spare instrument cluster

Ameer Antar ameer at
Thu Dec 14 21:30:31 EST 2000

ya, any 10v regulator would do as long as it's rated for .22A+. The most 
common and cheapest v-reg size is a TO-220, which are usually rated for 1A 
which would be plenty. You can get a fixed 10v regulator from Digikey or 
any good electronics shop, but not Radio Shack. They only have the 5V and 
12V reg's. Make sure to get pin out right. I think the 33 ohm resistor they 
added boosted the voltage a little, by referencing the ground to a higher 
voltage than zero [voltage across the 33-ohm resistor].


>The 8851 is a date code: 88 for the year, 51 for the week number of the year
>on which the chip was manufactured.
>TCA700Y is the actual part number.  It's a positive voltage regular,
>10V output, 0.22A max current rating, in a TO-202 plastic package.
>The pin-out (when looking at the face of the package, from left to
>right) is output, GND, input.
>This particular part is used on many models of VWs and Audis (particularly
>the 70s and 80s).  Early models (1980 and before) the GND pin is wired
>directly to ground on the instrument cluster flex circuit, later models
>have the ground go through a resistor (usually low value, like 33 ohms)
>to ground.
>Unless you look in junkyards, it's probably going to be difficult to buy
>a 'real' TCA700Y (although a web search shows that a couple of electronic
>parts warehouses in the UK still sells them).
>No BTDT, but I would imagine substituting a National Semiconductor
>LM78M10 or LM342-10 would work just fine (and you can cross-reference
>these numbers to other manufacturers as well).  The only caveat is that
>the pin-outs are reversed on these parts (input, GND, output).  So, when
>mounting these on the cluster you need to do so with the part's face-side
>down to match the flex circuit's pin-connections.
>Hope this helps.
>01 S4 2.7 biturbo quattro
>84 5000S 2.1 turbo
>80 4000 2.0
>96 A4 2.8 quattro (sold but not forgotten)
>     ///  Ti Kan                Vorsprung durch Technik
>    ///   AMB Research Laboratories, Sunnyvale, CA. USA
>   ///    ti at
>  //////

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