"I see how the motor on the PCB drives the gears for the odo but it's unclear to me what makes the speedo needle move."
Hi Peter,
If the speedometer drops while the miles keep ticking away on the odo, there's very little left to go wrong. I haven't had this occurrence, so I can say I'm stumped for an internet suggestion based on experience.
When you look at the blue and black wires leading from the board to the speed meter, you are seeing most of the vulnerable aspect of this part of the circuit. Then, if you follow the traces on the circuit board, from the blue wire especially, you may see some solder connections you didn't reflow, perhaps, and the 220 microfarad capacitor in the corner.
If all that looks good, then I'd be getting out a powerful light and a good pair of specs to examine the meter itself, which is least repairable of all, and as delicate as an instrument can be hauled around in a car for hundreds of thousands of miles. It works like this: D'Arsonval Movement
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Art Benstein near Baltimore
You can say any foolish thing to a dog, and the dog will give you a look that says, 'Wow, you're right! I never would've thought of that!'
- Dave Barry
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