Did you make sure to use a tip that was listed as compatible with the M700?
I believe the Targus Universal tips #2, #44c, and #T are compatible with the M700, depending on which Targus adapter you have. You can double-check here http://www.targus.com/us/configurato...us/default.asp
Of course, you'd make sure it's set to the U.S. standard of 110V if here in the States, or to 230V in Europe.
The M700's dc range is from 10 to 19 volts (to mimic the battery, of course).
... and you're pretty sure the sound is from the voltage converter board, and not a POST error beep code? The M700 codes are:
S-S-S-P-S-S-L-P The DMA page registers are faulty.
S-S-S-P-S-L-S-P The refresh circuitry is faulty.
S-S-S-P-S-L-L-P The ROM checksum is incorrect.
S-S-S-P-L-S-S-P The CMOS RAM test failed.
S-S-S-P-L-S-L-P The DMA controller is faulty.
S-S-S-P-L-L-S-P The interrupt controller failed.
S-S-S-P-L-L-L-P The keyboard controller failed.
S-S-L-P-S-S-S-P Graphics adapter is faulty.
S-S-L-P-S-S-L-P Internal RAM is faulty.
S = Short, L = Long, P = Pause
Does everything run Ok when started from a charged battery?
. . . Gary