Anyone have the ALi M1429 datasheet? I may need to start probing if I can find the time.

-- on the POST card is a pretty common problem. I have several motherboards that have the same problem, and the cause could be just about anything.

More than likely, there's a bad solder joint or tantalum somewhere on the board. Check the BIOS socket for corrosion.

No visible corrosion anywhere, not on a joint or a DIP socket. The board is clean. I suspect a bad connection somewhere, not sure where though.

The plot did thicken a bit today though. I removed the Keyboard controller IC and put in a VIA-branded one with PS/2 mouse support. The POST card went crazy - it ran through a bunch of numbers, then cycled around and ran though the same numbers again in an infinite loop. The display was still blank though. So I removed the VIA and put in a Winbond branded KBC. Same thing. Removed the Winbond, put in a Lance. Same thing. Removed the Lance and put in the original AMI Megatrends KBC, and the damn thing booted up just fine.

With the battery still removed, I entered the BIOS and told it I had a 1.44 MB floppy drive on A:\. Set BIOS Defaults and rebooted. The floppy drive light remained on and I get a FDC error. I removed the Acer-branded ISA multi I/O card and put in a Winbond. This removed the floppy error and the light turned off. I tried to boot from floppy, but received an error. Perhaps due to the missing CMOS battery? Not sure at this point. So I removed the Winbond ISA multi I/O and put in a generic Holtek VLB multi I/O. The board is dead again. -- on POST.

I removed the Holtek VLB multi I/O and powered up. -- on POST card. Feeling flustered, I removed the AMI KBC and put the VIA one back in. -- on POST. No running through a sequence of codes this time. Tried Winbond KBC, Lance, and AMI again. The result was -- on POST and blank screen. Frustrating. I am back to where I started.

I applied pressure to the chipset with my finger, but that didn't help. I carefully checked all the pins to ensure that they weren't loose. What am I to do, reflow everything on the board? Is there a place I should start? KBC joints and tantalums? When I look at the bottom, all the joints looks tight. I checked Vcc while on and I get 5.09 V.

I had a similar problem with my MSI MS-3131 board and the issue was due to a bad joint on a QFP chipset. It could be something else entirely though.

There are these transistors which switch between AT power and battery power. I wonder if one is acting up. However, I wouldn't imagine this would cause a blank screen. Would it?

Well, its booting again. Not quite sure what I did, just a lot of goofing around. Not sure if it will last, but I managed to snap images of the CMOS and Chipset settings in the BIOS. A lot of these settings look unique to me for a 386 motherboard.

I am having trouble loading HIMEM.SYS. I am getting an error that HIMEM cannot control A20 line. HIMEM, thus, does not load. Sometimes, selecting an option in the BIOS, "Fast Gate A20" corrects this problem. Unfortunately, this feature is not available on this BIOS. Any idea what setting might correct this issue?

I have already tried wiring A20M# on the CPU socket to Gate A20 on the keyboard controller socket. Something else which had worked for me in the past was the change the computer type with HIMEM. I tried the following line, but to no avail: HIMEM.SYS /TESTMEM=ON /CPUCLOCK=ON /MACHINE=1 /V

I think I traced the issue down to an intermittent reset switch, which is surprisingly because the Reset light on the POST card should have lite up. Maybe the issue was something else, we'll see as time goes on.

A20 control issue was related to a jumper not being set for DLC CPUs.

feipoa wrote on 2018-08-23, 23:05:

Anyone have the ALi M1429 datasheet? I may need to start probing if I can find the time.

sorry for necroposting, but this link seems to have an extensive but incomplete (missing some registers and bit values) register reference to the M1429. still looking for full datasheet though 😒