RS232 Chip problem

[rangeyrover]

Hi Guys,
I am using an old laptop with an inverter from the car.
I seem to have killed the RS232 chip on the board. The unit is still working, but I cannot talk to it.
I have revisited all the solder pads and capacitors around the chip.
Has anyone else had one die like this?
I am reluctant to connect up my 2nd one to the laptop if it is a regular failure mode?
Maybe some opto isolators on the way in may help this problem?
I have checked continuity on the serial port to rs 232 chip 2- 14 and 13- 3 and they are good.
My leads and setup are good, because I am talking to another unit.
This might well have to be my one, as I am building for friends, I can still program the chip using a friends unit just annoying...

[Gilesy998]

Sounds like a typical component failure to me. I've heard of this one myself, but the fact it's just the one that's done it does seem to point that way. You could try desoldering it and fitting a socket as per the processor and transistor-bank chips?

[brentp]

I'd have to say this is the first MAX232A failure I've seen here. A quick test is to replace the chip. you can also check the traces between the MAX232A and the processor.

if you have an oscilloscope, you should be able to monitor the bitstream coming from the serial cable and then on to the processor, and back. Compare this against the other unit and you could verify if the signals are not passing through the MAX232A- might be useful before you start desoldering.