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Re: FIC 486-VP-IO lose BIOS settings

Posted on 2020-05-22, 23:03

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

From the DS12885 datasheet: Active-Low RAM Clear. The RCLR pin is used to clear (set to logic 1) all the general-purpose RAM, but does not affect the RAM associated with the RTC. To clear the RAM, RCLR must be forced to an input logic 0 during battery-backup mode when VCC is not applied. The RCLR …

Re: DFI CA-64TC MOSFET type?

Posted on 2020-05-22, 09:30

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I think that's a date code or something like that, and the chip is a 74HC74.

Re: Rant: please stop linking to "Stason .org" for Total Hardware 1999 (TH99) pages

Posted on 2020-05-21, 13:40

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

What if we combined the versatility of stason with the cleanness of TH99 ? Looking great, and I think the TH99 very much needs an overhaul. Things that are a must, IMO: being able to filter boards by chipset, number and type of slots. Including additional information such as the BIOS ID string, …

Re: 286 Does not hold BIOS settings

Posted on 2020-05-21, 12:36

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Probably the voltage is too low. 3V from the CR2032 is equivalent to the "fully discharged" voltage of the NiMH pack, and you also lose ~200mV on the diode. For the external battery connector, many boards require 4.5 or even 6 volts. You can try with 3xAAA or 4xAAA / 2xCR2032 packs.

Re: 486 motherboard won't post - DRAM config?

Posted on 2020-05-21, 12:14

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I'm not familiar with flashrom, but I guess it is a Linux tool with pretty much the same functionality as uniflash, which is a DOS tool made by Rainbow Software. There's also another uniflash by Texas Instruments, in fact most of the results returned by Google are related to this one, but you'll …

Re: 486 motherboard won't post - DRAM config?

Posted on 2020-05-20, 22:38

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes they are compatible. I'm almost sure 27C512 EPROMs from all manufacturers are compatible. Reading it on the TNT2 should work, you can also use a network card. Also, if flashrom fails you can try uniflash. Building an EPROM programmer certainly has its charm, but I took the shortcut and got the …

Re: FIC 486-VP-IO lose BIOS settings

Posted on 2020-05-20, 20:56

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Agreed, CMOS data gets stored on the DS12885. I would try with a 4.5 volts battery pack connected to the external battery header, just to see if anything changes.

Re: -12v (negative 12 volt) line appears to be shorted to ground

Posted on 2020-05-19, 12:26

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

One of the caps is shorted, most certainly. They don't always explode or go up in flames. I guess it depends on the amperage available to the respective rail, and the internal resistance after the short (close to zero ohm should be better than, say, 1 or 2 ohms, because of lower dissipation).

Re: Missing chip from 9800pro ?

Posted on 2020-05-18, 11:15

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Umm, no. Still wondering why the card only has 3 mosfets in the few photos on the net that show it with that tiny heatsink removed. Maybe the glue is stronger than the solder for that one :D. You could try and solder it back. Take care of the orientation, and check first with a multimeter if it …

Re: Identifying a CPU and a mobo

Posted on 2020-05-18, 11:07

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

DX2-80 for sure. Beeps are good, means the board isn't completely dead 😀. Make sure the RAM is FPM not EDO.

Re: CD-ROM drives that "lose the strength" to open

Posted on 2020-05-18, 11:00

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Could be very dirty lens, the drive doesn't "see" the disc so it doesn't try to spin up.

Re: Missing chip from 9800pro ?

Posted on 2020-05-18, 10:57

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

These are IRF7822 MOSFETs. However, there are other photos on the net with 9800 Pros having only 3 installed, so I guess it came this way from the factory.

Re: CD-ROM drives that "lose the strength" to open

Posted on 2020-05-17, 16:49

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

In most of the cases I solve the problem by cleaning the belt and pulleys with a strong degreaser such as 99% IPA or Sanitec DEINK . I think, in time, oils from whatever grease they used for the mechanism find their way to the belt, and together with the belt wear and tear they are causing it to …

Re: Fixing a DTK PTM-1230C

Posted on 2020-05-16, 22:05

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Being near the 32.768KHz crystal, my guess is that its purpose is fine-tuning the timekeeping. Also, the KBC seems to be missing.

Re: Fixing a DTK PTM-1230C

Posted on 2020-05-16, 19:59

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Y2 is the 32.768KHz for the RTC 1.8432MHz is for the 82C452 UART, I think the board should boot without it but I'd remove the chip entirely to be on the safe side. Give the board a good scrub before continuing, those solder blobs can kill a chip instantly. Edit: also missing is a variable capacitor …

Re: Strange problem with 486 motherboard

Posted on 2020-05-16, 19:14

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

A20 line error? Try with another KBC.

Re: Strange problem with 486 motherboard

Posted on 2020-05-16, 08:34

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Check for cold or broken solder joints at the chipset. Power the board while applying pressure to the chips, see if anything changes. Make sure the board is on a hard and flat surface so it doesn't warp.

Re: Help me identify this LS-486E (Lucky Star 486)

Posted on 2020-05-15, 23:50

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

There seem to be many revisions of the LS-486E, most of them are a few cm shorter and have a different layout (most striking are the location of cache and BIOS chips, VRM and southbridge). Got two of those also 😀 But this one is bigger, and I've attached the right manual (I hope).

Re: Help me identify this LS-486E (Lucky Star 486)

Posted on 2020-05-15, 23:05

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I have one of those. Dunno what revision it is, so I just call it "LS-486E bigger version". Because it's bigger 😀

Re: Hyper386sx 286 Upgrade CPU

Posted on 2020-05-15, 18:22

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thanks keropi, you've spared me some minutes. So it's nothing to "rearrange", the pinouts are already 1:1, just the form factor differs.

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