defect COM port: can it be easily repaired?

Hi all,

one of my COM ports probably got damaged while I connected my external modem to it without turning off the computer.

My question is whether a defect COM port can easily be repaired by tech service people or is it a complicated task and my MB would need to be replaced once the other COM port gets damaged?

Thanks in advance,

Ralf

 

You can simply buy an I/O card (PCI or ISA) with com ports - that's the quickest fix. Roughly $10-30 depending on how good of a shopper you are.

 

Hi ralfska

I'm not a hardware guru, but "attaching" an externel modem to the port should NOT damage the port... unless the modem or cable are shorting out the port. I have attached many externel modems to powered up computers will no ill effect. If your port is damaged, install a new card. BUT check any "short out" problems in cable / modem prior to using them.

 

Thanks for replying ...
Since a new card with COM ports can be bought, is a good news.

However, I determined that one of the ports could get damaged, because when I connected the external modem to the other free COM port, then it works O.K. and the internet connection is available.
If this is the case, then can it be normally repaired or not?

Ralf

 

Is it possible that something is using the other port ( or the IRQ for it )

Like an Internal Modem still activated ?

BillyBob

 

Billy Bob:

I think the potentially damaged com port is not in use. I have used SiSoft Sandra 2003 to determine this, but maybe there is another utility which can entirely check out com ports?

Ralf

 

My motherboard (Asus) is one month old. I was given a 3-year-warranty for it.
Do you know if the MB qualifies for being exchanged for a new one due to a defect communication port (COM 1)?

Ralfska

 

Hi ralfska

is COM1 actually on the motherboard (like on my Compaq) or on a plugin card pls?

if it's "normal" Tx and Rx interface chips then yes it's very hard to blow them up - does indeed indicate wiring problem. But "proper" line interface chips are rated to be safe with o/p shorted to ground or either supply rail... So it's perhaps some kind of bad wiring problem, take care

my pesky Compaq (blown up) motherboard COM1 uses ASIC (=Application Specific IC). These are probably easier to blow up, also very hard to get replacements (in my case have to get from Compaq and go back in time 5 years that's when they ran out of spares)

I found I could fit an ISA card with new ports and the blown up one on the motherboard doesn't matter - it sits there dead but doesn't interfere. I jumpered the ISA card to put the COMports as COM3 and COM4 - you can do this with almost all the plugin cards. Keep the info sheet with the jumper settings on it!

what blew mine? brand new shop bought mains lead - moulded connectors - and no earth inside the moulding I should have checked first I know but was in a hurry

if you are looking for plugin cards: serial COM ports have two types of UART: either 16550 or 8250 the 8250 ones don't have buffers and are much slower so get 16550. Can't use "acceleration" with 8250 type.

you probably cannot check this by looking at the numbers on the chips. Yes they do make chips with these numbers - but on almost all "real world" cards the UART is part of one of the big square chips, if software reports it as "16550" it just means that it works like its a 16550

Hope these notes help

Best Wishes, Hugh

 

ralfska,

You don't say if you ever got anything to work on this com port.

Assuming that you haven't could it be that the port is not turned on in the BIOS?

I have an old Asus p5A-B board that arrived to me with both com ports disabled in the BIOS.

Just something else to check.

Cheers,

ICE