printer port problem

[KMD]

Hi all, I'm working on a motherboard out of an IBM laptop that won't print. I'd really like to try and fix this, can someone give me run through on how printing actually works in a computer? Does the CPU handle this itself or do other chips get involved in printing. I'm mostly concerned with what happens to the data once the OS sends it on it's way. Thanks for any help or websites that get into this kind of thing.

 

[Nigel Goodwin]

Hi all, I'm working on a motherboard out of an IBM laptop that won't print. I'd really like to try and fix this, can someone give me run through on how printing actually works in a computer? Does the CPU handle this itself or do other chips get involved in printing. I'm mostly concerned with what happens to the data once the OS sends it on it's way. Thanks for any help or websites that get into this kind of thing.

A common cause is that the printer port has been damaged, laptops are particularly prone to this - probably with people plugging and unplugging printers with the computer powered up.

As far as I'm aware, the CPU handles the printing, an IBM PC is a pretty 'thick' machine :lol:

 

[KMD]

Thanks Nigel, Yea, I've run into the broken port problem many times, usually a quick hit with the soldering iron fixes it right up, not this time though .

If it's pretty much a straight shot from the CPU to the port, I might be able to trace it and find the problem, but if it's getting routed through other chips on the board, that would make things allot harder and not worth the time.

 

[Nigel Goodwin]

Thanks Nigel, Yea, I've run into the broken port problem many times, usually a quick hit with the soldering iron fixes it right up, not this time though .

If it's pretty much a straight shot from the CPU to the port, I might be able to trace it and find the problem, but if it's getting routed through other chips on the board, that would make things allot harder and not worth the time.

In very old machines the port was seperate TTL chips, but in anything remotely modern it's usually incorporated inside a large chip with many other functions.

BTW, I didn't mean the CPU connected directly to the port, but that the CPU actually does all the work - there's no co-processor that does the printing.

 

[eblc1388]

Hi KMD,

Take a look at this and see if this helps. It is a software that runs on PC and tests the individual output of the printer port. Scroll down the webpage to see the software. I have not downloaded and tried the testing software myself.

test the LPT port and help you debug interfaces

 

[KMD]

Ahhhh, gotcha. By port you meant like the port on a PIC.

I found another board from an almost identical unit, I'll try and look up a few of the chips, if I can find out which one runs the printer port, I might be able to swap. Thanks for the info Nigel.

 

[shamikrudra]

Hi all, I'm working on a motherboard out of an IBM laptop that won't print. I'd really like to try and fix this, can someone give me run through on how printing actually works in a computer? Does the CPU handle this itself or do other chips get involved in printing. I'm mostly concerned with what happens to the data once the OS sends it on it's way. Thanks for any help or websites that get into this kind of thing.

hi kmd
if u have brok your LPT port
then take great care for soldering because PC main boards are made in min of four layer PCB and there is a single chip for communication like serial parralal and Floppy drive

 

[Laplink]

Isn't it controlled by the south bridge chip, or super I/O chip, whichever one it has?