Asus P2-99B stopped working

[pfrcom]

Resigned to thinking one of my garage "reference" system's time had come, but read

I understand that not everyone is a jobless bum like me right now, doing nothing all day and posting on the forum.

and decided to ask for some thoughts

This Baby AT Slot1 board ran a Slocket'd Celeron 1000 by virtue of self-modified BIOS, maximum supported 512MB memory, four SCSI disks and two SCSI CD drives

At boot time its Asus SC-875 SCSI controller is able to spin up only disk(s) required, and lately it's been using the one disk with DOS on it

Last time I used it, a month or so ago, it came up with CMOS missing message where I continued, making a mental note I'd have to replace its battery which involves getting out & into a heavy case sitting under an even more heavy 17" Diamondtron CRT monitor

Needing to use it again recently, I pressed the button and not quite "sounds of silence" but only that of spinning fans

First thing I tried was a new battery and it booted, but after saving CMOS settings I recall seeing a message flash by about unable to save ESCD

Then after booting into DOS I tried the reset button and just silence again

I've tried changing components like memory, graphics card, processor, power supply, even put in a pre-flashed BIOS chip, all to no avail

It's now sitting on my work bench with a vanilla P3-450 in it, but still no result

The board looks visually perfect, and I'm at a loss what to do next - have tried it with both AT and ATX power supplies - getting a replacement board isn't a realistic option

[ChaosLegionnaire]

Re: Asus P2-99B stopped working

when u changed to a new battery, did u try to clear the cmos as well? i recall some boards had a problem whereby if it was throwing up cmos errors due to a weak battery, u had to clear the cmos as well when replacing the battery or else some "bad data or errors" will remain in the cmos or the escd area that was caused by the weak battery. then upon the post screen appearing, u had to enter the cmos setup and then choose load cmos defaults and save and reboot. then enter cmos setup again and this time u can customise the cmos settings to your liking.

also, the symptom of being unable to post upon a reboot when it posted fine the first time indicates an issue with a bad eeprom that is slowly losing its stored data for the system bios. just posting this as a fyi since u swapped it out with a newly reflashed bios chip and that didnt fix the problem.

btw, do u got a post card? it could help diagnose what is hanging up the system in early post (before display is initialised and during cpu, ram, chipset early initialisation).

[pfrcom]

Re: Asus P2-99B stopped working

My POST card shows nothing - also shows nothing on another, working, Slot1 board - maybe too new a model POST card

I should also add that sometimes the P2-99B would beep three times, then start a continuous beeping

And other times just continuous beeping

And most recently just silence

I think only once when I removed all memory, did I get continuous beeping - at a different frequency to what I mentioned above

BTW, it doesn't have a Clear CMOS jumper, just a pair of solder points which I shorted with a screwdriver tip later in the saga

[pfrcom]

Re: Asus P2-99B stopped working

I've tried another BIOS chip, this time a known quantity SST 39SF020A, pre-flashed with stock standard second-last production BIOS

And swapped in a Pentium2-450 processor

Now it won't recognize any AGP graphics card - and I've tried more than a dozen - just gives three beeps, then a brief pause followed by continuous beeping

Same thing happens with an ET4000 ISA graphics card

And also with some PCI graphics cards - less sophisticated ones like Trident and S3 produce a pattern of coloured rectangles on the monitor before beeps as above - more sophisticated ones like Matrox Millenium, nothing happens, just silence

Trident AGP cards also do colours prior to beeps

If I remove all memory I get continuous beeping, at a different frequency to graphics related

I'm at a loss what to do next, apart from move on - what has gone wrong that it has such fundamental problems with graphics ?

The board looks absolutely perfect - all electrolytics are Rubycon YXG 6.3v 1000uf - I can't see any smaller ones

Seems like ASDS (Asus Sudden Death Syndrome) isn't a recent phenomenon - the board's had very little power on hours relative to its age

[RJARRRPCGP]

Re: Asus P2-99B stopped working

Seems like ASDS (Asus Sudden Death Syndrome) isn't a recent phenomenon - the board's had very little power on hours relative to its age

Sounds like reflow time...

[mockingbird]

Re: Asus P2-99B stopped working

I don't want to sound obvious, but are the caps ok on the thing? What kind of PSU do you have in it?

[pfrcom]

Re: Asus P2-99B stopped working

are the caps ok on the thing? What kind of PSU do you have in it?

All are Rubycon YXG - visually perfect

I've tried it with both AT and ATX power supplies, no problems with the latter on other boards

[RJARRRPCGP]

Re: Asus P2-99B stopped working

All are Rubycon YXG - visually perfect

I've tried it with both AT and ATX power supplies, no problems with the latter on other boards

Recap the motherboard.

[ChaosLegionnaire]

Re: Asus P2-99B stopped working

might wanna invest in an esr/capacitance meter before that. dont wanna replace all the 20+ caps on that board only to find out it wasnt the caps...

good thing p3 boards dont have as many caps like a p4 or athlon 64 board! was a nightmare recapping the 30+ on mine!

[pfrcom]

Re: Asus P2-99B stopped working

It's a moot point now

Reflow sounded like a good idea but, in retrospect, I probably used too much heat or heated for too long

I stopped after hearing a snap noise from the north bridge

Now, even though it looks cosmetically perfect, the board's as dead as a dodo, not even beeping without memory installed

[ChaosLegionnaire]

Re: Asus P2-99B stopped working

i thought asus boards of that era are known to be bulletproof and rock solid? really sorry about the board, man. i hate good ol' stuff to go just like that too.

[pfrcom]

Re: Asus P2-99B stopped working

i thought asus boards of that era are known to be bulletproof and rock solid?

Yes, so did I - was gobsmacked when it failed to start next time after the CMOS missing message

And things got worse - I thought I'd try it one more time before scrapping - a pop and smoke came from my Seventeam ST-250GL power supply

I'm still in shock after looking at prices for Baby AT boards on eBay - and those mainly Socket7 or older, not a Pentium3 class board to be found

[ChaosLegionnaire]

Re: Asus P2-99B stopped working

wtf so it could be the psu at fault not the mobo? thought u changed the psu at the first post but that didnt fix the problem... have a feeling the psu might have been on its last legs tho and that final bit tipped it over the edge and caused catastrophic failure. did psus in the late 90s have the kind of over protection that recent psus have at the time?

EDIT: googled your psu and it seems to have over voltage, overload and short circuit protection. wonder what could have caused the protection to not work and make the psu blow up. what caps did the psu have?

[pfrcom]

Re: Asus P2-99B stopped working

thought u changed the psu at the first post but that didnt fix the problem

The board had been tried with three power supplies
1) Macase AT in its original case
2) Delta AT after I'd removed board from case ...
3) ... then Seventeam ATX

have a feeling the psu might have been on its last legs tho and that final bit tipped it over the edge and caused catastrophic failure

Always a possibility - however the Seventeam had just had no problems powering a non-booting dual P3-450 Supermicro P6DBS through the process of getting it going, then testing which included a complete install of XP