Hornby Elite No 1 Dial Faulty?

[Chrissaf]

The lhs No 1 dial on my hornby elite controller seems to be slightly eratic when pushing down to change direction arrows etc and sometimes doesnt respond at all. Makes programming very difficult at times. I would try a full reset but I have so much programmed into it and in its current form it would take forever to reinstall if there was no benefit. 

[96RAF]

The speed encoders can and do go wrong unfortunately. A left handed person will typically wear out the left one and vice-versa. A normal trait is you turn the knob to a value and just as you press it alters the value by one up or doen - very irritating. I hold the knob with finger and thumb to prevent it nudging as I press it with the other hand.

The encoders are easy to replace once you get inside the Elite if you can solder, but they are difficult to find. I have the spec.

Hornby should be able to repair it for you. Give them a call - number is bottom of every webpage.

A unit reset will lose any favourites you have programmed in as well as any names, etc. A reset is unlikely to help with the encoder problem.

[ColinB]

I have never looked at the endoders on my Elite, I just assumed that it was a rotary encoder with a switch. I don't know, but probably someone can help me, but I imagine it is the same sort that we used to use on the Ford Radios I used to design, a "Gray code" encoder with an in built switch. I remember these things were incredibly cheaply made, hence why we used them, so I am not surprised they fail, although these seemed to be pretty reliable on the radio. It annoys me that I select a value on the rotary switch, but changes when I press it but that is because as you press it down the rotary bit probably moves a little. Really what Hornby should have done was to include a separate enter button, but I would have made the same mistake in design as it is not something that you think about. I have got the same issue with my Fleishmann controller when you turn the dial, the value quite often goes up when it should be going down and vice versa. I assume someone like Radio Spares or Farnell does replacements.

[96RAF]

They are push on/push off with an endless rotary potentiometer. What they need is a more positive click detent to prevent movement when pushed.

Encoder is identified as E460 and PN 2457-X034. I have the PCB footprint if anyone turns any up and wants to confirm they will fit.

[ColinB]

I assume it is the same thing as in the radio, as you rotate the dial the encoder produces two square wave signals. So if you look at then at the same time you get two digital signals the software intepretes these to work out whether you are turning the dial left or right, it is called a "Gray code" ( after Frank Gray, according to Wikopedia), because the signal only changes one state at a time, you get 00, 01,11, and 10 for the two signals, so if you read 01 after 00 you know it was turned upwards if you read 10 after 00 then the dial was turned downwards. It only works if you have a microprocessor, you generally use one of the inputs as an interrupt to the microprocessor to tell the micro the signal has changed, or aternatively you can read it every some many milliseconds (no so good) . Potentometers are resistive with end stops, so they may be refered to as endless rotary potentiometers, but they are not really. i think Panasonic used to make ours, but it was a long time ago.

[96RAF]

More than likely Colin. I think your description of off kilter square waves is probably as close as it gets.

They are not pots at all hence why they are called encoders. A pot generally has a wiper scraping over a resistive track. These are more like induced voltages as gleaned from a generator/altenator.

The Elite ones are also rate dependant so if you turn it slow nothing much ever happens but if you spin it the output goes exponential.

[ColinB]

Yes, you would get that the faster you move the encoder, the distance between the pulse edge decreases. So in 1 revoluition you will get probably all four states, or a multiple of them (4,8,12,16 etc), so the faster you move it, the more pulses you get in a given time. I used to write the software on the radio to read it, so I know about all the issues you get with it. On some of our old radios if  you turned it in a certain way the volume would go down instead of up, that is why I had to rewrite the previous software ( you have to be careful; how you read the edges of the pulses).. 

[96RAF]

Much the same as wheels on an old cowboy movie used to appear to go in either direction according to how the revs synched or not with the film frame rate.