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IBM NetVista A40 (6578-RAU): Video signal constantly goes out

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First post, by EvieSigma

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I received an IBM Netvista A40 (model 6578-RAU) as part of a lot and I was initially really excited. I had been wanting one of these machines with the Pentium III for a few months now but was turned off by eBay prices. This one in particular is a 933MHz Socket 370 PIII with 128MB of RAM and a 20GB hard drive.

However, it's got a bizarre problem I can't seem to find any answers for anywhere else. The video signal constantly drops out. I tried a video card in addition to the onboard VGA and got the same problem, and I tried both a LCD monitor and a CRT. It's gotten to the point now that it's a struggle to get any video signal at all, and then in addition to that the machine can only be turned off by unplugging it because it refuses to respond to the power button. Caps on the motherboard all look fine, no bulged tops or liquid underneath, but something has got to be wrong.

Anyone have any ideas? Do I perhaps have a bad motherboard or power supply?

Reply 1 of 6, by Horun

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Yes it could be bad board or bad PSU. Have also seen odd behavior with NetVista's when the coin cell battery is weak. What type of add-on video card did you try, was it PCI ?

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 6, by EvieSigma

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Nah, AGP. Radeon 9600SE. I could try a PCI card too but after getting the same results with both onboard and AGP I kinda just assumed PCI would be the same story. As for the battery, it has a brand new battery that stores date/time and settings just fine.

Reply 3 of 6, by Horun

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Ok. Did you replace the battery or are you assuming it is new? Does the video drop out only when in Windows ? Have you tried booting to a DOS floppy and see if it drops out? Have you tested the PSU voltages to see if they are within spec ?
added: Can you post some good images of the board ?

Last edited by Horun on 2020-09-13, 13:34. Edited 1 time in total.

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 5 of 6, by EvieSigma

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Horun wrote on 2020-09-13, 04:36:

Ok. Did you replace the battery or are you assuming it is new? Does the video drop out only when in Windows ? Have you tried booting to a DOS floppy and see if it drops out? Have you tested the PSU voltages to see if they are within spec ?
added: Can you post some good images of the board ?

I did replace the battery myself, with a brand new CR2032. Video was originally dropping out only when trying to boot Windows 98 but then I couldn't get video out at all, before that I got video in the BIOS and when booting off a 98SE boot floppy. I'll have to test the PSU voltages and snap some pictures of the board.

Reply 6 of 6, by EvieSigma

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It took a while to get back to this one but I probed the PSU voltages just now and got 5.02v on the 5v line and 11.75v on the 12v line, both of which are apparently normal. Power supply tester backs this up, power supply is good. Motherboard doesn't have any leaking or domed capacitors, and I even updated to the absolute newest BIOS this computer supports with no change in the forced sleep mode behavior. Going to try reinstalling Windows 98SE after having updated the BIOS and cleared the previous settings.

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