486 seems dead - Please help!

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486 seems dead - Please help!

Postby Dougal » 2018-7-12 @ 13:49

It worked fine but was losing the bios settings due to the battery/clock ODIN (like Dallas).

Anyway, stupidly I removed the ODIN clock damaging it in the process and then it would no longer boot. Nothing, no display, no POST beeps nothing.

So, ordered a new ODIN clock with same model number etc and soldered a socket while waiting for the ODIN clock to arrive.

Today the ODIN clock arrived, so I installed it and tried to boot. NOTHING, no POST beeps, no display :(

I am lost as what to try out.

I also did another mistake, while trying to diagnose before realizing that it wont boot or POST without the clock I accidently put the CPU the wrong way and powered it up. The CPU is a 100Mhz DX4 AMD CPU 486.

I have another two CPU's to test if I damaged the CPU but I doubt that managed to damaged the CPU.
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Re: 486 seems dead - Please help!

Postby DankEngihn » 2018-7-12 @ 14:23

Upon putting the CPU in the wrong way, you probably fried the motherboard.
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Re: 486 seems dead - Please help!

Postby Dougal » 2018-7-12 @ 14:44

Oh crap :(
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Re: 486 seems dead - Please help!

Postby amadeus777999 » 2018-7-12 @ 17:19

I once put in a cpu the wrong way too - it was on a LS486E.

Due to hours of testing and repetitious in/out(not the good way) I made formerly mentioned mistake. Both the cpu and the board survived but the voltage regulator was fryed. I initially thought the board was toast(no sign of life on power on), but due to the gods' retro fetish I tested a 5V cpu and voila... it came back from the dead.

Try a 5V cpu + good luck.
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Re: 486 seems dead - Please help!

Postby BLockOUT » 2018-7-12 @ 17:37

amadeus777999 wrote:I once put in a cpu the wrong way too - it was on a LS486E.

Due to hours of testing and repetitious in/out(not the good way) I made formerly mentioned mistake. Both the cpu and the board survived but the voltage regulator was fryed. I initially thought the board was toast(no sign of life on power on), but due to the gods' retro fetish I tested a 5V cpu and voila... it came back from the dead.

Try a 5V cpu + good luck.


so
Board not fried?
CPU not fried ?
only broken voltage regulator?
only that is broken or other components suffered too?

did you replace the regulator later on? did it boot a 3.45 cpu after that?
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Re: 486 seems dead - Please help!

Postby amadeus777999 » 2018-7-12 @ 18:15

No, both survived.

I'm running the board with an Evergreen 5x86 x133 cpu now and it's been working for hours on end since. It even runs at 50mhz fsb with all settings maxed out, so I doubt there's other components fried.

I'm in the process of installing the voltage mod, so that I can regulate the voltage from 5 down to to 1.xV(theoretically).
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Re: 486 seems dead - Please help!

Postby kixs » 2018-7-12 @ 18:56

I once inserted the cpu in the wrong way and everything turned out fine. I guess it depends which way you turned it.

Recently one of my better 486 VIP motherboards and POD5V83 that worked fine at 100MHz just froze at booting. After that no life whatsoever. Both dead :dead: I searched long time to find POD5V83 that works fine at 100MHz without mods. :depressed:

In the end this is old hardware and I guess everything is possible..
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Re: 486 seems dead - Please help!

Postby Eleanor1967 » 2018-7-12 @ 21:07

amadeus777999 wrote:I once put in a cpu the wrong way too - it was on a LS486E.

Due to hours of testing and repetitious in/out(not the good way) I made formerly mentioned mistake. Both the cpu and the board survived but the voltage regulator was fryed. I initially thought the board was toast(no sign of life on power on), but due to the gods' retro fetish I tested a 5V cpu and voila... it came back from the dead.

Try a 5V cpu + good luck.


I did the exact same thing: inserted a CPU the wrong way on a LS486e and my voltage regulator was dead... Board and CPU survived though too. So OP you maybe should do some more testing before scraping the board
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Re: 486 seems dead - Please help!

Postby feipoa » 2018-7-12 @ 23:47

I think it also depends on how long you had the motherboard turned on while the CPU is inserted incorrectly. I have friend a motherboard once because I turned on the board with the CPU inserted incorrectly, but looked the other way. I had the PSU engaged for about 10 seconds. The board (or CPU) started smoking. The CPU survived and the board died. Since then, and before, I have accidently powered on about half a dozen times with the CPU inserted incorrectly, but I always keep my finger on the power button now until I see a CMOS screen. If I don't see a sign of life within about 3 seconds, I shut the PSU off. This habit I've developed has saved those half dozen other boards/CPUs.

When you get tired and just want to run a quick test is when the CPU goes in backwards. Developing a habit to hold your finger on the power button for test beds might save yourself some hardware in the future.
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Re: 486 seems dead - Please help!

Postby Dougal » 2018-7-13 @ 15:46

I have 3 CPU's - The original one it had a AMD DX4-100, a Intel DX2 66 and a AMD 486 DX 40

How do I know what voltages these are ?
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Re: 486 seems dead - Please help!

Postby TheMobRules » 2018-7-13 @ 15:57

The DX4 is 3.3V, the other two should be 5V.
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Re: 486 seems dead - Please help!

Postby dogchainx » 2018-7-14 @ 04:24

My brother, on upgrading the family's business computer back in early 90's, fried a $450 486dx2-66 cpu along with the motherboard because he put it in the wrong way. Oops.
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Re: 486 seems dead - Please help!

Postby feipoa » 2018-7-14 @ 05:39

Do you think not keying the CPUs was a deliberate attempt to sell more CPUs [because users have to buy again when they fry 'em]?
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Re: 486 seems dead - Please help!

Postby amadeus777999 » 2018-7-14 @ 09:51

That would be a pretty efficient scam... sometimes, when changing cpus, exactly the same thoughts came to mind.

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Re: 486 seems dead - Please help!

Postby ATauenis » 2018-7-14 @ 10:04

Did you tried to use a PC Analyzer card to see if there are really no signs of life or the board simply stops on yearly steps of POST? I've successfully :) damaged a Odin RTC on Socket-7 board and now it is looking like your - nothing is smoking and nothing works. The board is stopping at 07 POST code (the firmware is Award 4.51). It is dead only due to RTC chip.

Also broken or fried CPUs sometimes may lock RESET signal, so the Reset LED will not blink on the PC Analyzer (POST Card) when cpu is installed.
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Re: 486 seems dead - Please help!

Postby Dougal » 2018-7-15 @ 16:30

There was two or 3 damaged pads where the RTC/Battery (ODIN) sits. They are fixed now and it POSTS but still more issues which it did not have before.

It says something about the BIOS checksum failing and system halted. I can get into bios settings but it cannot detect hard disks when using a controller card (i tried 2) but it detects it on the onboard IDE connector but then it freezes when I try to save the bios settings and when I reboot I get the same checksum failed and system halted.
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Re: 486 seems dead - Please help!

Postby amadeus777999 » 2018-7-15 @ 17:09

Hey, at least it "lives" and there's chance of repairing it.

I also had the freeze issue with an GA486 AMS board which later refused to boot up again... it's kept in a safe place but "dead". So this could mean it's just the battery?
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