Friday, Aug 29 was physical assembly day. Orientation confusion proved to make this section challenging and error-prone for me.
First I needed to plug the 6x1 and 4x2 Blocks into the EXT2 Header. It was not completely clear how to orient the processor board so that the Header’s orientation matched that of the wiring diagram, because no pin labels were visible on the board. Gary explained that pins 1 and 2 are labeled on the opposite side of the board. You can see these labels in the lower left corner of the photo below. In the correct orientation, the lettering on the side you plug into (the board’s “bottom” side) is right-side up.
In this photo, the Zener diode looks dangerously close to another connector pin. This has been corrected.
Next I installed the buttons and the switches. The washers on the buttons should be removed to provide a little more clearance on the inside from the display board. For the switches, retain the lock washer for the outside, but discard the keyed flat washer. Be sure the hex nut on the inside is screwed down all the way before mounting each switch to the box, because it is difficult to turn this nut afterwards in the cramped space.
Despite careful study of both the instructions and the wiring diagram, I managed to install both switches upside down, so the toggles point the wrong way. The source of the confusion was that I assumed that when either double-throw switch’s toggle was “up,” its center contact(s) were connected to the “top” contact(s). Actually, the switch action is reversed, so when the toggle is “up,” the bottom contact(s) are connected. In my next post I will submit detailed editing suggestions to help insure no one else makes these mistakes.
While stuffing the computer board, connector, and cable into the box, I broke the connection between the red wire from the Zener diode and the power switch’s center terminal. The Zener diode itself is stiff, and it seems I had soldered it on the “wrong” side of the cable in some sense. Because I didn’t want to start all over with the assembly, I needed to re-solder the connection inside the box, on the other side of the cable, and this proved embarrassingly difficult. I finally managed it late Friday night. I didn’t want to test HTB’s policy on soldering at their tables
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For either testing a kit or updating the firmware, Gary applies power to the 2-pin white header in the upper right corner of the photo. It was encouraging to see the display cycle through its test patterns successfully. I liked the safety of doing this first test without the car connected. It validated the processor, display, and button connections, but only connection to the car can validate the cable and switch connections. It would be nice to have a test socket to emulate just enough of the car’s signal levels to give confidence that there are no wiring errors or shorts that could damage the car’s bus, but this might be difficult. When I did plug my unit into my car, it was great to see my battery’s SOC
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Gary uses the 10-pin header in the upper left corner of the photo to load firmware updates. This is why he does not need to disturb the packaging.
When replacing the box cover, Gary advises that you first gently turn the little screws backwards until they drop into the threads previously cut into the plastic. Otherwise there is a danger that the metal screws will cut new, weaker threads.
