Slow NW 2

E

electricity_bill

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Hello
Just acquired a USA Trains NW 2 in excellent condition and I have fitted my standard MRC 1817 sound decoder to it. Two questions
1. Flat out, it runs at approximately half the speed of my other USA Trains and other locos. The CVs are correct so is this normal as it is a switcher?

2. There are three wires going into the power brick – yellow, green and blue (plus red and black) and I cannot understand what the blue wire does and I have ignored it. What does it do?
Bill
 
Hi Bill
The slow speed could be due to the 'shunting' speed being selected on the handset. I am not sure what button calls this up on MRC but some makes use button 5 or button 6. This function can be turned on or off or the level of drop in power set in the CVs..not sure which one for MRC.

As to the blue cable...very strange as there should just be the red and black ones. Is it going into the motor block or is it going into the fuel tank or to the front/rear of the loco under the chassis

This is for battery conversion as opposed to DCC, but it does detail the wiring...
http://ovgrs.org/the-trains/battery-power-radio-control-and-sound/usa-trains-nw-2/
 
[quote author=electricity_bill link=topic=299193.msg320350#msg320350 date=1404424894]
The blue wire is factory fitted to both blocks. Similar to the older LGB wiring arrangement.
[/quote]
I have got two of them and had a couple of others pass through my hands and none of them had a blue cable going to the blocks.
All current USA Trains blocks have the track feed black and red and the motor feed, also black and red...no blue one.

nw2_opened.jpg

EDIT:  I have seen your piccy on Facebook and it looks like a very very old block. Even the slider pick-up shoes are not like they have been for many years.
Sorry but I have not experienced this age of block at all.
 
Just edited my post Bill...I saw your photo on Face-ache.
Must be a very very old block indeed.....

One cable will probably be a common negative lead whilst the other two will be track feed positive, motor feed positive
 
From memory I think the middle blue wire from the motor blocks was for a common to the motor case in case better motor "noise" suppression was required.
 
Converted it back to analogue and it runs at normal speed. On DCC it appears to accelerate OK initially but then stops accelerating at half speed. Any ideas?
 
The CV parameters for acceleration and the amount of speed allowed would have been changed at some time. Just reset the decoder back to factory settings and the acceleration and speed should be normal.
 
Tried the reset without it making any difference. Started playing with the speed curve and I can now get it running at normal speed at the top of the control range only. Slows down very quickly after the top notches. Some progress.!!!
 
The back-emf maybe not be 'reacting' well to the feedback from the old style power brick.
Try turning back-emf off in the CVs.
 
analogue = OK
DCC = not

Sounds like the decoder could be faulty. Likely
Could be a mis-match in speed-step settings. Not so likely
Could be a 'feature' between the Central Station you are using, and the make of decoder. - I have this problem using a Digitrax Zenith on my programming track. Certain things do not work as they will when on a MTS (or Massoth) Central Station. Different 'dialects' of DCC
 
electricity_bill said:
It is switched off!!
Click to expand...

Well that told me...........
obviously I can be not be of any help......oh well, I tried.......
 
Isnt the blue wire a common feed for the lights on the decoder ?
Graham
 
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