possible DCC system problem?
#16
First off BRASS is a PITA. The whole locomotive is a conductor. So you have to be real careful in how you run wires and mount decoders.
The trucks can sometimes touch the frame and cause shorts. I have seen where the brake shoes on a locomotive would touch the wheel(s) and short. They can even short out on the track if they hang to low.
You should ALWAYS try your locomotives on a program track after working on them, no mater how simple the repair was. That has saved many decoders for me. The brass units get check and rechecked, then checked again, then they go to the program track.
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#17
woodone Wrote:First off BRASS is a PITA. The whole locomotive is a conductor. So you have to be real careful in how you run wires and mount decoders.
The trucks can sometimes touch the frame and cause shorts. I have seen where the brake shoes on a locomotive would touch the wheel(s) and short. They can even short out on the track if they hang to low.
You should ALWAYS try your locomotives on a program track after working on them, no mater how simple the repair was. That has saved many decoders for me. The brass units get check and rechecked, then checked again, then they go to the program track.

I think i agree. The curious thing is that the previous decoder, even though it would behave hay-wire in the E44, did work, and it worked perfectly fine in a regular atlas engine. I changed nothing other than plugging in a different decoder to see if the problem would go away.

I'm going to have to search the whole engine again. I added additional contact pickups which could also be causing problems. I'm starting to wonder if there is a way i can make sure the whole engine is electrically isolated.
Modeling New Jersey Under the Wire 1978-1979.  
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#18
Well you can insulate the trucks from the frame. That is going to require some work. Use a fiber washer between the truck and frame, next use a nylon screw to hold the truck in place. Now make wipers for both sides of the truck so they will pickup power from both wheels on both sides. Or you can use the truck for one side and then make wipers for the insulated wheel side. Run a wire from the wipers and or the truck to the inside of the loco. You should now have right rail pick up on both front and rear trucks, and all wheels on the right rail. The same applies to the left rail pick up. You will still have to watch for wheels hitting the frame.
From what you had posted it sounds like you have a motor wire touching the frame some where- As it is now I think the frame is a conductor for the right rail and if any motor lead touches the frame there would be a motor to rail short.
Brass- you have to look for everything that even looks like short.
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#19
woodone Wrote:Well you can insulate the trucks from the frame. That is going to require some work. Use a fiber washer between the truck and frame, next use a nylon screw to hold the truck in place.

The truck was already isolated from the frame, but it has a metal screw. this is because power is transmitted through the screw to the wire without touching the frame. if the screw is tightened properly, a plastic bolster is held in place and does not allow the screw to touch the frame. it also keeps the truck in place so that it doesn't touch the frame. You can believe i've tightened this,


Quote:Now make wipers for both sides of the truck so they will pickup power from both wheels on both sides. Or you can use the truck for one side and then make wipers for the insulated wheel side. Run a wire from the wipers and or the truck to the inside of the loco. You should now have right rail pick up on both front and rear trucks, and all wheels on the right rail. The same applies to the left rail pick up. You will still have to watch for wheels hitting the frame.

I've also done this before the decoder burn out. the wire from the trucks to the metal screw is my only concern, but i've already ensured that it cannot brush the frame. I've glue paper-thin plastic behind the contact wipers, and similarly blocked any chance for the metal wipers or their wires to touch the metal.

Quote:From what you had posted it sounds like you have a motor wire touching the frame some where- As it is now I think the frame is a conductor for the right rail and if any motor lead touches the frame there would be a motor to rail short.
Brass- you have to look for everything that even looks like short.

This is what i've come to conclude as well, but I'm not sure. the motor is mounted to the frame by a pair of metal screws. I think that the metal screws might be shorting the motor to the frame.

I wish there was a way to test without risking the decoder. Maybe i can temporarily connect it back to DC to see if it still shorts.
Modeling New Jersey Under the Wire 1978-1979.  
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#20
You CAN test for shots before you install a decoder. Use your DVM ( digital volt meter). Test each motor lead to the frame. If you have any conductivity you have a short. Also if the motor has a metal frame and is mounted to the frame of the locomotive there could be a short there . Some times this short will not show up, but I would insulate the motor and use nylon screw to hold in place.
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