P75 machine weird behaviour \ VOGONS

P75 machine weird behaviour

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First post, by Martin85

Posted on 2023-12-20, 20:12

Martin85 Offline

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Hi there,

after a long time I have some new stuff in my collection and one that particularly has a special place.

It's a pentium 75MHz machine with 16MB ram and 850HDD, S3 Trio64v+,...

Today I finally checked the PSU, earlier I removed the Farta™ battery, very little to none damage on the board, maybe will have to clean a little bit the Cache slot on the board eventually.

So, the problem is that when I enter into BIOS to set things up, I see the DATE and/or TIME going fast like I was keeping a finger on a key... There is no way of stopping that, tried disconnecting the keyboard, but to no avail.

Oh yes, the board is a Gigabyte GA586AM with some Genoa stickers on the chips... Anyone had any issue like that?

Reply 1 of 6, by Rawit

Posted on 2023-12-20, 20:19

Rawit Offline

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Is the keyboard controller perhaps near the place the Varta battery was? And does it do this only in the BIOS?

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Reply 2 of 6, by Martin85

Posted on 2023-12-20, 20:42

Martin85 Offline

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Well, I would say it's quite far away from the battery and there is no actual damage or sign of leakage around the chip.
The chip is that one (the one in the middle - UM8287): https://theretroweb.com/expansion-chips/4560

And yes, it does it only in BIOS and only with DATE and TIME, all the others settings are normally settable... No problems there... So I am inclined to rule out the keyboard.

Reply 3 of 6, by geertjanb

Posted on 2023-12-20, 21:02

geertjanb Offline

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Could you make a video and post it on YouTube?

Reply 4 of 6, by Rawit

Posted on 2023-12-20, 21:04

Rawit Offline

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Did you replace the battery with something else? If not that might be the problem.

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Reply 5 of 6, by Martin85

Posted on 2023-12-20, 21:45

Martin85 Offline

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Great call! I took an external battery and connected it on the header. Everything is working fine now. Even when if I disconnect the battery... The time is working correctly as it's the date.

In the meantime I think the HDD failed... It's a pitty because I think this computer had literally minutes of usage in the last 25 years... Everything is in near mint state and the seller label lists all the hardware that is in the machine. Also no dust whatsoever, just some yellowed plastics (but very little) and some rust in the corners where the metal was bent and cut and I guess not protected as should be, so rust started forming during the years.

Anyway, will put a CF card as a boot disk and hopefully can make the HDD live again, maybe is just old bad caps.

Reply 6 of 6, by Disruptor

Posted on 2023-12-20, 23:03

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Martin85 wrote on 2023-12-20, 21:45:

In the meantime I think the HDD failed... It's a pitty because I think this computer had literally minutes of usage in the last 25 years...

HDDs do not like to be stored without getting its platters and actuators moved from time to time.

Perhaps you can try to rotate the uninstalled drive horicontally in your hand with some force. Repeat it a few times in both directions.

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