The handles on my modern ZW have been mismatched since I purchased it about 6 years ago. After reading Dick Teal's article titled "Servicing Lionel's Modern ZW Controller" (CTT Feb 07), I decided to open it up and attempt a repair. The repair essentially consisted of reclocking the pots so that I could get full travel on the throttles. There was nothing loose or broken in the ZW and the potentiometer mounting brackets were metal. After the reclocking was complete, I calibrated the ZW per the procedure in the owner's manual.
Here is the voltage data before and after the reclocking for handles A and D. The voltages were read on the ZW volt-amp meter. A lighted caboose was set on the track to slightly load the ZW. The column on the left represent the markings on the ZW for throttle position.
Handle
Before
After
Setting
A
D
Off
0
6
8
2.5
5.5
0.3
0.4
10
6.6
11
0.5
12
16
3.9
4.1
14
17
7.2
7.1
(*)
18
20
Max
(*) Handle travel inadequate to reach point.
Is the large deadband for near zero volts normal? I have to go to throttle position 12 before the ZW starts to output voltage. I would like the ZW to put out a linear voltage curve from OFF to MAX throttle position. I suspect that the potentiometers may have a flat band that might be causing this problem. The problem with the steep voltage curve between position 12 and MAX is that my conventional engines become very sensitive to throttle position.
Earl
Earl,. I too fooled around with my new zw after reading the article. I still have a right loose handle though, even after following the article.
I did this because I was getting about 14 volts off of channel B and it always bothered me. This happenned after I sent it to Davis for repair a year ago. I played around with the pot gears and got all readouts from the zw/amp meter to read 18 with no load. This according to the article is suppposedly in range.
I just checked mine but didn't do the extensive testing you did. On channel A when my zw dial says 6 volts, my readout is about 3.2 with an engine on the track as load. On Channel D when the dial says 6 volts, the actual is about 4.5 or so. So I do seem to get voltage pretty quickly when moving the dial from off to the first dial position.
I'm not sure if this info is exactly what you're looking for, but let me know and maybe you can direct me toward more specific testing.
Mike S.
Mike,
Thanks for the info. I may open my ZW up again and checking the pots for linearity. I will probably try a different clock position on the pots. The interesting thing is that the degrees of travel from where the voltage starts to rise to max value didn't change much before and after the reclocking. All it did was change the handle position where the starting voltage and ending voltage occurred.
There is probably an adjustment on the circuit board that adjusts sensitivity which would affect the range of travel from min to max voltage.
Yeah, Earl, I played around with the pot gear and the handle gear relationship, and found you can change the max votlage and the starting voltage, so I would go for it. I don't remember how I did it, I just tried different positions and eventually got it.
earl,
I brought this thread up again because I really goofed. I was giving you the wrong reading on my A channel. I was looking at the mark for the B channel.
I too, do not get starting voltage to late on the dial. Maybe like 14 volts or so. Have you resolved this issue?
No, I was not able to get voltage at low handle settings. I checked the pots on the A and C channels and the resistance values matched up with each other and were very linear. The degrees of handle rotation and degrees of pot rotation were essentially the same so I could not re-clock the pots. There does not appear to be any adjustments on the circuit board to adjust the sensitivity. I have run out of ideas. I am open to suggestions.
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