Airpax Snapac "Instant" Hydraulic-Magnetic Circuit Breaker

@SteveH,

Thanks for getting back so quickly.  That picture totally clarifies this project.  Regarding the secondary issue I had with the fastrack operating track, the uncoupler was okay, a wire underneath was totally fried.  I replaced just that wire, and it's working.  I have some PTCs on order, and will put them in as you suggested, however your track wiring you posted on the other thread isn't close to what I have, as far as I can tell.  The B&W stock picture below looks like what I have.  (FYI, the wire connecting the 2 red circles was the one that was fried.)  It looks like the wire connected between the green and blue circle is what provides power the uncoupler.  I think the PTC should go between the green circle and the uncoupler, Correct?

@texgeekboy posted:

@SteveH,

Thanks for getting back so quickly.  That picture totally clarifies this project.  Regarding the secondary issue I had with the fastrack operating track, the uncoupler was okay, a wire underneath was totally fried.  I replaced just that wire, and it's working.  I have some PTCs on order, and will put them in as you suggested, however your track wiring you posted on the other thread isn't close to what I have, as far as I can tell.  The B&W stock picture below looks like what I have.  (FYI, the wire connecting the 2 red circles was the one that was fried.)  It looks like the wire connected between the green and blue circle is what provides power the uncoupler.  I think the PTC should go between the green circle and the uncoupler, Correct?

Short answer, yes, you're supposition is correct.

That's interesting that the wire between the two red circles melted.  It's a jumper between the two topside center power rails on either side of the magnet.  It's failure may or may not be related to the coil.

You're right of course about the Operating Track wiring being different from the 5" Uncoupler.  The connections for the PTC are similar though.  Here's how I connect them.  Desolder the hot side coil wire from the green auxiliary rail tab where the orange line is below.  Note that this is enamel coated wire and all but the end that's already soldered likely will not easily take solder without removing more of the enamel.

I would suggest covering the PTC leads with heat shrink tubing before soldering it between the rail tab and the coil wire as shown below.

@SteveH,

Would it be sufficient to connect the diode to the hot/ground wires going into the molex connector, or does it need to be where the 2 pickups get bound together with a wire nut (and the third wire of that binding is the one that goes into the molex)?

High frequency current waves (the transients) are much shorter than 60Hz waves.  High frequency voltage will be at a minimum inside the diode, inches away it can be at a maximum.  Protection offered by a TVS diode will be optimized by keeping the electrical path as short as possible from the Molex connector's Hot pin through the diode and back to the Molex Common pin.

@SteveH,

Sorry to bother you again on a revived old thread.  I successfully installed the TVS diode in my 6-18565 command control equipped GP-9.  I also bought a 6-38312 F3.  It is not command control equipped, but does have a circuit board or 2 inside for sounds.  I figured out where to install the diode on that, and have done so, and it runs fine.  The problem is the horn on the F3 only works about once every 5 times I click the whistle control, but the horn on the GP-9 is absolutely perfect.  I have a fully refurbished ZW with the upgraded diodes, so that's not the problem.

The question to you is, would the TVS diode in the F3 cause the horn to function very sporadically?  As I said, the horn in the more advanced GP-9 works fine.

Depending on track voltage the diode could be interfering with the circuit that sounds the horn since i think the horn button is a diode and capacitor itself that adds a DC offset.

@rplst8,

Thanks.  I should have also asked if the TVS diode is important in the non-control equipped F3.  The discussions on the TVS diode installs always centered on the need to protect the expensive circuit boards for the command control.  Are the sound boards as susceptible to damage if the TVS diode is removed?  Unfortunately I never ran that F3 without a TVS diode so I have nothing to compare it to.

Before the end of the week I plan to remove the TVS diode to give  it a whirl.

With a 1.5KE39A correctly installed across the incoming track power leads to the sound board, there shouldn't be any interference with horn operation. Unlike a typical rectifier diode which blocks current flow in one direction, this TVS diode, is a bi-directional Zener diode. When good, and the voltage across it is below 33V, it acts like a its not there ( except for a high capacitance). It should not interfere with normal track voltage even with the additional 5VDC horn/whistle offset.
I suspect the intermittent horn operation is unrelated to the TVS diode.

Starting a new topic for this specific issue may yield more help from others here on the forum.

I agree with Steve, if the proper TVS was used, I seriously doubt that is the issue.  I build TVS diodes into products, and they've never been an issue or caused any such malfunctions.

Thanks @SteveH and @gunrunnerjohn, I’m guessing it’s something with the F3. I’ll start a new topic on it if I get annoyed enough with it.

If second best location for a TVS is at the track feeds and you are using FasTrack is there a place to put them NOT under the layout or under the FasTrack roadbed to make them easy to test or replace since the FasTrack is screwed down. 

John

@Craftech posted:

If second best location for a TVS is at the track feeds and you are using FasTrack is there a place to put them NOT under the layout or under the FasTrack roadbed to make them easy to test or replace since the FasTrack is screwed down.

John

How about on top of the layout.  Could be hidden with an easily removable piece of scenery or a building.

@SteveH posted:

How about on top of the layout.  Could be hidden with an easily removable piece of scenery or a building.

That's what I was asking.  Do you mean a surface mounted terminal block on the layout next to the track hidden under scenery?  With non-roadbed track this is really straight forward, but since so many people have FasTrack I was wondering if there were any new and clever ideas.

Thanks

John

@Craftech posted:

That's what I was asking.  Do you mean a surface mounted terminal block on the layout next to the track hidden under scenery?  With non-roadbed track this is really straight forward, but since so many people have FasTrack I was wondering if there were any new and clever ideas.

Thanks

John

Could be a terminal block.  Could also be two leads with the diode soldered to the ends on top of the layout.

@SteveH posted:

Could be a terminal block.  Could also be two leads with the diode soldered to the ends on top of the layout.

That gives me an idea Steve.  I have two terminal Euro type terminal blocks.  I may just screw them right onto the roadbed.  Low profile and easy to replace then.

Thanks,

John

@Craftech,

Would you mind posting a pic if you do that?

These are installed under my layout at each power drop, but could be adapted to the topside.

@texgeekboy posted:

@Craftech,

Would you mind posting a pic if you do that?

I'd be happy to.

John

@texgeekboy posted:

@Craftech,

Would you mind posting a pic if you do that?

Here you go:

John

Not screwed down yet.  Could be screwed down at angle on roadbed or on layout.

Be careful installing too many TVS diodes across the tracks if you run DCS.  The capacitance of the TVS devices add up and will degrade the DCS signal.

@gunrunnerjohn posted:

Be careful installing too many TVS diodes across the tracks if you run DCS.  The capacitance of the TVS devices add up and will degrade the DCS signal.

Thanks John

John

@PLCProf posted:

As an experiment, I set up my layout about 10 years ago with a "textbook" TMCC/Legacy arrangement, each 180 watt brick is connected to a Legacy Powermaster, using the recommended Lionel cables and fuses, with absolutely no other breakers, fuses, TVSS diodes or anything. No electronic failures so far despite the typical share of derailments and tools on the track. I run Legacy, TMCC, Lionchief Plus and a tiny bit of conventional.

The protection in the 180 watt bricks is fast, but the Legacy Powermaster is even faster, it is almost impossible to trip the breaker in the brick; the Powermaster almost always trips first.

No pre-war/post-war transformers involved. Personally, I think pre-war/post-war transformers are the root of a lot more electronic evil than is generally appreciated.

YMMV.

I’m curious. Did you mean otherwise unprotected layouts using pre/post-war transformers?

The reason I ask, is that after adding TVS diodes and magnetic/hydraulic breakers or wiring them through a PowerMaster, how are they any different from a modern transformer?

@PLCProf posted:

As an experiment, I set up my layout about 10 years ago with a "textbook" TMCC/Legacy arrangement, each 180 watt brick is connected to a Legacy Powermaster, using the recommended Lionel cables and fuses, with absolutely no other breakers, fuses, TVSS diodes or anything. No electronic failures so far despite the typical share of derailments and tools on the track. I run Legacy, TMCC, Lionchief Plus and a tiny bit of conventional.

The protection in the 180 watt bricks is fast, but the Legacy Powermaster is even faster, it is almost impossible to trip the breaker in the brick; the Powermaster almost always trips first.

No pre-war/post-war transformers involved. Personally, I think pre-war/post-war transformers are the root of a lot more electronic evil than is generally appreciated.

YMMV.

@rplst8 posted:

I’m curious. Did you mean otherwise unprotected layouts using pre/post-war transformers?

The reason I ask, is that after adding TVS diodes and magnetic/hydraulic breakers or wiring them through a PowerMaster, how are they any different from a modern transformer?

Ryan, good question.  I'm hoping it will entice PLCProf to revisist the forum soon.  His last visit was 10/18/22.  I enjoy learning from his insights.

@Richie C.

Please provide the source, part number, & description of your 4-screw black terminal blocks (?).

I want to buy some of those for my layout. 

Thanks in advance !!!

CB&Q Bill

@CBQ_Bill  I notice Richie C. has been away from the forum for a few days.  If you're looking for a 10-pack of the 2-position (4 screw) terminal blocks similar to Richie's, Amazon has them:

https://www.amazon.com/TDA-02-...676835164&sr=8-3

There are of course other sellers with lower prices, but if you have Prime, these are a decent deal if you want them quickly.

Here is how I set up my feed lines to the track.

These are a great alternative.

I remember this thread from the summer.  Looking at my old posts in this thread I just realized I never did close the loop on the horn on my F3.  Unfortunately I can't remember all the details.  I did remove the diode from the engine, but I believe I convinced myself that wasn't the problem with the horn.  It may have been poor track connections.  In any case, the horn works great now albeit there is no diode in the engine.

@texgeekboy  Glad you got it working.

Been using airpax 5 amp breaker with no issues for several years.  When running my large texas special (Neal Young version) my airpax starts making a very noticeable vibration noise.  Thoughts?  Thanks!

@texasspeciallionel posted:

Been using airpax 5 amp breaker with no issues for several years.  When running my large texas special (Neal Young version) my airpax starts making a very noticeable vibration noise.  Thoughts?  Thanks!

In my experience the vibration noise happens when the current starts to get close to the rated amps of the breaker. Use a 7.5 or 10 amp Airpax and the noise should go away.

The 5A Airpax are prone to buzzing in 18V AC applications. The 7.5A version hits the sweet spot for most O-Gauge applications.

Thanks!  Been trying to find a 7.5 but look to be on back order.  Thanks for the feedback!

One of my Airpax Snap breakers failed open today. It did not trip.  The plunger, off/on switch, still works, but no power through the breaker. The layout is TMCC, 4 powermasters, and a ZW.  The load was heavy. TVS diodes on each ZW channel and in the locos. All of the TVS are still good. Took a while to track down the Airpax was the problem since it was not tripped. No damage to the loco. It still works fine. Powered the track block with the another channel on the ZW using the same Powermaster to test the wiring and integrity of the track.

I have not yet replaced the Airpax, but wanted suggestion on what to look for before I start taking the breaker box out.

Anyone have an Airpax fail open and not trip?

Well, this morning everything is working correctly.

Thanks for considering this.

Sounds like another breaker in front of the Airpax tripped and reset.

If it's going to fail I'd rather it fail open for sure.  I've only been using the Snapac a short while.  @Santa Bill K, what did you determine was the issue?

I ckecked voltage from the ZW, through Snapac. Voltage went to 0 after the Snapac. I am running TMCC with PowerMasters (4). I swapped power Masters with no change in the results. I checked continuity through the cable from the ZW to the power master and the cable was good. Everything was good on both sides of the Snapac. So I went to bed. The next morning I powered up the whole layout and the green lights were lit on all 4 of the power masters. Everything has been fine ever since. I may put the heavy load, 7 lionel 2500 passenger cars and a caboose on my Lionmaster 4017 Big Boy, on to see if it happens again. May take me a day or so. I have been running 4 Kline heavy weight passenger car with no problems.

I should add the tubular track is Menards O54.

Good luck finding the gremlin.