PS-2 flywheel size

 If you'd like the speed to match, you may have to make a custom tape. Using any of the supplied tapes will work with the reader, however the speed will probably be off. Sometimes they do work out as is.

If you do a search on custom tapes, Dave H posted a formula.  There is a minimum size were you may not get it to work right, because the tach reader won't be able to read the stripes.  In this case, the stripes are getting smaller.

You also will have a tach reader mounting problem to get the spacing right.  Which model is this?  G

I think the real issue is keeping the speed calibrated.  As George says, there is a minimum size for the stripes, I suspect 20mm diameter is probably a bit small.

The tach reader mounting isn't much of an issue if there's room anywhere to mount it.  I've mounted a couple using some spacers and simply gluing them to the motor for the correct spacing.

Thanks Guys,

GGG - the MTH box doesn't have a model no so, even though the engine is mint, I'm guessing it's v old. It came with a Seuthe smoke unit and QSI electronics.

I photo-reduced a 27.7mm tach tape to 76% (21mm) and I'm ready to give it a go.

John - I'm fairly confident that the reader will be able to see the reduced stripes and I'm fabricating a brass bracket to place the sensor 0.75mm from the tach strip.

BTW, I've seen a similar Pittman motor/20.9mm flywheel combo on Williams brass engines.

I'll let you know how the tach strip works

The number is 20-3008-1  There is a PS-2 upgrade file posted.  Let us know how it turns out.  G

The problem may be that at speed the sensor starts missing counts.  The experiment will be interesting.

Thanks GGG - got it.

I hope this loads OK because the last USRA 4-6-2 file I loaded had Chipmunk sounds.

If the tach tape stripes are narrower than those on the 27mm tape, PS2 will not work.  That's the official word I got some years ago from MTH R&D, when I upgraded a Weaver with a 21 or 22mm flywheel.  I had made a 22mm tape with same number of stripes as the 27, and loco went loco.  I used a 27mm shortened and have accepted that speed is off.

Good idea Hugh, but I think he said that the reason the flywheel was small was the space available.

Hugh,

John is correct, there is currently about 1.5mm clearance on either side of the flywheel so, after adding the tach strip, there's no space to increase the diameter of the flywheel.

The same reflective striping method is used on their HO engines with flywheels smaller than 21mm.  So if you're determined to get the correct scale speed I think you're on the right track.

I've got a Williams/Samhongsa USRA 2-8-2 and the flywheel measures 25.4mm.  I also have a Weaver 4-6-0 and I think the flywheel is the same diameter.

Does that mean I need to make new tach tapes?

I'm surprised both flywheels are that small, given there seems plenty of room for a larger one.

Sorry, I missed that in the read as being the major issue. On those very early engines with all the odd ball stuff, there is always much fabrication to do to get the fit right.

I finished a diesel up recently where I had to take a dremel tool to the inside of the cab because after mounting the reading mechanism on the motor there was no ability for motor to turn L & R. I had to remount the sensor and glue and tape it into place.

Is there room in your cab to grind away the space required?

Hugh,

The (mild steel?) frame sides are only 1.5mm from the flywheel and the 6mm thick diecast firebox/boiler sides fit very snugly over the frame at this point. If I remove the frame and "thin" the firebox sides to allow me to add a 3mm rim onto the flywheel, there won't be much firebox left.

Expensive lesson!

I installed the PS2 upgrade kit.

The good news is that my photo-reduced tach strip works well - I copied it onto an Avery self-adhesive label, trimmed it to size and then applied it to the 20.9mm flywheel.

The bad news is that, despite all the PS2 upgrade package warnings, a "whisker" of yellow speaker wire touched the speaker frame without me seeing it. When I applied power to load the sound file, there was a continuous "clacking" sound and, before I could kill the power, a puff of smoke from the bottom of the PS2.

I continued with the download and everything but the sound works great!

Thanks to you all for your help and advice.

There's a good chance you smoked the audio amp chip. Check the archives as there are threads with photos and what to look for. If it is the chip they are about $3 IIRC and replaceable if you are comfortable working with surface-mount chips.

It's odd the sound continues to work, I think that's what he's saying.

Britrailer, please clarify.  Does your tape have same number of stripes as thr MTH-produced tapes? If so, MTH must have made a change to the reader since 5 years ago, that lets it read narrower stripes.

Any of you close to MTH know of amy change?

No change in tach reader.  G

John he is saying everything EXCEPT sound works I think

Rod

GGG does sound chip replacements.

Rod

yes, the photo-reduced tach tape has 24 stripes, the same no as the original.

I'm shocked the speed control works.  When I produced a tach tape with the same number of stripes, for the 22mm flywheel in my Weaver 0-6-0, it went wild.

So I ask, does anyone out there in forumland, other than GGG,  know if there was some change in the tach system or software?  I wonder if minor variations in the gap, although within MTH's parameters, could have an effect on readability????

I missed the "but", that makes more sense.  That chip is pretty small and should be fairly easy to replace.  I see George is on the job.

Thanks Rod.

Maybe for you John. I would not try it.

I have a board I am going to send to GGG to get a fritzed sound chip replaced.

Rod

Small SMT chips are not a big issue, it's the big ones with leads on all four sides, those are a challenge.

While my PS-2 board is away for repair, I installed a 'spare' (after double-checking for wiring problems) and loaded a 4-6-2 sound file. The 4-6-2 files loaded and the sounds seemed OK but the motion was jerky. I checked for obstruction to the drive-train but found none.

I tried the Mikado file and everything worked perfectly.

Has anyone else found problems with 4-6-2 sound files?

I have not had problems with that specific file but with others.

I was in belief that certain of MTH's files that would download OK and load onto engine OK but had flaws were corrupt.

I no longer think that as with a lot of playing around and use of two different laptops can usually find some 'background' program in operation potentionally causing the problem.

One item for sure is a blu ray plug in a USB port and another is a virus scan program that starts up with out telling you and carries on while you are applying sound file to the engine.

Clear the air and try the whole process from download of file to install into engine all over again.

The 27mm tach tape has 7 black lines per inch. I've made & used tach tapes that have 10 black lines per inch and the PS2 electronics have no problem reading that. 11 lines per inch is where PS2 has a problem reading. Also shimming the tach reader in or out will help it to read the lines better to get a smooth running engine. All my labels are printed on plain Avery label paper ie; not shiny. Hope this helps. 

CRH, That's the paper I had used.  Maybe the tape I had made for the 0-8-0 flywheel was just over the edge.  I no longer have the unusable tape so I can't get a precise measurement of lines per inch.

The only way to mount the tach reader was to bond it to the motor shell, which yielded a gap within MTH tolerance.

Thanks for the tip, but at this point I'm not going to open the loco and try to rework it.  Since I don't lashup it, precise speed isn't a major issue.

Hugh,

Thanks for the info on background programs. I suspect that the culprit might be an anti-virus program.

I did some more looking because I need to make one for my Williams Mike.  Here's some of Dave Hikel's post links:

https://sites.google.com/site/...hing-ps2-conversions

https://ogrforum.com/t...r-tape-for-flywheels

All other programs should be closed when downloading a sound file according to the MTH directions.

Different sound files for 4-6-2 may perform differently depending on the gear ratio of that specific model, and motor control algorithm.

You may still have an issue with the reduction in your tach tape, coupled with the specific sound file used.  So sound files had issues with back fits since the PS-2 5V model of that engine may have had a different gear ration or driver size, etc...

So if you have a file that has removed the jerky motion I would stick with it, especially if scale speed is not a factor for your operation.  G

It is possible to tune the tach tape for different speeds if you end up with a non-scale speed, might be an option to look into.

It may not be possible to tune it with a flywheel this small.  G

I knew an antivirus program might prevent the computer from establishing comms with the TIU, but this is the first I heard that it could befuddle the transfer of a file---something other than a Go/NoGo situation.

If you have the space, easiest solution might be to use electrical tape on flywheel to increase diameter to 27mm, and then use a standard MTH tape.

For what it's worth, the Williams diesel that I upgraded has speeds consistent with MTH locos.

I have to say that all this hul-a-balo about speed and diameters and stripe spacing has never been an issue on the 25 plus upgrades that I have done. Everyone, including me on my own stuff (Williams included) can not tell the difference. It is how you manage the wheel on the DCS remote to what appears to be scale speed that counts. Hikel's method has been helpful but preciseness is really a 'rivet counter' issue. Who really cares what the handheld says in the final analysis of the results.

That is with one exception, and that is with station stops. It really makes a big difference if you wish station stops to work correctly. I looked but my post on this has expired. Essentially, station stop programming is directly related to motor flywheel diameter  and the particular sound file at issue. Took a lot of work to make my personal subway system (2 lines) to function nicely, but I finally got it. It was worth the effort and took a micrometer and custom tapes to make it happen. I now need time spend on my MU and BUDD car routes.