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Thread: Troubleshooting Asus PVI-486SP3 motherboard

  1. #1
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    Default Troubleshooting Asus PVI-486SP3 motherboard

    I got this motherboard on eBay a lonnnnng time ago. It came with a vl-bus vga card, two sticks of 4Mb EDO ram and a cpu with a voltage regulator on it. When I first got it, plugged in the video card and attached a power supply, and nada. The cpu cooler fan spun, the power supply fan spun, but nothing else. I might add here that the board didn't come with a speaker.

    Fast forward to last summer, and being bored (out of work, recovering health) I dug this contraption out. For laughs I tried a standard ISA vga card, and got the below:
    Unknown_cpu.jpg

    Hot diggety! So I went thru the jumpers (this board has an amazing number of jumpers) to make sure the cpu was set up properly. I got a bit confused as there were two sets of configs; I later figured out one set was referring to the board with an av9155 chip, and other other a vt8228 chip. I ended up using half of one and half the other. Naturally the board didn't even boot to CMOS after that. I suspect I fried the cpu somehow. Finally figured out my board has the vt8228 chip, and need to use those settings. NOW I understand.

    The board still works to a degree. At least when I plugged in a speaker and pulled both memory sticks I got the repeated single long beep indicating no memory. So I'm looking at getting a new 486 cpu. A dx-33 wouldn't need a cooler, while a dx2-66 would, not to mention some thermal paste.

    I invite suggestions. Right now I would be happy just to see the sucker running. I'm thinking of dropping it into a clone XT case just for laughs. It's only a half-inch wider than an XT motherboard.

    Check me on my logic with the memory sticks. The chips are marked km44v4004bk-6. They are 60ns EDO memory, but I was wondering about capacity (hey, I said I bought it a long time ago). If I the the math right from a spec sheet I found online, they're 2Mbit chips, so 2MB per side, 4 total for the stick. But at least one eBay seller advertises the exact same stick as 32MB?
    https://www.ebay.com/itm/32MB-PS-2-E...3D282064864648

    So a touch cornfused about how much memory is really there.

  2. #2
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    Each of the memory chips is 4M x 4bit, so 2 would give you 4MB. 8 would give you 32MB.

    Datasheet. FWIW, they're also 3.3V chips, not 5V.

  3. #3
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    I have a new 486 cpu, and I'm trying to make sure I don't kill anything this time. As I said before, it's been years since this sucker has been sitting in my closet, so I don't recall the specs as sold.

    My cache chips are labeled w24m512ak-15 (95191). Four of them, plus a smaller one labeled q24m257ak-15 (95171). I'm guessing the smaller one is a controller? (Hey, it's been a long time) And from the numbers I have 512Kb cache, yes? I am unsure after I got the memory wrong. If I set it for 256k cache when it's 512k (or vice versa) will it run less efficiently, or not at all?

  4. #4
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    The small one's probably a COASt module.

  5. #5
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    I left the cache jumpers alone, as well as the speed settings which were already at 33Mz. Plugged the new cpu in and nothing. Added a hard drive in case I needed to draw more power and still nothing.

    Pulled the two memory sticks, and got NO beep codes. AFAIK it shouldn't matter which way I have that little 10-cent speaker plugged in, but dead silence.

    I found a copy of the manual online and downloaded it. The cpu is an AMD 486dx4-100-100sv8b. That particular cpu was mentioned in the manual and I went thru the jumper block (jp 16-24) to make sure I had them set correctly, but nada.

    Also plugged in two different vga monitors; one 17" crt and a 19" Dell lcd. Both acted like there was no signal coming in.

    Is there another way besides the "pull all the ram" trick to see if the motherboard is dead? The last time I tried that a few months ago it worked; got a single, long, repeated beep indicating no memory found. Now nothing.

  6. #6

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    You can use an ISA "POST card" and see if it's outputting any codes.

  7. #7
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    Quote Originally Posted by Plasma View Post
    You can use an ISA "POST card" and see if it's outputting any codes.
    I think I have some around here somewhere...

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