Z-4000 Generations...Differences?

@Jon G may be your best bet for detailed info on the Z4000.  I know there are at least two versions, I would guess that the Korea built one was the original.

I believe the very first run, serial number 0398, were made in Korea.  All later production was Thailand.  Some 0398 models have a voltage leakage problem that only a few techs can fix.

Finally had chance to check the performance of the two Z-4K's...  Arbitrarily and for convenience, I used a Lionel PW 2343 F unit to check control performance.

The Korean version has serial number 039814141.   The owner's charge receipt for the original purchase was in the bottom of the box, dated 10/98.   I'd say this is rather certain to have been among the first generation of Z4K.  When powered up, no load (not hooked up to the test track/engine yet), the digital voltmeters registered 2.2v and 2.0v, L & R respectively,  When connected to the track/engine, the 'zero' settings dropped to 0.3v on both throttles.  Speed/direction control was excellent.  Max throttle voltage at idle was 21v.  The 10v and 14v fixed ports were nominal.

My selection of a PW engine meant I couldn't check the bell button, but the whistle/horn actuation was perfect...and then some (more on this later).

The Thailand version has serial number 090538288.  Clearly, it was made at a later date.  No load power-up voltages on the Z meters was 0.1v for L & R throttles.  Under track/engine load at the zero setting, there was no change...0.1v.  As with the Korean Z, performance was smooth, peak voltages of all four ports were nominal.  Again, the horn actuation was excellent.  The other thing noted was that the Korean throttle motion was much freer than the Thailand Z throttles.  The difference in actuation torque didn't seem to have any speed control affect, though.

So, the voltage 'leakage' of the Korean unit I've also learned is repairable...but hardly an easy job, and certainly not for a DIY'er.  OTOH, as I found in this comparison, the display of the no-load voltage leakage apparently has no effect on the performance of the transformer.   

But, my testing of these Z4K units has left me with a problem of a different sort...after experiencing actuation of the whistle/horn button: No significant (any?) speed sag of the engine during whistle/horn actuation!!

To wit...

When I transitioned (trainsitioned?) from many years of HO to O3R, the Z4000 was the "new kid on the block".  With MRC throttles in my HO years, I had had nothing but success...performance, warranty, etc.... When I built the O3R layout, I had my old childhood Lionel PW ZW, and had accumulated a couple more from friends, but considered what MRC had to offer.  Their Dual AH601 was pretty cool with those analog meters, and reasonable pricing!  After all, their products had served me well in the dark side.  I had developed a strong loyalty.  I'm not a riverboat gambler on electronic technology, so jumping into Z4000's at their infancy was ruled out!

And, so, I bought (3) AH601's for my layout train control (6 conventional control zones), relegating the ZW's to 4 variable channels of accessory/lights control!  It's all worked out well...except for one bugaboo: Engine speed sag when actuating the whistle/horn.  The MRC AH601's did the same thing as I experienced with the ZW's.  I supposed it was 'just one of those quirks of O3R life along with a center rail'  Until I tested those Z4000's!!!  Both of them.  NO perceptible speed sag!  NICE!!!

So, instead of choosing one of the two Z4K's, the unthinkable is occupying me...replacing the MRC's with the Z4000's!  It couldn't be an easier transition...I don't need/use the accessory ports, only the two throttles.  Bada-Bing, Bada-Boom!  Except for one minor detail...$$$$!!!  Ah, well, I'll assume that it need not be a total transition...3 for 3, ka-boom!  As long as they're confirmed to be phased properly I should be OK for interzone travel with a mix.  Right?

What to do, what to do?

KD

Our club uses no less than 5 Z4000 for a total of 8 active tracks. We phased them all on install and have no issues crossing zones provided the voltage is reasonably (ideally within 5V of each other but not that critical). Point being, as long as they are in phase and again the output channels are reasonably matched- a crossing between tracks or blocks is seamless.

I was going to say a mechanical difference:

Early Z4000 low serial numbers same as voltage leak- don't have the spring plungers for friction on the handles. They have provisions (mounting hole) for the spring and plunger, but also lack a hole in the bottom of the case and a matching adjuster screw to set handle tension.

MTH parts and sales is currently out of this part. It's a spring and plastic plunger, so being now on the 3D printing part of the group, should be pretty easy to make a printable version of the plunger friction device.

The later Z4000 has screws and labeling molded into the base for not just the spring and plunger- but they can be adjusted higher or lower compression on the plunger to put more friction on the handle.

https://ogrforum.com/...00-handle-adjustment

First 4 digits are date code.  0398 Mar 98, 0905 Sept 2005. G