What other circuits do is not relevant!



What??? +5V of which circuits? So long as you apply it to the appropriate pins and ensure that it meets all specifications (ripple, line and load regulation, noise limits), it shouldn't harm anything. Why would you want to do that? How could it help?

My original point was that devices external to your PC will not work with the PC if its handshaking is disabled, if they are expecting the handshaking to be enabled. All I meant was that you should ensure that the handshaking in the com ports be enabled once again before testing the PC to verify function of its com ports. If the device driver wants to operate these ports without handshaking, it will see to that, though it may not enable the handshaking, since it is enabled in the default. The PC "remembers" that handshaking is disabled when you power it off.

However, if the MAX232 is getting hot, there's probably something wrong in your MAX232 circuit, and not in the PC. The PC is supposed to be connected via RS232 drivers and receivers. They have a nominal K-ohm-range series impedance, which shouldn't allow damage either to the PC or to the MAX232.

Do you suppose something is not wired as intended? Have you verified, in detail, that it is connected as you intended? Have you tried isolating the MAX232 from the MCU and the PC, and verified that the V+ (pin 2)and V- (pin 6) are at approximately 10 volts to either side of GND? Have you examined the Vcc and GND connections with an oscilloscope? Have you considered adding a 0.1 uF cap between pins 16 and 15?

RE