Converting hornby hst to dcc

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Stano100
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Converting hornby hst to dcc

Postby Stano100 » Fri Dec 28, 2018 11:01 pm

Hi again

I have fitted my first dcc decoder to a old hornby hst swallow, after switching to zen decoders with stay alive it is running well

I have a second hornby hst to convert this time a Virgin, the wiring looks slightly different

On the swallow I had wired red and black to the pickups and orange and grey to the motor

On the virgin the pickup from wheels seems to go straight to the motor with no wire in between. can I connect the red and orange cables from decoder to the same point on the motor?

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End2end
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Re: Converting hornby hst to dcc

Postby End2end » Sat Dec 29, 2018 12:27 am

Stano100 wrote:On the virgin the pickup from wheels seems to go straight to the motor with no wire in between. can I connect the red and orange cables from decoder to the same point on the motor?

I'm not 100% sure but I would say No. (I assume you mean grey and orange, rather than red)

Because the pick ups need to be soldered to the black and red wires of the decoder making sure to isolate any direct connection between the pick ups and the motor.
Think of the decoder as sitting inbetween the pick ups and the motor.
No direct connection should be between pick ups and motor, only to the decoder.
So in it's basic terms, the power flows from track into the decoder that then passes on power to the motor (moving the loco).

Once you've soldered on the red and black wires on and isolated the pickups COMPLETLY , NOW you can solder on the orange and grey to the motor.
If you haven't isolated the pick ups properly you can blow your decoder.
Hope it helps
Thanks
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Stano100
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Re: Converting hornby hst to dcc

Postby Stano100 » Sat Dec 29, 2018 9:34 am

I mean red and orange to one side of the motor

As I am new to this I may not be describing their very well.

I put a meter on back wells where the motor is, also one side of the motor and I get a circuit. There is no other wire connecting from the chassy to motor like on the swallow I converted

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RAF96
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Re: Converting hornby hst to dcc

Postby RAF96 » Sat Dec 29, 2018 9:37 am

It sounds like the pickup from the front bogie goes to the motor housing which is likely live to the left hand brush. If so the brush needs isolating from the housing normally by using a nylon screw in lieu of the metal screw or there may be a lug on the housing that the brush retainer strip bears on, this time the isolating methodology is by way of an insulating slip of plastic.

The other pickup is on the none geared side of the power bogie direct to the right hand brush. The geared side wheel is live to the axle which is live to the motor housing forming the retrun circuit with the front bogie.

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Re: Converting hornby hst to dcc

Postby Flashbang » Sat Dec 29, 2018 10:59 am

For DCC operation, any motor regardless of its type MUST be fully isolated from all rail power and wheel pick ups. All existing wires or connections to the motor MUST BE REMOVED.
The other thing to be ensured before any conversion is considered is that the loco must run faultlessly on DC power with no hesitancy to start or general poor running noted. Any that is found must be corrected as once converted a poor DC runner will become far worse on DCC!

Once the motor isolation is proved (tested and proved ideally with a multimeter on its continuity setting range) then and only then proceed as follows....
Decoder Orange and Grey wires are soldered one wire to each of the motor terminals. Then the decoders Red and Black wires are soldered via in-line joints to the wires previously removed from each side of the motor.
If there was no wire on one side of the motor then that feed was originally to the motor via the metal of the chassis and wheels (This connection must have now been isolated at the motor). So then it will be necessary to connect either the black decoder wire to the chassis somehow with the other red decoder wire connecting to the wire previously removed from the motor by an in-line joint.

Place loco onto the Programming track and set its address to whatever is required. Once done and only then place the loco onto the main tracks and test under its new address. If it runs in the opposite way to that of the consoles setting reverse the Orange and Grey wires on the motor. Or use CV29 to reverse normal direction of travel. Tidy all motor and rail pick up wiring and ensure the decoder cannot touch any metal items and tidy any function wires. Replace body and enjoy!
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RAF96
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Re: Converting hornby hst to dcc

Postby RAF96 » Sat Dec 29, 2018 3:15 pm

It may not be clear to a begineer what motor isolation actually is...

Using a multi-meter check for continuity between each motor brush (usually at the brush connection) and the wheels on both sides of the loco, after you have disconnected every bit of wire.

There should be no continuity. If there is you have to find that path and isolate it, as stated previously usually on ringfields by use of an isolating shim or a nylon screw. Some can motors can have one or more brushes pressing directly on the wheel pickups.

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Re: Converting hornby hst to dcc

Postby TimberSurf » Sat Dec 29, 2018 11:11 pm

Obviously there are different variants, as I have just stripped two down, to convert to DCC, there is a VERY short wire (black) between the side of the (metal) motor case to the left terminal of the motor. It needs a new wire from the case to the decoder input (DCC in) and a new wire from the decoder output to the left motor terminal (+ or -)
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Re: Converting hornby hst to dcc

Postby Bufferstop » Sat Dec 29, 2018 11:31 pm

I don't know if it applies to the HST but on some Ringfield chassis that short wire is replaced by a tag on the brush connector with a screw through it into the block. That needs to be replaced by a nylon screw, (or modify the tag) and a new wire attached somewhere to the block as one side going into the decoder, and another wire between the decoder output and the brush connector. The nylon screw is the better solution, otherwise you end up with two bits of metal in close proximity which must not be connected. The nylon screws used to be available from Peter's Spares, I don't know if they still are.
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Stano100
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Re: Converting hornby hst to dcc

Postby Stano100 » Sun Dec 30, 2018 12:46 am

Thanks for all your replies

I have on got 2 wires on the that connect to the motor, 1 from well block at front of the loco and 1 that goes from the other side of the motor to the front light.

There is also a wire from front block to light

The short wire is not there

I will will look again at your suggestions

Thanks

Stano100
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Re: Converting hornby hst to dcc

Postby Stano100 » Sun Dec 30, 2018 12:48 am

Sorry how can I post a picture on here, that would make thing clearer

Thanks

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Re: Converting hornby hst to dcc

Postby Stano100 » Sun Dec 30, 2018 11:10 am

Think I have sorted the pictures
Should be 3 below
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08C8D4C7-1EEC-466C-A33F-FBB4491DF7C4.jpeg
02FF3242-AE15-4122-8610-C0A41651B06C.jpeg
A5C5E6DD-8D99-4CDC-910E-0CCD57614549.jpeg

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RAF96
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Re: Converting hornby hst to dcc

Postby RAF96 » Sun Dec 30, 2018 11:27 am

I would think your power route is ...
Motor bogie left wheels via motor housing to left brush, hence to front light.
Other side of light and front pickup right wheels back to right brush.

If you pull off the wires from both brushes you will find the left brush is still live to the motor bogie left wheels and that route needs isolating as above if you want to fit a decoder.

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Re: Converting hornby hst to dcc

Postby Flashbang » Sun Dec 30, 2018 12:10 pm

I'm rather unclear as to what exactly your actually after? But...
For DCC operation there must be no other wires on the two silver motor brush strips OTHER THAN the two decoder wires - Orange and Grey.
Any lighting or other wires MUST BE REMOVED from these two strips.

Once all wires are removed from the two silver coloured brush strips, you should then test each brush strip in turn to ensure there is no connection to the wheels or any metal chassis of the motor itself. Failure to test and there is a connection will result in immediate and terminal decoder failure as soon as full DCC rail power is applied - Be fully aware of this requirement! Any connection discovered MUST be removed before proceeding.
Testing....
A) This can be carried out with a multimeter set onto it continuity range (Ohms) and no reading obtained when one lead is held on one strip and the other lead touched in turn onto each motor bogie wheel and any metal of the motor bogie. Swap to the other brush strip and retest to all wheels and any metal.
B) Instead of a multimeter you can use a buzzer or suitable Grain of Wheat or Grain of Rice lamp etc and a battery to suit the lamp or buzzers voltage plus two testing fly leads with their insulation stripped from the free ends by about 5mm. Made up so as when the two fly lead ends are touched together the lamp will light or the buzzer sounds. Then using this testing, hold one test lead onto one silver brush strip and touch the other lead onto each wheel in turn and any metal to ensure the lamp doesn't light or the buzzer sound. Do the same to the other silver brush strip.

Only once all is proved to be isolated (No connections to either silver brush strip).... Proceed as .... Solder decoder Grey and Orange wires one to each silver brush strip. Make an in-line joint to the wire removed from the right hand strip to the decoders Red wire. This leaves the decoder Black wire which needs to pick up power from the opposite sides wheels to that which the red decoder wire connects onto. How you make this connection is a bit unclear, as we can't see the whole loco. It may be via a wire that is on the other side of the front lamp which will need to be removed from the lamps wiring if this wire goes directly to the wheels or it may be necessary to connect the Black decoder wire to any metal of the motor that is live to the one wheel set that is the opposite to the red decoder wires wheel set???

This now leaves the front lights..

1) If this is a filament lamp and not LED then connect the decoders Blue wire to one wire coming from the light and the decoders White wire to the other wire from the lamp. Doesn't matter which way around. The wires from the lamp only go to the decoders wires no where else!
2) If the front lamp is an LED you need to ensure there is a series resistor wired into one lead of the LED (Doesn't matter which lead) the resistor should be a minimum of 470R and ideally a 1K0 (1000 Ohm) resistance would be better. If the LED is mounted on a small circuit board it may have ready fitted a resistor, but you will have to check this. You will have to find out which one of the two LED wires or connections is the positive (Anode) of the LED then connect the decoders Blue wire to that and the decoders White wire to the negative (Cathode) wire. Again no other wires are connected to the LED or run off anywhere except the two decoder wires.

In either case filament or LED front lamp the DCC consoles 'F0' key will turn On or Off the headlight and it will be automatically controlled by the normal direction of travel too. i.e. On when going forward and Off when running in reverse. It is no longer controlled as per the DC wiring.
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End2end
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Re: Converting hornby hst to dcc

Postby End2end » Sun Dec 30, 2018 12:14 pm

I'm in the middle of DCCing a HST myself. viewtopic.php?f=49&t=51555&start=60#p654167
Thanks
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