PS2 port failure
 

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?

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?

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.

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.

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).

Re: PS2 port failure
 

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.

Re: PS2 port failure
 

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. :mad:

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).

Re: PS2 port failure
 

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. :smile:

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

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.

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

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.

Re: PS2 port failure
 

No KVM - keyboard & mouse plugged directly into ports

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

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

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.

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..??

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.

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.

Re: PS2 port failure
 

Far chance your problem is the +5v on the PSU you are using drops below the threshold for the IC chip inside the keyboard.

Re: PS2 port failure
 

that is what i kinda thought. that is why when i read that they fix was to take it off, my first thought is "if you take it off and dont short it out, you kill the power source, so how does it work if you kill the power?' that was my thought at least.

From what i have read about it, it is the same problem with this board as the TUSL2-C board. I did take the cover off the PS2 port and nothing was broke or bent or shorting out in there, I also checked the solder joints under the board and all was solid there too. The power supply is a 300 watt but that should be enough to power a 1 gig processor system. there is not much extra in it and i did pull out the pci cards and tried it that way too. still the same.

Do you know if the whole c151 chip thing was a hoax or was there some merit behind it?

Re: PS2 port failure
 

it may not be a hoax,

i'v had acade pcb's that use ceramic aray's on the inputs.

think a line of ceramic's between the signals and the ground.
it's for noise suppression, but sometimes one goes short and the input looks stuck on.

if you get one of these ps2 problems, try metering the resistance between ground and the clock,data & reset pins.

Re: PS2 port failure
 

I desoldered the C151 eight leg capacitor, did NOT "remove it by force" as suggested in the Asus forum

That board is in storage most of the time, but its PS/2 ports do work fine every time I use it

Re: PS2 port failure
 

so someone has had luck with doing this then.. I guess I will give it a try and hope for the best. If all it does is act on behalf of the PS2 and it messes somehting up, well... they dont work now so no harm done. Ill let you know how it turns out.. probably wont get to it till more towards evening..

Re: PS2 port failure
 

I wasn't suggesting your PSU is too small, I was suggesting it's bad and doesn't hold voltage on +5v.

Also P3 boards pull CPU power from +5v so if that's a "P4 PSU" you may have too much load on +5v and too little on +12v for it to regulate properly.

.

Re: PS2 port failure
 

well, it is the same power supply that has been in there for years. and it just stopped working one day. I removed the extra stuff like the roms, hard drive.. well i disconnected everything but the motherboard and processor and fans and tried it again same response.. and by that point in time, there is nothing to overload even a P4 power supply. I did check the power readings per voltage and they were all within 0.1v of there rating. also just for the heck of it i tried a different power supply.. 400 w this time.. same response.

Re: PS2 port failure
 

Ok. I got the chip out and that did it. Removing that c151 chip did it. Both PS2 ports are now working. I just wish that they put it in a better place. If it was just a little better positioning, then i would not have had to take the motherboard out. But i did not want to damage any other parts since they were so close so I had to remove it. Fun!!! I think i read that there were something like a half dozen or so boards that this was a problem with.

Re: PS2 port failure
 

May be useful for someone Googling, to know it works on CUSL2, as well as TUSL2

Re: PS2 port failure
 

I did find this while searching

so obviously it is a problem in a lot of asus motherboards.

Did i ever say how much i dont like asus motherboards??? I said it before.. I have had nothing but problems with any model i have ever bought.. funny thing is that it is the only brand that i have had major problems with..

Re: PS2 port failure
 

if the CUV4X series is also affected, this may also apply to the Medion 2001 Mainboard (which is an Asus CUV4X-VM (microATX) just without the temp. monitoring)

kinda shocked though that they say the CUBX is affected. was one of the last Asus boards i've had (and still have somewhere) that was absolutely rock solid and glitch-free.. (much like the "legendary" Asus P3B-F slot 1 boards).
after that board generation, the quality took a massive nosedive (imho)..

Re: PS2 port failure
 

asus dont make the capacitor array, this could effect a lot more than asus and a lot more than motherboards!

clearly there is/was a big batch of defective arrays made.

Re: PS2 port failure
 

Asus hasn't been good since the 90's.
CUSxx and TUSxx were right about when Asus turned bad.
.

Re: PS2 port failure
 

Can't disagree with that

P4P800-E Deluxe I have, has CRAPacitors in the VRM (OST or Elite, can't remember which), which get pretty warm, along with the Mosfets

Been considering a pre-emptive re-cap

Re: PS2 port failure
 

well, i guess i do have to give some credit to this one.. it is a good running system.... rock solid... and this was the first problem.. considering it is a P3.. that isnt all to bad. but like they say, it was about P4 and up that went to crap.. and all the systems i built with ASUS boards were all P4 and up. I had 1 board that I returned 3 times to get it fixed. they still could not get it right. after that i just gave up. what i find really funny is i have had decent luck with cheapo boards like elitegroup, biostar, MSI and gigabyte. They are all cheaper boards that i used, and no returns, but every ASUS board that i got, which had longer warranties and higher prices are the ones i always had problems with..

as for the list of bad boards or effected boards. I did not do any research to them. I just found that on the net and copy and pasted the info. I can not say to how much if them is actually faulty and / or if any are any good.

Re: PS2 port failure
 

Some of Asus brand new boards [last 2-3 years] seem to be having stability problems because they went nuts using 100% polys 'for show' and they lowered ESR too far in the non-VRM areas of the board.

If you don't have -some- ESR [or other resistance] then the board looks like a dead short to the ripple in the PSU and all that ripple current makes a bee-line for the mobo instead of getting filtered out before it reaches the board.

Looks to me like Asus just stuck polys in were the designs called for electrolytics [rather than -designing- boards for polys from the ground-up] and that's pulling PSU noise [and ripple CURRENT] that shouldn't be there out to the chipset and slots.

100% poly in the VRM is fine [we know this from experience] but taking a design that calls for [say] 6 lytics out by the slots and sticking in 6 polys is going to -encourage- ripple current to bypass the PSU caps and go through the board to the slots where the ESR [aka 'resistance'] is lower. - That's just going to heat-up the traces on the board as well as destabilize the voltages along the trace's path.

.

Re: PS2 port failure
 

From the intel side of the fence, but I had an a7v133 and a nforce2 asus that were alright. They went bad after that for AMD though.
The a7v133 was overclocked and overvolted it's whole life, so died a gallant death. The asus nforce2 was killed by an antec SP

Re: PS2 port failure
 

did you give it a good salute and burry it with honers?? kinda reminds me of one of those movies where a knight dies defending a town from evil beings..

Re: PS2 port failure
 

you could pull a c hegge and cremate it!