to know. Do you happen to know what Ohms MTH uses?

MTH resistors are 16 ohms, for PS/2 or PS/3 they're wired in parallel for an 8 ohm load.  For PS/1, the smoke unit logic dynamically regulates the power to the resistors.

gunrunnerjohn posted:

Well, the TAS unit with the thermistor always used the coated resistor, and it functions pretty well, so I'd try it that way.  However, if you were looking to try one with the coating off, I find using this one is easiest.  I put the package in a vice at a 45 degree tilt and then just take a turn on the handle and it crushes the outer shell and leaves you with the bare WW resistor.  It's easier than knocking the powdered coating off the round ones.

https://www.digikey.com/produc...J/A137434-ND/2365743

I bought some of these resistors and removed 100% of the ceramic coating, re-wicked, and made sure that wire with the black thing on the end was not touching the resistor.  I get smoke sometimes and sometimes I don't, I have refurbished a lot of Lionel and MTH smoke unitis normally buying the resistors from them directly. I have always had success with them but this thing has me stumped.  I contacted Atlas and they requested photos of the wicking and placement of the wick. I am sure that the resistor is touching the wick correctl and that pleanty of air is passing through. Any suggestions of what may be wrong? 

From that description, I'd have to see it I suspect.  I have use a ton of these in MTH and Lionel applications and they've always worked great.  I've only put a couple of resistors in the Atlas (TAS) smoke units, and I used a coated 10 ohm resistor to match the old resistor.

I have done a lot of these too except for Atlas so I will let you know what Bill over there at Atlas tells me after I send the photos to him. Can I buy ceramic coated resistors for MTH PS 1, 2, and 3 locomotives as this is a lot more cost effective way of stocking up?

You can buy any resistor you like.   I've found that the exposed windings do a better job, and specifically get the smoke going a lot quicker.  The point of the ceramic coating is to dissipate heat, but for a smoke resistor we want to dissipate the heat in the fluid soaked wick and let the hot resistor vaporize it.

Does the PS 1 locomotive have 8 OHM resistors?

MTH standard resistors are 16 ohms for the full sized smoke units.  The PS/1 smoke unit has two 16 ohm resistors and an electronic regulator to allow them to operate on a wide range of voltage for conventional operation.  PS/2 and PS/3 smoke units have two parallel 16 ohm resistors.

Thank you very much for all the help.

I contacted Atlas and there were great at walking me through getting this thing smoking. I replaced their resistor with one of the ones John suggested and positioned the  thermistor in the position Bill at Atlas suggested. I have included a photo of the proper position that they sent me. I hope that this helps other newbies to Atlas locomotives. 

Excellent, thanks for the update.  I'll keep that in mind if I run across these.