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@SteveH,

I traced the wires from the pickups (center and outer).  The center wires were yellow, and the were joined together with a wire connector and red wire was output.  The outer rail wire was black.  I found the molex like your pic.  Now a final, and embarrassingly basic question.  I expose some of the red and black wire before the molex, and then solder one end of the diode to the exposed red wire, and the other end to the exposed black wire, right?  I couldn't discern that detail for sure from your pic.  I have shrink tubing as you suggested.

I don't want to make any assumptions on a brand new engine.  I am a quick learner, so I won't be asking this again!

Last edited by texgeekboy

To the TVS diode leads (which I trimmed to ~1/2" inch) , I opted to connect short wires to each before connecting those extensions into a three way splice (one 3-way splice for each of hot and common). The other 2 wires going into each of the 3-way connections are the cut ends of the original wires running into the molex connector.

This allowed a little more flexibility positioning the diode amongst the wire bundle, easier replacement of the diode later on, and enough room to slide the heat shrink tubing into position after soldering.  I did try to make the extensions as short as possible to keep the diode as close in the circuit as possible to the board, without actually soldering it to the board.

Here's another picture with a wider overview.

TVS in TMCC Locomotive-overview

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  • TVS in TMCC Locomotive-overview
Last edited by SteveH

@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?

Fastrack Operating Track

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  • Fastrack Operating Track
@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?

Fastrack Operating Track

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.

Operating Track with PTC-mu

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  • Operating Track with PTC-mu
Last edited by SteveH

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.

Last edited by texgeekboy

@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.

@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.

@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.

@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.

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.

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.

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