First post, by dionb
- Rank
- l33t++
Today I picked up a board hoping to test P66 vs P75 head-to-head in as near identical hardware as possible (So4 and So5 Asus boards with SiS501 chipset). Of course, that is only going to work if the boards actually work. The So5 Asus PCI/I-P54SP4 is pretty DOA :'(
Here's the board:
Ignore the SIMMs at an angle, I've replaced them with two known-good 32MB SIMMs, from my PCI/I-P5SP4 (identical to this one except for voltage regulator and socket). I've also added a Diamond Stealth3D 2000 (S3 Virge PCI card), and hooked up a keyboard. That's all.
Symptoms:
I power on the AT PSU and nothing happens - POST card resolutely sticks at 00, no image via VGA or any other sign of life. CPU gets warm.
What I've done so far:
- checked jumper settings: correct for P75 and double-sided SIMMs. Bus speed set to 50MHz
- checked fuse by keyb controller: <0.1Ohm
- checked the voltage planes on the board:
+5V = 4.86V - lower than I would like but within 5% tolerance (>4.75V)
+12V = 11.66V - not bad, well within 5% tolerance (>11.4V)
- measured output of VRM: 3.43V - spot on.
- swapped BIOS chip for a newly flased version 0106 0204 0106 was confusion with P5SP4... (newest from Asus site) - no change
- swapped CPU for another P90 - no change
- disabled I/O and (awful) CMD IDE - no change
- looked for obvious damage to both sides of PCB and components - nothing I can spot
The Dallas RTC is an obvious suspect, but at the same time it's a DS12887, not a DS1387, so it shouldn't cause anything worse than not saving settings. It's soldered, not socketed, so can't immediately swap it out. Don't want to attempt to de-solder unless I absolutely have to.
Any other suggestions for things to try?