Intermittent sound loss

Try the battery test, It's easy,,, Start up the engine , get the sound working so at least you can hear it. Now shut off track power  (not shut down with remote) The sounds should continue on for at least 6 or 7 seconds, if not the battery may be part or all of the problem..... I'm assuming this engine has a battery and not a proto-3.

Does this only happen when the Horn is on at full volume? Turn the volume way down and see if it behaves better.  If so, then you may have a weak PS3 supercapacitor which warranty ought to cover.  The supercapacitor effectively provides reserve power to keep audio running during heavy loads such as the Horn blasting at full volume or the more obvious loss of track power. 

Stan,  Do you have some insider information on the circuit design for PS-3?  It is an interesting comment to say the Super capacitor is a reserve for the audio processor.

In the PS-2 design the audio chip/speaker is driven by the Power Supply 5VDC Regulator chip.  If you overload it, the engine will shutdown other functions as all the processors are driven via this regulator (3 secondarly driven via the 3.3V regulator).  As long as track power is available, I don't see how the capacitor is helping, since it is suppose to replace the battery when track power is not available.

Sounds like Gromet is operating in DCS mode with full track power available.  Interested in why you conclude this?  G

Gromet, so does the behavior change if you lower the volume using the remote to the point where, say, you just hear the engine and horn sounds?  This should not take long to try and does not require opening up the engine.

G, in PS-2 with the battery consider the case of pressing the Direction button in conventional.  The sounds should play through the short power interruption.  But if the Horn is blasting at full volume during a Direction change and there's a weak battery it will not make it through the Direction change and the electronics runs out of gas.  In such a case, if you lower the volume, it might make it through the power interruption and you can reverse direction and at least run you trains until you charge or replace the weak battery. 

Stan, that is different then what you said in your original post.  It is not a reserve for a specific function, instead it keeps continuity of power for the regulator.  I agree for a conventional operation.  In this case he is running on DCS and even with a direction change, smoke on full, and pressing the whistle button, the battery and or Super capacitor should not matter.  G

G, you are absolutely correct.  I should have said it keeps the audio running and other things too.  With a Z-4000, track voltage drops to zero 120 times per second in command mode or conventional mode.  Something is keeping things running and if you look at potential energy storage components on a PS3 vs. PS2 board, some conclusions can be drawn. 

This does not apply to Gromet since he's using AC, but in addition to reducing the load (turning down the volume, or perhaps turning off the green Evolution light show) a related experiment is to apply the same track voltage but DC so there are no power interruptions.  If the behavior changes I'd think that too would be enough to justify pursuing a warranty repair.

Stan, Regardless, he has a warranty claim since the engine is not designed to have sounds cut out.

There are several capacitors and inductors that are used to filter that incoming AC to steady DC for the regulator and the microprocessors.  Not the the battery and super capacitors.

I think the volume pot, wiring, connector, speaker or a faulty microprocessor are more likely problems.  G

Good to hear.  G