Hi,
Let me say something
I usually ask the customer what caused the PCB burnout, and what ELSE has been damaged in the PC?
If he says only the HDD, CDrom, soundcard, or old 10M network card, we can be almost sure the problem came in only on the 12V line. almost
Should he mention motherboard, CPU, RAM, we can suspect the 5V line to be the problem (or both).
In the first case it is very rare the HDA gets damaged, usually only the motor/VCM combo is burnt and some components nearby.
In the second one we can get the idea of checking the preamp with the models using -5V/+5V alimentation strategy for the preamp.
Calypso belongs to this group, so if the 5V line caused the problem, almost surely the preamp is burnt out, U will have to replace it (not the MHA, but only the preamp).
I usually check it with a multimeter in diode checking mode, check first the power lines going into the HDA against the GND and compare the values to a known good HDA's similar values.
Should they match, I check the other IO pins. Note that there can be difference, but not significant, usually within 20%.
It is a good idea to check the preamp if the small 8pin IC is damaged near the Combo, because its damage can point out that the -5V power line is shorted (by the preamp) and if U put a good board on this HDA, this IC will go smoking and probably the combo too
regards,
pepe