MTH PRR K-4 Conversion PS1 to PS2-3V

The number of black stripes on the flywheel is 24, regardless of flywheel size.

As for the sound volume, PS2 3v and PS3 boards use 4 ohm speakers.

@Jon G posted:

The number of black stripes on the flywheel is 24, regardless of flywheel size.

As for the sound volume, PS2 3v and PS3 boards use 4 ohm speakers.

Jon, Thanks for the reply. I tried 24 black stripes and the loco was way faster than now and that is why I went back to the 48 stripes. it is slower but not near enough. It seems that if the original PS-2 K-4 sound sets had 24 stripe flywheels they were likely to have the same wheel diameter and gearing so 24 stripes should work fine on my upgrade. The speaker is 4ohms.         j

Your PS-1 probably has a different gear ratio than the PS-2 versions.  The SF has the ratio info for scale speed.  Adjusting speed with tape is fine.  Use what you prefer.  PS-1 had 8 ohm speaker, as mentioned 4 ohm is needed.  G

Thanks G,  The .050 spacing with 48 stripes is still WAY too fast I don't know know if the tach sensor can read 64 stripes but I think I will make one and try it. The G-box on the K-4 is 16: 1 where most of the Premier MTH steam that I have counted were 18:1.   So 18/16 X 24=27 should be a good starting point. That is if I did not already know that 48 stripes were too fast. The K-4's may be destined for ERR CC boards. Hope not. I was saving my CC boards for a couple of Lionel 700e I was going to add Pittmans to. Think I'll try a 27 and a 64 stripe if neither work I'll re-install the sounds.  Thanks again to all.            j

As mentioned, older K4 different than later K4. They made a gear change on the latter. Double lead screw, so latter is also back drivable. Not sure if this change was PS2 3V or PS3 line. I do own an example, and can verify gear ratio if needed John, …..I do not know the gear ratio of the latter off the top of my head…..

Pat

@JohnActon posted:

Thanks G,  The .050 spacing with 48 stripes is still WAY too fast I don't know know if the tach sensor can read 64 stripes but I think I will make one and try it. The G-box on the K-4 is 16: 1 where most of the Premier MTH steam that I have counted were 18:1.   So 18/16 X 24=27 should be a good starting point. That is if I did not already know that 48 stripes were too fast. The K-4's may be destined for ERR CC boards. Hope not. I was saving my CC boards for a couple of Lionel 700e I was going to add Pittmans to. Think I'll try a 27 and a 64 stripe if neither work I'll re-install the sounds.  Thanks again to all.            j

I think you're going to find at faster speeds, the 64 strips start to get missed, there is a minimum resolution of the sensor.

Truthfully, if the gear ratio was really 16:1 vs 18:1, the number of strips for proper speeds should be 27 stripes assuming the same driver diameter as the Premier steam.  So, either you're measuring the gear ratio wrong or using the wrong numbers for the Premier steam.  Basic math shouldn't fail you here.

My guess is you're having some issue reading the tach strips since the math isn't working.

@gunrunnerjohn posted:

I think you're going to find at faster speeds, the 64 strips start to get missed, there is a minimum resolution of the sensor.

Truthfully, if the gear ratio was really 16:1 vs 18:1, the number of strips for proper speeds should be 27 stripes assuming the same driver diameter as the Premier steam.  So, either you're measuring the gear ratio wrong or using the wrong numbers for the Premier steam.  Basic math shouldn't fail you here.

My guess is you're having some issue reading the tach strips since the math isn't working.

Printing a 27  but still wondering why the 48 is WAY too fast. Via the math it should be slow. I went to some  trouble to make sure the sensor was square with the tape thinking the sensor could be missing some stripes even at 48 let alone 64. I don't have the experience with PS2 that I do with TMCC however I am on my 5th PS conversion and this is the first time I have had trouble with the tach sensor or tape. These two K-4 are not exactly my favorite locos I did think it would be fun to double head them. Worst case, I can stick a couple TAS boards in them. Thanks John,          j

@harmonyards posted:

As mentioned, older K4 different than later K4. They made a gear change on the latter. Double lead screw, so latter is also back drivable. Not sure if this change was PS2 3V or PS3 line. I do own an example, and can verify gear ratio if needed John, …..I do not know the gear ratio of the latter off the top of my head…..

Pat

Pat, I had no idea that MTH had any twin helix worms that were back-drivable. Good to know. Are they on the newer K4 ?    Thanks for info.          j

@JohnActon posted:

Pat, I had no idea that MTH had any twin helix worms that were back-drivable. Good to know. Are they on the newer K4 ?    Thanks for info.          j

Yes, I believe it to be PS3 run, but perhaps as early as PS2 3V wireless tether. I’ll pull them out of the case after supper and give you some information.

Pat

The twin lead also cuts the gear ration in half.  Pat may remember my fiasco with a certain Lionel Legacy Atlantic and a bad motor.  I found a motor that has the "right" worm, and it ran perfectly... except it was running at twice the speed and only had 2-chuffs!  Turned out it was a twin lead worm, somehow it meshed perfectly with the worm gear in the chassis and the locomotive ran great, just at warp speed!  The proper worm restored sanity to the operation.

@gunrunnerjohn posted:

The twin lead also cuts the gear ration in half.  Pat may remember my fiasco with a certain Lionel Legacy Atlantic and a bad motor.  I found a motor that has the "right" worm, and it ran perfectly... except it was running at twice the speed and only had 2-chuffs!  Turned out it was a twin lead worm, somehow it meshed perfectly with the worm gear in the chassis and the locomotive ran great, just at warp speed!  The proper worm restored sanity to the operation.

Ugh, ….I remember the frantic Atlantic,…….it had us in the cross hairs for a good bit!…we about came out with our hands up!..

Pat

@harmonyards posted:

Ugh, ….I remember the frantic Atlantic,…….it had us in the cross hairs for a good bit!…we about came out with our hands up!..

That was the big ugly, that's for sure.  On the bright side, it runs like a top now, all it needed was....well, pretty much everything mechanical!   It's a good looker now with the MTH running gear.

I ran into the twin helix worm vs single with the 21/42:1 gearbox on the Williams and Weaver locos. I even posted some pix of the two boxes apart and side by side .  You can swap the worms and not notice any great miss-match with the gear mesh. The twin helix has about a 40degree skew angle on the worm wheel where the single helix had about a 30degree angle. When you swap them you would never notice any binding when running the only difference was in the motor whine. However if you put on your strongest glasses you could see the shiny area the worm was riding on the edge of the teeth of the worm wheel. When the worm and worm wheel were properly matched the worm rode on the broad surface of the teeth rather on one edge.       

       Well I got the 27 stripe tach tape mounted on the flywheel right after dinner and tried her out. The slowest speed was 5.5smph 638 seconds/mile. 5.75 laps on an O-72 circle. I can live with that. however the chuff was still off. One chuff every 1.5 turn of the drivers. May try another sound set tomorrow.          j

You can also tinker with the chuff rate in the remote to adjust the chuff timing.

@harmonyards posted:

Yes, I believe it to be PS3 run, but perhaps as early as PS2 3V wireless tether. I’ll pull them out of the case after supper and give you some information.

I would love to know more about this... I wasn't aware that ANY MTH locos had back-drivable gears!  Yes, a multi-threaded worm would give a numerically-lower gear ratio and higher top speed.  I'm surprised that MTH would make such a change after so many years.

I have been hawking the .mth sound/personality files for a while now.  If you look at byte 0x08 with a hex editor, it gives you a value proportional to motor revolutions per inch (which is like the effective gear ratio taking drive wheel diameter into account.)  As far as I can tell from these files, all Premier Pacifics going back to 1995 are 16:1 self-locking, and that includes recent special runs.  However, the RailKing ones did undergo a change...  Sometime around 2017, the gear ratio changed from about 17:1 to 28:1 (still self-locking.)  This was a welcome change.  28:1 is the gear ratio that MTH had been using in their starter set steam locos for about 20 years; it's surprising that their higher-priced separate sale locos didn't benefit sooner from the greater precision afforded by this numerically-higher ratio.

@JohnActon, IF your sound file came out of a late-model RailKing K4, that would explain why the chuff and actual speed are off.  Based on the values I'm seeing in the personality files, because the gear ratio in the Premier model is much taller, you would need only 12 stripes on the flywheel to normalize sound and operation.  Following!

[Edit: corrected misinformation in my first draft of this post.]

Ted, that is great info.  Both loco files installed were premier locos but just for kicks I am going to make a 12 stripe tape. and try it. Something else I just thought about and need to consider is I was under the impression that only PS3 locos had Chain files however I was looking around the MTH  site and ran across a page with a list of PS2-3v locos which have chain files and may give that a try also.  Both of my boards with K-4 sounds are on that list (20-3125-1 and 20-3296-1). I was playing around with the Chuff rate function on the remote and #16 was close to right (two chuff per rev) however every time I remove power I have to re-apply #16 on the remote when I power up. I think that may be a chain file problem ?          j

@JohnActon posted:

Something else I just thought about and need to consider is I was under the impression that only PS3 locos had Chain files however I was looking around the MTH  site and ran across a page with a list of PS2-3v locos which have chain files and may give that a try also.

The chain files listed are for the PS3/2 board to replace the PS/2 board.  No PS/2 board has chain files.  The PS3/2 board is a drop-in (sort of) replacement for the PS/2 3V and 5V boards since those are no longer available.  If you have a real PS/2 board, forget about chain files, they don't exist.

Well I've been over at a friends house for several days and did not get to try any new ideas till tonight. Ted as far as speeds are concerned the 12 stripe tach tape certainly works better than 24, 27, 36 and 48 . The slowest speed when 1mph is set on the remote is 2.5smph (that is based on 5.83 laps=110' one scale mile in 1/48 scale) on a circle of O-72 track taking 1431.75 seconds. That is about as slow as any of my other MTH locos. None will go down to actually 1smph. I am happy with that as a slow speed. However the timed speeds get progressively faster and by the time I get to 10mph on the remote the loco is doing the scale mile in 97.75 seconds or 36.828smph. If I could get the chuff right I could live with this speed glitch.  The best I can do with the chuff rate is two per wheel revolution at about 190 degrees rotation per chuff. So they tend to drift to a slightly different wheel location each turn of the wheels. I have tried #1~16 on the remotes chuff adjustment. No luck thus far. A question I posed in my first post that no one has answered is "Do the PS-2 boards have a factory loaded file that is analogous to the chain file in a PS-3 board ? That might answer some of the questions I am having. Not sure but the board I am having problems with may have come from a railking diesel.          j

@JohnActon posted:

A question I posed in my first post that no one has answered is "Do the PS-2 boards have a factory loaded file that is analogous to the chain file in a PS-3 board ? That might answer some of the questions I am having. Not sure but the board I am having problems with may have come from a railking diesel.          j

The PS/2 boards obviously have factory loaded code, and it does determine some of the functionality of the board.  There were special "FLASH" boards with additional memory for locomotives with operating pantographs, subways and trolleys, etc.  There are also special configurations for locomotives with small smoke units, think VO-1000, etc.

The only way to know if you have a problem board is to know exactly what model it came out of.

John Thanks so much . I bought some boards at shows and removed some from RailKing locos but I did not mark which locos they were removed from. This does confirm my suspicion and explains why previous upgrades had no problems. The one I put in a N&W J was very easy and made me think all my upgrades would be just as easy. I think I will remove this board from the K-4 install it in a diesel and reinstall an appropriate sound set.  Fortunately I think the second board I have with K-4 sounds came from a RailKing steamer.  I was looking out for steamers as donors and only found one diesel that was such a deal I could not pass. I was thinking that in the future I would upgrade diesels with TMCC and steamers with PS2 or 3. I got tired of building 4 chuff smoke systems for all my steamers. Protosounds seemed like an easy answer. Thanks again,                   j          

Sorry you're having so much trouble John.  I'm not an expert when it comes to PS2 upgrades, but perhaps your tach reader is not reading all the stripes?  The ones on the 12-stripe tape are certainly wider, which might explain why it works better now.  But if it were reading them all, the speed match would be closer, and you would be getting almost four chuffs.  (Of course all of this assumes that the sound/personality file currently installed is from a late-issue RailKing K4 geared 28:1 over 1.375" drivers.)

I would double-check the spacing and alignment of your tach sensor, or perhaps try replacing it rather than replacing the whole PS2 board.

Of course if you ever load an .mth file from a PS2 or early PS3 Premier K4 geared 16:1, you'll want to change back to a standard 24-stripe tape.  Good luck and please keep us posted!