Speedo Bounce FIx

[Phil Rose]

At 9:25 AM -0500 11/13/06, W.G. Giles wrote:
>Hi
>My speedo bounces sometimes what is the fix.  Is it in the cluster or
>the trans?

Most commonly it's the IC. I fixed mine about a year ago --after 
doing two things. First-- was to run an extra ground wire as shown in 
the following link.
http://www.lanikamal.com/audi/dashboard.html?

  That repair wire jumpers over a crack that commonly occurs in the 
upper PC board's circuit--a crack which prevents the "other side" 
(left side in the photo) of the board from having a good ground. That 
crack tends to occur near  the base of a small two-pin connector (you 
can see the underside of this connector in the second photo--two 
small holes and associated solder points). Merely installing this 
repair wire as shown serves to cure a common problem with the IC, 
whereby there is very dim IC backlighting along with simultaneous 
display of both green turn-signal arrows (also erroneous indiication 
of high-beam headlights). But this "fix" alone was *not* enough to 
cure my bouncing speedo.

It happens that a crack (or cold solder joint) can also occur at the 
base of the little (green plastic) 2-pin connector, and this can be 
the  cause of  the bouncing speedo needle. A bad solder joint at the 
base of this 2-pin connector makes the connector unable to 
adequately ground its mating pins (these pins carry ground to the 
speedo circuit board below). Using an 8x magnifier, I was able to see 
a faint crack right at the soldered metal base of the 2-pin 
connector. I heated this spot carefully with my low-wattage soldering 
iron and my bouncing speedo was fixed. At least for the time being 
(one year so far).

I've added a photo that shows the two small "speedo ground pins" 
which are located near the top edge of the IC (--arrow-- at bottom of 
photo); here they're shown emerging from the white, intermediate 
circuit board cover. When the uppermost circuit board is put in 
place, these pins must slide into the 2-pin connector discussed 
earlier.
http://phil-rose.com/miscellaneous/speedo_ground_pins.jpg

This all probably sounds about as clear as mud. Will be easier to 
understand once you have the IC removed and begin disassembly. Use 
only a low-wattage iron.

Phil


-- 

Phil Rose				Rochester, NY USA
'91 200q	(156K, Lago blue)
			mailto:pjrose at frontiernet.net