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Reply 40 of 50, by froller

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Continuing my adventures with LS-486e Rev:D

I've managed to replace fried power BJT with new TIP127 and got 3.3V and mobo started with Am5x86-P75-133ADZ and 2x4MB FPM RAM.
Then I decided to check if it supports EDO and installed 2x64MB EDO and mobo started and checked all 128MB and asked for floppy.
I turned everything off to tie up floppy and... nothing went up. Mobo refused to start.
Replacing EDO with FPM also didn't help. Removing memory lead to POST beeps 'bout missing memory. But now it refuses to start either with RAM or without. With RAM it doesn't even get to video initialization so no beeping 'bout missing VGA.

Don't know if it matters but EDO RAM has its own 3.3V regulators onboard and I checked RAM chips are powered by 3.3V.

Did I run into some sort of electrical incompatibility of newer RAM?

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Reply 41 of 50, by quicknick

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AFAIK EDO/FPM use 5 volts and SDRAM is 3.3V. Check the datasheets of your memory chips and see what they'll take.

Reply 42 of 50, by froller

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quicknick wrote on 2021-02-11, 13:00:

AFAIK EDO/FPM use 5 volts and SDRAM is 3.3V. Check the datasheets of your memory chips and see what they'll take.

For sure they are 3.3V. Otherwise there no need of 3.3V LDO onboard of SIMM.
I don't care of fried SIMMs. I have more of them either EDO 3.3V or 5V or FPM 5V.
I'm afraid they damaged north bridge SIS496 of latest revision that I can't obtain in other way than buying another mobo.

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Reply 43 of 50, by feipoa

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Back in 2001 I bought some EDO RAM from eBay for my PC Chips M919 motherboard; the board was ruined thereafter. Booted it up and got an NT4 BSOD straight away. I put the original RAM back in, but I kept getting BSODs thereafter. The board had worked fine for years prior. The only thing I changed was some EDO RAM which I guess ruined the northbridge? I still have that board sitting in a bin but it is awefully flakey now. I have some chipsets I have been meaning to solder on but never got around to it.

Plan your life wisely, you'll be dead before you know it.

Reply 44 of 50, by froller

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feipoa wrote on 2021-02-11, 13:45:

Back in 2001 I bought some EDO RAM from eBay for my PC Chips M919 motherboard; the board was ruined thereafter. Booted it up and got an NT4 BSOD straight away. I put the original RAM back in, but I kept getting BSODs thereafter. The board had worked fine for years prior. The only thing I changed was some EDO RAM which I guess ruined the northbridge? I still have that board sitting in a bin but it is awefully flakey now. I have some chipsets I have been meaning to solder on but never got around to it.

Unfortunately this could be the case. Do you still have SIS496 supporting EDO?

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Reply 45 of 50, by feipoa

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Wasn't there only one revision of the LuckyStar LS-486e which supported EDO? I forget which one it was now.

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Reply 47 of 50, by froller

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gerwin wrote on 2021-02-11, 14:22:
feipoa wrote on 2021-02-11, 14:17:

Wasn't there only one revision of the LuckyStar LS-486e which supported EDO? I forget which one it was now.

SIS 496 'PR' Revision Northbridge supports EDO-RAM.

Is SiS85C496 'NV' produced in 1997 capable of EDO?

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Reply 48 of 50, by dionb

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feipoa wrote on 2021-02-11, 13:45:

Back in 2001 I bought some EDO RAM from eBay for my PC Chips M919 motherboard; the board was ruined thereafter. Booted it up and got an NT4 BSOD straight away. I put the original RAM back in, but I kept getting BSODs thereafter. The board had worked fine for years prior. The only thing I changed was some EDO RAM which I guess ruined the northbridge? I still have that board sitting in a bin but it is awefully flakey now. I have some chipsets I have been meaning to solder on but never got around to it.

Electrically, EDO is no different to FPM, so the damage won't be due to short circuit or similar. Sounds more like ESD damage, tbh.

Reply 49 of 50, by gerwin

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froller wrote on 2021-02-11, 15:45:
gerwin wrote on 2021-02-11, 14:22:
feipoa wrote on 2021-02-11, 14:17:

Wasn't there only one revision of the LuckyStar LS-486e which supported EDO? I forget which one it was now.

SIS 496 'PR' Revision Northbridge supports EDO-RAM.

Is SiS85C496 'NV' produced in 1997 capable of EDO?

AFAIK 'NV' is not EDO compatible, only 'PR' is.
The LS-486E that I have is also an 'NV'. I suppose it is the most common one.

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Reply 50 of 50, by froller

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While waiting for 85C496's to be delivered I bought another damaged LS-486e Rev:D. After replacing power BJT (this one had TIP127 instead of H2585) it started.
But when I tried to boot I encountered some strange problems:
- Boot-up floppy seek works ok but freezes on booting from floppy
- It boots from HDD but accessing floppy leads to freeze
- Serial mouse driver loads ok but moving mouse after that leads to freeze

So it freezes when it get IRQ4 (COM1) or IRQ6(Floppy). Haven't tried with IRQ3(COM2) and IRQ5(LPT2) but probably it ends the same.
I tried both FPM and EDO even with slowest timing settings.

Does anyone experienced similar problems?

UPD: problem was solved by turning "Turbo" on with jumper. Switching "Turbo" off leads to immediate freeze on floppy access. It looks related to ugly implemented de-turbo functionality of LS-486e.

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