Re: Anyone can identify this 286 motherboard?

Posted on 2020-07-25, 22:22

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I would suggest to first identify and mark out all tantalums that are connected to the +12V rail. Then desolder one leg of each tantalum and measure again for shot. Like that you can solder the good ones back later. If you cut the legs then you'll need to replace them later. There is another more …

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Re: Anyone can identify this 286 motherboard?

Posted on 2020-07-25, 09:09

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I have only cut off about 3 or 4 near the power connector. I think the short us somewhere else but blow if I know what would be shorting the 12V rail if the positive side of them all measure 1400 ohms to ground. One of them should read as a short so those tantalums are probably fine. Yeah that's …

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Re: Anyone can identify this 286 motherboard?

Posted on 2020-07-25, 05:22

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yeah its about all I can do. Not looking forward to desoldering them all! You wrote previously that you checked them all. Check the red ones again in "buzzer" mode. A short is a short in-circuit too. If no short then check their resistance again and remove the ones with unusual values (compared to …

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Re: Anyone can identify this 286 motherboard?

Posted on 2020-07-25, 05:10

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Is it likely a faulty IC would cause a short? Anything is possible especially with lightning damaged boards. Most of these chips get supply from the +5V rail. You could also check the (not socketed) IC pins if any of them connect to the +12V rail. I doubt that though. If you started removing (+12V) …

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Re: Anyone can identify this 286 motherboard?

Posted on 2020-07-24, 22:49

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I still suspect the tantalums. I'd probably clip 1 probe to the +12V rail and find every tantalums that connect to it. Remove socketed chips first. Thats a good idea, looks like all the red caps will be the 12v rail as they are all rated for 16 volts. Is it likely a faulty IC would cause a short?

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Re: Problems using secondary IDE channel on VLB cards with 486

Posted on 2020-07-24, 22:40

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

OK thats sweet, makes things much simpler. So handy to have the XTIDE ROM, never used to have that once!

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Re: Anyone can identify this 286 motherboard?

Posted on 2020-07-24, 12:08

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Miphee wrote on 2020-07-24, 11:58: ISA contact pins touching? Checked all that, and the pins are fine. If what ive measured on the meter is anything to go by, the 12V rail on the motherboard is where the short is happening, If I had a schematic it would help. Not very easy to find one for even a …

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Re: Problems using secondary IDE channel on VLB cards with 486

Posted on 2020-07-24, 12:05

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

VLB cards with multiple IDE ports but no own BIOS used to come with drivers that would enable the other port and detect the hard drives. I don't think many (if any) motherboards without integrated IDE controller have support for secondary IDE channel in BIOS by default. I see this is an old thread, …

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Re: Anyone can identify this 286 motherboard?

Posted on 2020-07-24, 11:52

by

by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I tested the board for shorts with my multimeter and im getting a short between the yellow(12V) and the ground pins on the power connector. Have cut off a few of the tantalums in the area, but no difference. Any ideas where else to look? I cant find shorts on any of the caps.

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Re: Anyone can identify this 286 motherboard?

Posted on 2020-07-24, 04:42

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes if you can get it to boot the BIOS may tell who made it :) I searched thru all my TH99 and old .pdf's and found nothing quite like, not even a hint. Will keep looking around...It is possible the original BIOS tapes were coming off and someone swapped with tape, have done that myself. Hopefully …

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Re: Anyone can identify this 286 motherboard?

Posted on 2020-07-24, 02:24

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I can't identify it, but it's pretty interesting...not just for the unusual shape, but also because it has an Intel chipset. I think it's really a Zymos chipset, but this is the first one I have ever seen one branded as "Intel" especially on a 286. The PCB quality looks good from the photos. Must …

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Re: Ultimate 386 system?

Posted on 2020-07-24, 01:37

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Few days ago I also restored this mobo with the same rev 2.1. If anyone has later rev (2.5 probably) then please post photo. It is a very nice motherboard. Performance is better than others 386 which I have (~17500 on nssi) Mr Bios 1.44 works well + Cyrix DLC (cpu/fpu) 2.4fps on quake 1 :) From …

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Anyone can identify this 286 motherboard?

Posted on 2020-07-24, 01:27

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I can't get it to post. My power supply won't even power up like normal, no fan, etc. All I can see on the board is part no: P1.830813.02 And B-1310B Any ideas what could be wrong? I cleaned it up and removed all the chips and repeated everything, removed a leaky battery but damage was minimal and …

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Re: 16MB of RAM only shows as 12MB

Posted on 2020-07-24, 00:06

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Just tried those simms in my 386 machine and they show as 15424 KB which I guess is about right. Oddly enough I tried some other simms that I know are 16 MB total on my 386 and they show up exactly as 16MB on the 486 board in question. So my guess is that its a compatibility issue? This board had …

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Re: 16MB of RAM only shows as 12MB

Posted on 2020-07-23, 12:27

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

ISA Memory hole? Bad RAM ? Mismatched modules ? Can you boot and run stable? Dont know anything about the ISA memory hole, looks like a BIOS setting? Will take a look in the morning. Have no idea if its bad, as i have not tested it yet, interestingly the second bank was full of 4mb 9 chip modules …

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16MB of RAM only shows as 12MB

Posted on 2020-07-23, 10:07

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Well 11.904 to be precise. Simms had 4MB written on them.

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Re: ASUS ISA-486SV2

Posted on 2020-07-23, 06:43

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Anyone familiar with this board? Is it a good model? Looks like I have found another early example of an ASUS board. Has an SiS 85C461 chipset. I know SiS chips are not always anything special alot of the time, with a few exceptions. I can't comment on the board's intrinsic fitness, but I can say …

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ASUS ISA-486SV2

Posted on 2020-07-23, 01:56

by

by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Anyone familiar with this board? Is it a good model? Looks like I have found another early example of an ASUS board. Has an SiS 85C461 chipset. I know SiS chips are not always anything special alot of the time, with a few exceptions.

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Re: Graphics card benchmarks/rankings for DOS machines. (ISA and VESA local bus)

Posted on 2020-07-21, 08:32

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

[...] I agree that compatibility is important. From what I gather the likes of a Tseng card is great for DOSgames, but terrible in Windows. As with everything else, key is getting your requirements clear - particularly as in the ISA and VLB period great DOS and Windows performance could be mutually …

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Re: Ultimate 386 system?

Posted on 2020-07-21, 03:04

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by nzoomed

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I am working on a nice 386 computer right now too. If that barrel battery replacement leaks you will be in trouble again. Hard to find a nice motherboard in good condition. Funny you say that about the battery, from what I can tell, its never had a NiCad battery on this board, there is no jumper to …

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