SMD DIODE in 0603 case needed "HELP"

[MrsR]

Hi!Guys,
I am trying to repair some Digital Servos and have run into a problem.After a great deal of research I have found all the Data Sheets for the The active components and reverse Engineered the circuit so I have a schematic.

The plug from receiver to servo is a 3 pin type that can be put in both ways. The V+ is the center pin at 7.4v to 8.4v DC  and the outer pins are V- and Signal.

The Signal is an AC 3v to 5v 50Hz square wave with the positive part of the pulse Min. .9ms to Max. 2.1ms.
I don't know what the Max. current is but there is a 1k resistor on input to the signal circuit and the max amperage to the ATMEG Microcontroller is 40Ma.

The problem:
There is a Diode in parallel reverse bias at the input of the voltage regulating circuit from what I can understand it is to protect the circuit from the V+ half of the AC Signal and this Diode I don't seem to be able to find. I have found D size case types but I need a 0603 case size. Can anyone help me please?

THANK YOU
Rachael

[MrsR]

Thanks,
I forgot about ELEMENT14, Ive been using RS lately and I went over and found a couple that would do the job and I found that the HexFets I needed were half the price.

Thanks again
Rachael