This post explains for the regualtor.
The Part Number is TCA700Y.
The function of this semiconductor is Voltage Regulator.
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A voltage regulator is an electronic circuit that maintains a constant voltage level. It is designed to provide a stable output voltage that is independent of the changes in input voltage, load current, temperature, and other environmental conditions.
LM7810 is 10v, positive voltage regulator.
The main difference between the LM7810 and the original TCA700Y is the way its installed. On the TCA700Y, the regulator is laid flat onto the original metal heat sink.
With the LM7810, you flip it over, so the heat sink is up in the air.
You need to provide a metal spacer for the regulator to transfer the heat to the original VW heat sink. This is only required if you source your LM7810 from an electronics parts supplier.
This is because the LM7810 pins are opposite of the original TCA700Y.
Since the TCA700 is no longer made, its just makes sense to use the cheaper LM7810 and it handles 1A current. The TCA700 only up to 0.220 mA.