VOGONS


First post, by markjw

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following up to the drive issues (Windows 98SE on Shuttle SN41G2 - need help with drives) I was having with the SN41G2 I was wondering if anyone has any thoughts on what has been going on with the CMOS settings on it.

Symptoms:
1. System would report floppy drive error and date/time lost on POST - going into the BIOS all CMOS settings would be at default values - put correct settings in and save, system boots OK
2. Leave machine connected to mains power and turn it off then back on a while later - CMOS settings still OK
3. Power off and unplug from mains - CMOS settings lost

Things tried (BIOS was already updated due to issues with correct drive size identification):
1. Replaced the CR2032 CMOS battery as given the age of the machine it was the obvious thing to do - no change in behaviour (used a new CR2032 and a known good one from a spare board)
2. Cleaned and checked the battery contacts were making good contact with the battery - still had same issue
3. Reseated the CMOS clear jumper and confirmed that it was bridging the correct pins (1&2) - still same issue
4. Stripped machine down to the basics - removed HDD, Radeon 9800Pro and Audigy 2ZS - still had the same issue
5. Removed motherboard from chassis just to ensure nothing had got underneath it that could cause a short (nothing was found)
6. Checked the condition of the electrolytic capacitors - all looked good, no bulging or leakage observed (machine only ever had minimal use)

When I reassembled the machine (again just the basics) I tested again and it held the CMOS settings for 15 minutes without issue with the mains disconnected - unplugged again and left it for 2 hours and still OK. Things I did different this time were:
1. When the machine was put back together the DDR memory module was put in the slot nearest the CPU rather than the 2nd slot
2. I put the clear CMOS jumper on pins 2&3 to force a reset for 10 seconds with mains disconnected.
3. After it reported errors on POST, went into the BIOS and chose 'Load Optimised Defaults' before putting in the settings I wanted.

Anyone seen this sort of behaviour before? Every other machine I've worked on (likely into thousands over the years from the original IBM PC-AT to fairly new machines) I've never seen the CMOS behave in such a fashion - everyone that has CMOS settings lost has been new battery then re-enter the settings and nothing else needed.

Next step will be to reinstall the Radeon and Audigy along with the HDD and see what happens.
thanks, Mark

Edit: nope, spoke too soon problem is back again - this machine is driving me mad!

Reply 1 of 4, by philmac

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I know this is an ancient post, but in the event you still have this board, I'd suspect the caps.

I've had 2 of these FN41 boards and an FN45 board fail - the OST capacitors on them tend to fail but without swelling or leaking, leaving no visible signs of an issue.

Reply 2 of 4, by markjw

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found the machine in the garage again the other day - still has the same issue and reminded me of my oringinal post

I'll have a look at the caps when I get some spare time - I suspect you are right as I would think the board would from around the time of the 'capacitor plague'

philmac wrote on 2023-03-14, 09:14:

I know this is an ancient post, but in the event you still have this board, I'd suspect the caps.

I've had 2 of these FN41 boards and an FN45 board fail - the OST capacitors on them tend to fail but without swelling or leaking, leaving no visible signs of an issue.

Reply 3 of 4, by bogdanpaulb

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markjw wrote on 2021-02-22, 18:33:
Symptoms: 1. System would report floppy drive error and date/time lost on POST - going into the BIOS all CMOS settings would be […]
Show full quote

Symptoms:
1. System would report floppy drive error and date/time lost on POST - going into the BIOS all CMOS settings would be at default values - put correct settings in and save, system boots OK
2. Leave machine connected to mains power and turn it off then back on a while later - CMOS settings still OK
3. Power off and unplug from mains - CMOS settings lost

This happens to any atx motherboard when the voltage from the cmos battery doesn't reach the intended circuitry. Use a multimeter in voltage mode and measure between ground and the clear cmos jumper (conducive top of the jumper/use one that's not isolated on the top part) when he's in the Normal position, you should have ~3v. If this voltage is not present check the battery/holder. Do this with the computer unplugged from the mains.

Reply 4 of 4, by markjw

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thanks, I'll have a check - also I'll see if I can identify the CMOS chip and find a pinout for it - been a long time since I've done any motherboard work (mainly an os / network guy these days)

'Unplugged from the mains' - very true as would get false results, but also learnt my lesson on working on live equipment years back - Epson printer, 240V open-frame power supply!!!

bogdanpaulb wrote on 2023-04-13, 18:54:
markjw wrote on 2021-02-22, 18:33:
Symptoms: 1. System would report floppy drive error and date/time lost on POST - going into the BIOS all CMOS settings would be […]
Show full quote

Symptoms:
1. System would report floppy drive error and date/time lost on POST - going into the BIOS all CMOS settings would be at default values - put correct settings in and save, system boots OK
2. Leave machine connected to mains power and turn it off then back on a while later - CMOS settings still OK
3. Power off and unplug from mains - CMOS settings lost

This happens to any atx motherboard when the voltage from the cmos battery doesn't reach the intended circuitry. Use a multimeter in voltage mode and measure between ground and the clear cmos jumper (conducive top of the jumper/use one that's not isolated on the top part) when he's in the Normal position, you should have ~3v. If this voltage is not present check the battery/holder. Do this with the computer unplugged from the mains.