type 89 speedo data information?

[Huw Powell]

Doug Yoder wrote:

> I *know* I've read this procedure somewhere before.... now where?
> 
> Ah, here it is! Chris Miller to the rescue again!
> http://members.aol.com/c1j1miller/body.html#Spedometer/Odometer

Excellent!

So, I wired the speedo/odo unit up, 12v, ground, and a sine wave around 
200 Hz or so.  Brought up the voltage, and the speedo sprang to life.

At this point, I could hear and feel the little stepper motor thumping away.

So I had to open the assembly up to see what was going on.

Off comes the needle, two screws and off comes the dial, three more and 
the "crystal" is off.

Then I undid two more screws that hold the PCB/motor to the odometer 
body, and the tiny planetary gear that is driven by the motor has a 
couple of busted teeth.  Dang!

So the only hope is to find a suitable replacement somewhere, somehow, 
or to actually *make* a new gear (good luck on that!).

But at least I know what is wrong, and how to "correct" the odo if I get 
it working.

>> I am wondering if anyone out there has ever analyzed the signal that
>> drives the electronic speedometer/odometer (the late coupe and various
>> type 44's are probably similar).
>>
>> I have two busted odometers, and want to try to fix one "on the bench",
>> which would mean needing to synthesize the data stream from the sender
>> in order to see if I've succeeded.
>>
>> So, anyone know... frequency to speed ratio; nature of signal - square
>> wave, sine wave, duty cycle if assymetrical, etc.?
>>
>> -- 
>> Huw Powell
>>
>> http://www.humanspeakers.com/audi
>>
>> http://www.humanthoughts.org/
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>>
> 
> 
> 

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/