Which is pin 1 on the DCC decoder on a class 87 PCB.

[ColinB]

Does anyone have a diagram or photo of what is pin 1 of the DCC connector on a class 87 circuit board. I have looked for dots, squares on the pcb but so far have found nothing. The reason I ask is I cannot get the cab lights to work, so does anyone know where the resistors are on the board? There are loads of diodes on the PCB so trying to do a continuity check is not that easy. Trouble is normally pin 1 doesn't matter by this has lights so it is so important.

[Rog RJ]

Is this the same as your PCB?

https://d63oxfkn1m8sf.cloudfront.net/3000x1876/jpg/7216/0035/0533/x6503.webp%3Ffit%3D1

[P-Henny]

@ColinB

Suprised nobody has replied yet, so offering my pennith worth. Should it help.

I would have thought, based upon your DCC decoder posting history, you would have worked out how to check Pin 1 location for yourself. Assuming an 8 pin socket here.

On the 8 pin socket, Pin 1 is directly opposite Pin 8 and Pin 8 goes to the pickups on the right hand side of the loco relative to a drivers point of view. In other words the drivers right hand side when facing forward.

Pin 1 goes directly to the motor right hand side, but what is motor left and what is motor right is not always obvious, but Pin 8 & right rail side should be more obvious & traceable. Thus, identify Pin 8 with your multimeter and you automatically find Pin 1.

Sorry can't help with PCB circuit details as don't have any 87's. But that said, the diesel class PCBs I have seen are usually screen printed with labels such as, for example, MR, ML, TR, TL or some form of equivalent labelling such as M+, M-, TR, TL.

MR (Motor Right) would be Pin 1 and TR (Track Right) would be Pin 8

[Howbi]

According to this photo capture of the decoder installation pin 1 is top rt hand corner from this viewpoint.

[ColinB]

P-Henny I must admit I forgot about the pickups having defined pins. I am so used to the pin not mattering on the ones I wire up that I forgot this is a production one so the wiring should be correct. Great thank you for telling me, I honestly never thought about. As the wiring, on this one I get the opinion that the cab lights never worked properly but I am slowly getting there. Yes this one has those labels but I am looking for how the cab lighting is enabled so there should be a connection to the function 1 output which there isn't. Unless of course it is not meant to work on this model.

[96RAF]

Cab lights may be mapped to direction and if directional lighting is on or off. Usually these functions are tagged to F2.

[P-Henny]

I don't use 8 pin decoders as all my locos are Non-Hornby Loksound, but on many of them 'cab lights' are mapped to F8. So you can't assume that 'cab lights' on your loco will be F1.

On a Hornby R8249 the cab light might be on the F2 purple flying wire i.e reserving F1 for a TTS decoder. Which of course would then mean that the purple wire has to be terminated somewhere to access the cab light LED.

So look at the screen printed wire terminating locations on the PCB. Look initially for any locations that do not have a wire currently terminated on it, where the screen printed label might be construed as being a cablight (CL for example or just C or L for Light/LED etc).

I assume that you can actually see a phyisical LED in the cab? If you can't then you have your answer.

[ColinB]

It is normally F1 as F2 is the flying lead, there is something weird going on with this one, it was supposedly never used but the wiring looks suspicious, as the soldered joints look like they have been done with leaded solder, so I wonder if it is a rework by Hornby. Fortunately I have another class 87 with the same mechanism but different colour, so I will do a back to back comparison. I have tried all combinations lighting on/off, directional. Thanks to the information I have now found pin 1 so at least I can identify the Vref and F1 pins.

[96RAF]

Service sheet 436 doesn’t seem to show any cab lights.

[ColinB]

Well unless I am doing something seriously wrong, on none of my three class 87s do the cab lights work, although the wiring and spring connectors are there to give you the impression it should do. Looking at the wiring on the fitted cab lights on one set of leds the wiring is the wrong way round so that is one issue. I will check with Hornby in the morning.

[ColinB]

Having got a response from Hornby, it appears it works on Function F0, not F1. The other thing that I found out by myself is that the switch on the underside must be set to N (night time running). Normally the cab lights are on a separate function to the main lights, but I suppose this is an old design so I suppose that is the reason.

[96RAF]

Sounds perfectly logical to me. Cab lights are on when the running lights are on and when its dark i.e. the light switch is set to night.

[ColinB]

Normally on most locos normal lights are F0 and cab lights are F1. As Jenny Kirk will tell you cab lights are a bit like the interior light in a car, only switched on when stationary so a good idea to have it on a different function. In fact on a lot of the new locos the cab lights go out once the loco starts to move. This is an old loco hence why I can see it being on F0 although if I remember rightly, on the class 71 the cab lights are on F1. Either way now I know.