Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-30, 17:03

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Doh, the 74612 is DMA address extender. I should've looked at the schematics, this really is an early AT clone - basically upgraded XT guts with 16-bit wide data bus and some quirks to support that (and 286 in general). Anyway, I did look at the schematics now - it seems this mobo is not 100% …

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Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-29, 12:38

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by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So, I reflowed all pins for the CPU socket, and the kbc socket. No difference.

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Re: What retro activity did you get up to today?

Posted on 2020-03-29, 11:52

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Bought this motherboard as dead 6months ago, was cheap because of deadness. Tested it then and yeah, it was completely dead. So I just put in the pile of dead stuff. And now I took it out again. It was still dead (surprise). Anyway, checked all jumpers according to silkscreen and all seemed right. …

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Re: Help with non booting OPTi-localbus motherboard

Posted on 2020-03-29, 11:34

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

As I'm going through my dead motherboards I came across this one again. I put supersoft in this one and it's painfully slow. From power on it takes right under 4minutes to get an image on screen. And the actual tests take about 10 minutes until it freezes at cpu protected mode. But all tests until …

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Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-29, 11:22

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Removing '612 does nothing except supersoft lists that chip as failed. Same with the 8042. With the U15 pal removed it still boots but fails 8254 Timer channel 2 and 8042 parity. With either of the two pals at u14 and u19 removed I get no boot at all. I've been amusing myself with checking …

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Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-27, 05:24

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

This is quoted from minuszerodegrees website: These diagnostics primarily require a CGA or MDA/MGA video card (although, strangely, an IBM MDA card does not work for the 5170 version of the ROM). EGA cards will work, but poorly. Only some VGA cards are expected to work (more information here). If …

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Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-26, 20:51

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Only 00FF. The LED for ready is lit but not as bright as with the supersoft roms. I dumped both bioses if it helps. Checksum is correct so the image is good, but since it dies so soon I'd expect a problem with reading it by CPU. Possibly a cold or cracked solder on the sockets? Worth checking out. …

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Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-25, 17:00

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

What POST codes do you get with original BIOS, and what brand it is (Phoenix, AMI, other?) Only 00FF. The LED for ready is lit but not as bright as with the supersoft roms. https://youtu.be/nHhGMIrlTks I don't know what type of bios it is. This is all it shows when I got it to boot. Not much info …

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Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-25, 13:25

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

J9 is to jumper between the original keyboard and ibm compatible keyboard. Traces are measured, the only one with any damage was the one to the battery positive. Jumperwire in place for that one. I can go over the area again just in case. But so far all traces look fine and measures 0 Ω. No clear …

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Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-25, 10:38

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I have cleaned everything two or three times by now, just in case. 😀 With orginal bios it only shows 00FF and no ready light.

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Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-25, 06:14

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

There seems to be clockactivity on all pins where there should be.

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Re: Bought these (retro) hardware today

Posted on 2020-03-25, 06:00

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Very slow with purchases here. Got this yesterday, slotket with p3 800. Slotkets are always good to have around. IMG_5131.JPG Then something wierd. I have a bookshelf in my computer-room, and just in passing I saw this and pulled it out. I have no idea when I got it or where. Can't remember it at …

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Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-23, 20:34

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

All pins on all chips are already cleaned. Taking the board down to 512k makes no difference.

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Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-22, 19:48

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Filename 15.JPG File size 1.07 MiB Views 2046 views Filename 16.JPG File size 1.06 MiB Views 2046 views phew

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Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-22, 19:47

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

...schematics Filename 10.JPG File size 1.37 MiB Views 2047 views Filename 11_1.jpg File size 1.52 MiB Views 2047 views Filename 12.JPG File size 1.36 MiB Views 2047 views Filename 13.JPG File size 1.28 MiB Views 2047 views Filename 14.JPG File size 1.25 MiB Views 2047 views one more..

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Re: Help needed with dead 286 board. With schematics.

Posted on 2020-03-22, 19:44

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

...schematics Filename 5.JPG File size 1.34 MiB Views 2047 views Filename 6.JPG File size 1.12 MiB Views 2047 views Filename 7.JPG File size 1.28 MiB Views 2047 views Filename 8.JPG File size 1.59 MiB Views 2047 views Filename 9.JPG File size 1.18 MiB Views 2047 views more to come...

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Help needed with dead 286 board. With schematics.

Posted on 2020-03-22, 19:43

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So I've had this machine for a while, a Copam PC-501 Turbo. It was dead when I got it, but I was fiddling with it and got it to boot a few times, then moved on to testing other new stuff. But I took it out again last week and it's completely dead. No Irdy signal on the bootcard, no beeps, just dead. …

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Re: What retro activity did you get up to today?

Posted on 2020-03-14, 20:34

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I took a break from the machines on two wheels to fix some machines. So over a few days I have repaired and cleaned two Amiga 500s, one regular and one plusmodel. Vartakiller IMG_4321.JPG Saved IMG_4997.JPG And this morning I replaced a RAM-chip on an early VIC-20, and then the same fix on an C64 …

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Re: Bought these (retro) hardware today

Posted on 2019-11-25, 17:13

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Today was a good day. A customer came by and gave me this: IMG_4294s.jpg Amiga 500, Amiga 500Plus, a bunch of games and some other stuff. The manuals and one of the PSUs belongs to an Amiga 600HD, also got the box for it but sadly not the machine itself. He said there had also been both c64 and c128 …

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Re: What retro activity did you get up to today?

Posted on 2019-11-24, 19:24

by

by Vegge

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Since I finally got the RAM I just had to boot it. IMG_4278s.jpg IMG_4281s.jpg So yeah, dual P3 733 with 8GB of RAM. Now what? Windows 7? :lol: Man, you have some serious dual Slot 1 action at your place. IIRC you also grabbed a NOS dual Slot 1 Supermicro board awhile back. Speaking of which, did …

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