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Old 23-09-2017, 12:32 PM   #1
PaulM381
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Default Help with DCC conversion

Hi everyone. I wonder if someone could help me with a confusing problem. I have converted quite a few locos from DC to DCC some old and some new. I'm in the process of converting a Triang DMU to dcc and come across a problem. I have wired everything as I normally do but the motor doesn't want to kick in. The confusing bit is that if I connect the input power to the chip directly to the rails the motor runs fine and even if I connect one side to the power coming into the body of the motor and the other side to the track and it still works. Now here's the strange bit. If I connect the pick up to the one side and the other to the track I don't get anything. Now I hear you all say 'dodgy pick up' which is what I thought. But when I test the connection with a meter I get a good result connection wise and even testing the volts I get good results.
Does anyone have any ideas why this is and is there any solutions for this problem.
Thank you in advance.
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Old 23-09-2017, 12:49 PM   #2
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Hi
Welcome to the forum.

These older units often have power collection from one sides rear wheels and the motor bogies opposite wheel side.

What style of motor does the unit have. Open frame XO3 or XO4 or the later Ringfield (Pancake) motor?

Are both motor brush connections isolated from the rest of the motor?

Knowing the part number e.g. Rxxx or a few clear close up photos may help us further.
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Old 23-09-2017, 08:01 PM   #3
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Hope you dont mind me stepping in here as I used to have some of those DMU's, though I'm going by memory as I no longer have any.
Basically, those old Triang DMU's that I used to have were either made so the drive bogie would run on its own having all four wheels with current collection, or some better designs had this with an additional power collection to the unpowered wheels. II hope this helps as it has the potential for one to isolate the additional pickups (On the second design I quoted) whereby one can assume that it was job done, when the power bogie itself has its own pickups. Of corse, this could happen vice versa. So one needs to find a way of isolating all the pickups from the motor.
I seem to remember the easiest way to isolate such motors was to isolate at the brushes themselves. That is normally a simple procedure of adding an extra isolating tube on the spring that holds the brushes. I just cut my isolating tube thing in half to use on both sides as it had plenty of length to it for me to do this and know it was safely isolated. Of corse, any wires going to tiny plates touching the brush will need to be isolated as well. My memory keeps getting confused between the power bogie and the similar X03/X04 design motor so I hope it generally makes sense. The orange and grey wires then are connected to the brushes via a little plate (Which are easy to make if you need one) which is held in place by the spring along with the brush, and the red and black go to the pickups on either side.
II may not have answered your question directly, but this is the basic procedure. As long as you can fully isolate the brushes you are half way there.

Last edited by Mountain Goat; 23-09-2017 at 08:18 PM.
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Old 23-09-2017, 08:29 PM   #4
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Thanks guys for the info.
My phone is out of charge at the moment so I cant take a picture but I have found an identical motor on Ebay which are the pictures attached.

I have removed all the electronics and all there is left wiring wise is the feed from the pickups on one side.
I have completely isolated the brushes and this is where I have attached the motor wires. The power feed is from the bronze plate (which has been isolated from the spring) coming from the magnet housing and the other feed from the pickups on the other side.
As I mentioned before the motor springs to life if I connect the feed from the underside pickups directly to the track but not when it is connect via the wire from the pickup. The thing is when I meter the connection everything seems to be ok.
I will try and take some photos when I get me camera phone up and running.
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File Type: jpg s-l1600.jpg (171.0 KB, 14 views)
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Old 23-09-2017, 08:56 PM   #5
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Yes. Take some photos. In the picture the orangy red (Red?) wire going to the brush needs to be cut and an additional sleeve needs to be fitted to isolate the brush on the other side.
Of corse, one needs to ensure the spring makes the brushes touch the commentator as I seem to remember one motor I had (Running on DC) where I had put a new wire on it, the stiffer wire didnt allow enough flex so the one brush failed to make contact.
Also recommended is to cut the TV suppressor (Capacitor thingie!) so it does not suppress the DCC signal. I tend to cut a single leg at the bottom and position it so it does not make contact, so if one wants to convert back to DC, one can just solder it back into position.
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