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Serial port problem ?


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#1 crazycrazyjohn

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Posted 18 December 2010 - 09:47 AM

Hi my serial port stopped working recently i use a serial mouse amongst other things they all work fine in other peoples pc but not my one.They used to work up till 1 week ago when for no apparent reason stopped functioning.Ive attempted a simple loop back test with pin 2 and pin 3 shorted and that failed.

What do i do now to resolve the problem?

My motherboard is a gigabyte p35-dq6 with a single serial port.

Thanks

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#2 MrBruce1959

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Posted 18 December 2010 - 05:08 PM

Please check if your serial port is soldered to the motherboard or it is connected via a ribbon wire to the motherboard.

If it is via a ribbon wire, you may want to open up the computer locate the serial port ribbon wire and trace it back to the motherboard.
Here at the motherboard, disconnect the plug from the motherboard, blowing into the plug wouldn't hurt here either. Now re-connect the plug and see if the problem has been resolved.

Here I will explain to you why I suggested this to you.
Over time, metal to metal connections suffer from oxidation, a white corrosive powder which is the by-product of the chemical oxidation process, of air O and water H2O cause a chemical break-down of metal alloys.
Eventually, the electrical connection between the metals suffers from what is called "resistance"
Resistance is the amount of current flow that is being stopped or slowed.
A perfect example to explain this is using a water faucet with a valve as an example, the more flow, the lesser the resistance, the lesser the flow, the more resistance.

Oxidation build-up causes resistance in electrical circuits, if enough resistance is applied, the circuit fails to work at all.

Bruce.
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#3 crazycrazyjohn

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Posted 18 December 2010 - 05:31 PM

Its attached to the motherboard itself no ribbon cable.During the loop back test i measured a current between the rxd and txd pin 2 and pin 3 of around 10ma so no breaks in the connection between serial port and motherboard.

Ive tried flashing the bios,disconnected all devices that might mess with it still no joy.

#4 dpunisher

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Posted 18 December 2010 - 05:37 PM

If you need a serial port, you need a serial port.

Next step is to throw an expansion serial card at it and see if that fixes the problem.
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=40000073%20600022011&IsNodeId=1&Description=serial%20port%20card&name=PCI%20to%20Serial%20Port%20Card

Is there some special equipment that is serial only that needs to run with this board?

EDIT: Its been so long since I dealt with serial ports, some things are forgotten.

The serial port/com port is turned on in BIOS? Never know, flakey mobo/CMOS batt/BIOs defaults reset etc.
Any IRQ conflicts? Serial port/Com port conflicts even occur in XP. I realize you likely already checked this, but I gotta ask.

Edited by dpunisher, 18 December 2010 - 06:26 PM.

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#5 crazycrazyjohn

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Posted 19 December 2010 - 07:21 AM

Serial port is switched on in bios yes ive tried setting the port to different settings and to default,tried the bios defaults aswell all fail to make the loopback test fail or any devices attached to the port.
How do i find if there has been any irq conflicts ?

#6 MrBruce1959

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Posted 19 December 2010 - 10:01 AM

Hello I am putting up your motherboard's support page at the link below.

Can you please varify if your motherboard is either revison 1.0 or 1.1?

You may find this information on either the motherboard or the owners manual, but I believe it's best to check the motherboard as it is most the accurate.
It may be in very small lettering located somewhere on the motherboard, it should have the letters REV. just before the number which is either going to be 1.0 or 1.1

http://www.gigabyte.bz/support-downloads/download-center.aspx?kw=p35-dq6

Thanks in advance.

Bruce.
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