MTH loco sounds question

Try putting a load on the tracks, maybe a couple lighted passenger cars. In order to get the whistle to work, you want to only to the first step on the whistle control, the second step drops the DC voltage with a large low value resistor.  Without a load, the DC voltage drops to pretty much zero.

Obviously, you're not going to get the bell working with the KW without swapping the track polarity, you only have one control.

Wow thanks for the quick reply.

I'll try with some additional load on the tracks. And as for whistle-Bell, yes I understand that it's either-or, but in the PS1 boards the bell rings when the whistle handle is used while in neutral. Do the Loco Sounds work the same way?

And am I right to ignore those other 2 wires? Do they go to an optional light something?

PS/1 has odd operating modes, and in order to use the whistle in neutral, you have to program option #25.

Yeah still no luck on this even with lighted pass cars on the track.  John, it's not PS1, It's Loco-Sounds...does that make a difference?

I do have a few other PS1 engines and boards that I've been making my way through.  For what it's worth, I can get the whistles to run pretty consistently on all my PS1 boards, just hitting the handle about halfway.  But it has the undesirable side effect of essentially stopping the train every time.  Happens on all my PS1 setups.  

And one of my PS1 boards will simply NOT recognize the whistle at all.  Makes it a real pain, because I can't factory reset (#18).   I can advance all the way through to program 18, but once I'm there I sjust can't get the bell clank and the reset confirmation.  I always end up pulling the handle just a bit too far, the power drops out and the loco advances to program #19.  And any of the other functions that require the whistle, no-go.  Can't arm or fire the couplers, which is a pain because there is no manual release on the proto-couplers.

Thanks for the help!

I think you need to go with a more modern transformer.

You could also build yourself a whistle/bell controller, they're pretty simple.

Ignore the exact configuration of the larger push-button, all you need is a SPST one, you are just shorting out all but one diode in one direction for the horn or bell function.

John, would that gadget still allow enough AC to flow during the horn blow for the train to keep moving?  I still don't understand the electrical stuff happening that kills the AC through the motors whn the DC offset is initiated.  Does the DC wipe out the AC altogether?  So there is no way to blow a horn on a PS1 with a postwar transformer without stopping the train?

This rig just reduces the voltage all the time from the transformer, but when you blow the horn, it doesn't have a voltage drop.   The DC just "rides" on the AC waveform, it doesn't "wipe it out".

Many PW transformers just need a new diode in the whistle circuit to work properly with newer electronic boards.

Would the input side of that diode array go right off the "A" pin of my transformer?  And then one pushbutton shorts out 2.8V of half of the AC wave (creating a slight DC current in one direction) and the other pushbutton shorts out part of the opposite leg biasing the DC in the other direction?  And the direction of the DC bias is what tells the board to do "horn" or "whistle"?

I guess I don't completely understand the mechanics of a DC signal "on top" of the AC signal, but that's why I'm a mechanical engineer and not an electrical engineer!

So does the default state of the entire array (no buttons pushed) mean I will drop my overall AC voltage by 3.5 volts constant?  So to achieve the same speed of my locos, I have to push the transformer harder?

Here's an illustration of a DC offset of an AC signal.

John, I'm going to try my hand at a controller first, and then if I get frustrated with that I'll do the Zener in the KW upgrade.  I like the idea of the controller so I can do the offset in either direction and easily get whistle or bell.

I'm a bit overwhelmed by diode choices, can you recommend critical specs for them so I can make sure I get the right ones?  I can get them from a local shop here in Orlando (Skycraft Surplus) that has **** near every type of diode, resistor, switch and wire known to man.

Thanks again!

For totally reliable operation, I'd do something like these, six to a string.  So you short 5 with the switch, leaving one remaining active.  This gives a little more DC offset.  I've never seen any issues with my rig, but several people have told me they needed that extra diode each way.

MCC 6A2-TP, they're 41 cents each. These are 6A diodes, should be enough for any single train you'd be running.

If you want to wait longer, you can get similar diodes on eBay from Asia for much less, but it's a few weeks, and I don't know how shipping times have been impacted by the global virus issue.  Figuring the 12 diodes you need with shipping from Digikey are less than $10, it's not that bad to just get the ones you can have in a couple of days.

Thanks!  I'll let you guys know how I make out.