You know what the pinout of these parts is, and you undoubtably have a digital multimeter. The first thing you probably have checked is the output voltages (V+ and V-). You did that, didn't you? If those are V+>9V, and V-<-9V, then the cap's aren't the issue, as the charge pump is working. You probably should have done that during the first 5 minutes, and before even attaching the PC.

Verifying normal operation of a Max232 is so simple, even with just a voltmeter, I'd guess you've done all that ... right? When you pull an input from your MCU low or high, the RS232 levels should follow it, inverted, of course. OTOH, if you pull the RS232 inputs to V+ or to V-, you should get the corresponding (inverted) logic levels on the MCU side.

If that happens, there's nothing broken or counterfeit about your chips.

From what's been written thus far, it looks far more likely that the problem you're experiencing lies in the PC <=> MCU interface, and that's probably a cabling/configuration issue.

RE