VOGONS


First post, by majestyk

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Here´s some strange issue I wasn´t able to fix so far.

While testing my FIC PA-2011 mainboard (VIA Apollo VP2 chipset, AWARD BIOS 113ca14) I found that in about 50% of the cases when I boot DOS from a floppy the startup will hang with a blinking cursor like this:

The attachment dos_start.JPG is no longer available

in the remaining 50% the cursor will go down two lines and the full screen DOS prompt will appear.
When I hit any key while the startup process hangs the DOS-prompt will appear and show the key I pressed just as if the system had already completed startup and was running in the background. For example after hitting "A" I get "A:\>A" after hitting "enter" I get
"A:\>"
"A:\>"

There´s an older AMI BIOS for this board (626cc15) where the issue won´t happen. It´s also independant of: CPU, graphics card, RAM, floppy drive, floppy, floppy cable, BIOS settings, FSB.
When I boot DOS from a harddrive the issue will also be absent.

I´d love to run the AWARD BIOS because it´s newer, detects more recent CPUs correctly and because with the AMI BIOS benchmarks are horrible.
I wonder In any of you have had this or a similar issue...

Reply 1 of 6, by Pierre32

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Funny, I was just having this issue a few hours ago after reassembling my 386 (Asus ISA-386C, AMI BIOS). In my case, I have two floppies on the cable (3.5 & 5.25), and the BIOS had only autodetected the 5.25. Yet, it would seek the 3.5 on boot and would even read a 3.5 disk, before stalling at the same place as you. Once I entered both drive details in BIOS, it came good.

I know you said this happens regardless of BIOS settings. But I wonder if that offers any insight into where the AWARD BIOS is failing you.

Reply 2 of 6, by majestyk

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I now connected two floppy drives, set "Drive A" to 1.44 / 3.5 and "Drive B" to 1.44 / 3.5 and enabled the "Swap Floppy Drives" option.
Now the sysem boots from Drive B (the one before the cable twist) but still hangs.

Reply 3 of 6, by majestyk

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It turned out the AMI BIOS didn´t solve the problem. It finished starting DOS but hang when launching an application.

Further tests showed that the frequency of the error depended on the PSU I used. Some improved the behaviour some worsened it.

Then I decided to recap the whole board and replaced all larger filter caps. The original ones were made by the infamous "I.Q." brand.
I checked the old capacitors, they still reached their nominal capacity, but ESR for the large 1500µ 16V was at 3-6 Ohm - far too high.

Everything´s working perfectly (at least for) now with both AMI and AWARD BIOS.
Time will tell...

Reply 4 of 6, by Pierre32

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Good to get an update 👍 Fingers crossed it keeps behaving.

Reply 5 of 6, by majestyk

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I started to suspect the VRM circuits when a new smaller (250W) ATX PSU repeatedly broke down temporarily during boot up or when resetting the board.
Maybe the onboard VRM had too little reserves for peaking loads.
Now it´s all Rubycon and Panasonic:

The attachment pa2011recap.JPG is no longer available

Reply 6 of 6, by majestyk

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I wasn´t quite finished with this project since broken and/or falling off clamps at the SD-RAM slots demanded the replacement of both RAM sockets. After desoldering 336 pins in total I could finally remove the sockets.

The attachment PA_2011_so1.JPG is no longer available

After soldering two brand new sockets (those seem to be increasingly hard to find today) they are fully functional again.

The attachment PA_2011_so2.JPG is no longer available