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Author Topic: Graham Farish Class 08 DCC Conversion Issue  (Read 1264 times)

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Offline andyt55

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Graham Farish Class 08 DCC Conversion Issue
« on: February 11, 2018, 02:43:23 pm »
I am trying to convert an old Graham Farish Class 08 08113 to DCC using a DCC Supplies Digi-Hat and a TCS Z2 decoder, following Andrew Roscoe's instructions.

So I have connected the orange cable to the upper brush, the grey cable to to bottom brush with the Digi-Hat, the black to base of the capacitor and the red to the bolt through the plastic.

My issue is that JMRI Decoder Pro reports a short circuit on my test track.  I tested the installation with my multimeter and there is a 100 ohm resistance between the chassis (decoder black) and the upper brush (decoder orange).

Has anyone else converted this loco and had a similar problem?

Andy

Offline Caz

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #1 on: February 11, 2018, 03:38:48 pm »
Get rid of the resistor and capacitor and all should work.

Offline andyt55

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #2 on: February 11, 2018, 03:53:57 pm »
Get rid of the resistor and capacitor and all should work.


I have done.

The black cable is soldered to the base wire of the capacitor which I have cut off.  I have also removed the resistor.  See the photos below.









Offline Caz

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #3 on: February 11, 2018, 04:01:53 pm »
It's a bit hard to make out the colours.  Digihat fitted to the bottom motor bush,  orange and grey to the motor brushes, red and black to the pickups.  Normally red to the right track pickup, black to the left, orange to the bottom motor (digihat) motor brush and grey to the top motor brush.  Check that the heatshrink on the bottom motor bush completely insulates the brush.

Offline andyt55

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #4 on: February 11, 2018, 04:37:55 pm »
It's a bit hard to make out the colours.  Digihat fitted to the bottom motor bush,  orange and grey to the motor brushes, red and black to the pickups.  Normally red to the right track pickup, black to the left, orange to the bottom motor (digihat) motor brush and grey to the top motor brush.  Check that the heatshrink on the bottom motor bush completely insulates the brush.

I've got Grey connected to the bottom (DigiHat) motor brush and Orange connected to the top as in Andrew Roscoe's instructions. Looking at the TCS Z2 diagram that shouldn't make any difference.

I have tested the bottom bush clip and it is totally insulated.

The problem seems to be with the top bush clip, where there is 100 ohm resistance between it and the chassis (the decoder black lead) which connects to the left hand wheelset.

Andy


Offline Lindi

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #5 on: February 11, 2018, 05:01:47 pm »
Check that the soldering of the black and orange wires are not touching on the decoder.  It is hard to tell from the photos but they look very close. I have had an issue with wires being badly soldered on a decoder before although this was a digitrax decoder

Offline andyt55

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #6 on: February 11, 2018, 05:11:43 pm »
Check that the soldering of the black and orange wires are not touching on the decoder.  It is hard to tell from the photos but they look very close. I have had an issue with wires being badly soldered on a decoder before although this was a digitrax decoder

It's a tiny decoder and my eyesight's not what it used to be but it looks like the orange and black wires are soldered on different sides of the board.

Andy

Offline Caz

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #7 on: February 11, 2018, 06:48:21 pm »
Looking at this picture something doesn't look right. 

You seem to have 2 black wires one of which is wired to the orange wire that goes to the bottom brush but next to the cut off blue wire there seems to be a cut off grey wire and the grey is normally the other motor wire and in this picture it looks like it is not being used?


Offline Only Me

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #8 on: February 11, 2018, 07:11:48 pm »
Wiring looks correct to me... it will be a pickup thats been pushed in too far whilst you have been fettling and those pickups of pushed too far in touch the other isolated pickup plate



Offline Caz

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #9 on: February 11, 2018, 07:20:51 pm »
@Only Me is it my eyes or is that a grey wire hiding behind the red wire and the cut off blue wire in the picture I inserted?

Offline Izzy

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #10 on: February 11, 2018, 07:46:40 pm »

I think you need to make sure the top clip which holds the top brush/spring in place is not touching the chassis somehow. Both motor brushes must be totally isolated from the chassis and I wonder if the capacitor leg is still touching it

To ensure this you need to remove the clip - don't let the spring or brush 'spring' out and get lost -  and solder the orange wire onto it, and then clip it back into place and get rid of the capacitor completely.

Izzy

Offline Only Me

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #11 on: February 11, 2018, 08:17:36 pm »
@Only Me is it my eyes or is that a grey wire hiding behind the red wire and the cut off blue wire in the picture I inserted?
zooming in, it looks like a white wire thatbyou mentioj not a grey one?



Offline JanW

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #12 on: February 11, 2018, 08:45:23 pm »
It certainly looks as if the grey wire is cut.
If you zoom in on the second picture there is clearly a grey wire (looks a bit blueish) which disappears behind the heat shrink tubing.
Below it are a white and a yellow wire, also cut short.

The wire connected to the motor terminal seems to be brown.

Jan

Edit: seems the whitebalance is confusing me. Could very well a blue wire instead of grey!!
« Last Edit: February 11, 2018, 08:48:08 pm by JanW »

Offline stevewalker

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #13 on: February 11, 2018, 09:00:41 pm »
There seems to be some comfusion of colours, but to my eyes and on my monitor, working from left to right across the decoder, there are:

1) a cut-off blue wire
2) a cut-off white wire
3) a red wire connected to the isolated wheels
4) a grey wire, extended by an orange wire to the lower brush
5) an orange wire connected to the upper brush
6) a black wire connected to the chassis by the remaining leg of the removed capacitor

Offline Paul-H

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Re: Graham Farish Class 08 DCC Conversion Issue
« Reply #14 on: February 11, 2018, 09:50:42 pm »
Why is there a capacitor connected between the decoder grey and the orange wire going to the bottom brush?
Please excuse any poor spelling, I am Dyslexic, just think yourself lucky if you can actually read what I typed.

All tiepin as bean spell chequed on mi Pea Sea

 

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