VOGONS


First post, by Miphee

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When I set the CMOS clear jumper to the normal position (1-2) the board won't start at all when I press the power button. Probably a short circuit that prevents the PSU from starting.
When I set it to the clear position (2-3) or remove the jumper the board starts automatically when I plug it in. All fans spinning and the diagnostic card shows 00C1 error code. If I plug the jumper in the normal position it stops immediately. When I remove it, it starts again. Something spooking the PSU.
Things I checked so far:

- voltages are present
- CLK present but irdy and frame aren't
- no visible damages on either side: no broken traces, no contacting chip legs, no burn marks, solder joints are good
- the 82443 chip is missing the original heatsink. I measure 47 C° (116 °F) on that chip
- Measured all chips and FETs and they all generate some heat between 28-47 C°. It doesn't mean much but it's a sign of some life and no sign of anything overheating
- CPU is good, tried 3: PII/350, PII/400, PIII/500
- BIOS chip is good
- no short circuit on the main rails
- no short circuit between slot contacts
- fresh battery installed
- no configurable jumpers other than the CMOS clear, KB pwr on and the case open alert.

So far nothing. Any ideas?

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Reply 1 of 35, by Roman555

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Miphee wrote on 2020-06-19, 18:23:

When I set the CMOS clear jumper to the normal position (1-2) the board won't start at all when I press the power button.

It might be when the power button is connected to wrong pins.

Last edited by Roman555 on 2020-06-20, 03:56. Edited 1 time in total.

Reply 2 of 35, by auron

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not that it will help much, but coincidentally have a dead 6LTM board as well. the difference to yours is that mine does have the chipset heatsink and also has some trace damage on the back that i only noticed later. originally the board would just do nothing at all, but after patching said damage and plugging the ATX cable in, the PSU started up without any button press and soon there was a burning smell coming from it. fortunately not a PSU i really cared about and the RAM used for that test is also still good...

since it's a 440LX board i had the thought that maybe it's one of those boards with underspecced voltage regulators and has been operated with a later AGP card with too high power draw, burning something out.

Reply 3 of 35, by Miphee

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Roman555 wrote on 2020-06-19, 19:47:
Miphee wrote on 2020-06-19, 18:23:

When I set the CMOS clear jumper to the normal position (1-2) the board won't start at all when I press the power button.

It might be when the power button is connected to wrong pins.

It does the same thing when I short the SW pins with a screwdriver.

Reply 4 of 35, by Miphee

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auron wrote on 2020-06-20, 01:02:

since it's a 440LX board i had the thought that maybe it's one of those boards with underspecced voltage regulators and has been operated with a later AGP card with too high power draw, burning something out.

Well, I could live with burned regulators but not with burned BGA chips. Too bad I can't see damage anywhere.

Reply 5 of 35, by Roman555

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Miphee wrote on 2020-06-20, 05:08:
Roman555 wrote on 2020-06-19, 19:47:
Miphee wrote on 2020-06-19, 18:23:

When I set the CMOS clear jumper to the normal position (1-2) the board won't start at all when I press the power button.

It might be when the power button is connected to wrong pins.

It does the same thing when I short the SW pins with a screwdriver.

I mean the correct pins are designated as "PWS". You have to connect the power button to these pins.
If it's already done properly then disconnect the button, turn ATX PSU switch ON and just measure voltage between each pins "PWS" and GND rail using multimeter setting to voltage mode "20V". One of the pins should have some voltage (something like 5V or 3.3V).
BTW "00C1 error code" means "RAM error" or memory slots just aren't populated with DIMMs.

Reply 6 of 35, by evasive

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BIOS chip is good

if it gives a memory error code, how come it is not beeping? Did you attach a speaker?

I'm suspecting bios corruption here, if the chip is removable, have it flashes in an EEPROM programmer or use hotflshing technique with another board that is using the same or a similar bios chip.

Reply 7 of 35, by CHiLL72

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It's a long shot, but you are trying 100MHz FSB CPUs on a 66MHz board. I know, it normally works at a lower frequency, but still...

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Reply 8 of 35, by evasive

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CHiLL72 wrote on 2020-06-20, 11:19:

It's a long shot, but you are trying 100MHz FSB CPUs on a 66MHz board. I know, it normally works at a lower frequency, but still...

Would a missing microcode prevent it from reading the memory properly? I'd expect the bios to crash sooner then. What bios revision is it on anyway?

Reply 9 of 35, by Miphee

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I tried with 2 different BIOS chips from slot1 boards and they all did the same. I read this chip in the TL866 and it's OK.
Why does the computer start automatically if it's a compatibility issue? The board starts up as soon as I apply power to it (when the JP5 pins are in the 2-3 position or the jumper is removed).
I measured the PWS pins: one is GND the other is 5V. The same as on a functioning board.
I measured JP5 pins: GND, 3,7V, 3,2V.
When I short JP5 1-2 it stops immediately, indicating a short that triggers the PSU short-circuit protection.
I replaced the one tantalum capacitor but it wasn't the problem.

Reply 10 of 35, by Roman555

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Miphee wrote on 2020-06-21, 05:10:
I tried with 2 different BIOS chips from slot1 boards and they all did the same. I read this chip in the TL866 and it's OK. Why […]
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I tried with 2 different BIOS chips from slot1 boards and they all did the same. I read this chip in the TL866 and it's OK.
Why does the computer start automatically if it's a compatibility issue? The board starts up as soon as I apply power to it (when the JP5 pins are in the 2-3 position or the jumper is removed).
I measured the PWS pins: one is GND the other is 5V. The same as on a functioning board.
I measured JP5 pins: GND, 3,7V, 3,2V.
When I short JP5 1-2 it stops immediately, indicating a short that triggers the PSU short-circuit protection.
I replaced the one tantalum capacitor but it wasn't the problem.

Next operations are not so easy. And there are many difficulties to help you because there is no the circuit diagram of the mainboard. So I'll try to guess something. Maybe I'm digging too deep 😀

I suppose you have already inspected the mainboard visually and haven't found any mechanical damages. Fresh CMOS battery is installed.
1) A motherboard doesn't turn on at all if a 32.768KHz crystal is bad. So check presence of sinusoidal signal on its pins using an oscilloscope. Or just change a 32.768KHz crystal to a working for sure one. It's better to remove a CMOS bat. from the socket when do soldering.
2) Try to understand where PWS pin (one where is 5v) is connected. It can be connected, for example, (maybe via resistors) to pin #73 (PANSWIN means "Panel Switch input") of SuperIO W83977TF-AW.
If that is so - when you short PWS pins with a screwdriver the voltage on the pin #73 should drop. After that the voltage on pin #72 (PANSWOUT means "Panel Switch output") should drop too.
All this information you can find in the datasheet for Winbond W83977TF-AW.

P.S. Some old ASUS training materials, maybe would be handy.
https://www.slideserve.com/leiko/asus-mother- … eshooting-guide

Reply 11 of 35, by Miphee

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Roman555 wrote on 2020-06-22, 15:51:

Maybe I'm digging too deep 😀

Thank you for the help, I appreciate it! I'll try your suggestions tomorrow.

Reply 12 of 35, by Tetrium

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Your board uses the 440LX chipset. It may be acting up because you are trying out 100MHz FSB P2 CPUs in them. Do you have a 333MHz or slower P2 CPU with which you can test the board, just to rule out this is the issue here?

I do recognize boards powering up right away after power is applied. Some Fujitsu Siemens boards tended to do this and I remember it from other boards as well. Often this was to do with either the BIOS battery being empty or with some default setting telling it to power up after a power failure (which might cause it to power up when testing on the bench).
You do mention having swapped out the BIOS chip twice, so this might not be the case.

I am kinda surprised to see an LX board with heatsink, as the vast majority of the ones I encountered did not have a heatsink at all. Only BX and newer tended to have a heatsink most of the time.

I could find Chaintech 6LTM mainboards, but didn't have an exact match for the Chaintech 6LTM-L. You reckon this could be some OEM board?
EDIT: I think the model number printed on the PCB is probably the correct one. The model number is probably also on the BIOS chip itself but it's missing in the pics.

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Reply 13 of 35, by Horun

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Tetrium wrote on 2020-06-22, 22:47:

Your board uses the 440LX chipset. It may be acting up because you are trying out 100MHz FSB P2 CPUs in them. Do you have a 333MHz or slower P2 CPU with which you can test the board, just to rule out this is the issue here?

^^ This ! You can not run a 100Mhz cpu on a 66Mhz only board, the BIOS would not recognize the S spec and disallow a boot (accidentally tried it with a 440EX, no go).

Hate posting a reply and have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. 🤣 Second computer a 286 12Mhz with real IDE drive ! After that came 386, 486, Pentium, P.Pro and everything after....

Reply 14 of 35, by Roman555

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Tetrium wrote on 2020-06-22, 22:47:

Your board uses the 440LX chipset. It may be acting up because you are trying out 100MHz FSB P2 CPUs in them.

I've thought about it. It worth to try if 66MHz-FSB CPU (not Pentium it might be Celeron too) is in hand. But IMHO, the motherboard should turn on by pressing a power button despite CPU model or even without installed CPU at all. (I am aware that more modern MBs often wants CPU in their socket to just turn on).
Also mainboards may deny to turn on when jumper "Clear cmos" is in the wrong position (not "Normal"). As I understood , in this case the behaviour is just opposite - it denies to run when the jumper is "Normal".

Miphee wrote on 2020-06-19, 18:23:

When I set the CMOS clear jumper to the normal position (1-2) the board won't start at all when I press the power button. Probably a short circuit that prevents the PSU from starting.
When I set it to the clear position (2-3) or remove the jumper the board starts automatically when I plug it in.

Miphee, the most important question is where do you think pin #1 of the CMOS clear jumper? Is it designated on the board?
Please check, in my opinion it looks like on the picture:

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Reply 15 of 35, by Miphee

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Tetrium wrote on 2020-06-22, 22:47:

Your board uses the 440LX chipset. It may be acting up because you are trying out 100MHz FSB P2 CPUs in them. Do you have a 333MHz or slower P2 CPU with which you can test the board, just to rule out this is the issue here?

Should this work with a PGA370 Celeron 400 / 66 using a slotket? I don't have a slot1 P2 CPU with 66 Mhz FSB right now.

Reply 16 of 35, by Miphee

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Tetrium wrote on 2020-06-22, 22:47:

I do recognize boards powering up right away after power is applied. Some Fujitsu Siemens boards tended to do this and I remember it from other boards as well. Often this was to do with either the BIOS battery being empty or with some default setting telling it to power up after a power failure (which might cause it to power up when testing on the bench).

The battery is new. So is this a feature? It's really annoying because it starts whether I want it or not, but it's better than a malfunction.

Reply 17 of 35, by Miphee

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Roman555 wrote on 2020-06-23, 04:38:

Please check, in my opinion it looks like on the picture:

The thick line represents pin1 as in your picture. When 1-2 (normal) are shorted with a jumper the board stops. Does the exact opposite of what it's supposed to do.
I'm looking for shorts now in contact with these pins.

Reply 18 of 35, by Tetrium

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Miphee wrote on 2020-06-23, 10:41:
Tetrium wrote on 2020-06-22, 22:47:

Your board uses the 440LX chipset. It may be acting up because you are trying out 100MHz FSB P2 CPUs in them. Do you have a 333MHz or slower P2 CPU with which you can test the board, just to rule out this is the issue here?

Should this work with a PGA370 Celeron 400 / 66 using a slotket? I don't have a slot1 P2 CPU with 66 Mhz FSB right now.

My guess is it should. Try out the Celeron on Slotket on another board just to make sure that that combination will work.
Btw, trying out to power on the board without a CPU installed like Roman555 suggested would be the first thing for me to try since it is so easy and relatively foolproof.

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Reply 19 of 35, by Tetrium

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Horun wrote on 2020-06-22, 23:28:
Tetrium wrote on 2020-06-22, 22:47:

Your board uses the 440LX chipset. It may be acting up because you are trying out 100MHz FSB P2 CPUs in them. Do you have a 333MHz or slower P2 CPU with which you can test the board, just to rule out this is the issue here?

^^ This ! You can not run a 100Mhz cpu on a 66Mhz only board, the BIOS would not recognize the S spec and disallow a boot (accidentally tried it with a 440EX, no go).

I did manage to make a 400MHz Deschutes run at 366MHz by setting the FSB to 66MHz and the CPU multiplier to 5.5x (There are several threads on vogons where people were testing multipliers on some of the older Slot 1 CPUs), but it had to start at the default settings first iirc and then re-set the multiplier I wanted from within the BIOS.

Iirc you could also tape a couple of the contacts beneath the CPU to trick the board into thinking it has a 66MHz FSB CPU but I don't know if your boards perhaps wants some microcode instead.

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