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Can someone with an ASUS CUSL2/TUSL2 motherboard help me out?

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First post, by 8bitbubsy

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I have a CUSL2 and it's misbehaving. Only sometimes will it allow to be powered on, and after some minutes, the ICS chip next to the dipswitches and IDE connector gets really hot, like 75c or so. The system appears to work fine when it powers on, though.

So I was wondering, can someone with a CUSL2 (or TUSL2) board try to power it up and let it warm up for a few minutes, then put your finger on that ICS chip to see if it's very hot?

Here's the location of the chip (ICS 94201DF):
cusl2_hot_chip.jpg

EDIT: After reading the schematics for ICS 94201, it seems like it can handle temps up to 115c on the packaging, and that it can operate in ambients up to 70c. So maybe this is actually normal behavior... Would be great to confirm that this chip really gets hot in use though, and that mine is not getting hot because of a problem.

Unisys SG2400:
- CPU: 486DX2-66
- RAM: 16MB (0 waitstates)
- VGA: Diamond SpeedSTAR VGA (ET4000AX 1MB ISA)
- Audio: Sound Blaster 16 CT2800
- 8GB SSD
- ISA USB card (for USB sticks)
- MR BIOS

Reply 1 of 4, by Horun

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I have a CUSL2 and that is the clock chip, yes that chip runs very warm with a 1Ghz P3 cpu. Yours could be having bad cap syndrome or PSU issue if it does not power on every time. Have you checked the PSU outputs ? Any bulging or tan residue on top of any of the caps ?

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 2 of 4, by 8bitbubsy

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Ok, but it gets blazingly hot even with no CPU or RAM connected! Do you think that's normal as well?

I have inspected all caps, and they look prestine. I tested ESR, but only in circuit. Nothing seems off, and none of them seem to be shorting either.
I also measured the PSU rails under load, and they are all within tolerance... PSU has been recapped, and has been confirmed to be stable on other mobos.

EDIT: Also worth mentioning that the PSU doesn't turn on either, but I can still measure 3.3v going to the "power on" header. When you short the pins, absolutely nothing happens. The LED on the mobo is still glowing.

Unisys SG2400:
- CPU: 486DX2-66
- RAM: 16MB (0 waitstates)
- VGA: Diamond SpeedSTAR VGA (ET4000AX 1MB ISA)
- Audio: Sound Blaster 16 CT2800
- 8GB SSD
- ISA USB card (for USB sticks)
- MR BIOS

Reply 3 of 4, by Horun

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Am sure you already checked but what CPU are you using ? If BIOS was not updated to 1007 then it will not turn on if CPU is not a Celeron ( i remember using a Celery 366 to flash my board for the 1Ghz to work).
https://www.asus.com/supportonly/CUSL2/HelpDesk_CPU

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 4 of 4, by 8bitbubsy

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The system turns on sometimes (most of the time, lately), so this can't be the issue. I use a 1GHz Pentium III with the latest 1014 Beta BIOS.

I have found out that if the mobo doesn't turn on after shorting the "power on" pins, dropping it from a small height will actually make it turn on.
Sounds like there is a connection problem somewhere. I tried to carefully warp the board a little, push on some chips, try to look for dry solder joints etc, but no luck.
It's kinda strange, because the system appears to work fine when it manages to turn on, no instability issues and so on.

Unisys SG2400:
- CPU: 486DX2-66
- RAM: 16MB (0 waitstates)
- VGA: Diamond SpeedSTAR VGA (ET4000AX 1MB ISA)
- Audio: Sound Blaster 16 CT2800
- 8GB SSD
- ISA USB card (for USB sticks)
- MR BIOS

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