At 06:14 PM 12/8/2010, mark drillock wrote:
>The original TCA 700Y part is no longer made.

These folks will sell you one for ahem $80.58 plus shipping from UK...
http://www.littlediode.com/components/TCA700Y_Integrated_Circuit.html

>  The replacement has the
>order of the legs reversed so it must be installed upside down. There is
>a metal spacer installed on the heatsink part of the new reversed part
>so you can install it backwards and still screw it down as VW intended.
>That is, places selling the new part as a replacement have a modified
>new part to better substitute for the old part.

Do they include a longer mounting screw I wonder?

FWIW, as you look at the back of the panel, left is output, right is
input.  On the '85 panel I'm looking at the heat sink is isolated and
the middle leg goes to ground through 22 ohms.

I rather think that on my '89 panel the middle leg is clipped and the
heat sink connected to the resistor instead.

Yrs,
d