CJH wrote:
Version 0.4 is still the most up-to-date version that I have. But it does need some additions (mostly around the DOPS option) and some corrections as spotted by various kind people.
While I'm still working on an update to the guide, I thought it might be useful to show the details of the DOPS option, to save me retyping it for everyone that I send a kit to.
There are two main points:
1) the orientation of the ribbon cable and the corresponding pins on the back of the speedo
2) the need to omit resistor R3
1) Cable and socket orientation
When soldering the 2x3 box header, note that the socket is keyed so that the DOPS cable can only go one way round. There is also a numbering convention for the pins, with the location of pin 1 being indicated by a small triangle on both the plug and socket.
You'll also see that the PCB itself has a small number '1' to indicate which is pin 1. Because of the way that I've assembled the plug onto the ribbon cable, you should therefore aim to solder the box header such that the keyway gap is on the right hand side, closest to the edge of the PCB.
If you do it this way, you'll find that the ribbon cable exits the plug in the direction of the speedo pod.
The colours of the ribbon cable aren't significant - they're different for every kit, as I just peel off the next 6 strands. But the important thing is that whichever strand is at the bottom of the ribbon (blue in the above photo) is pin 1, and pin 1 should connect to the leftmost pin in the speedo - the others then just connect in sequence. The photo below shows this. By routing the cable up the side of the speedo pod, then turning it through 90 degrees (with a 45 degree fold - the photo explains this better!), the pins should naturally fall in the right positions.
.
2) Resistor R3
When assembling the components, you should OMIT resistor R3, since the current to the OIL LED is controlled by the DOPS circuit board. Soldering R3 in place would put that LED under the joint control of the 0.3bar pressure switch and the DOPS circuit, which would probably cause problems.