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Discussion Starter · #1 ·
Art Machine Font Grass Paint

I bought a 60s Triang DMU R157 and R158. The drive bogie just about ran, so I began dismantling it and cleaning it up, but this is the first of these motors I have tried to fix. I am wondering if anyone has any schematics of the connections as the motor seems to be shorting through the wheels if all 4 touch the rails, sometimes if pair touch the track the motor turns if the insulating base is loose. Is the orientation of the wheels critical? I am missing something. Any pointers would be appreciated.
 

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Discussion Starter · #2 ·
Solved. Bakelite base, I assumed was insulating, but I twigged it could be shorting between the copper and solder point to the bogie frame itself. A small slice of PTFE plumbers sealing tape placed between the plate and the bogie wire hope recess worked like a dream. I do wonder if I have the whole insulation base upsidedown though still or I have lost an insulating piece. Hey-ho, it works!
 

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Discussion Starter · #4 ·
Diagram here to show the original construction:
Make a note of what you have done, in case the PTFE tape wears through and the short returns; I do this on the assembly diagrams, keeps all the information in one place.
Thanks for the sheet. The DMU is motoring now, if a little noisy. The collector X289 is a flat plate or copper sheet rather than a spring wire which I have seen on other of my Triang models but otherwise it is the same. I do have the collector plate the right way up, so how it did not short before I took it apart I don't know. It was very oily.

I have seen a lot of suppressors on my old models and have been wondering if there is a guide to their ratings on old Hornby and Triang locos. I guess they are capacitors but what uF or pF etc ratings if they fail? Mind you, I have not found one that has failed as yet.....
 

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The knurling on the tyres dosen't help with what is an intrinsically noisy mechanism design, all the slack and chatter in the motor and gears conducted directly to the rails, and then efficiently coupled to the air mass by the baseboard for good propogation to your ears.

Suppression components for DC motors of this type, the recommendation back in the day was circa 5uH and 100pF.
 

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Discussion Starter · #6 ·
Brilliant, not thought of the knurling effect. Thanks again. The noise makes sense and does not really bother me. It has rather a pleasing growl!. It seems to run really smoothly even at a crawl, which I can't say for quite a few of my collection. My baseboard is raised in this area too so drum effect will be there too. Capacitor insight spot on too.
 
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