In one of my engines, a Kato SD40-2, I have a Digitrax chip… I think it is the #123. The throttle has to be turned up pretty high for the loco to start to move, so I’m thinking I need to reprogram it. Is that done through CV2, the start voltage? What is the difference between CV 2, 3 and 4?
If someone could enlighten me as to how to do it, I’d appreciate it.
Jarrell
Jarrell,
If you have a drop in decoder, it is most likely a 163. If you hard wired it yourself, it could be either a DH123, 143 or 163.
In any case, CV2 is for Start Voltage, you set it so the loco just starts to move when you increase the throttle. CV3 is Acceleration Rate. The higher the number you program in the longer it takes the loco to reach top speed. CV4 is Deceleration Rate. The higher the number the longer it takes the loco to come to a stop. Sorta like momentum.
Be careful with CVs 3 & 4. I usually program in a value of about ‘10’ and work from there. Too high a number and it can take MINUTES for the loco to move or come to a stop.
The Digitrax Decoder manual, which covers all of their current production and most of the old production decoders, is available on-line at:
[url=“http://digitrax.com/”]
Hope this helps.
Thanks Allan, that’s what I needed to know!
Jarrell
I have found that the best way to get CV2 programmed for that specific loco is to set it initially at about 42, and work down to the value where the loco just gets to turning its wheels at speed step “1”. You will find, later, that it doesn’t seem right, especially when the loco won’t begin to move on up slopes until you set the throttle to about 4, or so, and that it will move quickly into motion when you input speed step “1” on a down-grade, depending on train load. That’s the nature of the beast.
Also, CV’s 3 and 4 are among those that must be tailored to an individual’s preferences. I like prototypical start-ups and braking, so my values are in excess of 90. If it appears that there is to be a cornfield meet, the emergency button, and the braking function (F7 on QSI decoders), have their places. I use them daily.
Okay, several times daily.
I though F7 was just the sound of braking? Is that the new QSI decoders?
Ken.
Thanks for the suggestions guys. I see that CV’s 3 and 4 are going to require tweaking to get them right to suit me. Right now I’m just trying to get the loco to start moving without having to turn the throttle half way to full power. Evidently I’ve got something set wrong, but that’s par for the course for me… 
Jarrell
That is the case with my early BLI J1d Hudson and my Lionel QSI-equipped Challenger, Ken, but the (newer?)K4s, Niagara, and PRR J1 all grind to a fairly panicky halt when I press F7…not a dead stop like the emergency button, but a stop taking between three and four seconds, with hiss and screeching, from speed step 30 when I have CV4 set to about 100.
-Crandell
Crandell I had to go and find out, I ran my BLI C30-7 and PK2 2-8-8-2 and your right!! They really do come to a screeching stop. Nice thankyou.
Ken.
I use Digitrax on my Stewart FT’s and set v-start around 8 to 10. I can turn the throttle one click then back to ‘0’ to move the loco to the train and couple. After a reasonable time for air and brake test I can open it a couple of notches to run out the slack and just get the train moving. It takes playing with the settings and trying repeatedly to get the results you want for your loco(s).