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D.C.C Overload





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#1 shaunthesheep277

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Posted 06 December 2017 - 19:26

Hello I've had most problems but I can't get my head round this one

 

I've built a working railway excavator before but it's never been reliable so I've started building a new one

After seeing a thread on here of one built using a Tenshodo motor bogie link below

 

http://www.rmweb.co....rail-excavator/

 

now I've seen the insides of this motor and realized the motor needed separating from the rail pickups before fitting a decoder

DC running works fine but once I add a decoder into the mix the controller comes up with O.L (I assume overload)

 

Now since I've never used a Tenshodo motor before so It maybe the bogie but I've tried two decoders and both come up O.L

 

The old motor on the old digger was off a old Bachmann Plasser Tamper D.C.C fitted too



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#2 Phil S

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Posted 07 December 2017 - 09:49

My first question is increasingly: 'Do you have a multimeter?' - If not - get one now - the cheapest costs less than a basic decoder (better ones cost more of course ... but there is no need to pay more than a sound decoder!! 8-)

 

The Tenshodo bogie is constricted with no 'wiring' - just metal contact strips from the wheel pickups to the motor - these MUST be split by cutting them, and moving them apart to ensure a safe gap.  CHECK NOW with a multi meter that NO CONNECTION exists between track/wheels/pickups and the motor.

Then you will need to solder to each pickup, and and then to the 2 motor connections - hopefully finding a place on the metal strip rather than the actual motor (think where it is best to split their connection before you cut it).

I would also recommend insulating tape over any exposed part of the motor-side wiring in case some (magnetic) metal object is 'picked up' from the track by the motor bogie .....  (on the current Hornby motor bogie design, the contacts are exposed on the side, and I have had a decoder destroyed when the magnet attracted a small piece of metal across them whilst running)


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#3 johnb

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Posted 07 December 2017 - 12:47

I fully agree with Phil, the contact strips from the wheel pickups MUST be split on BOTH sides. I've done that by first epoxy gluing the strips to the side of the bogie letting it fully cure and then cutting them and making sure that the cut parts DO NOT TOUCH each other. It can be done without gluing first, but I found things to be a bit wobbly with risk of touching across the split.

Then I simply soldered the decoder wires as usual, the red and black to the the section connected to the wheels and the orange and grey to the upper part of the split strips. Checking with a meter at intervals to make sure that no contact was possible.

Try not to linger with the soldering iron and it will not damage the plastic bogie structure.

I'd add a photo but that particular model is buried deep in the stored stock pile.

 

It's all a bit of delicate work, but taking it slowly and carefully all will be fine.

 

John



#4 shaunthesheep277

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Posted 07 December 2017 - 18:11

I did take it apart to see if they were connected before starting, there's a tiny screw underneath and with a little persuasion pops off to reveal the motor and wheels

I carefully cut the contacts between the rail pickups from the motor just at the point of them looping round the bodywork/frame

there is motor contacts popping through the top which are only connected to the motor not the rail pickups

 

Now I did all this before starting the project but before add a chip I soldered a wire to each pickup, wire to either side of the motor tags

(right rail to right motor left rail to left motor) and tested D.C runs a treat no problems

Now Orange motor right, Red right rail pickup, Grey motor left, Black left rail pickup

 

As soon as the power is on the O.L is displayed on screen (I'm using a Hornby select controller) (I do have a roco controller and a elite controller to hand if needed)

I've done this before to other locos and other motors so it's not my first time D.C to D.C.C but I haven't had it before working for D.C but not D.C.C

Normally if I'd did it wrong it wouldn't work for either :jester: or blown a chip before today so I'll double check them tags on the top

 

Oh the multi meter I've got isn't working lucky I got a new one at Warley this year must of been on the list

 

The two chips I've tried are a gaugemaster and a Hornby spare I had lying around



#5 shaunthesheep277

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Posted 07 December 2017 - 18:47

I've just had a look and a thought

The lugs for the motor stick up from the top a bit

the digger I'm using, parts are diecast

I'm using the main body of the digger to cover the decoder

Could the metal be conducting between the two lugs on top of the bogie

If I could find another decoder I could wire it all separate and see if that works

I may have solved it, I'll have to try it first



#6 johnb

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Posted 07 December 2017 - 19:10

That sounds a real possible. But, have you tried running the bogie with only the decoder attached? One other point, are you sure that there isn't a whisker of wire or a whisker from the brass pickup strips bridging somewhere. You mention some earlier DC wiring, I assume that as you are DCC/DC savvy that there isn't a strand from that bridging something.

 

Just clutching a straws here, but been there done that!!

 

John



#7 shaunthesheep277

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Posted 07 December 2017 - 19:34

Hot wired a decoder still no luck checked the bogie no stray wire yet still ol on screen my head hurts never had this before why would it run dc some motors are protected from current could the chip be receiving the full amount

#8 shaunthesheep277

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Posted 07 December 2017 - 19:35

Sorry about grammar but the last post was typed on my phone

#9 shaunthesheep277

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Posted 07 December 2017 - 20:08

Ok I'm not sure here but the Hornby decoder doesn't wanna know now and isn't working, the Gaugemaster decoder is still coming up O.L

Puzzled is one thing as both work or did on the donor loco of the Hornby decoder

Now I'm looking at the bogie as the main problem, more looking at the motor



#10 Phil S

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Posted 07 December 2017 - 20:16

Whenever converting locos to dcc, always insulate exposed metal - either the body or chassis or any other parts that can be protected or sods law will ensure they do short at some time in the future!  

I am concerned you seem to be throwinfg decoders at the problem rather than verifying with a meter that there is no connection.

If the meter is not available - then a 9V battery and LED and resistor in series could be used to verify continuity or non-continuity..

Running on dc is not always a reliable test for correct dcc wiring 8-)  - there have beeen cases of miswired commercial products which work on dc and blow decoders instantly ! 

 

A bit concerned by yoyur description of adding the wires,after cutting, to test on dc ... then adding the decoder ...I can only assume the dc wiring links were removed 8-)    Did you then try this decoder on a 9V battery before connecting to the dcc controller ??

 

Nothing wrong with the Roco Multimaus, if that is the one you have: But I recommend using a SMPS for it if yours came with the old 50Hz transformer (labelled 230:16VAC)  - all new units are supplied with an 18V DC SMPS (small or large current rating) - and this gives a perfect 16V dcc on the track at ALL times . unlike the unregulated transformer which can give 22V dcc on track when nothing is moving (ie off load voltage).  I use lots of Mulimauses - even for G Scale on the level - (but not in a sloping garden where i need 5A or more).

If you have an older Maus2 then you will fiond it a very useful option for programming locos that other controllers fail to !  (read its manual for all the options it tries on sequence)



#11 johnb

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Posted 07 December 2017 - 20:19

I'm getting to an absolute stand here.

 

As you will have seen there is no complex, or indeed any, protection on an out-of-the-box Tenshodo, just the hard connection between pickups and motor. Tenshodos should not draw anywhere near enough current to trip any reasonable decoder. If it was that faulty the DC supply should have tripped or the bogie would get very hot.

 

Phil has mentioned a point, you have removed your dc wiring links haven't you?

 

John



#12 shaunthesheep277

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Posted 07 December 2017 - 22:41

Not electrically minded but yes I have a multi meter the track reads DCV 200  at 05.1 if that's helpful

Not sure how to check the bogie but they are simply little things 

 

I've added a picture of hows it's wired up now (I know it's a mess it was a lot neater and looked like a digger)

20171207_221118.jpg

 

As soon as it's wheels touch the track the screen reads O.L

I apologies if your all pulling your hair out you've all being helpful up to now just humor me just a little bit more I'm sure we'll figure it out



#13 Phil S

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Posted 08 December 2017 - 09:11

You have tucked the 'unused' wires beneath the decoder sleeving.....it might be worth pulling those out to ensure they are not touching something on the decoder egba function short.
Wires to the tenshodo look rather heavy.... As thin ad the decoder but more flexible than the Hornby ones would be best.
But otherwise no obvious problem showing ( best to avoid use of 'wrong colour' wires, even though it doesn't affect the electrons, as it can have an effect on the han brain making a mistake later 8-)

Concerned about your multimeter reading...
Track voltage on DCC may not show accurately because many meters are only calibrated for a sinusoidal ac, and not the square wave of DCC... So is best used for comparison voltages around a layout only....is the same voltage at the controller and around the track, whatever it shows.( DCC measured on AC Volts range)

More accurate measurement can be made by including a bridge rectifier between the track and meter ( ac terminals to track, and +/- terminals to meter ) and the meter then on a DC Voltage range.

When measuring for CONTINUITY the meter should be on an (Ohms) or (diode symbol/ loudspeaker symbol) range, and no track power present.
There should be NO connection between track and motor terminals and this will show the same on a digital meter as when the leads are not touching anything....so confirm correct meter operation by touching the leads together and the reading should go to 0000 and maybe have a beep.
If you think a diode maybe included in the path, then try the leads both ways round....one way would show open circuit and the other some 'mid value' in the range perhaps '500' as being between the open circuit 1000 display and 0.000 of a short circuit.

A typical 00 motor will show about 20-40 ohms....and will vary as the motor is turned as 1 or 2 coils are in circuit.

#14 johnb

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Posted 08 December 2017 - 09:52

Cannot add anything useful to Phil's comments, looks ok but do pull out those wires tucked into the decoder sleeve.

 

John



#15 mezzoman253

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Posted 08 December 2017 - 11:16

Not sure if this will help. http://www.metromode...onversion_a.jpg

 

Sounds like you've done this already.

 

Rob


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#16 Dagworth

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Posted 08 December 2017 - 11:19

Try disconnecting the orange and grey wires and put it on the track. If is still shows as overload then you've blown the decoder.

 

Andi









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