PS2 port failure

[BluBlur]

Recently, I'm receiving a lot of boards with PS2 port problems. This include initial detection of a PS2 keyboard (after cautionary recap), but within an hour the port became non-functional or intermittent. Other cases are simply dead ports after power up.

The bulk came from Asus CUSL2-C, and a few Gigabyte GA-6OMM7Es as well. The Asus had OSTs 1000uf6.3v that I replaced with Rubycon YXGs, and Gigabyte had a mix of GSCs and CHOYOs which I replaced with Panasonic FCs.

Anyone can guide on any meter/components to detect/repair the fault?

[willawake]

Re: PS2 port failure

i have the same problem on a CUSL2-C. boots into windows and then after a few minutes keyboard stop working. i thought it was a driver issue, from switching between usb and ps2 keyboards. your post indicates something else.

what happens if you use usb keyboard? also is ps2 mouse ok?

[stretch0069]

Re: PS2 port failure

Back in the old days , I read something about making sure the PC was turned off before connecting/disconnecting anything from the PS2 port. If I remember correctly, there is a chip that gets hosed. There was nothing about cap replacement to fix it. The fix was to return the board or replace the chip. Unless the circuit is on a BGA, it should be an easy fix provided you can get a replacement chip.

[kc8adu]

Re: PS2 port failure

i see more ps2 port problems caused by busted sockets,bad solder, and open fuses than anything.could you have multiple bad kb/mouse?
been there done that busted them in 2 and swept up the mess!those keycaps go all over.

[Rainbow]

Re: PS2 port failure

I've seen bad PS/2 connectors on some boards. I've also seen cracked solder joints on the (big) zero-ohm SMD resistors used as fuses on Abit BX133-RAID board.
But I've also seen dead KB controllers - one an QDI Explorer board (KB controller integrated into National Semiconductor Super I/O chip), one on Chaintech 6OJA3T board (ITE Super I/O chip completely dead - getting hot and PS/2, floppy, COM, LPT dead).

[BluBlur]

Re: PS2 port failure

i have the same problem on a CUSL2-C. boots into windows and then after a few minutes keyboard stop working. i thought it was a driver issue, from switching between usb and ps2 keyboards. your post indicates something else.

what happens if you use usb keyboard? also is ps2 mouse ok?

I used a USB to PS2 adapter as I don't have a USB keyboard. This works fine with the CUSL2-C from Windows XP setup, but not with the Gigabyte. The keyboard and mouse stopped responding after some point in "Detecting devices". After more and more tinkering, I can hear long and very short continuous beeps after cold/warm reboots (just like when you hold on one of the keys). The Gigabyte looks rather hosed as it's impossible to even install Windows.

[BluBlur]

Re: PS2 port failure

i see more ps2 port problems caused by busted sockets,bad solder, and open fuses than anything.could you have multiple bad kb/mouse?
been there done that busted them in 2 and swept up the mess!those keycaps go all over.

Will do a check later. The kb/mouse combo worked fine with 3 other mobos (MS-6337LE5, Gigabyte 6OXT and AB-BH6).

What's worse, I had 5 of these Gigabyte (OMM7E) boards and all had the keyboard problem.

[Rainbow]

Re: PS2 port failure

Does FDD, COM and LPT work?
Trace kb and mouse DATA and CLOCK from the PS/2 connectors all the way to the super I/O chip. There should be also some pull-ups (usually resistor network near the connectors).
I had weird PS/2 mouse problem on Intel SE440BX-2 board - the mouse stopped working after a while, disconnecting and reconnecting allowed it to work again for a while. First I resoldered the pull-up resistor network and some other joints there - it helped. But the problem reappeared then - I'm going to replace PS/2 connectors (the board is sitting here because it has some really weird AGP problem too).

[BluBlur]

Re: PS2 port failure

Does FDD, COM and LPT work?
Trace kb and mouse DATA and CLOCK from the PS/2 connectors all the way to the super I/O chip. There should be also some pull-ups (usually resistor network near the connectors).
I had weird PS/2 mouse problem on Intel SE440BX-2 board - the mouse stopped working after a while, disconnecting and reconnecting allowed it to work again for a while. First I resoldered the pull-up resistor network and some other joints there - it helped. But the problem reappeared then - I'm going to replace PS/2 connectors (the board is sitting here because it has some really weird AGP problem too).

The FDD is working. Can't tell for the COM and LPT because Windows XP Setup couldn't proceed beyond hardware detection.

Frankly I'm kind of confused at your advice (not engineering trained), but my brother has a multimeter and I'm very eager to pick up some basic skills. Will get back with a pic of the area close to the PS2 ports, hope you can help identify any components that can be tested.

[pfrcom]

Re: PS2 port failure

The PS/2 mouse port didn't work on my TUSL2-C, and the PS/2 keyboard port was erratic

From a cold start I could press Del to get into BIOS settings, but then keystrokes wouldn't work after one or two presses of arrows to navigate BIOS menus

If I was patient enough to wait, sometimes keystrokes would work after many seconds delay

There were no problems with USB keyboard and mouse

Then I found this posting on Asus forums

TUSL2-C keyboard

The TUSL2-C's PS/2 ports were always irritating, so I decided to give it a try ...

... desoldered the C151 eight leg capacitor, then fired it up ...

... all keystrokes worked, and mouse driver loaded in DOS, which never happpened before

Did an install of WinXP from scratch - keystrokes and mouse continue to work, without side effects

Now I can use the P3-1400s I got for a Compaq TR100 motherboard which I subsequently bricked trying to cross-flash LiteOn BIOS

The TR100 is non-maintainable design, with BIOS chip soldered direct to the board

BTW, the TR100 with latest 1.11 ROMPAQ does operate a P3-1400s, but seems lethargic with Compaq BIOS

[KeriJane]

Re: PS2 port failure

Hello

I saw this recently.

An old-timer brought in his K6 system for upgrades. He mentioned that the KB port was dead, which it was. Being older, I thought he knew about PS/2 ports.

After upgrading to a modern Core-series board and urging him to discard the old keyboard, he promptly complained the new keyboard wouldn't work.

I asked him if he had plugged it in with the system running. After a long pause, the answer was "Could that have something to do with it?"

I then prompted him to restart the system and the keyboard worked fine.
Lastly, he got the obligatory "NEVER plug or unplug the round KB or Mouse connectors with the system on or it will damage the motherboard" lecture.

Have Fun,
Keri

PS. He was in the habit of switching KB mouse and monitor between two running systems.

[pfrcom]

Re: PS2 port failure

This wasn't a problem where the keyboard didn't work, but was intermittent where it would work initially, then fade away

Doesn't hot plugging keyboards pop fuses (which may be resettable type) ?

I don't think C151 was a keyboard fuse - the area where it was, has 8 tiny solder pads

FWIW, my CUSL2 also has a C151 in the same area, but its keyboard and mouse are fine, no reason to attack it with a soldering iron

I do not know the history of the TUSl2-C, having bought it used, with faulty PS/2 connections

[gdement]

Re: PS2 port failure

Are you using a KVM? If so, eliminate it just in case.
I know mine causes problems sometimes, some machines hate it more than others.

[pfrcom]

Re: PS2 port failure

No KVM - keyboard & mouse plugged directly into ports

[pfrcom]

Re: PS2 port failure

BTW, I don't have a problem

I fixed a problem, and published the answer, in case it helps someone else fix the PS/2 ports on a TUSL2-C

My thanks to puzzleman on the Asus forum

[kaniki]

Re: PS2 port failure

Sorry to bring back such an old topic but have a question. I have an Asus CUSL2 motherboard. It is my nephews. The PS2 ports are not working. Everything seems good an intact, nothing loose, the board is full of Rubycon caps. I read about the C151 cap and about removing it. My question is does removing it work with this board too, and if so, do you just break it off (or desolder it) or do you have to make sure that there is a solder path in place of it or what?

As far as I can see, every thing works except the PS2 ports. Trying to get the PS2 ports up and working if possible. If you have any other ideas, they are welcome.

For anyone in the future, the C151 cap is about 3 mm long by 1 mm wide

[stj]

Re: PS2 port failure

sounds like an array probably between the clock/data lines and ground.
ceramic caps can short out so it could be the cause.

[kaniki]

Re: PS2 port failure

i read a couple of different places that they say to just do something like take a pair of pliers and just rip or break it off and the keyboard / mouse (PS2 ports) will start working again.. but if you just pull it off and do not at least put a little solder to make a circuit, then would just removing that part really work? I don't want to mess up the motherboard and if it will fix it, them I'm for giving it a try, but i don't want to take a chance at breaking soemthing in the process... and the USB does work so can stick with a USB keyboard and mouse and do have extra PCI USB cards to add extra USB if needed.. I was just wondering if that actually worked.. and if so, then what does need to be done to do it..??

[PCBONEZ]

Re: PS2 port failure

Check +5v at PS/2 port both before and after the keyboard 'goes away'.
Check from under the board at the solder joints so you don't have to disconnect to check the volts.

[stj]

Re: PS2 port failure

you shouldnt rip or break anything off - ever.
you risk ripping the tracks up doing that.

and you dont short anything together afterwards either.